Physicochemical methods of analysis

In physical and chemical analysis, a whole set of methods is used, each of which is, in fact, a combination of various operations and techniques. With their help, the study of the qualitative and quantitative characteristics of substances and materials is carried out. Physicochemical methods of research are used in laboratories of various profiles in the form of methods, that is, documents in which the method is concretized and brought to an algorithm or instruction. In addition, to obtain the results with a given accuracy, conditions (including requirements for measuring equipment) are established, in which error (uncertainty), its systematic and random components are attributed to the technique.

Physicochemical methods are an important component of analytical chemistry. They include chemical transformations or dissolution of the analyzed sample (aliquots), concentration of the desired component, elimination of the influence of interfering substances and so on. Analytical methods can be divided into classical and instrumental. Classical methods (known as "wet analysis") use qualitative (by smell, color, precipitation, release of gas or melting) and quantitative analysis (with measurement of mass or volume). Many of them arose in the period from the 17th to 19th centuries and are still applied in those cases when their threshold of sensitivity is sufficient.

Physicochemical methods of analysis, based on instrumental studies, are more accurate. In this case, instruments measure physical quantities such as light absorption, fluorescence, current strength, potential difference, electrical conductivity, radiation intensity, and others. In some cases, it is assumed that the sample (sample) is preliminarily prepared by fractional distillation, by separating into components in a chromatographic column, by electrophoresis, and so on.

Physicochemical methods of analysis are applied everywhere. In the sanitary, ecological, medical, pharmaceutical and food laboratories. Supervisory authorities and forensic studies. For scientific and industrial purposes. They are based on an assessment of the quality of raw materials, intermediate samples, finished and marketable products in chemistry, petrochemistry and oil refining. If the analysis was performed using classical analytical methods, staff with low qualifications (grades 2 to 4 of the ETCC), and in many cases there was enough secondary or specialized secondary education, then specialists with higher qualifications (5-6 grades) , Having higher education.

In classical studies, analytical scales and measuring glassware (cylinders, flasks, pipettes, burettes) are usually used as measuring instruments. Physicochemical methods of analysis involve the use of photocolorimeters, refractometers, spectrophotometers, chromatographs, mass spectrometers, and so on. Most of them are equipped with personal computers, thereby reducing the total and active time for analysis, consumables (chart paper, etc.), reducing the role of the human factor, thereby minimizing the risks of obtaining unreliable test results.

Physicochemical methods of analysis, based on the use of the latest models, despite their high cost, allow to reduce further the costs of analytical control, which is due to a significant reduction in the time for analysis. This can be considered using chromatographic methods. Analysis on older models required after fixing the signals of the detector on the chart paper to perform the following operations:

• Remove the diagram from the instrument;
• Each signal (looks like a peak resembling a triangle) corresponding to a particular component is identified by the time of the output of the connection from the column;
• Calculate the area of each peak, as the area of the triangle (measure the ruler height and width at the middle of the height of the magnifier);
• Calculate the content of components;
• Formalize the test result with a protocol or other record.

In the case of modern chromatographs, whose detector signal is output directly to the computer, all the above operations are excluded, since they are performed in an automatic mode, almost instantly. But this is not the only advantage when modern physicochemical methods of analysis are used. The results obtained in this way can be automatically transferred in an automatic mode not only to the database of the laboratory information management system (LIMS), but also to the organization's database and to the central control panels of the technological process.