1. INTRODUCTION

2. CLASSIFICATION OF METHODS

3. ANALYTICAL SIGNAL

4.3. CHEMICAL METHODS

4.8. THERMAL METHODS

5. CONCLUSION

6. LIST OF REFERENCES USED

INTRODUCTION

Chemical analysis serves as a means of monitoring production and product quality in a number of sectors of the national economy. Mineral exploration is based to varying degrees on the results of analysis. Analysis is the main means of contamination control environment. Determining the chemical composition of soils, fertilizers, feed and agricultural products is important for the normal functioning of the agro-industrial complex. Chemical analysis is indispensable in medical diagnostics and biotechnology. From level chemical analysis The development of many sciences depends on the laboratory's equipment with methods, instruments and reagents.

The scientific basis of chemical analysis is analytical chemistry, a science that has been a part, and sometimes the main part, of chemistry for centuries.

Analytical chemistry is the science of determining the chemical composition of substances and, partly, their chemical structure. Analytical chemistry methods make it possible to answer questions about what a substance consists of and what components are included in its composition. These methods often make it possible to find out in what form a given component is present in a substance, for example, to determine the oxidation state of an element. It is sometimes possible to estimate the spatial arrangement of components.

When developing methods, you often have to borrow ideas from related fields of science and adapt them to your goals. The task of analytical chemistry includes developing the theoretical foundations of methods, establishing the limits of their applicability, assessing metrological and other characteristics, and creating methods for analyzing various objects.

Methods and means of analysis are constantly changing: new approaches are involved, new principles and phenomena are used, often from distant fields of knowledge.

The method of analysis is understood as a fairly universal and theoretically justified method for determining the composition, regardless of the component being determined and the object being analyzed. When they talk about a method of analysis, they mean the underlying principle, a quantitative expression of the relationship between the composition and any measured property; selected implementation techniques, including identification and elimination of interference; devices for practical implementation and methods for processing measurement results. The analysis technique is detailed description analysis of a given object using the selected method.

Three functions of analytical chemistry as a field of knowledge can be distinguished:

1. solution general issues analysis,

2. development of analytical methods,

3. solving specific analysis problems.

You can also highlight qualitative And quantitative tests. The first solves the question of which components the analyzed object includes, the second provides information about the quantitative content of all or individual components.

2. CLASSIFICATION OF METHODS

All existing methods of analytical chemistry can be divided into methods of sampling, sample decomposition, separation of components, detection (identification) and determination. There are hybrid methods that combine separation and determination. Detection and definition methods have much in common.

Highest value have methods of determination. They can be classified according to the nature of the property being measured or the method of recording the corresponding signal. Determination methods are divided into chemical , physical And biological. Chemical methods are based on chemical (including electrochemical) reactions. This also includes methods called physicochemical. Physical methods are based on physical phenomena and processes, biological - on the phenomenon of life.

The main requirements for analytical chemistry methods are: accuracy and good reproducibility of results, low detection limit of the required components, selectivity, rapidity, ease of analysis, and the possibility of its automation.

When choosing an analysis method, you need to clearly know the purpose of the analysis, the tasks that need to be solved, and evaluate the advantages and disadvantages of the available analysis methods.

3. ANALYTICAL SIGNAL

After sampling and preparation of the sample, the stage of chemical analysis begins, at which the component is detected or its quantity is determined. For this purpose, they measure analytical signal. In most methods, the analytical signal is the average of measurements of a physical quantity at the final stage of analysis, functionally related to the content of the component being determined.

If it is necessary to detect any component, it is usually fixed appearance analytical signal - the appearance of a precipitate, color, line in the spectrum, etc. The appearance of an analytical signal must be reliably recorded. When determining the amount of a component, it is measured magnitude analytical signal - sediment mass, current strength, spectrum line intensity, etc.

4. METHODS OF ANALYTICAL CHEMISTRY

4.1. METHODS OF MASKING, SEPARATION AND CONCENTRATION

Masking.

Masking is the inhibition or complete suppression of a chemical reaction in the presence of substances that can change its direction or speed. In this case, no new phase is formed. There are two types of masking: thermodynamic (equilibrium) and kinetic (nonequilibrium). With thermodynamic masking, conditions are created under which the conditional reaction constant is reduced to such an extent that the reaction proceeds insignificantly. The concentration of the masked component becomes insufficient to reliably record the analytical signal. Kinetic masking is based on increasing the difference between the rates of reaction of the masked and analyte substances with the same reagent.

Separation and concentration.

The need for separation and concentration may be due to the following factors: the sample contains components that interfere with the determination; the concentration of the component being determined is below the detection limit of the method; the components being determined are unevenly distributed in the sample; there are no standard samples for calibration of instruments; the sample is highly toxic, radioactive and expensive.

Separation is an operation (process) as a result of which the components that make up the initial mixture are separated from one another.

Concentration is an operation (process) that results in an increase in the ratio of the concentration or amount of microcomponents to the concentration or amount of macrocomponents.

Precipitation and coprecipitation.

Precipitation is typically used to separate inorganic substances. Precipitation of microcomponents with organic reagents, and especially their coprecipitation, provides a high concentration coefficient. These methods are used in combination with determination methods that are designed to obtain an analytical signal from solid samples.

Separation by precipitation is based on the different solubilities of compounds, mainly in aqueous solutions.

Co-precipitation is the distribution of a microcomponent between a solution and a sediment.

Extraction.

Extraction is a physicochemical process of distributing a substance between two phases, most often between two immiscible liquids. It is also a process of mass transfer with chemical reactions.

Extraction methods are suitable for concentration, extraction of microcomponents or macrocomponents, individual and group isolation of components in the analysis of a variety of industrial and natural objects. The method is simple and quick to implement, provides high efficiency separation and concentration and is compatible with various determination methods. Extraction allows you to study the state of substances in solution at different conditions, determine physical and chemical characteristics.

Sorption.

Sorption is well used for separating and concentrating substances. Sorption methods usually provide good separation selectivity and high concentration coefficients.

Sorption– the process of absorption of gases, vapors and dissolved substances by solid or liquid absorbers on a solid carrier (sorbents).

Electrolytic separation and cementation.

The most common method is electrolysis, in which the separated or concentrated substance is isolated on solid electrodes in an elemental state or in the form of some kind of compound. Electrolytic separation (electrolysis) based on the deposition of matter electric shock at controlled potential. The most common option is cathodic deposition of metals. The electrode material can be carbon, platinum, silver, copper, tungsten, etc.

