Determination of Key Flavor Components in Methylene Chloride Extracts from Processed Grapefruit Juice

1998 ◽  
Vol 46 (1) ◽  
pp. 242-247 ◽  
Author(s):  
P. Jella ◽  
R. Rouseff ◽  
K. Goodner ◽  
W. Widmer
Keyword(s):  
Grapefruit Juice ◽  
Methylene Chloride ◽  
Flavor Components

Determination of Hexachlorobenzene and Mirex in Fatty Products

1975 ◽  
Vol 58 (3) ◽  
pp. 557-561
Author(s):  
Rodney L Bong
Keyword(s):  
Petroleum Ether ◽  
Electron Capture ◽  
Methylene Chloride ◽  
Fats And Oils ◽  
Fat Injection ◽  
Liquid Chromatographic ◽  
Ppm Level

Abstract A procedure is described for the isolation and cleanup of hexachlorobenzene (HCB) and mirex in fats and oils for gas-liquid chromatographic (GLC) analysis. The fat or oil is distributed on unactivated Florisil, and the HCB and mirex are eluted with acetonitrile. The pesticides are then partitioned into petroleum ether. Elution through activated Florisil with methylene chloride-hexane (20+80) is used for the final cleanup. HCB and mirex are then measured by GLC, using the appropriate electron capture conditions with a 15% OV-210 column for HCB and a 3% OV-101 column for mirex. The method demonstrates recoveries greater than 90% for HCB and mirex and allows screening at or below the 0.1 ppm level in fats with a 3 mg fat injection.

Colorimetric Determination of Carbaryl in Apple, Lettuce, Chard, and Tomato

1971 ◽  
Vol 54 (5) ◽  
pp. 1083-1085
Author(s):  
Maria H C K De Riveros ◽  
Eugenio E Vonesch
Keyword(s):  
Methylene Chloride ◽  
Zinc Hydroxide ◽  
Colorimetric Determination ◽  
Color Complex

Abstract A direct Spectrophotometric technique for determination of carbaryl in apple, lettuce, chard, and tomato has been developed, based on formation of a specific color complex with diazotized 2,5-dichloroaniline sulfate. Carbaryl is extracted with methylene chloride, concentrated, and cleaned up with zinc hydroxide. The color produced with diazotized 2,5-dichloroaniline is measured at 510 nm. Recoveries of added carbaryl from the 4 crops tested ranged from 89.6 to 105%.

Capillary Column Gas Chromatographic Determination of Trace Residues of the Herbicide Chlorsulfuron in Agricultural Runoff Water

1987 ◽  
Vol 70 (4) ◽  
pp. 745-748
Author(s):  
Uaz Ahmad
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Method ◽  
Capillary Column ◽  
Methylene Chloride ◽  
Chromatographic Determination ◽  
Agricultural Runoff ◽  
Runoff Water ◽  
Florisil Column ◽  
Gas Chromatographic Method

Abstract A capillary column gas chromatographic method is described for determining parts-per-trillion (ppt) levels of chlorsulfuron in agricultural runoff water. The water sample is acidified with acetic acid and extracted with methylene chloride. The chlorsulfuron in the extract is derivatized to its monomethyl derivative. After Florisil column cleanup, the methylated chlorsulfuron is determined by electron-capture gas chromatography. Recovery of chlorsulfuron from fortified water samples is greater than 80%. Detection limit of the method is 25 ng chlorsulfuron/L water (25 ppt). There are 2 reaction sites on the chlorsulfuron molecule, both of which are susceptible to methylation leading to monomethyl chlorsulfuron and dimethyl chlorsulfuron. A procedure is described to methylate selectively the sulfonamide nitrogen of chlorsulfuron.

