Quantitative Determination of Tris-(2,3,-dibromopropyl) Phosphate by Densitometry of Thin Layer Chromatograms

1979 ◽  
Vol 62 (6) ◽  
pp. 1315-1318
Author(s):  
Albert M Gardner
Keyword(s):  
Sewage Sludge ◽  
Thin Layer ◽  
Quantitative Determination ◽  
Ethyl Acetate ◽  
Silver Nitrate ◽  
Flame Retardant ◽  
Silica Gel ◽  
White Background ◽  
Ppm Level

Abstract The flame retardant tris-(2,3-dibromopropyl) phosphate (Tris) was chromatographed on silica gel thin layer plates, using ethyl acetate-hexane (30+70) as the developing solvent. Tris was visualized by spraying the chromatogram with 1% aqueous silver nitrate followed by exposure to ultraviolet light for 40 min. Tris appeared as dark gray spots on a white background; the spots were quantitated by densitometry at 600 nm. The lower level of sensitivity was 50 ng; calibration plots were linear from 50 to 800 ng. The procedure was developed to determine the levels of unmetabolized Tris remaining after exposure to sewage sludge suspensions. Recovery of Tris from 3 sewage sludge samples fortified at the 1.0 ppm level averaged 97%.

Improved Method for the Thin Layer Chromatographic Determination of Patulin in Apple Juice

1973 ◽  
Vol 56 (4) ◽  
pp. 813-816 ◽  
Author(s):  
Peter M Scott ◽  
Barry P C Kennedy
Keyword(s):  
Thin Layer ◽  
Ethyl Acetate ◽  
Thin Layer Chromatography ◽  
Silica Gel ◽  
Apple Juice ◽  
Chromatographic Determination ◽  
Improved Method ◽  
Layer Chromatography ◽  
Hydrochloride Solution

Abstract Apple juice from a freshly opened container is extracted 3 times with ethyl acetate. The extract is dried, concentrated, diluted with benzene, and added to a silica gel column. Patulin is eluted by benzene-ethyl acetate (75+25) and detected by thin layer chromatography, using a 3-methyl-2-benzothiazolinone hydrazone hydrochloride solution as the spray reagent. Satisfactory recoveries were obtained for patulin added to apple juice at levels of 25–400 μg/L.

Quantitative Determination of Carbaryl in Apples, Lettuce, and Water by Densitometry of Thin Layer Chromatograms

1978 ◽  
Vol 61 (3) ◽  
pp. 616-620
Author(s):  
Joseph Sherma ◽  
Andrew J Kovalchick ◽  
Richard Mack
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Fiber Optics ◽  
Silica Gel ◽  
Chromatographic Method ◽  
Visual Estimation ◽  
Carbamate Insecticides

Abstract A method for the quantitative determination of carbaryl insecticide by in situ densitometry was developed. After separation on silica gel thin layer plates, carbaryl residues were detected by using p-nitrobenzenediazonium fluoborate reagent and quantitated by scanning the resultant blue spots with a fiber optics densitometer and comparing them with standards. The method was applied to water fortified with carbaryl at 8 ppb and apples and lettuce fortified at 0.10 ppm; all recoveries were greater than 89%. The 2 crop extracts were cleaned up by using the AOAC thin layer chromatographic method for visual estimation of carbaryl. Related carbamate insecticides were detected by using the same reagent, and the potential for quantitation was demonstrated.

Determination of 3-Methoxy-4-Hydroxymandelic Acid (VMA) in Urine by Thin-Layer Chromatography

1965 ◽  
Vol 11 (10) ◽  
pp. 905-913 ◽  
Author(s):  
J S Annino ◽  
M Lipson ◽  
L A Williams
Keyword(s):  
Thin Layer ◽  
Ethyl Acetate ◽  
Thin Layer Chromatography ◽  
Silica Gel ◽  
Potassium Carbonate ◽  
Several Variables ◽  
Fast Red ◽  
Layer Chromatography

Abstract From studies of several variables, a method has been developed for the separation and quantitation of 3-methoxy-4-hydroxymandelic acid (VMA) in urine by thin-layer chromatography. The urine is pretreated with acid and Florisil, and then extracted with ethyl acetate. Thin-layer chromatography is performed on silica gel with a butanol: acetic acid:water solution. The VMA spot is located by spraying with fast red GG and potassium carbonate. After removal from the plate, maximum color is developed and quantitated by reading in a spectrophotometer at 510 mµ.

Determination of Quinomethionate (6-Methylquinoline-2,3-diyldithiocarbonate) Residues in Crops by In Situ Fluorometry

1976 ◽  
Vol 59 (1) ◽  
pp. 172-173
Author(s):  
Yves Francoeur ◽  
Victorin Mallet
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Petroleum Ether ◽  
Thin Layer Chromatography ◽  
Pesticide Residue ◽  
Simple Method ◽  
Layer Chromatography ◽  
Ppm Level

Abstract A simple method is described for the quantitative determination of quinomethionate (6-methylquinoline-2,3-diyldithiocarbonate) in crops. The pesticide residue is extracted with acetonitrile and partitioned in petroleum ether. After separation from the co-extractives by thin layer chromatography (TLC), the fluorescence is measured directly on a silica gel TLC plate. An average of 89% recovery is obtained at the 0.05 ppm level in apples, peaches, pears, and tomatoes.

