In physical and chemical analysis, a whole complex of methods is used, each of which is, in fact, a set of various operations and techniques. With their help, the study of qualitative and quantitative characteristics of substances and materials is carried out. Physico-chemical research methods are used in laboratories of various profiles in the form of techniques, that is, documents in which the method is concretized and brought to an algorithm or instruction. In addition, to obtain results with a given accuracy, conditions are established (including the requirements for measuring equipment) under which an error (uncertainty), its systematic and random components are attributed to the methodology.
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, gas or melting) and quantitative analysis (with mass or volume measurement). Many of them arose from the 17th to the 19th century and are still used in those cases when their sensitivity threshold is sufficient.
Physicochemical methods of analysis based on instrumental studies are more accurate. In this case, with the help of instruments, physical quantities are measured, such as light absorption, fluorescence, current strength, potential difference, electrical conductivity, radiation intensity and others. In some cases, preliminary preparation of the sample (s) is expected by fractional distillation, separation into components in a chromatographic column, electrophoresis, and so on.
Physicochemical methods of analysis are used everywhere. In sanitary, environmental, medical, pharmaceutical and food laboratories. Supervisory authorities and in forensic research. For scientific and industrial purposes. They are based on the assessment of the quality of raw materials, intermediate samples, finished and commercial products in chemistry, petrochemicals and oil refining. If analysis using classical analytical methods could be carried out by employees with low qualifications (from 2 to 4 categories according to ETKS), and in many cases there was enough secondary or secondary specialized education, then specialists with higher qualifications are involved in instrumental studies (5-6 grades) having higher education.
In classical studies, analytical scales and volumetric glassware (cylinders, flasks, pipettes, burettes) are usually used as measuring instruments. Physico-chemical methods of analysis involve the use of photocolorimeters, refractometers, spectrophotometers, chromatographs, mass spectrometers and so on. Most of them are equipped with personal computers, which reduces the total and active time for analysis, consumables (graph paper, etc.), reduces the role of the human factor, thereby minimizing the risk of obtaining false test results.
Physico-chemical methods of analysis based on the use of the latest models, despite their high cost, can further reduce the cost of analytical control, which is due to a significant reduction in analysis time. This can be considered by the example of chromatographic methods. Analysis on older models required, after fixing the detector signals on graph paper, to perform the following operations:
- remove the chart from the device;
- each signal (looks like a peak resembling a triangle) corresponding to a particular component is identified by the time the compound exits the column;
- calculate the area of each peak as the area of the triangle (measure with a ruler the height and width at the middle of the height with a magnifying glass);
- calculate the content of components;
- to issue the test result with a protocol or other record.
In the case of using modern chromatographs, the detector signal of which is output directly to a computer, all the above operations are excluded, since they are performed in automatic mode, almost instantly. But this is not the only advantage when modern physical and chemical methods of analysis are used. The results obtained in this way can be automatically transferred promptly not only to the database of the laboratory information management system (LIMS), but also to the organization’s database and to the central process control panels.