Determination of Halogenated Contaminants in Human Adipose Tissue

1986 ◽  
Vol 69 (3) ◽  
pp. 451-458
Author(s):  
Guy L Lebel ◽  
David T Williams
Keyword(s):  
Gas Chromatography ◽  
Adipose Tissue ◽  
Methylene Chloride ◽  
Gel Permeation Chromatography ◽  
Human Adipose Tissue ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Fat Extraction ◽  
Capillary Column Gas Chromatography

Abstract <A method has been developed for determination of organochlorine contaminants in human adipose tissue. After fat extraction from the tissue with acetone-hexane (15 + 85, v/v), organochlorines were fractionated from fat by gel permeation chromatography with methylene chloride-cyclohexane (1 + 1, v/v) as solvent. After Florisil column cleanup, the GPC extract was analyzed by capillary column gas chromatography using 2 columns of different polarity. Compound identity was confirmed by gas chromatography-mass spectrometry using selected ion monitoring. Recoveries for fortification levels of 10-500 ng/g were greater than 80 % except for trichlorobenzene and hexachlorobutadiene (ca 60%).

Qualitative Determination of Syringaldehyde and Dihydroconiferyl Alcohol in Maple Sirup

1965 ◽  
Vol 48 (4) ◽  
pp. 689-693
Author(s):  
J C Underwood ◽  
V J Filipic
Keyword(s):  
Standard Deviation ◽  
Methylene Chloride ◽  
Single Peak ◽  
Two Samples ◽  
Qualitative Determination

Abstract The combined amount of syringaldehyde and dihydroconiferyl alcohol in maple sirup was determined by extracting the sirup with methylene chloride, isolating the compounds by GLC (SE-30 column), and comparing the height of the single peak representing the two compounds with a standard of syringaldehyde. The procedure accounts for 97–98% of the SA-DHCA in the sirup with a standard deviation of ± 4% of the value obtained. Two samples of sirup were found to contain 5 and 8 ppm SA-DHCA.

High Pressure Liquid Chromatographic Determination of Melengestrol Acetate in Dry Feed Supplements

1981 ◽  
Vol 64 (3) ◽  
pp. 661-664
Author(s):  
Jose E Roybal
Keyword(s):  
High Pressure ◽  
Standard Deviation ◽  
Methylene Chloride ◽  
Animal Feed ◽  
Confirmatory Test ◽  
High Pressure Liquid Chromatographic ◽  
Melengestrol Acetate ◽  
Feed Supplements ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic (HPLC) method is described for the quantitative determination of melengestrol acetate (MGA) in dry animal feed supplements containing 0.000027-0.000220% MGA (0.125-1.00 mg/lb). Ground feed is Soxhletextracted with hexane, and the extract is partitioned from hexane into aqueous methanol and then into methylene chloride, followed by mixed column chromatography. MGA is then quantitated by HPLC. Average recovery of standard MGA through the method at 1.00 ppm (0.454 mg/lb).was 94.8% with a 3.58% standard deviation. Average spike recovery of MGA in fortified feed at 0.100 ppm (0.0454 mg/lb) to 2.00 ppm (0.907 mg/lb) level was 97.8% with a standard deviation of 5.39%. In addition, the method includes a 2-dimensional thin layer chromatographic confirmatory test for MGA.

scholarly journals Typical Phthalate Ester Contamination Incurred Using EPA Method 8060*

1990 ◽  
Vol 73 (5) ◽  
pp. 709-720 ◽  
Author(s):  
Viorica Lopez-Avila ◽  
June Milanes ◽  
Franklin Constantine ◽  
Werner F Beckert
Keyword(s):  
Environmental Protection Agency ◽  
Environmental Samples ◽  
Methylene Chloride ◽  
Phthalate Esters ◽  
Aluminum Foil ◽  
Phthalate Ester ◽  
Laboratory Evaluation ◽  
Single Laboratory ◽  
Common Laboratory

