Analysis of Fat-Soluble Vitamins. XXIX. Liquid Chromatographic Determination of Vitamin D in AD Concentrates: Collaborative Study

1985 ◽  
Vol 68 (5) ◽  
pp. 822-825
Author(s):  
Ellen J De Vries ◽  
Ben Borsje
Keyword(s):  
Vitamin D ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Single Column ◽  
Liquid Chromatographic Determination ◽  
Repeatability And Reproducibility ◽  
High Level ◽  
Fat Soluble Vitamins ◽  
Liquid Chromatographic

Abstract A simplified liquid chromatographic (LC) method for determining vitamin D in vitamin AD concentrates (> 5000 IU vitamin D/g) was collaboratively studied. In the simplified method, the 2 columns specified in AOAC LC method 43.101-43.109 are replaced by a single column, which separates the vitamin D isomers and the vitamin A esters. The procedure for oils includes dissolution and quantitation by normal phase LC. Dry multivitamin concentrates and aqueous dispersions are treated with an enzyme system and the vitamins are extracted with n-pentane. Six coded samples were distributed to 16 laboratories; 15 collaborators returned their results. Estimates of repeatability and reproducibility for the oil samples were 1.1 and 3.1%, respectively; for the high-level concentrated dry preparation 1.4 and 3.9% and for the low-level concentrated dry preparation 1.3 and 11.4%, respectively. These values are a considerable improvement over the results obtained in the 1979 multivitamin collaborative study. The method has been adopted official first action for determination of vitamin D in vitamin AD concentrates containing s 5000 IU vitamin D/g.

Liquid Chromatographic Determination of Methyldopa and Methyldopa-Thiazide Combinations in Tablets: Collaborative Study

1984 ◽  
Vol 67 (6) ◽  
pp. 1118-1120
Author(s):  
Ting Susan ◽  
◽  
R L Brown ◽  
L A Dougherty ◽  
J B Schepman ◽  
...  
Keyword(s):  
Chromatographic Method ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Repeatability And Reproducibility ◽  
Liquid Chromatographic

Abstract A reverse phase liquid chromatographic method for the determination of methyldopa, methyldopa-hydrochlorothiazide, and methyldopachlorothiazide in tablets was collaboratively studied by 8 laboratories. Each collaborator received 20 samples that included drug substance, synthetic and commercial tablet compositions. The overall repeatability and reproducibility standard deviations for commercial tablets were 1.11 and 1.75% for methyldopa, 0.96 and 1.62% for chlorothiazide, and 1.21 and 2.15% for hydrochlorothiazide, respectively. The overall recoveries of methyldopa, chlorothiazide, and hydrochlorothiazide added to synthetic tablets were 100.78, 100.70, and 101.34%, respectively. The method has been adopted official first action.

High Pressure Liquid Chromatographic Determination of Glycyrrhizic Acid or Glycyrrhizic Acid Salts in Various Licorice Products: Collaborative Study

1982 ◽  
Vol 65 (3) ◽  
pp. 572-574
Author(s):  
Peter S Vora ◽  
◽  
H Estes ◽  
Dr Grigor ◽  
B Hodge ◽  
...  
Keyword(s):  
High Pressure ◽  
Glycyrrhizic Acid ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Repeatability And Reproducibility ◽  
Liquid Chromatographic ◽  
Acid Salts

Abstract A collaborative study determining glycyrrhizic acid or glycyrrhizic acid salts content of various licorice products has been conducted using high pressure liquid chromatography (HPLC). Five samples containing various concentrations of glycyrrhizic acid were analyzed in blind replicates by 8 collaborators. The results indicate excellent repeatability and reproducibility with coefficients of variation less than 7.5%. In addition, this method allows the determination of glycyrrhizic acid in less than 15 min compared with 3 days for the conventional gravimetric and colorimetric methods. The method has been adopted official first action.

Analysis of Fat-Soluble Vitamins. XXV. High Performance Liquid Chromatographic Determination of Vitamin D in Multivitamin Preparations: Collaborative Study1

1981 ◽  
Vol 64 (1) ◽  
pp. 61-70
Author(s):  
Ellen J De Vries ◽  
Frits J Mulder ◽  
Ben Borsje ◽  
◽  
L Ameika ◽  
...  
Keyword(s):  
Vitamin D ◽  
High Performance ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Hplc Method ◽  
Phase System ◽  
Single Column ◽  
Liquid Chromatographic Determination ◽  
Fat Soluble Vitamins ◽  
Liquid Chromatographic

Abstract The HPLC method for determining vitamin D in multivitamin preparations was studied collaboratively. Samples were distributed to 43 laboratories in 10 countries. Twenty-four laboratories gave their results. The method specifies a reverse phase system for the cleanup and a straight phase system for the determination. Difficulties arise when laboratories are equipped with HPLC apparatus with a single column. Laboratories experienced in vitamin D analysis reported good results, even if they were equipped with a single column HPLC apparatus. Eleven of the 24 laboratories reported satisfactory results. For this rather complicated method, the coefficient of variation for a single assay is acceptable. The method has been adopted official first action as an alternative procedure to the chemical method for determining vitamin D in multivitamins.

