High Pressure Liquid Chromatographic Determination of Nitrogen Derived from Urea and Water-Soluble Methylene Ureas in Urea Formaldehyde Fertilizers: Collaborative Study

1983 ◽  
Vol 66 (3) ◽  
pp. 769-774
Author(s):  
Allan D Davidson ◽  
◽  
E R Austin ◽  
B M Christensen ◽  
D Coggin ◽  
...  
Keyword(s):  
High Pressure ◽  
Urea Formaldehyde ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Water Soluble ◽  
High Pressure Liquid Chromatographic ◽  
Paired Samples ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A melhod for measuring nitrogen derived from urea, melhylenediurea (MDU), and dimethylenetriurea (DMTU) was tested by 9 collaborators. Collaborators made single determinations on 2 separate days on 5 sets of paired samples. Samples were extracted with water, filtered, and analyzed after high pressure liquid chromatographic separation on a C-8 or C-18 bonded silica column, using a refractive index detector. Peak heights compared to external standard of each component were used for quantitation. Mean coefficients of variation for the completed study were 3.24% for urea, 3.48% for MDU, and 6.56% for DMTU. The method has been adopted official first action.

Liquid Chromatographic Determination of Nitrogen Derived from Urea and Water-Soluble Methylene Ureas in Urea Formaldehyde Fertilizers: Collaborative Study II

1984 ◽  
Vol 67 (4) ◽  
pp. 768-770
Author(s):  
Allan D Davidson ◽  
◽  
C Barry ◽  
J Carmany ◽  
A F Grigor ◽  
...  
Keyword(s):  
Urea Formaldehyde ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Water Soluble ◽  
Paired Samples ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Aoac Official ◽  
Liquid Chromatographic

Abstract A second collaborative study with 6 collaborators was conducted on the AOAC official first action method for measuring nitrogen derived from urea, methylenediurea (MDU), and dimethylenetriurea (DMTU). No variations were made. The collaborators made single determinations on 2 separate days on 5 sets of paired samples. The mean coefficients of variation for the completed study were 4.22% for urea, 5.08% for MDU, and 5.48% for DMTU, which are only slightly higher than the values reported in the first study: urea, 3.24%; MDU, 3.48%; and DMTU, 6.56%. The method has been adopted official final action.

High Pressure Liquid Chromatographic Determination of Oxazepam Dosage Forms: Collaborative Study

1983 ◽  
Vol 66 (4) ◽  
pp. 864-866
Author(s):  
Eileen S Bargo ◽  
◽  
E Aranda ◽  
C Bonnin ◽  
S Hauser ◽  
...  
Keyword(s):  
High Pressure ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A reverse phase high pressure liquid chromatographic method for the determination of oxazepam in tablets and capsules was collaboratively studied by 9 laboratories. Collaborators were supplied with 6 samples that included synthetic and commercial formulations. Tablet and capsule composites are diluted with methanol and filtered. Oxazepam is determined at 254 nm by using a C18 column. Mean recoveries of oxazepam from synthetic tablet and capsule formulations were 97.2 and 99.0%, respectively. Mean coefficients of variation for tablets and capsules ranged from 1.85 to 2.86%. The method has been adopted official first action.

High Pressure Liquid Chromatographic Determination of Antihistamine-Adrenergic Combination Products: Collaborative Study

1981 ◽  
Vol 64 (3) ◽  
pp. 564-569 ◽  
Author(s):  
William J Bachman ◽  
◽  
M Y Alpert ◽  
E Bargo ◽  
R E Draper ◽  
...  
Keyword(s):  
High Pressure ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Chlorpheniramine Maleate ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A reverse phase high pressure liquid chromatographic method in which ion-pairing is used for the determination of combinations of pseudoephedrine hydrochloride with triprolidine hydrochloride or chlorpheniramine maleate in syrups and tablets was collaboratively studied by 8 laboratories. Collaborators were supplied with 12 samples including synthetic and commercial syrup formulations and commercial tablet composites. Mean recoveries of pseudoephedrine hydrochloride and triprolidine hydrochloride from synthetic syrup formulations were 100.5 and 99.6%, respectively. Mean recoveries of pseudoephedrine hydrochloride and chlorpheniramine maleate from synthetic syrups were 98.8 and 100.5%, respectively. Mean coefficients of variation for syrups and tablets ranged from 1.68 to 3.07% for pseudoephedrine hydrochloride, from 2.92 to 3.85% for triprolidine hydrochloride, and from 1.34 to 2.15% for chlorpheniramine maleate. The method has been adopted official first action.

High Pressure Liquid Chromatographic Determination of Ethion in Formulations: Collaborative Study

1979 ◽  
Vol 62 (1) ◽  
pp. 11-14
Author(s):  
James E Launer
Keyword(s):  
High Pressure ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Peak Height ◽  
Hplc Method ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A simple and rapid high pressure liquid chromatographic (HPLC) method is described for determining ethion (O,O,O',0'-tetraethyl-S,S'-methylene bisphosphorodithioate) in formulations, using reverse phase columns of either μBondapak C18/Porasil or ODS Permaphase. The sample is dissolved in either methanol for μBondapak C18 or acetonitrile for ODS Permaphase; pentachloronitrobenzene is used as an internal standard. After inert materials are removed, the supernate is injected onto the HPLC column and the compound is quantitated by peak height ratios at 254 nm. Six collaborators made single determinations of 8 samples. The average coefficients of variation were 0.76% for the 2 technical samples, 0.63% for the two 50% formulations, 0.95% for the two 25% wettable powders, and 0.76% for the two 2% oil formulations. The method was adopted as official first action.

