Detection reagents used for on-plate identification of organic pesticides in biological samples with preliminary separat
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Detection reagents used for on‑plate identification of organic pesticides in biological samples with preliminary separation by TLC/HPTLC Qasim Ullah1 · Nahid Fatema1 · Ali Mohammad2 Received: 16 May 2020 / Accepted: 23 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Many specific and non-specific chromogenic spray reagents have been used to detect organic pesticides (organophosphorus, organochlorine, carbamates, and pyrethroids) on thin-layer chromatographic (TLC)/high-performance thin-layer chromatographic (HPTLC) plates. To realize high sensitivity and improved selectivity, several chromogenic reagents have been introduced. The physical properties of organic pesticides reported so far are also presented in tabular form. The colors produced on TLC plates due to reactions taking place between pesticides and spray reagents are illustrated in the form of chromatograms, and reaction mechanism is also presented. Keywords Pesticides · Specific chromogenic reagents · Thin-layer chromatography (TLC) · High-performance thin-layer chromatography (HPTLC) · Silica gel
1 Introduction Pesticides are chemicals which are generally used to either kill or protect from pests. The commonly used pesticides include insecticides, herbicides, fungicides, and rodenticides. Naturally, pesticides are potentially toxic to other non-target organisms, including humans. Hence, it is necessary to use them safely and dispose of properly. The use of modern pesticides in agriculture and public health is dated back to the nineteenth century. The first generation of pesticides involved the use of highly toxic compounds of arsenic such as calcium arsenate and lead arsenate and a fumigant hydrogen cyanide in the 1860s for the control of pests like fungi, insects, and bacteria. Bordeaux mixtures, which are mixtures of copper sulfate, lime, and water along with sulfur, were also used as pesticides. Due to their ineffectiveness,
* Qasim Ullah [email protected] 1
Physical Sciences Section, School of Sciences, Maulana Azad National Urdu University, Gachibowli, Hyderabad, TS 500032, India
Department of Applied Chemistry, Zakir Hussain College of Engineering and Technology, Aligarh Muslim University, Aligarh, UP 202002, India
2
these pesticides had been replaced by synthetic organic compounds. Dichlorodiphenyltrichloroethane (DDT), the first synthetic organic compound, was first synthesized by an Austrian scientist, Othmar Zeidler [1], and its insecticidal properties were discovered by a Swiss chemist, Paul Müller, in 1939. In its early days, DDT [2] was considered a boon for scientists because of its broad-spectrum activity, persistence, insolubility, being inexpensive, and easy to apply; DDT was used for killing pests, thus boosting crop yields. DDT was so inexpensive that its use quickly spreads over the globe. DDT was also used to delouse soldiers in World War II and in public health for the control of mosquitoes which are the vectors for malaria. Following the success of DDT, such other chemicals were synthesized
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