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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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Cymoxanil
Diuron
100 Detection Sample Ref.
UV (nm) Water 134a
200, 220, 240,
260, 280, 300
4-(4' -nitrobenzy 1) 134b
pyridine-tetraethylene
pentamine
UV Ground 134c
water Drinking water
800 Fodor-Csorba
Lenacil
Metribuzin
Benalaxyl
Bendiocarb
Bentazone
Dinoseb
DNOC
Methalaxyl
Nitrothal-
isopropyl
Pendimethalin
Terbumeton
Fluazifop-P
Fluroxypyr
Haloxyfop
Triclopyr
Amitrole
Alachlor
Atrazine
Chlorfenvinphos
Clortoluron
Cyanazine
2,4-D
MCPA
Metazachlor
Metobromuron
Metolachlor
Metoxuron
Monuron
Parathion
Pendimethalin
Propazine
HPTLC Silica gel 60
Methanol
Ammonia solution Formic acid Screening and confirmative gradient elution
HPTLC Silica gel 60
HPTLC silica gel (Merck)
Acetonitrile Carbon disulfide Dichloromethane Diisopropyl ether
Dichloromethane Diisopropyl ether Methanol Methanolic ammonia Formic acid tert- Butyl methyl ether acetonitrile (90: 10) n-hexane Formic acid cc. ammonia solution
UV
1-naphtyl)- Water
ethylene diamine dihydrochloride
CATS" analysis Drinking
software water
UV, nm 200, 220, 240,
260, 280, 300
I34d
I34e
134f
Pesticides 801
Table 11 (continued)
Compound Stat. phase Mobile phase
Sebutylazine
Simazine
2,4,5-T
Terbutylazine
Trifluralin
Vinclozolin
Atrazine HPTLC Methanol
2, 4-D Silica n-hexane
Metoxuron gel dichloromethane
Parathion (Merck)
Procymidon 100, 200/xm
Propazine
Benzanilide
Vinclozolin
Detection
Sample Ref.
UV/VIS Drinking 134g
water
Pesticides
803
were analyzed in various commodities including smoke flavors, smoked meat, bacon, fish, eel, tea flavors, oleoresins, herbs, spices, vegetable oils, coffee, and coffee extracts (136). These samples were subjected to saponification, solvent partitioning, and column cleanup. TLC combined with fluorodensitometry gave results as good as HPLC.
The TLC plates should be very carefully preconditioned for in situ fluorodensitometry. The acetylated cellulose layers should be developed in ethanol (95%)-dichloromethane (1:1) before use. If this washing is not sufficient and some fluorescent impurities can be observed, then the plates should be washed again by ascending migration of the same solvent mixture overnight. These preconditioned plates allow detection of as little as 0.5 ng of PAHs (136). Eleven PAHs were analyzed in food and environmental samples by in situ fluorodensitometry. The interferences between the following pairs of PAHs were investigated: benzo[b]fluoranthene (B[b]F)-Chry, B[a]A-fluoranthene (Flu), and Flu-Py.
High-intensity mercury or xenon lamps and appropriate filters lead to limits of detection of about 2 pg. Special measurement conditions for each PAH enhance the selectivity and sensitivity of this method (137).
B[a]P and Flu were determined using a computer-controlled CAMAG TLC scanner with an Apple with ADALAB 12-bit AD-converters. HPTLC plates were developed in n-hexane and scanned. The PAHs were quantified in the 100 pg-to-1.5 ng range. The baseline structure and its correction, the accuracy and reproducibility of the data, and regression analysis were investigated and discussed (138). A recommended TLC screening method was developed for the determination of B[a]P in smoked food. This method detects samples containing concentrations of more than 0.6 (ig/kg. After extraction (1,1,2-trichlorotrifluorethane or cyclohexane) and several partitioning steps (MeOH-water-cyclohexane and dimethylformaimide-water-cyclohexane), the solvents were evaporated and the extract analyzed by TLC. Homemade acetylated cellulose or acetylated cellulose-alu-mina layers were spotted and developed in acetone-ethanol-water (25:60:15). The detection limit of B[a]P at 366-nm excitation wavelength was 0.5 ng (139).
I. Antioxldants and Food Additives
3-/-butyl-4-hydroxyanisole (BHA) is an important antioxidant that offers some protection against certain carcinogens. The antioxidants BHA and dodecylgallate (DG) were determined in fats, oils, and fatty foods after extraction with acetonitrile and separation on silica gel layers using a five-component mobile phase, xylene-chloroform-propanol-formic acid-acetic acid (45:45:10:1:1). These compounds were detected by 10% phosphomolybdate or by vanillin in sulfuric acid. The values observed were 0.52 (BHA) and 0.15 (DG) (140).
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