Abstract Methods for determination of trace levels of phthalate esters In environmental samples require procedures that avoid the Introduction of laboratory contaminants. Because It Is difficult to avoid contamination of samples with phthalate esters from laboratory reagents, materials, and glassware, we have undertaken a study to determine the sources, extent of contamination, and conditions under which background contamination can be minimized. Solvents such as acetone, hexane, diethyl ether, isooctane, and methylene chloride, and reagent water samples from various commercial suppliers were analyzed for 11 phthalate esters. Florlsll, alumina, silica gel, anhydrous sodium sulfate, filter paper, paper thimbles, glass wool, and aluminum foil were washed with organic solvents and the solvent washings were analyzed for 11 phthalate esters. Finally, we addressed the likelihood of contamination of laboratory glassware subjected to common laboratory cleanup procedures and the likelihood of contamination of hexane and Isooctane stored In sample vials of different sizes. The present study was conducted in conjunction with the single-laboratory evaluation of U.S. Environmental Protection Agency (EPA) method 8060 for determination of phthalate esters in environmental samples.

Determination of Cholesterol by p-Nitrobenzoate Derivatization and Liquid Chromatography

1994 ◽  
Vol 77 (5) ◽  
pp. 1190-1196 ◽  
Author(s):  
Thomas W Hamill ◽  
Abdel M Soliman
Keyword(s):  
Dairy Products ◽  
Isopropyl Alcohol ◽  
Methylene Chloride ◽  
Limit Of Detection ◽  
Lipid Extraction ◽  
Diode Array ◽  
Gas Chromatographic Method ◽  
Certified Values ◽  
Peak Purity

Abstract The method involves direct saponification and formation of the sterol p-nitrobenzoate (PNB) derivatives or lipid extraction with methylene chloride and isopropyl alcohol, saponification, fatty acid methylation, and formation of the sterol PNB derivatives. The sterol PNB derivatives are separated on a C8 column with a mobile phase of acetonitrile-hexane-water (250 + 30 + 3) and quantitated by UV detection at 280 nm. The limit of detection for cholesterol is 2 ng. The response was linear over a range of 4 to 250 ng (r = 0.999). Assays of NIST SRM 1845 and 1563 by this method gave results that were closer to the certified values than were results obtained by the AOAC gas chromatographic method. Reproducibility was evaluated by using foods containing low, medium, and high levels of cholesterol. The % coefficient of variation ranged from 1.8 to 6.7. Studies on a wide variety of food products (using lipid extraction and saponification-methylation) gave a mean recovery of 87.5 ± 10.1%. Direct saponification of poultry and dairy products gave a mean recovery of 101.3 ± 15.8%. Peak purity was determined by diode array spectrophotometry.

Gas Chromatographic-Mass Spectrometric Determination of Six Sulfonamide Residues in Egg and Animal Tissues

1990 ◽  
Vol 73 (6) ◽  
pp. 886-892 ◽  
Author(s):  
Keigo Takatsuki ◽  
Tadashi Kikuchi
Keyword(s):  
Methylene Chloride ◽  
Mass Spectrometric ◽  
Gas Chromatography Mass Spectrometry ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Animal Tissues ◽  
Selected Ion Monitoring ◽  
Ether Solution ◽  
Sulfonamide Residues

Abstract A gas chromatographlc-mass spectrometric method using selected Ion monitoring mode for simultaneous determination of 6 sulfonamides in egg and edible animal tissues has been developed. Sulfonamides are extracted from a sample with acetonltrlle. The extract Is passed through a silica cartridge column and concentrated. Dlazomethane in ether Is added to methylate sulfonamides. After evaporation, the residue Is dissolved In methylene chloride and cleaned up by silica gel column chromatography. The methylene chloride eluate containing sulfonamide-methyl derivatives Is evaporated to dryness, redlssolved In ether and partitioned between 6N hydrochloric acid. The acid phase is made alkaline, extracted with ether, and the ether solution, after concentration, Is analyzed by gas chromatography-mass spectrometry in selected Ion monitoring mode. Average recoveries from egg and silver salmon fortified at 1 and 0.2 ppm levels with 6 sulfonamides are 99.2 and 84.3%, respectively; coefficients of variation are 7.03 and 11.20%, respectively. Detection limits are 0.01-0.05 ppm.

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