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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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Almost 200 pesticides were analyzed in various systems using dichloromethane and ethyl acetate (129). These pesticides were visualized by the following selective detection methods: (a) o-tolidine-potassium iodide, (b) p-nitro-benzene-diazonium-fluoborate, (c) silver nitrate with UV irradiation, (d) p-dimethylaminobenzaldehyde, (e) bioassays with either fungispores of Aspergillus niger or an enzyme inhibition method. When horse blood serum was the enzyme source, acetylcholine iodide was its substrate in the presence of 2,6-dichloro-phenol-indophenol. Naphthyl acetate was applied as the substrate for the human blood plasma esterases. The Rf values and detection limits were also published (129).
Two-dimensional TLC was applied in the separation of about 150 pesticides. The first development was carried out with petroleum ether-ether (1:2), which separated the carbamates, carbamides, triazines, phthalimide-type compounds, OPs, and other pesticides. The more polar pesticides, having Rf0.25 or less, can be separated in the second direction with ether. When Rf was higher than 0.75, the development system was petroleum ether-ether (5:1), separating the nitro derivatives, thiocarba-mates, and some OP insecticides (130).
Another two-dimensional TLC method could resolve , OP, insecticides, triazines, and 2,4-D using a chloroform-ether system for polar pesticides and -hexane-acetone for nonpolar pesticides in water, soil, and plant samples. The /fy-values are summarized in Table 10 (131).
Table 10 Multiresidue Methods
Compound
Stationary phase
Mobile phase
DDT
Methoxychlor
Lindan
jV-phenylcarbamates
Fenuron
Diuron
Linuron Triazines Atrazine Simazine Prometrine Dimethoate Malathion Chlorphenoxy carbonic acids
2.4-D
2.4-DP
MCPA
CMPP
MCPB

OP
Kieselgel G
Kieselgel G
Kieselgel G
Kieselgel G
NP (analtech)
8% AgNOj
RP (Whatman)
C18
NP
RP
n-hexane:acetone (90: 10)
2-D TLC
(1) n-hexane:acetone (150:45)
(2) CHClj:nitromethane
(100:100)
2-D TLC
(1) CHCl,:CH3COOH
(190:10)
(2) Benzene:n-hexane:
CH3COOH (50: 100:20)
-heptane
-heptane-acetone (90:10) Me0H-H20-NaCl (95 :5 : 1.
Heptane-acetone (90: 10) Me0H-H20-NaCl (65 :35 : 1
Carbamates
y-HCH
NP
RP
Silufol
Toluene-ethyl acetate (80:20)
MeOH-H2O NaCl (65:35: I) n-hexane
Detection Sample Extraction Ref.
o-tolidine Water (I) -hexane, pH 6-7 22
UV
AgNO, Water (2) CHCI,, pH 6.5-7
UV
AgNO, Water (3) CHC13, pH 2
UV
UV 128
Fluorescence 128
Anisaldehyde Bromophthalein Anisaldehyde Dansyl chloride
Soil 0.05 N CaCl2-acetone 20
(1:1)
794 Fodor-Csorba
Dilor
a-thiodan
/-thiodan
Pyrethroids

OP
OP, , carbamates
Carbamides
Thiocarbamides
Triazines
Chlorophenoxy-
alkylcarbonic
2,4'-DDT
4,4'-DDT
4,4'-DDD
4,4'-DDE
or-HCH
7-HCH
Methaphos
Phosphamide
Phosalone
Atrazine
Prometryne
Simazine
2,4-D
Lindane
pp'-DDT pp' -DDE Dimethoate
Silica gel KSK
Kieselgel 60
Silufol
Polygram Cel 300 Polygram Sil G
Petroleum ether
-hexane-acetone (1:1)
/-hcxane acetone (1:9)
2-D TLC
(1) Petroleum ether-ether (1:2) (2a) Ether
(2bI Petroleum ether-ether (5:1)
2-D TLC
(1) CHClrether (5 : 2)
(2) n-hexane:acetone (20: I)
Mcvinphos
Chlorfenvinphos
Trichlorphon
Hexane
CHCI,
Cb-o-tolidine enzyme 130
inhibition
Rf x 100
(1) (2)
AgNO,. NH4OH Water 131
Soil 100 30
Plant 100 37
97 21
100 48
97 23
95 18
87 6
12 0
80 4
57 2
60 3
51 1
20 0
AgNO,-2-phenoxy- Peas 21
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