Electrophoresis based on differences in the speed of movement of particles of different charges, shapes and sizes in electric field. The speed of movement depends on the charge, field strength and radius of the particles. There are two options for electrophoresis: frontal (simple) and zone (on a carrier). In the first case, a small volume of solution containing the components to be separated is placed in a tube with an electrolyte solution. In the second case, movement occurs in a stabilizing environment, which holds the particles in place after the electric field is turned off.

Method cementation consists in the reduction of components (usually small quantities) on metals with sufficiently negative potentials or almagams of electronegative metals. During cementation, two processes occur simultaneously: cathodic (component release) and anodic (dissolution of the cementing metal).

Evaporation methods.

Methods distillation based on different volatility of substances. A substance changes from a liquid to a gaseous state and then condenses to form a liquid or sometimes a solid phase again.

Simple distillation (evaporation)– single-step separation and concentration process. Evaporation removes substances that are in the form of ready-made volatile compounds. These can be macrocomponents and microcomponents; distillation of the latter is used less frequently.

Sublimation (sublimation)- transfer of substance from solid state into gaseous and subsequent precipitation in solid form (bypassing the liquid phase). Separation by sublimation is resorted to, as a rule, if the components being separated are difficult to melt or difficult to dissolve.

Controlled crystallization.

When a solution, melt or gas is cooled, the formation of nuclei of the solid phase occurs - crystallization, which can be uncontrolled (volumetric) and controlled. With uncontrolled crystallization, crystals arise spontaneously throughout the entire volume. In controlled crystallization, the process is set external conditions(temperature, direction of phase movement, etc.).

There are two types of controlled crystallization: directional crystallization(in a given direction) and zone melting(movement of a liquid zone in a solid in a certain direction).

During directional crystallization, one interface appears between solid body and liquid – crystallization front. In zone melting there are two boundaries: the crystallization front and the melting front.

4.2. CHROMATOGRAPHIC METHODS

Chromatography is the most commonly used analytical method. The latest chromatographic methods can determine gaseous, liquid and solid substances with a molecular weight from units to 10 6. These can be hydrogen isotopes, metal ions, synthetic polymers, proteins, etc. Using chromatography, extensive information about the structure and properties of organic compounds many classes.

Chromatography is a physicochemical method for the separation of substances, based on the distribution of components between two phases - stationary and mobile. The stationary phase is usually a solid substance (often called a sorbent) or a liquid film deposited on a solid substance. The mobile phase is a liquid or gas flowing through the stationary phase.

The method allows you to separate a multicomponent mixture, identify components and determine its quantitative composition.

Chromatographic methods are classified according to the following criteria:

a) according to the aggregate state of the mixture, in which it is divided into components - gas, liquid and gas liquid chromatography;

b) according to the separation mechanism - adsorption, distribution, ion exchange, sedimentation, redox, adsorption - complexing chromatography;

c) according to the form of the chromatographic process - column, capillary, planar (paper, thin-layer and membrane).

4.3. CHEMICAL METHODS

At the core chemical methods detection and determination are based on three types of chemical reactions: acid-base, redox and complexation. Sometimes they are accompanied by a change in the state of aggregation of the components. The most important among chemical methods are gravimetric and titrimetric. These analytical methods are called classical. Criteria for the suitability of a chemical reaction as a basis analytical method in most cases, they are complete flow and high speed.

Gravimetric methods.

Gravimetric analysis consists of isolating a substance in pure form and weighing it. Most often, such isolation is carried out by precipitation. Less commonly, the component being determined is isolated in the form of a volatile compound (distillation methods). In some cases, gravimetry - The best way solving an analytical problem. This is the absolute (reference) method.

The disadvantage of gravimetric methods is the duration of determination, especially in serial analyzes of a large number of samples, as well as non-selectivity - precipitating reagents, with a few exceptions, are rarely specific. Therefore, preliminary separations are often necessary.

The analytical signal in gravimetry is mass.

Titrimetric methods.

The titrimetric method of quantitative chemical analysis is a method based on measuring the amount of reagent B spent on the reaction with the determined component A. In practice, it is most convenient to add the reagent in the form of a solution of a precisely known concentration. In this embodiment, titration is the process of continuously adding a controlled amount of a reagent solution of precisely known concentration (titran) to a solution of the component being determined.

In titrimetry, three titration methods are used: direct, reverse, and substituent titration.

Direct titration- this is the titration of a solution of the analyte A directly with a titran solution B. It is used if the reaction between A and B proceeds quickly.

Back titration consists of adding to the analyte A an excess of a precisely known amount of standard solution B and, after completing the reaction between them, titrating the remaining amount of B with titran solution B’. This method is used in cases where the reaction between A and B does not proceed quickly enough, or there is no suitable indicator to fix the equivalence point of the reaction.

Titration by substituent consists of titrating with titrant B not a determined amount of substance A, but an equivalent amount of substituent A’ resulting from a previously carried out reaction between the determined substance A and some reagent. This titration method is usually used in cases where direct titration is not possible.

Kinetic methods.

Kinetic methods are based on the use of the dependence of the rate of a chemical reaction on the concentration of reactants, and in the case of catalytic reactions, on the concentration of the catalyst. The analytical signal in kinetic methods is the rate of the process or a value proportional to it.

The reaction underlying the kinetic method is called indicator. A substance, by the change in concentration of which the speed of the indicator process is judged, is an indicator.

Biochemical methods.

Among modern methods chemical analysis important place are occupied by biochemical methods. Biochemical methods include methods based on the use of processes occurring with the participation of biological components (enzymes, antibodies, etc.). In this case, the analytical signal is most often either the initial rate of the process or the final concentration of one of the reaction products, determined by any instrumental method.

Enzymatic methods are based on the use of reactions catalyzed by enzymes - biological catalysts characterized by high activity and selectivity of action.

Immunochemical methods analyzes are based on the specific binding of the detected compound - antigen - by the corresponding antibodies. The immunochemical reaction in solution between antibodies and antigens is a complex process that occurs in several stages.

4.4. ELECTROCHEMICAL METHODS

Electrochemical methods of analysis and research are based on the study and use of processes occurring on the surface of the electrode or in the near-electrode space. Any electrical parameter(potential, current, resistance, etc.), functionally related to the concentration of the analyzed solution and amenable to correct measurement, can serve as an analytical signal.

