ANALYTICAL CHEMISTRY: WHAT IT STUDIES, METHODS AND APPLICATIONS - CHEMISTRY - 2025

The analytical chemistry, rather than a branch of this science, is a tool that can be applied in all fields of chemistry. In essence, all chemists, regardless of how, where and what they work with, make use of theoretical and practical knowledge to analyze their samples at some point.

What exactly is a sample? It is a matrix that contains the analyte, which is the substance on which all interest is focused. Analytical chemistry allows both to identify the nature of this analyte and to separate or quantify it. In other words: it allows determining what it is, differentiating it from the rest of the sample and knowing how much of it there is.

This is achieved through a series of techniques, classical or instrumental, following what is established by an analytical method. Thus, even if a study deviates from strictly analytical purposes, most of the time it resorts to any of these routine experiments.

Is there pure analytical chemistry? Yes. The analytical chemist can be considered as one who takes a sample, analyzes it and determines its qualities and composition, with the support of appropriate statistical analyzes.

What do you study?

In short, all the effort is directed to the analyte and how to identify and quantify it in the sample. For example: a certain number of fish are collected that float on the surface of a river, suspecting that their deaths have been due to contamination by a poisonous compound X.

Before dying, the fish integrated X into their organisms, perhaps retaining a considerable concentration unlike river water.

The samples are the fish and the analyte is X; it is necessary to identify it to rule out or not its possible poisonings. Because the biological matrix is ​​complex, it is impossible for X to be found alone, but accompanied by millions of other compounds.

According to an exclusive analytical method to determine X, it is necessary or not to treat the sample prior to chemical analysis. Thus, the meat of the fish is processed to eliminate all possible interferents in the analysis.

What are interferers? They are all those substances that could give false positives for X or prevent its detection. There are hundreds of methods for determining X: some cheaper and more sophisticated, others more rudimentary and expensive.

Qualitative analysis

If it is possible to determine X, as well as the series of compounds that make up those fish, then we speak of a qualitative result. In this case, the word qualitative comes from quality and refers to what substances are present in the sample (especially those that interest the researcher).

In the same way as the existence of X was verified, another qualitative analysis can be carried out to check if the fish have also ingested heavy metals (such as mercury, lead, cadmium, etc.).

It is also likely that the identification of X is not direct; that is, a simple classical rehearsal is not enough, but an instrumental technique is necessary. The options are many, but chromatography is one of the best to be able to discern the presence of X against other compounds.

On the other hand, if X absorbs ultraviolet radiation, then the most appropriate technique may be a UV-Vis analysis; if it is the case of a cation or anion, an analytical run is used to discard a series of ions in groups until finding the correct one: X.

Quantitative analysis

What is the concentration of X in the fish? In what units is it expressed and what is the percentage of error associated with this determination? When it comes to quantitative analysis, it is about those who seek to measure the amount of matter, and the selection of the method depends on the nature of the analyte (X) and many other variables.

Thanks to this type of analysis, the percentage composition of X and other substances related to the investigation can be obtained.

Analytical Chemistry Methods

The number of methods available for chemical analysis is very vast; however, it can be summarized into two categories: classical methods and instrumental methods.

Classical methods

It is made up of all traditional techniques, “bare-handed”, without the help or manipulation of any modern equipment.

Some classical methods allow the identification of a compound, as well as others are characterized by being quantitative. Classical qualitative methods include flame testing and chemical testing.

What does it consist on? The first seeks to excite the electrons of the metallic atoms by means of the heat of a flame, occurring the absorption and emission of light characteristic for each species; for example, the copper flame flashes a bluish-green color.

The second method, chemical tests, are nothing more than analytical steps or organic reactions that cause a visible change in the viewer.

An example of this is the identification of Al ³⁺ with the alizarin yellow dye, whose reaction in a basic medium gives rise to the formation of a reddish lacquer, which is a positive signal for aluminum.

In relation to classical quantitative methods, one can name the volumetric (volume measurement) and the gravimetric (mass measurement).

Instrumental methods

They are all those in which the sample is subjected to a physical stimulus (heat, radiation, electricity, etc.) and the response of the analyte is measured against some standards that dictate its presence, and even its quantity. Some of the instrumental methods include the following:

-Infrared spectroscopy.

-Nuclear magnetic resonance.

-Calorimetry.

-Mass spectrometry.

-Electrochemical analysis.

-Uv-visible.

-Absorption and atomic emission.

- Molecular fluorescence.

Applications

- It is used in the analysis of the quality of food, drugs or any good or product that is acquired in the market.

- It is used in the health area and provides valuable contributions for the diagnosis of diseases in patients.

- Determines the composition of soils, waters or any fluid or sample regardless of its phase. One of the main samples is made up of crude oil in the famous SARA analysis. Likewise, thanks to chromatographic methods, the fatty acid profile of any food, of plant or animal origin, can be broken down.

- It is the cornerstone in forensic analysis, in order to find clues that guide the resolution of a case; for example, determining if there is a DNA sample from the suspect at the crime scene.

- You can aim the target at the night sky and determine the composition of stars or other celestial bodies.

- In general, all industries need analytical approaches to solve problems or to increase their returns.

References

1. Wikipedia. (2018). Analytical chemistry. Retrieved on June 03, 2018, from: en.wikipedia.org
2. West & Vick. (1959). Qualitative Analysis and analytical chemical separations. The Macmillan Company.
3. Day, R., & Underwood, A. Quantitative Analytical Chemistry (5th ed.). PEARSON Prentice Hall.
4. BYJU'S. (August 02, 2017). Analytical Chemistry Theories. Retrieved on June 3, 2018, from: byjus.com
5. AZ chemistry. (April 17, 2017). 50 Applications of Analytical Chemistry in Daily Life - Agriculture - Pharmacy. Retrieved on June 3, 2018, from: azchemistry.com
6. Quimicas.net (2018). Analytical Chemistry. Retrieved on June 03, 2018, from: quimicas.net