Analysis of pesticides by the thin-layer chromatographic-enzyme inhibition technique

Mendoza, Celso E.

doi:10.1007/978-1-4615-8485-8_4

Cited by 35 publications

(2 citation statements)

References 62 publications

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“…The spots were visualized by spraying with 2,6-dichloro-N-bromo-p-benzoquinone imine, the enzyme spray as modified by Mendoza (1972) or by exposure to iodine vapor. Compounds were spotted on silica gel plates (0.25 mm, Polygram-Macherey Nagel & Co.) containing a fluorescent indicator and developed in either (a) 3:2 ethyl acetate/hexane, (b) 1:3 ethyl acetate/cyclohexane, or (c) 5:7:1 toluene/ethyl acetate/ acetic acid.…”

Section: Methodsmentioning

confidence: 99%

“…Nagel & Co.) containing a fluorescent indicator and developed in either (a) 3:2 ethyl acetate/hexane, (b) 1:3 ethyl acetate/cyclohexane, or (c) 5:7:1 toluene/ethyl acetate/ acetic acid. The spots were visualized by spraying with 2,6-dichloro-iV-bromo-p-benzoquinone imine, the enzyme spray as modified by Mendoza (1972) or by exposure to iodine vapor. The chromatographic behavior of the synthetic standards in each solvent system is given in Table I.…”

Section: S-mentioning

confidence: 99%

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Ultraviolet irradiation of fenitrothion and the synthesis of the photolytic oxidation products

Greenhalgh¹,

Marshall²

1976

J. Agric. Food Chem.

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The ultraviolet irradiation of fenitrothion in oxygenated solutions produced isomerization, oxidation, and solvolysis. In hexane, both the P=S and the aryl methyl group were oxidized to give fenitrooxon and formylfenitrothion. Small amounts of denitrofenitrothion were also formed. Irradiation in methanol gave carbomethoxyfenitrothion formed from oxidation followed by solvolysis. Isomerization of fenitrothion to its S-methyl isomer took place on a small scale in all solvents; however, no S-aryl isomer was detected. Irradiation of hydroxymethylfenitrothion in hexane readily gave formyl-and carboxyfenitrothion. This supports the suggestion that hydroxymethylfenitrothion is a reactive intermediate formed in the photolysis of fenitrothion. Several potential oxidation products, hydroxymethyl, formyl, carboxy, and carbomethoxy analogues of fenitrothion and fenitrooxon were prepared together with the S-aryl isomer. The mass spectral (MS) and nuclear magnetic resonance (NMR) data, gas chromatographic (GC), and thin-layer chromatographic (TLC) properties of these compounds and other fenitrothion derivatives are given.Fenitrothion [O,O-dimethyl 0-(4-nitro-m-tolyl) phosphorothioate] (I) is an important insecticide used in many countries for orchard and field crops. In Canada, its main use is to control defoliators in forests.It is structurally similar to parathion, the ultraviolet (uv) photolysis of which has been extensively studied (Cook and Pugh, 1957; Frawley et al., 1958;Koivistoinen and Merilainen, 1963;El-Rafai and Hopkins, 1966; and Joiner and Baetcke, 1974). In contrast, little work has been carried out on the photolysis of fenitrothion. Brewer et al. (1974) reported the formation of two products on irradiation of fenitrothion with light >300 nm, one of which was identified as 4-nitro-rn-cresol (11). A more exhaustive investigation was carried out by Ohkawa et al. (1974) who studied the photodecomposition in various solvents and as films by both uv and sunlight. Five products were isolated, resulting from photoinduced isomerization, oxidation, hydrolysis, and solvolysis. The predominant reaction in benzene, acetone, methanol, and aqueous methanol was oxidation of the aryl methyl group to give carboxyfenitrothion and its oxygen analogue, which were characterized by nuclear magnetic resonance (NMR) and infrared (ir) spectroscopy.

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Section: Methodsmentioning

confidence: 99%

Section: S-mentioning

confidence: 99%

Ultraviolet irradiation of fenitrothion and the synthesis of the photolytic oxidation products

Greenhalgh¹,

Marshall²

1976

J. Agric. Food Chem.

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Ein Vierteljahrhundert Dünnschicht‐Chromatographie — eine Zwischenbilanz

Stahl¹

1983

Angewandte Chemie

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A Quarter Century of Thin‐Layer Chromatography—An Interim Report

Stahl¹

1983

Angew. Chem. Int. Ed. Engl.

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Dedicated to Professor Wilhelrn Fresenius on the occasion of his 70th birthdayThin-layer chromatography (TLC) has been in general use since 1958. The prerequisites were the use of very small particle size material in the layers and the demonstration that not only lipophilic mixtures but also mixtures of cardiac glycosides, alkaloids, sugars, and amino acids could be separated quickly and simply on silica gel layers. The impressive separations obtained using the method later encouraged attempts to use adsorbants having such, narrow-range small particles in column chromatography. In order to achieve sufficient flow rates the use of high pressures was necessary. Thus, high pressure or high performance liquid chromatography (HPLC) was born, whose godfather, as far as instrumental development is concerned, was gas chromatography (GC). Today, chromatography is classified according to the nature of the transport phase: liquid, gas, or "electro" chromatography. Sample preparation often requires more time than the actual separation. Rapid thermal separation and application techniques (TAS, TFG) have brought advantages to TLC. As before, the art of chromatography consists in choosing the appropriate mobile phase, stationary phase, and separation technique. Gradient TLC offers new possibilities; for example, gradient layers make it possible to obtain selective information on the individual components of a mixture and also allow significant focussing effects to be achieved. Sequential and centrifugal TLC have paved the way for further advances. The questions arise whether the standard conditions, formulated 25 years ago, are still applicable and how the variations which have been introduced should be judged. Group-and substance-specific methods of detection are discussed in addition to universal methods. Quantitation is critically discussed and it is concluded that HPLC has the better chance in the future. Combination and coupling techniques ease the positive identification of individual substances. Finally, it is discussed why TLC is the simplest, most versatile, most cost effective, and most widely used chromatographic method and reasons are proposed as to why it will remain so for the foreseeable future. Historical Introductionalmost 100 years (cf. Table 1). The question arises as to why neither the pioneering research of Beyerinck"' nor subsequent contributions led to the general adoption of the method. My first contribution to this physico-chemicalThe principle of thin-layer chromatography, that is a thin, separating layer on a glass plate, has been known for was ignored just as much as its predecessors. The breakthrough only occurred when Merck was persuaded to produce a special grade of silica gel for thin-layer chromatography (TLC) and Desaga to manufacture the basic equipment and accessories. These were both first presented in 1958 at the International Chemistry Exhibition (ACHE- Thin-layer chromatography was soon in general use under the recommended standard condition^['^. The real scientific advance, however, was ...

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Analysis of pesticides by the thin-layer chromatographic-enzyme inhibition technique

Cited by 35 publications

References 62 publications

Ultraviolet irradiation of fenitrothion and the synthesis of the photolytic oxidation products

Ultraviolet irradiation of fenitrothion and the synthesis of the photolytic oxidation products

Ein Vierteljahrhundert Dünnschicht‐Chromatographie — eine Zwischenbilanz

A Quarter Century of Thin‐Layer Chromatography—An Interim Report

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