There are direct and indirect electrochemical methods. Direct methods use the dependence of the current strength (potential, etc.) on the concentration of the component being determined. In indirect methods, the current strength (potential, etc.) is measured in order to find the end point of titration of the analyte with a suitable titrant, i.e. The dependence of the measured parameter on the titrant volume is used.

For any kind of electrochemical measurements, an electrochemical circuit or electrochemical cell is required, integral part which is the analyzed solution.

Exist various ways classification of electrochemical methods - from very simple to very complex, including consideration of the details of electrode processes.

4.5. SPECTROSCOPIC METHODS

Spectroscopic methods of analysis include physical methods based on the interaction electromagnetic radiation with substance. This interaction leads to various energy transitions, which are recorded experimentally in the form of absorption of radiation, reflection and scattering of electromagnetic radiation.

4.6. MASS SPECTROMETRIC METHODS

The mass spectrometric method of analysis is based on the ionization of atoms and molecules of the emitted substance and the subsequent separation of the resulting ions in space or time.

The most important application of mass spectrometry is to identify and determine the structure of organic compounds. It is advisable to carry out molecular analysis of complex mixtures of organic compounds after their chromatographic separation.

4.7. ANALYSIS METHODS BASED ON RADIOACTIVITY

Analysis methods based on radioactivity arose during the era of the development of nuclear physics, radiochemistry, and nuclear technology and are successfully used today in conducting various analyzes, including in industry and the geological service. These methods are very numerous and varied. Four main groups can be distinguished: radioactive analysis; isotope dilution and other radiotracer methods; methods based on absorption and scattering of radiation; purely radiometric methods. The most widespread radioactivation method. This method appeared after the discovery of artificial radioactivity and is based on the formation of radioactive isotopes of the element being determined by irradiating a sample with nuclear or g-particles and recording the artificial radioactivity obtained during activation.

4.8. THERMAL METHODS

Thermal analysis methods are based on the interaction of a substance with thermal energy. The greatest application in analytical chemistry is thermal effects, which are the cause or effect of chemical reactions. To a lesser extent, methods based on the release or absorption of heat as a result of physical processes are used. These are processes associated with the transition of a substance from one modification to another, with a change in the state of aggregation and other changes in intermolecular interaction, for example, occurring during dissolution or dilution. The table shows the most common thermal analysis methods.

Thermal methods are successfully used for the analysis of metallurgical materials, minerals, silicates, as well as polymers, for phase analysis of soils, and determination of moisture content in samples.

4.9. BIOLOGICAL ANALYSIS METHODS

Biological methods of analysis are based on the fact that for life activity - growth, reproduction and generally normal functioning of living beings, an environment of a strictly defined chemical composition is necessary. When this composition changes, for example, when any component is excluded from the environment or an additional (detectable) compound is introduced, the body sends an appropriate response signal after some time, sometimes almost immediately. Establishing a connection between the nature or intensity of the body's response signal and the amount of a component introduced into the environment or excluded from the environment serves to detect and determine it.

Analytical indicators in biological methods are various living organisms, their organs and tissues, physiological functions, etc. Microorganisms, invertebrates, vertebrates, and plants can act as indicator organisms.

5. CONCLUSION

The importance of analytical chemistry is determined by the need of society for analytical results, to establish the qualitative and quantitative composition of substances, the level of development of society, the social need for the results of analysis, as well as the level of development of analytical chemistry itself.

Quote from the textbook on analytical chemistry by N.A. Menshutkin, published in 1897: “Having presented the entire course of classes in analytical chemistry in the form of problems, the solution of which is provided to the student, we must point out that for such a solution of problems, analytical chemistry will provide a strictly defined path. This certainty (systematic solution of analytical chemistry problems) is of great pedagogical importance. The student learns to apply the properties of compounds to solve problems, derive reaction conditions, and combine them. This entire series of mental processes can be expressed this way: analytical chemistry teaches you to think chemically. Achieving the latter seems to be the most important for practical studies in analytical chemistry.”

LIST OF REFERENCES USED

1. K.M. Olshanova, S.K. Piskareva, K.M. Barashkov “Analytical chemistry”, Moscow, “Chemistry”, 1980

2. "Analytical chemistry. Chemical methods of analysis", Moscow, "Chemistry", 1993.

3. “Fundamentals of analytical chemistry. Book 1", Moscow, "Higher School", 1999.

4. “Fundamentals of analytical chemistry. Book 2", Moscow, "Higher School", 1999.

Any method of analysis uses a specific analytical signal, which, under given conditions, is given by specific elementary objects (atoms, molecules, ions) that make up the substances under study.

The analytical signal provides information of both qualitative and quantitative nature. For example, if precipitation reactions are used for analysis, qualitative information is obtained from the appearance or absence of precipitation. Quantitative information is obtained from the sediment mass. When a substance emits light under certain conditions, qualitative information is obtained from the appearance of a signal (emission of light) at a wavelength corresponding to a characteristic color, and quantitative information is obtained from the intensity of light radiation.

Based on the origin of the analytical signal, analytical chemistry methods can be classified into chemical, physical and physicochemical.

IN chemical methods carry out a chemical reaction and measure either the mass of the resulting product - gravimetric (weight) methods, or the volume of the reagent spent on interaction with the substance - titrimetric, gas-volumetric (volumetric) methods.

Gas volumetrics (gas volumetric analysis) is based on the selective absorption of constituents gas mixture in vessels filled with one or another absorber, followed by measuring the decrease in gas volume using a burette. Thus, carbon dioxide is absorbed with a solution of potassium hydroxide, oxygen with a solution of pyrogallol, and carbon monoxide with an ammonia solution of copper chloride. Gas volumemetry refers to rapid methods of analysis. It is widely used for the determination of carbonates in minerals and minerals.

Chemical methods of analysis are widely used for the analysis of ores, rocks, minerals and other materials to determine components in them with contents from tenths to several tens of percent. Chemical methods of analysis are characterized high accuracy(the analysis error is usually tenths of a percent). However, these methods are gradually being replaced by more rapid physicochemical and physical methods of analysis.

Physical methods analyzes are based on the measurement of any physical property of substances, which is a function of composition. For example, refractometry is based on measuring the relative refractive indices of light. In activation analysis, the activity of isotopes, etc. is measured. Often, the analysis involves a chemical reaction first, and the concentration of the resulting product is determined by physical properties, for example, the intensity of absorption of light radiation by the colored reaction product. Such methods of analysis are called physicochemical.

