Thin Layer and Gas-Liquid Chromatography of Cholesterol in Fats and Oils. II. Collaborative Study

1969 ◽  
Vol 52 (4) ◽  
pp. 778-781
Author(s):  
C W Thorpe
Keyword(s):  
Unsaponifiable Matter ◽  
Collaborative Study ◽  
Fats And Oils ◽  
Gas Liquid Chromatography ◽  
Animal Fats ◽  
Animal Fat ◽  
Low Levels ◽  
Positive Results ◽  
Column Chromatographic

Abstract A method employing TLC-GLC for detecting animal fats in vegetable fats was subjected to collaborative study. The method involves preparative TLC of unsaponifiable matter followed by GLC of the isolated sterols. The results of this study, based on GLC determination of cholesterol in the isolated sterols, indicate that low levels (2.5%) of animal fat can be detected. The possibility of obtaining false positive results is greatly reduced compared with direct GLC of unsaponifiable matter or column chromatographic fractionation of unsaponifiable matter followed by GLC analysis.

Thin Layer and Gas-Liquid Chromatography of Cholesterol in Fats and Oils. I. Development of Method

1969 ◽  
Vol 52 (4) ◽  
pp. 774-778
Author(s):  
C W Thorpe ◽  
Linda Pohland ◽  
D Firestone
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Unsaponifiable Matter ◽  
Fats And Oils ◽  
Cholesterol Content ◽  
Gas Liquid Chromatography ◽  
Animal Fat ◽  
Low Levels ◽  
Layer Chromatography

Abstract A inethod is described for analysis of sterols by thin layer chromatography-gas liquid chromatography (TLC-GLC). Sterols are isolated from other components of unsaponifiable matter by preparative TLC. The sterols are quantitatively removed from the TLC plate, extracted from the silica gel, and analyzed by GLC. This method has been used to detect low levels (2–3%) of animal fat in vegetable oil by measuring the cholesterol content of the animal fatvegetable oil admixtures.

Collaborative Study of the Recovery of Hexachlorobenzene and Mirex in Butterfat and Fish

1977 ◽  
Vol 60 (1) ◽  
pp. 229-232
Author(s):  
Rodney L Bong
Keyword(s):  
Dairy Products ◽  
Methylene Chloride ◽  
Collaborative Study ◽  
Fats And Oils ◽  
Gas Liquid Chromatography ◽  
Fish Sample ◽  
Low Level ◽  
High Level ◽  
Different Levels

Abstract A previously published method applicable to the recovery of hexachlorobenzene (HCB) and Mirex (dodecachlorooctahydro-1,3,4-metheno-2H-cyclobuta (cd) pentalene) from fats and oils has been collaboratively studied by 8 laboratories. The method involves distribution of the fat or oil on unactivated Florisil and elution of the HCB and Mirex with acetonitrile. The 2 compounds are then partitioned into petroleum ether and eluted through activated Florisil with methylene chloride-hexane. Electron capture gas-liquid chromatography is utilized as the determinative step. In the collaborative study, samples of sablefish and butterfat were fortified at 2 different levels; each level was determined in duplicate. Average HCB recoveries of 98±7% and 95±13% at respective levels of 0.06 and 0.5 ppm were obtained from the fish sample. Mirex recoveries in the fish sample at the same levels were 85±l4% and 96±10%. The butterfat sample was fortified at a low level of 0.13 ppm for both compounds and at high levels of 0.62 and 0.66 ppm for HCB and Mirex, respectively. The low level HCB recovery was 104±6% and the high level was 99±10%. In the same order, Mirex was recovered at 104±7% and 103±6%. The method has been adopted as official first action for the determination of HCB and Mirex in fish and fatty dairy products.

An Isolation and Cleanup Procedure for Low Levels of Organochlorine Pesticide Residues in Fats and Oils

1973 ◽  
Vol 56 (3) ◽  
pp. 733-738
Author(s):  
Mildred L Porter ◽  
Jerry A Burke
Keyword(s):  
Organochlorine Pesticide ◽  
Pesticide Residues ◽  
Fats And Oils ◽  
Solvent System ◽  
Gas Liquid Chromatography ◽  
Organochlorine Pesticide Residues ◽  
Cleanup Procedure ◽  
Florisil Column Chromatography ◽  
Low Levels

Abstract An isolation and cleanup is described for low levels of organochlorine residues (about 0.005 ppm) in fats and oils, prior to electron capture gas-liquid chromatography. The fat or oil is distributed on a column of unactivated Florisil and the residues are partitioned into an eluant of 10% water in acetonitrile. Florisil column chromatography with an elution solvent system comprised of mixtures of methylene choride, acetonitrile, and hexane is used for the final cleanup. Extracts prepared in this manner are sufficiently free of fatty extractives to permit injection of the equivalent of 50–60 mg fat sample for GLC. The procedure should be especially useful in determination of low levels of organochlorine pesticide residues in the fat of certain dietary composites.