Purity Indicating TLC Method for Quantitative Determination of Phenylephrine and Dimethindine Maleate in Presence of Dimethindine Maleate Impurity: 2-ethyl pyridine in Nasal Gel

2016 ◽  
Vol 1 (1) ◽  
Keyword(s):  
Quality Control ◽  
Thin Layer ◽  
Quantitative Determination ◽  
Silica Gel ◽  
High Accuracy ◽  
Raw Material ◽  
Official Method ◽  
Good Precision ◽  
Developing System

The aim of this work was to establish, optimize and validate a sensitive, selective and accurate thin layer chromatographic (TLC) method for determination of Phenylephrine (PHE), Dimetindene maleate (DM) and its major toxic impurity; 2-ethyl pyridine (EP), in raw material and nasal gel. The proposed method was applied for analysis of PHE, DM and EP over the concentration range of 1.00–10.0, 0.50–8.00 and 2.00–20.0 µg/band, respectively. The method is based on the separation of three components followed by densitometric measurement of the separated peaks at 254 nm. The separation was carried out on silica gel TLC F254 plates, using toluene: acetone: isopropyl alc.: ammonia (5.3: 2.7: 1.8: 0.4, by volume) as a developing system. The suggested method was validated according to International Conference on Harmonization guidelines and can be applied for routine analysis in quality control laboratories. The results obtained by the proposed method were statistically com-pared with the official method revealing high accuracy and good precision.

Thin Layer Chromatographic Separation and Spectrophotofluorometric Determination of Thiabendazole Residues on and in Citrus

1972 ◽  
Vol 55 (6) ◽  
pp. 1239-1244
Author(s):  
S M Norman ◽  
D C Fouse ◽  
C C Craft
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Ethyl Acetate ◽  
Chromatographic Separation ◽  
Basic Solution ◽  
Citrus Fruits ◽  
Cattle Feed ◽  
Citrus Pulp ◽  
Significant Difference

Abstract A thin layer chromatographic (TLC)-spectrophotofluorometric method was developed for quantitative determination of thiabendazole on and in citrus. Whole citrus fruits are surface stripped with ethyl acetate and a concentrated aliquot is separated by TLC. Wholefruit blends, juice, oil, and dried citrus pulp cattle feed are extracted with ethyl acetate, partitioned into 0.1N HC1, and then partitioned into ethyl acetate-chloroform from an aqueous basic solution prior to TLC. Thiabendazole is eluted from the chromatogram with acidified methanol and the intensity of fluorescence is compared to standards similarly chromatographed and measured. The method is accurate in determining thiabendazole content ranging from 0.2 to 6 ppm. Recoveries of thiabendazole from fortified samples were 95–99% for surface strippings and 70–91% for rind and pulp extractives. No significant difference was found between residue values determined by the TLC method and by the Merck method. TLC eliminates citrus constituents which occasionally interfere with the Merck method.

Quantitative Thin Layer Chromatographic Multi-Sulf onamide Screening Procedure

1983 ◽  
Vol 66 (4) ◽  
pp. 881-883
Author(s):  
Michael H Thomas ◽  
Karen E Soroka ◽  
Sharon H Thomas
Keyword(s):  
Sample Preparation ◽  
Thin Layer ◽  
Ethyl Acetate ◽  
Silica Gel ◽  
Methylene Chloride ◽  
Adsorbent Layer ◽  
Ph Adjustment ◽  
Optical Scanning

Abstract In-situ optical scanning of f luorescamine derivatives on thin layer silica gel plates provides a rapid method for the determination of multiple sulfonamides at levels below 0.1 ppm. Sample preparation is minimal. Homogenized liver or muscle is extracted with ethyl acetate and then back-extracted into 0.2M glycine buffer. After pH adjustment, the extract is washed with hexane and extracted with methylene chloride. The organic phase is evaporated to dryness and reconstituted in methanol. Pre-adsorbent layer silica gel plates are used for chromatography. The method has been applied to residues of sulfamethazine, sulfadimethoxine, sulfathiazole, sulfaquinoxaline, and sulfabromomethazine in cattle, swine, turkey, and duck tissues.

Thin Layer Chromatographic Determination of Deoxynivalenol in Wheat and Corn

1984 ◽  
Vol 67 (1) ◽  
pp. 40-43 ◽  
Author(s):  
Mary W Trucksess ◽  
Stanley Nesheim ◽  
Robert M Eppley
Keyword(s):  
Thin Layer ◽  
Ethyl Acetate ◽  
Ultraviolet Light ◽  
Silica Gel ◽  
Steam Bath ◽  
Chromatographic Determination ◽  
Detectable Amount ◽  
Fluorescent Spot ◽  
Minimum Detectable Amount

Abstract A thin layer chromatographic (TLC) method for determining deoxynivalenol (DON) in corn and wheat was developed. DON is extracted from the grain with acetonitrile–water (84 + 16) and filtered through a column of mixed alumina–charcoal–Celite (0.5 g + 0.7 g + 0.3 g). The solvent is evaporated on a steam bath. Ethyl acetate is added to the residue and heated to dissolve DON. After cooling, the residue is transferred to a vial with additional ethyl acetate and is dissolved in CHCl3–acetonitrile (4 + 1) for TLC on an AlCl3-impregnated silica gel plate with CHCI3–acetone–isopropanol (8 + 1 + 1). The plate is heated in a 120°C oven for 7 min; a blue fluorescent spot is produced under longwave ultraviolet light. DON is quantitated visually and/or fluorodensitometrically by comparison with reference standards. The minimum detectable amount of DON is ca 20 ng/spot. The limit of DON determination is ca 40 ng/g for wheat and 100 ng/g for corn. Recoveries of DON added to wheat and corn at 100, 500, and 1000 ng/ g levels were 85, 93, and 88% and 77, 80, and 80%, respectively.

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