Ion Pairing High Pressure Liquid Chromatographic Determination of Amaranth in Licorice Products

1981 ◽  
Vol 64 (6) ◽  
pp. 1411-1413
Author(s):  
William J Hurst ◽  
James M Mckim ◽  
Robert A Martin
Keyword(s):  
High Pressure ◽  
Ion Pairing ◽  
Chromatographic Determination ◽  
Buffer Solution ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic method is described for the determination of amaranth (FD&C Red No. 2; Red No. 2) in licorice products. The Red No. 2 is extracted with a basic buffer solution, cleaned up on a Sep-Pak column, chromatographed on a reverse phase column in the ion pairing mode, and detected at 254 nm. The procedure is time-conservative with accurate and precise results. Recovery data ranged from 93 to 104%, and coefficients of variation were less than 4% for standards and samples.

High Pressure Liquid Chromatographic Determination of Theobromine and Caffeine in Cocoa and Chocolate Products: Collaborative Study

1980 ◽  
Vol 63 (3) ◽  
pp. 591-594
Author(s):  
Wesley R kreiser ◽  
Robert A Martin ◽  
◽  
R Bigornia ◽  
R Bond ◽  
...  
Keyword(s):  
High Pressure ◽  
Petroleum Ether ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Peak Height ◽  
High Pressure Liquid Chromatographic ◽  
Liquid Chromatographic Determination ◽  
The Mean ◽  
Liquid Chromatographic

Abstract Four duplicate samples of cocoa-containing materials, a practice sample, and standards were submitted to the collaborators for theobromine and caffeine analysis by HPLC. In the method the samples are defatted with petroleum ether, and dried. The fat-free residue is then extracted with water and an aliquot is injected into the chromatograph. Compounds are quantitated by comparison with internal or external standards, either by peak height or peak area. Results for all the analyses showed that few of the values were more than 2 standard deviations from the mean. The method has been adopted as official first action.

High Pressure Liquid Chromatographic Determination of Physostigmine Salicylate and Physostigmine Sulfate in Liquids and Ointments: Collaborative Study

1982 ◽  
Vol 65 (1) ◽  
pp. 132-137
Author(s):  
Norlin W Tymes ◽  
◽  
G Briguglio ◽  
C Corcoran ◽  
R Everett ◽  
...  
Keyword(s):  
High Pressure ◽  
Collaborative Study ◽  
Internal Standard ◽  
Pharmaceutical Formulations ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
High Pressure Liquid Chromatographic ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Results of 11 laboratories are presented for the collaborative study of a proposed method for the quantitative reverse phase high pressure liquid chromatographic (HPLC) determination of physostigmine salicylate and physostigmine sulfate in pharmaceutical formulations. The samples consisted of commercial solution, injection, and ointment preparations, each containing one of the physostigmine salts. The physostigmine salt is extracted from ointments with acetonitrile after the ointment is dissolved in hexane. Liquid preparations are diluted directly. Physostigmine is determined at 254 nm on a C18 column by comparison with a physostigmine standard. Flurazepam hydrochloride is the internal standard. The method has been adopted official first action for the solution dosage form.

High Pressure Liquid Chromatographic Determination of Theobromine and Caffeine in Cocoa and Chocolate Products

1978 ◽  
Vol 61 (6) ◽  
pp. 1424-1427 ◽  
Author(s):  
Wesley R Kreiser ◽  
Robert A Martin
Keyword(s):  
High Pressure ◽  
Chromatographic Determination ◽  
Hot Water ◽  
Reverse Phase ◽  
High Pressure Liquid Chromatographic ◽  
Hot Water Extraction ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A method was developed for determining theobromine and caffeine in cocoa and chocolate products by high pressure liquid chromatography. After a simple hot water extraction, both theobromine and caffeine were separated by using a reverse phase Cl s column and a mobile phase of methanol-water-acetic acid (20+ 79+1). Theobromine and caffeine were quantitated at 280 nm; average recoveries were 98.7 and 95.0%; and coefficients of variation were 2.31 and 3.91%, respectively.

High Pressure Liquid Chromatographic Determination of Carbadox and Pyrantel Tartrate in Swine Feed and Supplements

1983 ◽  
Vol 66 (3) ◽  
pp. 602-605
Author(s):  
Dwight M Lowie ◽  
Robert T Teague ◽  
Floyd E Quick ◽  
Clarence L Foster
Keyword(s):  
High Pressure ◽  
Chromatographic Determination ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Wide Range ◽  
Liquid Chromatographic Determination ◽  
Reliable Procedure ◽  
Liquid Chromatographic ◽  
Pyrantel Tartrate

Abstract A rapid yet reliable procedure for the simultaneous extraction and assay of carbadox and pyrantel tartrate is described. The feed is extracted with water-acetonitrile-methanol and cleaned up on a short alumina column. The eluant is separated by high pressure liquid chromatography and the compounds are detected at different wavelengths. The drugs of interest are well resolved in all feeds studied. The procedure has also been applied to a wide range of feeds which contained either one of the drugs or both in combination. No significant interferences were observed. Spiked sample recoveries were 97% for carbadox and 101% for pyrantel tartrate. Ruggedness test coefficients of variation were 2.0% for carbadox and 2.1% for pyrantel tartrate.

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.

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