Analytical chemistry, along with qualitative, quantitative, structural and process analyses, play a considerable scientific and practical role. They greatly contribute to the development of many fields of science, especially the natural and technical sciences. It is an indispensable tool for controlling and optimising many processes. But most of all, it delivers useful information about the tested materials.

 Basic information on analytical chemistry

Analytical chemistry is a highly interdisciplinary field of science which combines issues from such areas as chemistry, physics, mathematics, biology or engineering. It involves exploring, establishing and developing analytical rights, methods and techniques aimed at answering the query on the qualitative and quantitative composition of the tangible object under test with the assumed precision and accuracy.

The tool used to acquire information about the analysed material is the chemical analysis. This term directly refers to the practical use of analytical chemistry at research centres and chemical laboratories by applying appropriate analytical methods.

Applications of analytical chemistry

Analytical chemistry is an important pillar that allows us to determine the qualitative and quantitative composition of the object and thus establish its characteristics. It is co-responsible for the quality of the chemicals used in many areas of economy. Chemical analysis can be classified into four principal areas:

• Environmental analysis – this involves testing samples that originate from the environment, so from soil, air, water or plant and animal tissues. The results obtained make it possible to qualitatively assess the environment and determine the degree of possible pollution (usually caused by human interference).
• Medical and veterinary analysis – this involves testing samples of body fluids, tissues or excrements. Its outcomes are often used as a basis for diagnosing diseases and assessing the condition of the whole body.
• Industrial analysis – its principal role is to assess the quality of raw materials as well as semi-finished and finished products throughout their production cycle. The analysis of individual processes enables us to detect and relatively quickly mitigate any errors.
• Forensic analysis – used to analyse samples secured for criminal court proceedings. It concerns both forensic toxicology and criminological physical chemistry. It helps detect poisoning, forgeries or drugs.

Stages of an analytical procedure

Analytical chemistry is largely involved in developing and validating analytical methods to effectively detect the desired substances in various matrices and with the assumed accuracy. In order for the analytical chemistry to be effective, it is important to properly plan and execute each stage of the analytical procedure.

Sampling is the most important stage in the entire process of determining the analyte. The tested material should be sampled in a representative manner, so that it refers to the properties of the whole product. Any errors made at this stage are irreversible and bring about a result that is inaccurate.

Preparing samples for analysis – this is aimed at separating, where required, the determined component from the matrix which, especially for biological samples, is complex and disturbs the analytical measurement. At this stage, in addition to removing the interferents, we also derivatise the analytes. This consists in converting the determined component into a form that has properties appropriate for the analytical method applied.

Measuring – during measurement, we use the appropriate method to measure a specific physico-chemical characteristic. By measurement we obtain an analytical signal. The measuring technique should be selected in such a way to determine the analyte with a sufficient accuracy, precision and sensitivity.

Processing and interpreting results – today most analytical instruments are linked with computer systems, so the signal received during analysis and then transformed is presented in the form of, say, concentration. However, some measurements should be properly converted in order to determine the final result. The final result is a substantive and statistical assessment of the acquired information.

Identification and quantitative measurement of ingredients in analytical chemistry

• Qualitative analysis

Qualitative analysis provides an answer to the question about the compounds contained in the test material. Its role is usually to detect individual elements or ions composing the sample. It constitutes an important tool, particularly for materials whose chemical structure is unknown. Qualitative analysis is of great importance, as the choice of further chemical procedure depends on the outcomes it produces. Qualitative determination consists in converting individual analytes by a chemical reaction into new compounds whose properties we know (such as the colour, solubility, etc.). The separation is carried out by analysing cations and separately anions. Additionally, cations are divided into five, and anions into seven, analysis groups. Qualitative analysis is also applied to salts, metal alloys, minerals and functional groups.

• Quantitative analysis

This involves quantitative determination of the content of elements and ions that were previously detected on a qualitative basis. Quantitative analysis can be divided into chemical analysis, instrumental analysis and trace analysis. Conventional methods are based on the measurement of mass or volume of the ingredient. Mass is measured by weight analysis, electrogravimetric analysis and certain methods of gas analysis. Volume measurement is mostly used in titration methods (such as pH-metric, potentiometric, spectrophotometric or radiometric titration). Research and commercial laboratories particularly often use instrumental analyses. They consist in measuring a variable physico-chemical property that is proportional to the concentration of the ingredient. Trace analysis is based on measuring the content of the ingredient at an extremely low concentration level. It includes special procedures of sampling, concentrating and measuring the measurand.

• Structural analysis

It is based on determining the structure of chemical molecules. With structural analysis, we can establish the atomic composition of compounds, that is, how many compounds there are, what they are like, and how they interconnect. This is an area of analytical chemistry that is applied particularly by scientific entities. The information acquired in structural analysis extends our knowledge about the structure of many chemical compounds.