High Performance Liquid Chromatographic Determination of Intermediates and Two Reaction By-Products in FD&C Red No. 40: Collaborative Study

1981 ◽  
Vol 64 (2) ◽  
pp. 324-331
Author(s):  
Elizabeth A Cox ◽  
George F Reed ◽  
◽  
L Bille ◽  
R Bischof ◽  
...  
Keyword(s):  
High Performance ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic Determination ◽  
Repeatability And Reproducibility ◽  
Liquid Chromatographic ◽  
By Products

Abstract Nine laboratories participated in a collaborative study of an ion exchange high performance liquid chromatographic procedure for determining the intermediates and 2 reaction by-products in FD&C Red No. 40: cresidine sulfonic acid (CSA), Schaeffer’s Salt (SS), 4,4’-(diazoamino)bis(5-methoxy-2-methylbenzenesulfonic acid) (DMMA), and 6,6’-oxybis(2- naphthalenesulfonic acid) (DONS), respectively. The repeatability and reproducibility standard deviations (absolute) found in the study were 0.012 and 0.019 for CSA at the 0.2% level, 0.004 and 0.006 for DMMA at the 0.1% level, 0.067 and 0.087 for DONS at the 1% level, and 0.015 and 0.020 for SS at the 0.3% level, respectively. The method has been adopted official first action.

Liquid Chromatographic Determination of Glyphosate and Aminomethylphosphonic Acid (AMPA) in Environmental Water: Collaborative Study

1991 ◽  
Vol 74 (2) ◽  
pp. 317-323 ◽  
Author(s):  
Mark E Oppenhuizen ◽  
John E Cowell
Keyword(s):  
Collaborative Study ◽  
Chromatographic Determination ◽  
Environmental Water ◽  
Aminomethylphosphonic Acid ◽  
Relative Standard ◽  
Total Variability ◽  
Liquid Chromatographic Determination ◽  
Predicted Values ◽  
Liquid Chromatographic

Abstract A new method for determination of glyphosate and amlnomethylphosphonlc acid (AMPA) residues In environmental water was collaboratively studied by 6 laboratories. The method Is simpler and shorter than previous methods. A filtered volume of water is evaporated to dryness and the residue Is dissolved In a buffered EDTA solution. Glyphosate and AMPA are determined by liquid chromatography with postcolumn reaction detection. The method was validated over the range 0.50-5000 ppb, although one of the collaborating laboratories could not reliably quantltate below 1.0 ppb. Statistical analysis of the results showed that typical reproducibility relative standard deviations (RSDR) ranged from 11 to 20% for both glyphosate and AMPA, which compares very well with predicted values for this concentration range. Total variability (as measured by sR) Increased with increasing fortification level. The method has been adopted official first action by AOAC.

Collaborative Study of the Quantitative Gas-Liquid Chromatographic Determination of Fusel Oil and Other Components in Whisky

1972 ◽  
Vol 55 (3) ◽  
pp. 549-556
Author(s):  
J H Kahn ◽  
E T Blessinger
Keyword(s):  
Ethyl Acetate ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Official Method ◽  
Fusel Oil ◽  
Fusel Alcohols ◽  
Aoac Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Fifteen chemists participated in a collaborative study for the quantitative pas-liquid chromatographic determination of the individual fusel alcohols and ethyl acetate in whisky. Two levels of congeners represented by 4 coded samples of whisky were analyzed by using t h e proposed method, employing a glycerol-1,2,6-hexanetriol column, and the official AOAC method, 9.063-9.065. Since isobutyl and the atnyl alcohols comprise by far the greatest part of fusel oil, their determination is of major importance to the total fusel oil content . Statistical analyses show that the proposed method is superior to the AOAC method for the determination of these alcohols, whereas the official method is superior for the determination of ethyl acetate and n-propyl alcohol. In general, collaborators employing modern instrumentation preferred the proposed method over the AOAC method. The former method also separates and permits the quantitative measurement of active amyl and isoamyl alcohols. The proposed method has been adopted as official first action as an alternative to 9.063–9.065 for the determination of higher alcohols and ethyl acetate in whisky.