Physical methods of analysis are characterized by high productivity, low detection limits of elements, objectivity of analysis results, and a high level of automation. Physical methods of analysis are used in the analysis of rocks and minerals. For example, the atomic emission method is used to determine tungsten in granites and shales, antimony, tin and lead in rocks and phosphates; atomic absorption method - magnesium and silicon in silicates; X-ray fluorescence - vanadium in ilmenite, magnesite, alumina; mass spectrometric - manganese in lunar regolith; neutron activation - iron, zinc, antimony, silver, cobalt, selenium and scandium in oil; by isotope dilution method - cobalt in silicate rocks.

Physical and physicochemical methods are sometimes called instrumental, since these methods require the use of instruments (equipment) specially adapted for carrying out the main stages of analysis and recording its results.

Physico-chemical methods analysis may include chemical transformations of the analyte, sample dissolution, concentration of the analyzed component, masking of interfering substances, and others. Unlike “classical” chemical methods of analysis, where the analytical signal is the mass of a substance or its volume, physicochemical methods of analysis use radiation intensity, current strength, electrical conductivity, and potential difference as an analytical signal.

Of great practical importance are methods based on the study of the emission and absorption of electromagnetic radiation in various regions of the spectrum. These include spectroscopy (e.g. luminescence analysis, spectral analysis, nephelometry and turbidimetry and others). Important physicochemical methods of analysis include electrochemical methods that use the measurement of the electrical properties of a substance (coulometry, potentiometry, etc.), as well as chromatography (for example, gas chromatography, liquid chromatography, ion exchange chromatography, thin layer chromatography). Methods based on measuring the rates of chemical reactions (kinetic methods of analysis), the thermal effects of reactions (thermometric titration), as well as the separation of ions in a magnetic field (mass spectrometry) are being successfully developed.

Its subject as a science is the improvement of existing and development of new methods of analysis, their practical use, study of the theoretical foundations of analytical methods.

Depending on the task, analytical chemistry is subdivided into qualitative analysis, aimed at determining whether What or which substance, in what form it is in the sample, and quantitative analysis aimed at determining How many of a given substance (elements, ions, molecular forms, etc.) is in the sample.

Determining the elemental composition of material objects is called elemental analysis. Establishing the structure of chemical compounds and their mixtures at the molecular level is called molecular analysis. One of the types of molecular analysis of chemical compounds is structural analysis, aimed at studying the spatial atomic structure substances, establishing empirical formulas, molecular masses, etc. The tasks of analytical chemistry include determining the characteristics of organic, inorganic and biochemical objects. Analysis of organic compounds by functional groups is called functional analysis.

Story

Analytical chemistry has existed as long as chemistry has existed in its modern sense, and many of the techniques used in it date back to an even earlier era, the era of alchemy, one of the main tasks of which was precisely determining the composition of various natural substances and studying the processes of their mutual transformations. But, with the development of chemistry as a whole, the methods of work used in it were significantly improved, and, along with its purely auxiliary significance as one of the auxiliary departments of chemistry, analytical chemistry now has the significance of a completely independent department of chemical knowledge with very serious and important theoretical tasks. Modern physical chemistry had a very important influence on the development of analytical chemistry, which enriched it with a number of completely new methods of work and theoretical foundations, which include the doctrine of solutions (see), the theory of electrolytic dissociation, the law of mass action (see Chemical equilibrium) and the whole doctrine of chemical affinity.

Methods of analytical chemistry

Comparison of analytical chemistry methods

Totality traditional methods Determining the composition of a substance by its sequential chemical decomposition is called “wet chemistry” (“wet analysis”). These methods have relatively low accuracy, require relatively low qualifications of analysts and are now almost completely replaced by modern ones. instrumental methods(optical, mass spectrometric, electrochemical, chromatographic and other physicochemical methods) determining the composition of a substance. However, wet chemistry has its advantage over spectrometric methods - it allows, through standardized procedures (systematic analysis), to directly determine the composition and different oxidative states of elements such as iron (Fe +2, Fe +3), titanium, etc.

Analytical methods can be divided into gross and local. Bulk methods of analysis usually require a separated, subdivided substance (a representative sample). Local Methods determine the composition of a substance in a small volume in the sample itself, which makes it possible to draw up “maps” of distribution chemical properties sample along its surface and/or depth. Methods should also be highlighted direct analysis, that is, not related to preliminary preparation samples. Sample preparation is often necessary (eg crushing, pre-concentration or separation). Statistical methods are used when preparing samples, interpreting results, and estimating the number of analyzes.

Methods of qualitative chemical analysis

For determining quality composition of any substance, it is necessary to study its properties, which, from the point of view of analytical chemistry, can be of two kinds: the properties of the substance as such, and its properties in chemical transformations.

The first include: physical state (solid, liquid, gas), its structure in the solid state (amorphous or crystalline substance), color, smell, taste, etc. At the same time, it is often possible to establish the nature of a given substance based on external properties alone, determined using the human senses. In most cases, it is necessary to transform a given substance into some new one with clearly defined characteristic properties, using for this purpose some specially selected compounds called reagents.

The reactions used in analytical chemistry are extremely diverse and depend on the physical properties and degree of complexity of the composition of the substance being studied. In the case where a obviously pure, homogeneous chemical compound is subject to chemical analysis, the work is done relatively easily and quickly; when you have to deal with a mixture of several chemical compounds, the question of its analysis becomes more complicated, and when doing work you need to adhere to some specific system in order not to overlook a single element included in the substance. There are two types of reactions in analytical chemistry: wet reactions(in solutions) and dry reactions.

Reactions in solutions

In qualitative chemical analysis, only reactions in solutions are used that are easily perceived by human senses, and the moment of occurrence of the reaction is recognized by one of the following phenomena:

1. the formation of a water-insoluble precipitate,
2. change in solution color
3. gas release.

Formation of sediment in reactions of chemical analysis depends on the formation of some water-insoluble substance; if, for example, sulfuric acid or a water-soluble salt is added to a solution of any barium salt, a white powdery precipitate of barium sulfate is formed:

BaCl 2 + H 2 SO 4 = 2HCl + BaSO 4 ↓

Keeping in mind that some other metals can give a similar reaction to the formation of a white precipitate under the influence of sulfuric acid, for example, lead, which can form the insoluble sulfate salt PbSO 4, to be completely sure that this is exactly one or another metal, it is necessary to produce more calibration reactions, subjecting the precipitate formed in the reaction to appropriate research.

