scholarly journals Determination of Retinyl Palmitate (Vitamin A) in Fortified Fluid Milk by Liquid Chromatography: Collaborative Study

2003 ◽  
Vol 86 (2) ◽  
pp. 375-385 ◽  
Author(s):  
Douglas A Hite ◽  
L Angelo ◽  
S Bhandari ◽  
S Bhattacharyya ◽  
E Bonnin ◽  
...  
Keyword(s):  
Vitamin A ◽  
Milk Fat ◽  
Collaborative Study ◽  
Skim Milk ◽  
Internal Standard ◽  
Retinyl Palmitate ◽  
Test Portion ◽  
Standard Deviations ◽  
Fluid Milk

Abstract A liquid chromatographic (LC) method was developed for fast and simple measurement of retinyl palmitate (vitamin A) in fortified milk. Retinyl acetate internal standard was added to a test portion of milk followed by extraction into hexane. The hexane extract was analyzed by LC using a normal-phase silica gel column equilibrated with mobile phase (conditioned hexane–isopropanol, 99.85 + 0.15, v/v) about 1 h before injections. The retinyl palmitate concentration was calculated by using a relative response factor determined with calibration standards. In the collaborative study, 11 laboratories analyzed 13 pairs of fluid milk materials in blind duplicate. Twelve of the materials were composed of skim milk (<0.5% fat), 1% fat milk, 2% fat milk, and 1% fat chocolate milk. Each material was fortified at 3 concentrations of retinyl palmitate of approximately 581 μg/L (1000 IU/qt), 1163 μg/L (2000 IU/qt), and 2236 μg/L (4000 IU/qt). The 13th material, unfortified skim milk, served as a matrix blank. Repeatability standard deviations (RSDr) without outliers ranged from 1.5 to 5.7% and reproducibility standard deviations (RSDR) without outliers ranged from 5.0 to 22.7%. cis-Isomers co-eluted with the predominant trans-retinyl palmitate isomer and were included in the results reported by all the collaborative laboratories. Endogenous long-chain esters from milk fat were also measured with the retinyl palmitate additive. The Study Director recommends that this method for determination of retinyl palmitate in fluid milk by LC be adopted First Action.

Proton Magnetic Resonance Spectroscopic Determination of Disulfiram: Collaborative Study

1978 ◽  
Vol 61 (1) ◽  
pp. 55-59
Author(s):  
Eric B Sheinin ◽  
Walter R Benson
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Drug Product ◽  
Spectroscopic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Spectroscopic Determination ◽  
Standard Deviations ◽  
Bulk Drug

Abstract A proton magnetic resonance spectroscopic method for determining disulfiram in the bulk drug product and in the formulated material was collaboratively studied. The method depends on the use of chloroform-d as a solvent and hexamethylcyclotrisiloxane as the internal standard. No interference from tablet excipients was observed. The method is rapid and specific. Eighteen laboratories analyzed duplicate samples of a bulk drug product, a 250 mg tablet composite, and a 500 mg tablet composite. The average per cent results and standard deviations were 99.7±1.4, 100.9±2.0, and 99.9±2.2, respectively.

Fluorometric Determination of Alkaline Phosphatase in Fluid Dairy Products: Collaborative Study

1990 ◽  
Vol 73 (6) ◽  
pp. 842-849 ◽  
Author(s):  
Richard M Rocco
Keyword(s):  
Alkaline Phosphatase ◽  
Dairy Products ◽  
Collaborative Study ◽  
Skim Milk ◽  
Raw Milk ◽  
Chocolate Milk ◽  
Phenyl Phosphate ◽  
Whole Milk ◽  
Standard Deviations

Abstract Official methods for the measurement of alkaline phosphatase (ALP) in dairy products use either phenyl phosphate or phenolphthaleln monophosphate as substrate. Quantitation of results requires butanol extraction of the Indophenol (Scharer) or 3-h dialysis of the liberated phenolphthaleln (Rutgers). The Advanced Fluorophos® assay Is based on a self-indicating substrate which, when acted upon by ALP, loses a phosphate radical and becomes a highly fluorescent compound. The rate of fluorophore formation Is monitored for 3 mln In a fluorometer and the enzyme activity In mU/L Is calculated. Eight laboratories participated in a collaborative study to evaluate the Fluorophos® assay for determining ALP activity In whole milk, skim milk, chocolate milk, and cream (half and half). The comparative method was the AOAC quantitative phenyl phosphate method, 16.121-16.122 (14th Ed.). Mixed herd raw milk was added to pasteurized samples at 0.05, 0.1, and 0.2% (v/v). Method performance at 0.1% (v/v) added raw milk as measured by repeatability and reproducibility standard deviations (sr and sR) and relative standard deviations (RSDr and RSDR), respectively, were: whole milk, sr = 21.7%, sR = 34.6%, RSDr = 4.4%, RSDR = 7.0%; skim milk, sr = 19.2%, sR = 31.4%, RSDr = 3.8%, RSDR = 6.2%; chocolate milk, sr = 27.6%, sR = 45.8%, RSDr = 5.3%, RSDR = 8.8%. The method has been adopted official first action by AOAC for determination of alkaline phosphatase in whole milk, skim milk, and chocolate milk.