Analysis of Fat-Soluble Vitamins. XXII. High Performance Liquid Chromatographic Determination of Vitamin D in Concentrates. Collaborative Study1

1979 ◽  
Vol 62 (5) ◽  
pp. 1031-1040
Author(s):  
Frits J Mulder ◽  
Ellen J De Vries ◽  
Ben Borsje
Keyword(s):  
Vitamin D ◽  
High Performance ◽  
Chemical Method ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Hplc Method ◽  
De Vries ◽  
Fat Soluble Vitamins ◽  
Liquid Chromatographic

Abstract A collaborative study was carried out which compared the official chemical method (43.B14- 43.B24), the HPLC method according to Hofsass et al. including maleic anhydride treatment, and the HLPC procedure according to De Vries et al. for vitamin D concentrates. A total of 396 samples were distributed to 33 collaborators for analysis. Five laboratories performed both the chemical and the HPLC methods. Five laboratories performed the Hofsass method and 16 laboratories performed the De Vries method. The results for the chemical method agreed with the theoretical values for the samples, and the standard deviation was comparable to that obtained in previous AOAC collaborative studies. Collaborative results for the Hofsass method were low. In addition, incorrect use of a fixed conversion factor (1/0.586) and necessity of a double chromatographic system on a non-treated and a treated vitamin D sample reduce the effectiveness of the method. There were no adverse reactions to the De Vries HPLC method. It is recommended that the method be adopted official first action as an alternative procedure for determining vitamin D in concentrates, excluding powders containing irradiated 7-dehydrocholesterol.

Liquid Chromatographic Determination of Diazepam in Tablets: Collaborative Study

1985 ◽  
Vol 68 (3) ◽  
pp. 545-546
Author(s):  
Michael Tsougros
Keyword(s):  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
Photometric Detection ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
The Mean ◽  
Liquid Chromatographic

Abstract A stability indicating liquid chromatographic method for the determination of diazepam in tablets was collaboratively studied by 6 laboratories. The method uses a Cig reverse phase column, a methanolwater mobile phase, p-tolualdehyde as the internal standard, and photometric detection at 254 nm. The collaborators were supplied with a synthetic tablet powder and 3 commercial tablet samples. The mean recovery of diazepam from the synthetic tablet powder was 100.2%. For all samples analyzed, the coefficient of variation was < 1.5%. The method has been adopted official first action.

Liquid Chromatographic Determination of Methiocarb in Technical and Formulated Products: Collaborative Study

1984 ◽  
Vol 67 (3) ◽  
pp. 492-493
Author(s):  
Stephen C Slahck ◽  
◽  
A A Carlstrom ◽  
L T Chenery ◽  
N D Ellis ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
Reverse Phase Chromatography ◽  
Wettable Powder ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract An LC method for the determination of methiocarb in methiocarb technical and formulated products has been subjected to a collaborative study with 9 participating collaborators. Formulations are extracted with acetonitrile and analyzed by reverse phase chromatography, with acetophenone as an internal standard. Collaborators were furnished samples of technical, 75% wettable powder, 75% seed treater, 75% concentrate, and 50% hopper box treater. Coefficient of variation values obtained on the 5 samples were 0.71, 0.83, 0.62, 1.57, and 0.82%, respectively. The method has been adopted official first action.

Gas-Liquid Chromatographic Determination of Mirex and Photomirex in the Presence of Poly chlorinated Biphenyls: Interlaboratory Study

1980 ◽  
Vol 63 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Ross J Norstrom ◽  
Henry T Won ◽  
Micheline Van Hove Holdrinet ◽  
Patrick G Calway ◽  
Caroline D Naftel
Keyword(s):  
Chromatographic Determination ◽  
Interlaboratory Study ◽  
Gas Liquid Chromatography ◽  
Coefficients Of Variation ◽  
Fuming Nitric Acid ◽  
Liquid Chromatographic Determination ◽  
Repeatability And Reproducibility ◽  
Concentrated Sulfuric Acid ◽  
Liquid Chromatographic

Abstract Mirex and photomirex (8-monohydromirex) were separated from polychlorinated biphenyls (PCBs) and other aromatic compounds by nitration with fuming nitric acid-concentrated sulfuric acid and removal of nitro-PCBs on an alumina microcolumn; the compounds were then determined by gas-liquid chromatography. Recoveries of Mirex and photomirex were 102±8 and 104±5%, respectively, from standard solutions which had a PCB-to-Mirex and photomirex ratio of 1000. Recoveries from fortified, uncontaminated samples of sediment, fish, and eggs averaged 93±7 and 92±3% for Mirex and photomirex, respectively. The coefficients of variation for repeatability and reproducibility averaged 8 and 15%, respectively, in an interlaboratory study conducted by 4 laboratories using extracts of naturally contaminated substrates (sediment, carp, eel, and gull egg). Levels of Mirex in the samples ranged from 0.1 to 8 mg/kg, and levels of PCB ranged from 0.5 to 166 mg/kg.

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