The analytic chemistry, more than a branch of this science, it is a tool that can be applied in all fields of chemistry. In essence, all chemists, no matter how, where and with what they work, 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 to determine what it is, to differentiate it from the rest of the sample and to know 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, in most of the times 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 the appropriate statistical analyzes..
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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 that float on the surface of a river are collected, suspecting that their deaths have been due to contamination by a poisonous compound X.
Before dying, the fish integrated X into their organisms, so that it may retain 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 those 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 to determine X: some cheaper and more sophisticated, and others more rudimentary and expensive.
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 straightforward; that is, a simple classical rehearsal is not enough, but rather 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 suitable 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.
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..
The number of methods available for chemical analysis is vast; However, it can be summarized into two categories: classical methods and instrumental 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 one seeks to excite the electrons of the metallic atoms by means of the heat of a flame, taking place 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 the Al3+ 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 the classical quantitative methods, the volumetric (volume measurement) and the gravimetric (mass measurement) can be named.
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.
-Atomic absorption and emission.
- Molecular fluorescence.
- 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.
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