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Chromatographic scince series - Cazes J.

Cazes J. Chromatographic scince series - Marcel Dekker, 1996. - 1098 p.
ISBN 0-8247-9454-0
Download (direct link): сhromatography1996.pdf
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First we will discuss the methods dealing with the determination of these compounds, and later the combined methods for OP and other compounds.
Phosmethylane (55), a broad-spectrum nonsystemic insecticide, and chlorpyriphos (6) were separated from their major metabolites by TLC in various solvent systems (Table 3); later, quinalphos
(7) was determined in biological media (Table 3).
The breakdown of bromophos and iodofenphos was examined in rainwater under artificial conditions. After separation on polyamide layers, the alteration products were analyzed by mass spectrometry (56) (Table 3).
Analogous to the on-column derivatization used in gas chromatography, an oxidative chemical transformation was carried out on a TLC plate by m-chloroperbenzoic acid. The oxygen analogs of fenthion, disulfoton, and phorate that were produced were separated after this derivatization (57) (Table 3). Another example of on-plate derivatization involves a reduction reaction carried out in order to determine the residues of methylparathion, parathion, and fenitrothion. Parent compounds and corresponding amino derivatives were also separated (58) (Table 3).
Some OP insecticides were determined in green and dry tobacco leaves by TLC and gas chromatography. TLC detection required charcoal treatment, which diminished the recovery (88.5%) (59). Gardona content of fish tissues and water samples was established after chloroform or petroleum ether-chloroform extraction (9) (Table 3). Two solvent systems were reported for the separation of dimethoate, fonofos, and their oxygen analogs from disulfoton, fonofos, and oxydemeton methyl (60) (Table 3). Silica gel F254 or silica R (containing 5% 2) layers were applied for the analysis of 10 OP insecticides (61).
A temperature-programming gradient TLC elution of some OP insecticides was reported. Both silica gel R and neutral alumina R sorbents were suitable for the separation of OP insecticides using a temperature program between 30 and 40C. No separation was observed under isothermal conditions (62) (Table 3).
Eleven OP insecticides were analyzed on sorbents impregnated with metal salts or phenol (63).
RO^ O-Q RO^ ^,0-Q R0^ ySQ
RO / RO / RO ^ ^0
III IV V
RC\ /S-Q ROx ^O "4
P P
RO / RO ^ ^ R R'N 0R
H
VI VII VIII
Figure 2 Organophosphorus insecticides. Ill, phosphate; IV, phosphorothionate; V, phosphorthiolate; VI, phosphorodithioate; VII, phosphonate; VIII, phosphoramidate. R = alkyl; Q = alkyl, aryl, heterocycle.
Table 3 Organophosphorus Insecticidcs
Compound
Phosmethylan
metabolites
Chlorpyrifos
metabolites
Quinalphos
(Ekalax)
Bromophos Iodofenphos metabolites Fenthion Disulfoton Phorate Parathion Methylparathion Fenitrothion and reduction products
Stationary phase
Mobile phase
Silica gel
(1) Hexane-dioxane-AcOH (79:20: 1)
Silica gel G
Silica gel
(2) Hexane-dioxane
(80:20)
(3) Hexane-CH2CI2
(30:70)
(4) CHC1,-ether
(80:20)
(1) Hexane-CHCl,
(80:20)
(2) Hexane-acetone-MeOH-
glacial AcOH (63:30: 10:0.2)
(1) Hexane: benzene-CHCl3
(70:20:10)
(2) Hexane-benzene-EtOAc:AcOH
(60:25: 15:0.5)
(3) Hexane-benzene-MeOH;
AcOH(50: 30: 19: 1)
(4) Benzene-CHCli-MeOH;
acetone (50:30: 15 :5)
(5) Benzene-CHCIi-AcOH
(60:40:0.5)
Polyamide
Silica gel F on plate Hexane-acetone (3:1) oxidation
Limit of detection
Detection R, x 100 (#ig) Sample Ref.
o-tolidine Natural 55
+ K1 + CL water
PdCL 0.5
p-dimethylamino-benzaldehyde
AgNO, 0.10 Tapwater
0.25-0.50 Banana pulp
PdCl2
Rhodamine
Enzyme inhibition I O'3 Rainwater 56
Biol. 57
58
92
87
84
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