Monday, 13 June 2011

Lecture 2 - Identifying drugs and pesticides

Approximately a month ago I started a new label here in The Toxicologist Today regarding Analytical Toxicology. The first lecture offered an overview on current Analytical Toxicology methodology, and the second one will very briefly work the subject of analysing drugs and pesticides. 

What is the most used method in systematic toxicological analysis? In the study of specific substances capillary gas chromatography, usually associated to mass spectrometry (MS) detection, is a commonly applied method in the assay of determined analytes. However, basic gas chromatography, HPLC (again supported by MS) are used to analyse certain individual compounds or even groups of analytes. Two other techniques, the first called Diode Array Detector (see video below - it was chosen randomly as I am not paid for advertising) and the second called wavelenght rationing (don't know what it is exactly but will try to find it for a future post) can and are also applied in modern analytical toxicology.

What is important to consider when screening for unknown substances? There are three key steps when adopting systematic analytical toxicology procedures. They are based on three main groups of methods: a) Sample preparation, b) Differentiation and Detection, c) Identification. 

What is the goal of each objective? The aim of sample preparation (for example, homogenization and hydrolysis) is to retain all the important substances  and at the same time remove from the sample matrix those interfering components that can affect your results. Differentiation and Detection (for example, GC and MS) account for the identification of relevant compounds in the minimum timespan possible, whereas Identification is the final step consisting in comparing results obtained with information from available authentic compounds or from available reference databases.

TIP: In order to enhance the quality observation of analytes, a sample may be treated with beta-glucoronidase (an enzyme that breaks down complex carbohydrates) or even arylsulfatase (an enzyme that hydrolyses conjugated metabolites).

That's it for today, I hope you all enjoyed the lecture. I sure did as I revised previously learned concepts, I refreshed experimented methodology and got to know what is going on in the market in terms of lab material/equipment. See you son for a recycling experience here in The Toxicologist Today.

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