To successfully carry out the reaction of precipitation formation, in addition to selecting the appropriate reagent, it is also necessary to observe a number of very important conditions in relation to the strength of solutions of the salt and reagent being studied, the proportion of both, temperature, duration of interaction, etc. When considering precipitates formed in reactions of chemical analysis, it is necessary to pay attention to their appearance, that is, on color, structure (amorphous and crystalline precipitates), etc., as well as on their properties in relation to the influence of heat, acids or alkalis, etc. When interacting weak solutions, it is sometimes necessary to wait for the formation of a precipitate until 24-48 hours, provided they are kept at a certain temperature.

The reaction of precipitate formation, regardless of its qualitative significance in chemical analysis, is often used to separate certain elements from each other. For this purpose, a solution containing compounds of two or more elements is treated with an appropriate reagent capable of converting some of them into insoluble compounds, and then the resulting precipitate is separated from the solution (filtrate) by filtration, further studying them separately. If we take, for example, the salts of potassium chloride and barium chloride and add sulfuric acid to them, an insoluble precipitate of barium sulfate BaSO 4 and water-soluble potassium sulfate K 2 SO 4 are formed, which can be separated by filtration. When separating a precipitate of a water-insoluble substance from a solution, care must first be taken to ensure that it receives an appropriate structure that allows the filtering work to be carried out without difficulty, and then, having collected it on the filter, it is necessary to thoroughly wash it from foreign impurities. According to the research of V. Ostwald, it must be borne in mind that when using a certain amount of water for washing, it is more advisable to rinse the sediment many times in small portions of water than, on the contrary, several times in large portions. As for the success of the separation reaction of any element in the form of an insoluble precipitate, then, based on the theory of solutions, W. Ostwald established that for a sufficiently complete separation of any element in the form of an insoluble precipitate, it is always necessary to take an excess of the reagent used for precipitation .

Change in solution color is one of the very important signs in the reactions of chemical analysis and is very important, especially in connection with the processes of oxidation and reduction, as well as in work with chemical indicators (see below - alkalimetry and acidimetry).

Examples color reactions in qualitative chemical analysis the following can be used: potassium thiocyanate KCNS gives a characteristic blood-red color with iron oxide salts; with ferrous oxide salts the same reagent does not produce anything. If you add any oxidizing agent, for example, chlorine water, to a solution of ferric chloride FeCl 2, a weak green color, the solution turns yellow due to the formation of ferric chloride, which is highest degree oxidation of this metal. If we take potassium dichromate K 2 Cr 2 O 7 orange color and add a little sulfuric acid and some reducing agent to it in solution, for example, wine alcohol, the orange color changes to dark green, corresponding to the formation of the lowest oxidation state of chromium in the form of chromium sulfate salt Cr 3 (SO 4) 3.

Depending on the progress of the chemical analysis, it is often necessary to carry out these processes of oxidation and reduction. The most important oxidizing agents are: halogens, nitric acid, hydrogen peroxide, potassium permanganate, potassium dihydroxide; the most important reducing agents are: hydrogen at the time of release, hydrogen sulfide, sulfurous acid, tin chloride, hydrogen iodide.

Gas evolution reactions in solutions during the production of qualitative chemical analysis most often have no independent significance and are auxiliary reactions; most often we encounter the release of carbon dioxide CO 2 - during the action of acids on carbon dioxide salts, hydrogen sulfide - during the decomposition of sulfur metals with acids, etc.

Dry reactions

These reactions are used in chemical analysis, mainly in the so-called. “preliminary testing”, when testing sediments for purity, for verification reactions and when studying minerals. The most important reactions of this kind consist of testing a substance in relation to:

1. its fusibility when heated,
2. ability to color non-luminous flames gas burner,
3. volatility when heated,
4. oxidation and reduction abilities.

To carry out these tests, in most cases, a non-luminous flame of a gas burner is used. The main components of illuminating gas (hydrogen, carbon monoxide, swamp gas and other hydrocarbons) are reducing agents, but when it burns in air (see Combustion), a flame is formed, in various parts in which one can find the conditions necessary for reduction or oxidation, as well as for heating to a more or less high temperature.

Fusibility test carried out primarily in the study of minerals, for which a very small fragment of them, fixed in a thin platinum wire, is introduced into the part of the flame that has the most high temperature, and then use a magnifying glass to observe how the edges of the sample are rounded.

Flame color test is made by introducing a small sepia sample of a small sample of the substance on a platinum wire, first into the base of the flame, and then into the part of it with the highest temperature.

Volatility test is produced by heating a sample of a substance in an assay cylinder or in a glass tube sealed at one end, and volatile substances turn into vapors, which then condense in the colder part.

Oxidation and reduction in dry form can be produced in balls of fused borax ( 2 4 7 + 10 2 ) The substance tested is introduced in small quantities into balls obtained by melting these salts on a platinum wire, and they are then heated in the oxidizing or reducing part of the flame. Restoration can be carried out in a number of other ways, namely: heating on a stick charred with soda, glowing in glass tube with metals - sodium, potassium or magnesium, heating on charcoal using a blowpipe, simple heating.

Classification of elements

The classification of elements adopted in analytical chemistry is based on the same division that is accepted in general chemistry - into metals and non-metals (metalloids), the latter being most often considered in the form of the corresponding acids. For the production of systematic qualitative analysis each of these classes of elements is divided in turn into groups with some common group characteristics.

Metals in analytical chemistry are divided into two departments, which in turn are divided into five groups:

1. Metals whose sulfur compounds are soluble in water- the distribution of metals in this department into groups is based on the properties of their carbon dioxide salts. 1st group: potassium, sodium, rubidium, cesium, lithium. Sulfur compounds and their carbon dioxide salts are soluble in water. There is no general reagent for the precipitation of all metals of this group in the form of insoluble compounds. 2nd group: barium, strontium, calcium, magnesium. Sulfur compounds are soluble in water, carbon dioxide salts are insoluble. A common reagent that precipitates all metals of this group in the form of insoluble compounds is ammonium carbonate.
2. Metals whose sulfur compounds are insoluble in water- to divide this department into three groups, they use the ratio of their sulfur compounds to weak acids and ammonium sulfide. 3rd group: aluminum, chromium, iron, manganese, zinc, nickel, cobalt.