Qualitative Ampule and Multitest for Beta-Lactam Residues in Fluid Milk Products: Collaborative Study

1982 ◽  
Vol 65 (5) ◽  
pp. 1193-1207 ◽  
Author(s):  
Wesley N Kelley ◽  
◽  
J Andrews ◽  
A W Appelt ◽  
R Barber ◽  
...  
Keyword(s):  
Bacillus Stearothermophilus ◽  
Collaborative Study ◽  
Original Method ◽  
Penicillin G ◽  
Beta Lactam ◽  
Milk Products ◽  
Low Levels ◽  
Positive Results ◽  
Made In ◽  
Fluid Milk

Abstract A collaborative study was performed on a rapid Bacillus stearothermophilus agar diffusion ampule method to detect low levels of penicillin G in 7 types of fluid milk products. A multitest technique for processing a large number of samples simultaneously was also studied. Slight modifications were made in the original method to establish more uniformity and to eliminate doubtful responses by specifying a confirmation procedure. Twenty samples spiked with penicillin G (0.000 to 0.008 IU/mL) and tetracycline hydrochloride were frozen and sent to 20 laboratories in the ampule test, and 16 laboratories in the multitest. Each analyst was asked to do a screening run and a confirmation run. Results were reported by color reaction and also as positive or negative for β-lactam inhibitors. The concentrations (penicillin G) where percent positive results equal 100 or not significantly less than 100 (α = 0.05) ranged from 0.005 to 0.007 IU/mi in the ampule test and from 0.004 to 0.007 IU/mL in the multitest. Both techniques have been adopted official first action.

Determination of p-Toluenesulfonamide in Ice Cream by Combination of Continuous Flow and Liquid Chromatography: Summary of Collaborative Study

1994 ◽  
Vol 77 (3) ◽  
pp. 672-674 ◽  
Author(s):  
Paul R Beuaars ◽  
Remmelt Van Dijk ◽  
Arie Brands
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Continuous Flow ◽  
Collaborative Study ◽  
Ice Cream ◽  
Relative Standard ◽  
On Line ◽  
Positive Results

Abstract A collaborative study of the determination of p-tolu-enesulfonamide (p-TSA) in ice cream by a combination of continuous flow and on-line liquid chromatography was conducted. Seven ice cream samples containing 0-6.35 mg p-TSA/kg at 4 levels (1 blank and 3 pairs of split level samples) were analyzed by 11 laboratories. For all samples analyzed, the repeatability relative standard deviation varied from 2.08 to 3.67%, whereas the reproducibility relative standard deviation ranged from 7.79 to 11.68%. The average p-TSA values for the split levels 1,2, and 3 were 0.55,1.02, and 4.44 mg p-TSA/kg, respectively, with mean recoveries ranging from 76 to 79% (overall recovery range for all levels, 63-101 %). No false positive results were reported for the blank sample, and no interference was encountered by the presence of vanillin in samples. The method has been adopted first action by AOAC INTERNATIONAL.

Gas-Liquid Chromatographic Determination of TYans-Unsaturation in Fats and Oils on Packed Columns: Effect of Positional Isomers

1978 ◽  
Vol 61 (3) ◽  
pp. 702-708
Author(s):  
Henry B S Conacher ◽  
Jagannath R Iyengar
Keyword(s):  
Fats And Oils ◽  
Chromatographic Determination ◽  
Packed Columns ◽  
Gas Liquid Chromatography ◽  
Positional Isomers ◽  
Tubular Columns ◽  
Acid Isomerization ◽  
Cis And Trans ◽  
Liquid Chromatographic

Abstract Studies in our laboratories indicated that the trans contents of a number of commercial margarines, determined by gas-liquid chromatography (GLC) on a 15 ft column packed with 10% Silar IOC, were approximately 80-85% of those determined by infrared spectroscopy. This is mainly due to overlap of some of the trans positional isomers with the cis positional isomers in the octadecenoate fraction, shown by studies involving determination of the transoctadecenoate content of the margarines by silver ion thin layer chromatography/GLC, and by preparation and study of the GLC behavior of the cis and trans positional isomers of Δ6-, Δ9-, Δ12-, and Δl5-octadecenoates. The last 3 isomers were prepared by hydrazine reduction and nitrous acid isomerization of linoleic and linolenic acids. Since it is possible that longer, more efficient columns might result in better separation of the cis- and traru-octadecenoate isomers, it is recommended that studies be continued on longer packed columns (20 ft) and possibly on support-coated open tubular columns.

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