Determination of Low Level Isolated Trans Isomers in Vegetable Oils and Derived Methyl Esters by Differential Infrared Spectrophotometry

1971 ◽  
Vol 54 (1) ◽  
pp. 47-51
Author(s):  
Anita Huang ◽  
David Firestone
Keyword(s):  
Spectrophotometric Determination ◽  
Vegetable Oils ◽  
Methyl Esters ◽  
Tentative Method ◽  
Trans Content ◽  
Infrared Spectrophotometry ◽  
Aocs Method ◽  
Trans Isomers ◽  
Low Levels

Abstract A procedure is described for differential infrared spectrophotometric determination of low levels (1–6%) of isolated trans isomers in vegetable oils or derived methyl esters. Triglycerides and methyl esters of known isolated trans content were analyzed by the procedure and results compared with those obtained with the American Oil Chemists’ Society tentative method for isolated trans isomers. Results obtained by the described method are more accurate than those obtained by the AOCS method.

Determination of Isolated Trans Isomers by Infrared Spectrophotometry

1965 ◽  
Vol 48 (2) ◽  
pp. 437-443 ◽  
Author(s):  
David Firestone ◽  
Pauline LaBouliere
Keyword(s):  
Methyl Esters ◽  
Tentative Method ◽  
Trans Content ◽  
Infrared Spectrophotometry ◽  
Trans Isomers

Abstract A study was made of the AOCS Tentative Method for Determining Isolated Trans Isomers by Infrared Spectrophotometry. Triglycerides with zero or low trans content produced isolated trans values which were about 2–3% high, whereas derived methyl esters produced values which were about 1.5–3% low. Corrections are suggested for analysis of samples of low isolated trans content. It is recommended that the AOCS Tentative Method be adopted as official, first action by the AOAC, applicable to margarines and shortenings.

Comparison of Two Infrared Methods for the Determination of Isolated Trans Unsaturation in Fats, Oils, and Methyl Ester Derivatives

1971 ◽  
Vol 54 (6) ◽  
pp. 1288-1292
Author(s):  
Anita Huang ◽  
David Firestone
Keyword(s):  
Fatty Acids ◽  
Methyl Ester ◽  
Rapid Method ◽  
Unsaturated Fatty Acids ◽  
Methyl Esters ◽  
Tentative Method ◽  
Trans Isomers ◽  
Sample Matrix ◽  
Infrared Methods

Abstract A study was made to compare the rapid method reported by Allen with the tentative method of the American Oil Chemists’ Society for the determination of isolated (unconjugated) trans isomers of unsaturated fatty acids. The rapid method was found to be less accurate. The accuracy of the rapid method can be improved by using an oil or methyl ester matrix with the same composition as the sample matrix for the determination of K-and f-values used for calculation of per cent trans isomers. Results obtained with both methods for methyl esters were more accurate than results for vegetable oils. An analysis of variance was performed to compare the methods.

Spectrophotometric Determination of Raceophenidol in Feed at Very Low Levels

1968 ◽  
Vol 51 (4) ◽  
pp. 752-755
Author(s):  
Edward L Pratt ◽  
Morris E Auerbach
Keyword(s):  
Spectrophotometric Determination ◽  
Growth Promotion ◽  
Ultraviolet Spectrum ◽  
Average Value ◽  
Collaborative Studies ◽  
Low Levels ◽  
Concentration Levels

Abstract Raceophenidol in feed at concentration levels intended for growth promotion of poultry can be estimated by a curvature inversion measurement related to the ultraviolet spectrum of derived p-methylsulfonylbenzaldehyde. The drug can be accurately measured at the 0.0005% level. Collaborative studies on the method showed an average value of 94 ± 10% of claim. The method is recommended for adoption as official, first action.

Add Methanolysis and Gas Chromatographic Determination of Brominated Vegetable Oils in Soft Drinks

1983 ◽  
Vol 66 (6) ◽  
pp. 1385-1389
Author(s):  
James F Lawrence ◽  
Rajinder K Chadha ◽  
Henry B S Conacher
Keyword(s):  
Vegetable Oils ◽  
Chromatographic Method ◽  
Methyl Esters ◽  
Chromatographic Determination ◽  
Soft Drinks ◽  
Packing Material ◽  
Organic Extraction ◽  
Chromatography Columns ◽  
Gas Chromatographic Method

Abstract A gas chromatographic method has been developed for determination of brominated vegetable oils in citrus-flavored soft drinks. Oils were extracted from the drinks with ethyl ether and subjected to acidcatalyzed methanolysis. The resulting brominated methyl esters (dibromostearate, tetrabromostearate, and hexabromostearate) were separated and quantitated as single peaks on a 3% OV-3 column. Chromatography columns were stable for about 3 months of daily use; then the first 15 cm of column packing material was replaced or a new column was prepared. A number of citrus soft drinks were analyzed and contained 3.5-3.9 mg brominated oil/10 fl. oz. Recoveries from spiked samples after organic extraction and methanolysis were 94.5-105%.

Quantitative Determination and Confirmation of Low Levels of Diethylstilbestrol in Feeds

1972 ◽  
Vol 55 (6) ◽  
pp. 1345-1353
Author(s):  
Marshall T Jeffus ◽  
Charles T Kenner
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Official Method ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Before And After ◽  
Chromatographic Procedure ◽  
Low Levels ◽  
Cis And Trans

Abstract A method for the determination of diethylstibestrol in feeds, which is based on official first action method 38.048–38.051, is proposed. Interfering feed extractives are removed by using a tripotassium phosphate-Celite column prior to measurement at 415 nm before and after irradiation. Recoveries of equilibrated standards added to Soxhlet extracts of several samples averaged 94.3% compared to 86.3% by the official method. The background absorbance at 415 nm obtained by using the proposed method was approximately 6% of the background by the official method for solutions containing equivalent amounts of sample. A thin layer chromatographic method is also included for the confirmation and identification of the cis and trans isomers of the drug. The proposed method has been found satisfactory for the quantitative determination of 0.55–44 ppm diethylstilbestrol and the thin layer chromatographic procedure can detect as little as 0.07 ppm.

Chemometric Approaches In Analysis Of Vegetable Oils As A Way To Improve An Efficiency Of Forensic Examination

2019 ◽  
Vol 14 (4) ◽  
pp. 192-199
Author(s):  
V. Rudniev ◽  
E. Simakova-Yefremian ◽  
V. Khosha ◽  
V. Ostropilets
Keyword(s):  
Vegetable Oils ◽  
Methyl Esters ◽  
Principal Component ◽  
Detailed Examination ◽  
Chemometric Methods ◽  
Split Ratio ◽  
Forensic Examination ◽  
Hidden Correlations ◽  
Identification Research

The approach to forensic examination performance through accelerated classification and identification research of vegetable oils is demonstrated. It includes derivatization of the original objects, analysis of obtained methyl esters mixture using GC-MS technique and applying of chemometric tools for gathering preliminary data. Subsequent processing of obtained chromatograms using principal component analysis for grouping of objects simplifies further detailed examination. An analysis of hidden correlations between variables and influence of the initial data on the first to third major components formation is provided. Using values of content of only 5 most widespread fat acids leads to satisfied visual pattern for prior recognition of oil samples. Applying of various split ratios is recommended at different stages of gas-chromatographic analysis. Split ratio 1 : 50 is recommended for gathering of data treated by chemometric methods and 1 : 2 is useful for determination of minor components presence as specific features.

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