Aluminum and chromium do not form sulfur compounds by water; other metals form sulfur compounds, which, like their oxides, are soluble in weak acids. Hydrogen sulfide does not precipitate them from an acidic solution; ammonium sulfide precipitates oxides or sulfur compounds. Ammonium sulphide is a common reagent for this group, and an excess of its sulfur compounds does not dissolve. 4th group: silver, lead, bismuth, copper, palladium, rhodium, ruthenium, osmium. Sulfur compounds are insoluble in weak acids and are precipitated by hydrogen sulfide in an acidic solution; they are also insoluble in ammonium sulphide. Hydrogen sulfide is a common reactant for this group. 5th group: tin, arsenic, antimony, gold, platinum. Sulfur compounds are also insoluble in weak acids and are precipitated by hydrogen sulfide from an acidic solution. But they are soluble in ammonium sulphide and form water-soluble sulfasalts with it.

Nonmetals (metalloids) always have to be discovered in chemical analysis in the form of the acids they form or their corresponding salts. The basis for dividing acids into groups is the properties of their barium and silver salts in relation to their solubility in water and partly in acids. Barium chloride is a general reagent for group 1, silver nitrate in nitrate solution is for group 2, barium and silver salts of group 3 acids are soluble in water. 1st group: in a neutral solution, barium chloride precipitates insoluble salts; Silver salts are insoluble in water, but soluble in nitric acid. These include acids: chromic, serous, sulfurous, aqueous, carbonic, silicon, sulfuric, hydrofluorosilicic (barium salts, insoluble in acids), arsenic and arsenous. 2nd group: in a solution acidified with nitric acid, silver nitrate gives a precipitate. These include acids: hydrochloric, hydrobromic and hydroiodic, hydrocyanic, hydrogen sulfide, ferric and ferric hydrocyanide and iodine. 3rd group: nitric acid and perchloric acid, which are not precipitated by either silver nitrate or barium chloride.

However, it must be borne in mind that the reagents indicated for acids are not general reagents that could be used to separate acids into groups. These reagents can only give an indication of the presence of an acidic or other group, and to discover each individual acid one must use the private reactions belonging to them. The above classification of metals and nonmetals (metalloids) for the purposes of analytical chemistry was adopted in Russian schools and laboratories (according to N.A. Menshutkin); in Western European laboratories another classification was adopted, based, however, essentially on the same principles.

Theoretical basis of reactions

The theoretical foundations of reactions of qualitative chemical analysis in solutions must be sought, as already indicated above, in the departments of general and physical chemistry about solutions and chemical affinity. One of the first critical issues is the state of all minerals in aqueous solutions in which, according to the theory of electrolytic dissociation, all substances belonging to the classes of salts, acids and alkalis dissociate into ions. Therefore, all reactions of chemical analysis occur not between whole molecules of compounds, but between their ions. For example, the reaction of sodium chloride NaCl and silver nitrate AgNO 3 occurs according to the equation:

Na + + Cl - + Ag + + (NO 3) - = AgCl↓ + Na + + (NO 3) - sodium ion + chlorine ion + silver ion + nitric acid anion = insoluble salt + nitric acid anion

Consequently, silver nitrate is not a reagent for sodium chloride or hydrochloric acid, but only for chlorine ion. Thus, for each salt in solution, from the point of view of analytical chemistry, its cation (metal ion) and anion (acid residue) must be considered separately. For a free acid, hydrogen ions and an anion must be considered; finally, for each alkali - a metal cation and a hydroxyl anion. And essentially the most important task of qualitative chemical analysis is to study the reactions of various ions and how to discover them and separate them from each other.

To achieve the latter goal, by the action of appropriate reagents, ions are converted into insoluble compounds that precipitate from solution in the form of precipitation, or are isolated from solutions in the form of gases. In the same theory of electrolytic dissociation, one must look for an explanation for the action of chemical indicators, which often find application in chemical analysis. According to the theory of W. Ostwald, all chemical indicators are relatively weak acids, partially dissociated in aqueous solutions. Moreover, some of them have colorless whole molecules and colored anions, others, on the contrary, have colored molecules and a colorless anion or an anion of a different color; When exposed to the influence of free hydrogen ions of acids or hydroxyl ions of alkali, chemical indicators can change the degree of their dissociation, and at the same time their color. The most important indicators are:

1. Methyl orange, which in the presence of free hydrogen ions (acidic reaction) gives a pink color, and in the presence of neutral salts or alkalis gives a yellow color;
2. Phenolphthalein - in the presence of hydroxyl ions (alkaline reaction) gives a characteristic red color, and in the presence of neutral salts or acids it is colorless;
3. Litmus turns red under the influence of acids, and turns blue under the influence of alkalis, and finally
4. Curcumin turns brown under the influence of alkalis, and in the presence of acids again takes on a yellow color.

Chemical indicators have very important applications in volumetric chemical analysis (see below). In reactions of qualitative chemical analysis, one often encounters the phenomenon of hydrolysis, that is, the decomposition of salts under the influence of water, and the aqueous solution acquires a more or less strong alkaline or acidic reaction.

Progress of qualitative chemical analysis

In a qualitative chemical analysis, it is important to determine not only what elements or compounds are included in the composition of a given substance, but also in what, approximately, relative quantities these components are found. For this purpose, it is always necessary to proceed from certain quantities of the analyzed substance (usually it is enough to take 0.5-1 grams) and, when performing the analysis, compare the amount of individual precipitation with each other. It is also necessary to use solutions of reagents of a certain strength, namely: normal, half-normal, one tenth of normal.

Every qualitative chemical analysis is divided into three parts:

1. preliminary test,
2. discovery of metals (cations),
3. discovery of non-metals (metalloids) or acids (anions).

Regarding the nature of the analyte, four cases may occur:

1. solid non-metallic substance,
2. solid substance in the form of a metal or metal alloy,
3. liquid (solution),

When analyzing solid non-metallic substance primarily produced visual inspection and microscopic examination, as well as preliminary testing by the above methods of analysis in dry form. Initially, a sample of a substance is dissolved, depending on its nature, in one of the following solvents: water, hydrochloric acid, nitric acid and aqua regia (a mixture of hydrochloric and nitric acids). Substances that are unable to dissolve in any of the above solvents are transferred into solution using some special techniques, such as: fusion with soda or potash, boiling with soda solution, heating with certain acids, etc. The resulting solution is subjected to systematic analysis with preliminary isolation of metals and acids into groups and further dividing them into individual elements, using their characteristic private reactions.

