gh PESTICIDES AROUND US, OR CHEMISTS FOR ECOLOGISTS

Researchers from Lipetsk State Technical University have developed a method for identifying organochloride pesticides. A question can arise what is unusual about it? After all, if pesticides are produced, then, there should be methods to identify their content, should not there? That is all true, but with a minor amendment. A collective of chemists under the guidance of Professor Tatiana Ermolaeva, working in tight cooperation with their colleagues from the Lomonosov Moscow State University, has managed to develop an approach, which enables to measure even track concentrations of these substances, which are very dangerous to health even in objects of such complicated composition as soil, edible raw material and foodstuff. This is real success indeed.

The point is that a lot of pesticides, molecules of which contain chlorine atoms, dissociate very long and hard in natural conditions, i.e. in water, soil and plants. Therefore, they are accumulated in the environment objects and, in the end, get to out table together with food. Moreover, event decay products of organochloride pesticides may be toxic, at that in very low doses. Due to that, some pesticides containing chlorine (including aldrin) are prohibited for application at all (alas, but they are still used), and the content of other pesticides is necessary to control in the most strict way. The latter has become possible die to the Russian researchers’ investigations.

The method is based on the so-called immunochemical assay. Its essence is that the antigen (in this case, pesticide molecules) interact with specially obtained antibodies, molecules of which “recognize” antigen molecules and bind them strongly enough. And, simply speaking, they do not pay attention to other substances. In principle, this approach has been known for a long time, its high sensitivity and specificity being considered the main advantages (not without grounds). However, to identify each compound or a group of compounds, the approach should be developed separately, in fact it should be invented. This is what has been done by the Lipetsk analysts. The researchers’ effort, which is so important to our safety, was sponsored by the Russian Foundation for Basic Research and the Ministry of Education and Science of the Russian Federation.

Depending on the toxicant molecule structure, the authors applied two methods to identify the quantity of pesticides in the sample. For some of them, the authors suggested to apply the piesoelectric immunosensors developed by them. This is in a way the balance, which enables to “weigh” if not individual pesticide molecules but at any case a very small quantity of them. It is necessary that molecules of identified substance, roughly speaking, would stick to the covering of such “balance” sensor. This can be achieved with the help of specific antibodies.

The other approach has turned out to be more efficient to identify some organochloride pesticides – to this end, derivatives of pesticides, into molecules of which bright fluorescent markers were introduced, had to be synthesized. Per se, this is a variant option of polarized fluorescent immunoanalysis. And some pesticides can be identified by both methods, the first method being particularly good due to its highest sensitivity, and the second – although slightly yielding in sensitivity – enables to fulfill the analysis very quickly, literally within minutes.

Certainly, chemical “zest” and original solutions are inevitably beyond the scope of a short article. However, the outcome of the researchers’ effort is undoubtedly important and interesting even for amateurs, at least because all of us (disregarding education) eat and drink. Now, the quantity of organochloride pesticides can be identified in our food and drinks not only at the maximum allowable concentration level but even in smaller concentrations (because they are accumulated!).

So, the methods developed by the researchers from Lipetsk State Technical University enable to identify concentrations of a whole range of pesticides at the level of thousandth parts through to dozens of – attention! – nanograms (this is one billionth part of a gram) in a milliliter. The scientists leveraged this opportunity to check real samples of soil, milk, apple juice, potato, rice and sausage. Fortunately, it has turned out that the majority of sample showed on the quantity of pesticides which had been added expressly for analysis – that is the samples were secure. However, pesticides have been found in some samples, sometimes in the quantities that exceed permissible norms. So, it is very good that ecologists now have such an excellent control method at their disposal.

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