When analyzing metal alloy a certain sample of it dissolves in nitric acid (in rare cases in aqua regia), and the resulting solution is evaporated to dryness, after which the solid residue is dissolved in water and subjected to systematic analysis.

If the substance is liquid, first of all, attention is paid to its color, smell and reaction to litmus (acidic, alkaline, neutral). To verify the presence of any solids in the solution, a small portion of the liquid is evaporated on a platinum plate or watch glass. After these preliminary tests, the liquid is apalized using conventional methods.

Analysis gases produced by some special methods indicated in the quantitative analysis.

Methods of quantitative chemical analysis

Quantitative chemical analysis aims to determine the relative amounts of the individual constituents of any chemical compound or mixtures. The methods used in it depend on the qualities and composition of the substance, and therefore quantitative chemical analysis must always be preceded by qualitative chemical analysis

To perform quantitative analysis, two different methods can be used: gravimetric and volumetric. With the weight method, the bodies being determined are isolated in the form of, if possible, insoluble or poorly soluble compounds of known chemical composition, and their weight is determined, on the basis of which the amount of the desired element can be found by calculation. In volumetric analysis, the volumes of titrated (containing a certain amount of reagent) solutions used for analysis are measured. In addition, a number of special methods of quantitative chemical analysis differ, namely:

1. electrolytic based on the separation of individual metals by electrolysis,
2. colorimetric, produced by comparing the color intensity of a given solution with the color of a solution of a certain strength,
3. organic analysis, consisting in the combustion of organic matter in carbon dioxide C0 2 and water H 2 0 and in determination by the amount of their relative content of carbon and hydrogen in the substance,
4. gas analysis, which consists in determining by some special methods the qualitative and quantitative composition of gases or their mixtures.

Represents a very special group medical chemical analysis, covering a number of different methods for studying blood, urine and other waste products of the human body.

Gravity quantitative chemical analysis

Methods of gravimetric quantitative chemical analysis are of two types: direct analysis method And method of indirect (indirect) analysis. In the first case, to be determined component is isolated in the form of some insoluble compound, and the weight of the latter is determined. Indirect analysis is based on the fact that two or more substances subjected to the same chemical treatment undergo unequal changes in their weight. Having, for example, a mixture of potassium chloride and sodium nitrate, you can determine the first of them by direct analysis, precipitating the chlorine in the form of silver chloride and weighing it. If there is a mixture of potassium and sodium chloride salts, you can determine their ratio indirectly by precipitating all the chlorine in the form of silver chloride and determining its weight, followed by calculation.

Volumetric chemical analysis

Electrolysis analysis

Colorimetric methods

Elemental organic analysis

Gas analysis

Classification of analytical chemistry methods

• Elemental analysis methods
  • X-ray spectral analysis (X-ray fluorescence)
  • Neutron activation analysis ( English) (see radioactivation analysis)
  • Auger electron spectrometry (EOS) ( English); see Auger effect
  • Analytical atomic spectrometry is a set of methods based on the transformation of analyzed samples into the state of individual free atoms, the concentrations of which are then measured spectroscopically (sometimes X-ray fluorescence analysis is also included here, although it is not based on sample atomization and is not associated with atomic vapor spectroscopy).
    • MS - mass spectrometry with registration of masses of atomic ions
      • ICP-MS - inductively coupled plasma mass spectrometry (see inductively coupled plasma in mass spectrometry)
      • LA-ICP-MS - mass spectrometry with inductively coupled plasma and laser ablation
      • LIMS - laser spark mass spectrometry; see laser ablation (commercial example: LAMAS-10M)
      • MSVI - Secondary Ion Mass Spectrometry (SIMS)
      • TIMS - thermal ionization mass spectrometry (TIMS)
      • High-energy particle accelerator mass spectrometry (AMS)
    • AAS - atomic absorption spectrometry
      • ETA-AAS - atomic absorption spectrometry with electrothermal atomization (see atomic absorption spectrometers)
      • SVZR - cavity decay time spectroscopy (CRDS)
      • VRLS - intracavity laser spectroscopy
    • AES - atomic emission spectrometry
      • spark and arc as sources of radiation (see spark discharge; electric arc)
      • ICP-AES - inductively coupled plasma atomic emission spectrometry
      • LIES - laser spark emission spectrometry (LIBS or LIPS); see laser ablation
    • AFS - atomic fluorescence spectrometry (see fluorescence)
      • ICP-AFS - atomic fluorescence spectrometry with inductively coupled plasma (Baird devices)
      • LAFS - laser atomic fluorescence spectrometry
      • APS on hollow cathode lamps (commercial example: AI3300)
    • AIS - atomic ionization spectrometry
      • LAIS (LIIS) - laser atomic ionization or laser-intensified ionization spectroscopy (eng. Laser Enhanced Ionization, LEI )
      • RIMS - laser resonance ionization mass spectrometry
      • OG - optogalvanics (LOGS - laser optogalvanic spectroscopy)

• Other analysis methods
  • titrimetry, volumetric analysis
  • gravimetric analysis - gravimetry, electrogravimetry
  • spectrophotometry (usually absorption) of molecular gases and condensed matter
    • electron spectrometry (visible spectrum and UV spectrometry); see electron spectroscopy
    • vibrational spectrometry (IR spectrometry); see vibrational spectroscopy
  • Raman spectroscopy; see Raman effect
  • luminescence analysis
  • mass spectrometry with registration of masses of molecular and cluster ions, radicals
  • ion mobility spectrometry (

Environmental engineers need to know chemical composition raw materials, products and waste from production and the environment - air, water and soil; it is important to identify harmful substances and determine their concentration. This problem is solved analytical chemistry - the science of determining the chemical composition of substances.

Problems of analytical chemistry are solved mainly by physical and chemical methods of analysis, which are also called instrumental. They use the measurement of some physical or physicochemical property of a substance to determine its composition. It also includes sections devoted to methods of separation and purification of substances.

The purpose of this course of lectures is to familiarize yourself with the principles of instrumental methods of analysis in order to navigate their capabilities and, on this basis, set specific tasks for specialist chemists and understand the meaning of the obtained analysis results.

Literature

Aleskovsky V.B. and others. Physico-chemical methods of analysis. L-d, "Chemistry", 1988

Yu.S. Lyalikov. Physico-chemical methods of analysis. M., publishing house "Chemistry", 1974

Vasiliev V.P. Theoretical basis physical and chemical methods of analysis. M., Higher School, 1979.

A.D. Zimon, N.F. Leshchenko. Colloidal chemistry. M., "Agar", 2001

A.I. Mishustin, K.F. Belousova. Colloidal chemistry ( Toolkit). Publishing house MIHM, 1990

The first two books are textbooks for chemistry students and are therefore quite challenging for you. This makes these lectures very useful. However, you can read individual chapters.

Unfortunately, the administration has not yet allocated a separate credit for this course, so the material is included in general exam, along with a course in physical chemistry.

2. Classification of analysis methods

A distinction is made between qualitative and quantitative analysis. The first determines the presence of certain components, the second - their quantitative content. Analysis methods are divided into chemical and physicochemical. In this lecture, we will consider only chemical methods that are based on the transformation of the analyte into compounds that have certain properties.

In the qualitative analysis of inorganic compounds, the sample under study is transferred to a liquid state by dissolving it in water or a solution of acid or alkali, which makes it possible to detect elements in the form of cations and anions. For example, Cu 2+ ions can be identified by the formation of a complex 2+ ion that is bright blue.

Qualitative analysis is divided into fractional and systematic. Fractional analysis - detection of several ions in a mixture with approximately known composition.

Systematic analysis is full analysis using a specific method for the sequential detection of individual ions. Separate groups of ions with similar properties are isolated using group reagents, then the groups of ions are divided into subgroups, and those, in turn, into individual ions, which are detected using the so-called. analytical reactions. These are reactions with an external effect - the formation of a precipitate, the release of gas, and a change in the color of the solution.

Properties of analytical reactions - specificity, selectivity and sensitivity.

Specificity allows you to detect a given ion in the presence of other ions by a characteristic feature (color, smell, etc.). There are relatively few such reactions (for example, the reaction of detecting the NH 4 + ion by the action of an alkali on a substance when heated). The specificity of the reaction is quantitatively assessed by the value of the limiting ratio, equal to the ratio concentrations of the detected ion and interfering ions. For example, the droplet reaction to the Ni 2+ ion by the action of dimethylglyoxime in the presence of Co 2+ ions is possible at a limiting ratio of Ni 2+ to Co 2+ equal to 1:5000.

Selectivity(or selectivity) of a reaction is determined by the fact that only a few ions produce a similar external effect. The selectivity is greater, the smaller the number of ions giving a similar effect.

Sensitivity reactions are characterized by the detection limit or dilution limit. For example, the detection limit in the microcrystalloscopic reaction to the Ca 2+ ion under the action of sulfuric acid is 0.04 μg Ca 2+ in a drop of solution.

A more difficult task is the analysis of organic compounds. Carbon and hydrogen are determined after burning the sample, recording the released carbon dioxide and water. There are a number of techniques for detecting other elements.

Classification of analysis methods by quantity.

Components are divided into main (1 - 100% by weight), minor (0.01 - 1% by weight) and impurity or trace (less than 0.01% by weight).

Depending on the mass and volume of the analyzed sample, macroanalysis is distinguished (0.5 - 1 g or 20 - 50 ml),

semi-microanalysis (0.1 - 0.01 g or 1.0 - 0.1 ml),

microanalysis (10 -3 - 10 -6 g or 10 -1 - 10 -4 ml),

ultramicroanalysis (10 -6 - 10 -9 g, or 10 -4 - 10 -6 ml),

submicroanalysis (10 -9 - 10 -12 g or 10 -7 - 10 -10 ml).

Classification according to the nature of the particles being determined:

1.isotopic (physical) - isotopes are determined

2. elemental or atomic - a set of chemical elements is determined

3. molecular - the set of molecules that make up the sample is determined

4. structural-group (intermediate between atomic and molecular) - functional groups in molecules of organic compounds are determined.

5. phase - the components of heterogeneous objects (for example minerals) are analyzed.

Other types of classification analysis:

Gross and local.

Destructive and non-destructive.

Contact and remote.

Discrete and continuous.

Important characteristics of the analytical procedure are the rapidity of the method (speed of analysis), the cost of analysis, and the possibility of its automation.

Depending on the task at hand, there are 3 groups of analytical chemistry methods:

• 1) detection methods allow you to determine which elements or substances (analytes) are present in the sample. They are used to conduct qualitative analysis;
• 2) determination methods make it possible to establish the quantitative content of analytes in a sample and are used to carry out quantitative analysis;
• 3) separation methods allow you to isolate the analyte and separate interfering components. They are used in qualitative and quantitative analysis. Exist various methods quantitative analysis: chemical, physico-chemical, physical, etc.

Chemical methods are based on the use of chemical reactions (neutralization, oxidation-reduction, complexation and precipitation) into which the analyte enters. A qualitative analytical signal in this case is the visual external effect of the reaction - a change in the color of the solution, the formation or dissolution of a precipitate, the release of a gaseous product. In quantitative determinations, the volume of the released gaseous product, the mass of the formed precipitate, and the volume of a reagent solution with a precisely known concentration spent on interaction with the substance being determined are used as an analytical signal.

Physical methods do not use chemical reactions, but measure some physical properties(optical, electrical, magnetic, thermal, etc.) of the analyzed substance, which are a function of its composition.

Physicochemical methods use changes in the physical properties of the analyzed system as a result of chemical reactions. Physicochemical methods also include chromatographic methods of analysis, based on the processes of sorption-desorption of a substance on a solid or liquid sorbent under dynamic conditions, and electrochemical methods (potentiometry, voltammetry, conductometry).

Physical and physicochemical methods are often combined under common name instrumental methods of analysis, since analytical instruments and devices that record physical properties or their changes are used to carry out analysis. When conducting a quantitative analysis, the analytical signal is measured - a physical quantity associated with the quantitative composition of the sample. If quantitative analysis is carried out using chemical methods, then the basis of the determination is always a chemical reaction.

There are 3 groups of quantitative analysis methods:

• - Gas analysis
• - Titrimetric analysis
• - Gravimetric analysis

The most important among chemical methods of quantitative analysis are gravimetric and titrimetric methods, which are called classical methods analysis. These methods are standard for assessing the accuracy of a determination. Their main area of ​​application is the precision determination of large and medium quantities of substances.

Classical analysis methods are widely used in enterprises chemical industry for progress control technological process, quality of raw materials and finished products, industrial waste. Based on these methods, pharmaceutical analysis is carried out - determining the quality of drugs and medicines, which are produced by chemical and pharmaceutical enterprises.