Gas-Liquid Chromatographic Determination of Nicotine Contained on Cambridge Filter Pads: Collaborative Study

1979 ◽  
Vol 62 (2) ◽  
pp. 229-236 ◽  
Author(s):  
John R Wagner ◽  
Neil A Thaggard
Keyword(s):  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Helium Flow ◽  
Injection Port ◽  
Paired Samples ◽  
Liquid Chromatographic Determination ◽  
Standard Deviations ◽  
Liquid Chromatographic

Abstract Nicotine was extracted from Cambridge filter pads with 10 mL 2-propanol containing 1 mg anethole/mL as the internal standard. Five standards ranging from 0.25 to 1.25 mg nicotine/ mL were injected into a 6 ft × 1/8 in. column packed with 2% KOH and 10% Carbowax 20M on 45—60 mesh diatomaceous earth to standardize the procedure. The injection port and detector were operated at 200—250°C, the column was operated at 165°C, and the helium flow was adjusted to ca 40 mL/min. Data were taken with systems giving resolutions of 1 count/mv-sec. Results from 16 laboratories gave standard deviations ranging from 0.02 to 0.06 mg nicotine/mL. Suggested improvements were incorporated into a second study, and 13 laboratories analyzed 5 paired samples; standard deviations ranged from 0.02 to 0.03 mg nicotine/mL. The method has been adopted as official first action.

Gas-Liquid Chromatographic Quantitation of Pheneyclidine.HCl in Powders: Collaborative Study

1979 ◽  
Vol 62 (3) ◽  
pp. 560-563
Author(s):  
Charles C Clark
Keyword(s):  
Aqueous Solution ◽  
Collaborative Study ◽  
Internal Standard ◽  
Water Soluble ◽  
Standard Deviations ◽  
Hcl Concentration ◽  
Liquid Chromatographic

Abstract Six laboratories collaboratively studied a method for the quantitative gas-liquid chromatographic (GLC) determination of pheneyclidine. HCl in powders. The pheneyclidine.HCl and other water-soluble compounds are dissolved in dilute HC1. A portion of the aqueous solution is made weakly basic with K2HPO4, and the organic-soluble compounds are extracted in CHCI3 for the GLC determination of the pheneyclidine.HCl. Eicosane (n-C20) is incorporated in the extracting CHC13 as an internal standard. The samples collaboratively studied included samples of known pheneyclidine. HCl concentration and one sample of unknown purity. Recoveries ranged from 92.1 to 104% and per cent standard deviations from 1.05 to 3.39. The method was adopted as official first action.

scholarly journals Determination of Total Fumonisins in Corn by Competitive Direct Enzyme-Linked Immunosorbent Assay: Collaborative Study

2002 ◽  
Vol 85 (2) ◽  
pp. 404-410 ◽  
Author(s):  
Chuck B Bird ◽  
Bruce Malone ◽  
Larry G Rice ◽  
P Frank Ross ◽  
Robert Eppley ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Fusarium Species ◽  
Collaborative Study ◽  
The United States ◽  
Enzyme Linked Immunosorbent Assay ◽  
Test Portion ◽  
Relative Standard ◽  
Standard Deviations ◽  
Different Levels

Abstract Fumonisins—mycotoxins produced by some Fusarium species—have been shown to be the causative agent of diseases in horses and other domesticated animals as well as possible carcinogens in humans. A collaborative study was conducted to evaluate the effectiveness of a competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for the determination of total fumonisins (B1, B2, and B3) in corn. The test portion was extracted with methanol–water (7 + 3), filtered, diluted, and tested on the CD-ELISA. Naturally and artificially contaminated corn test portions were sent to 13 collaborators in the United States. Naturally contaminated field test portions were prepared at 3 different levels. Artificially contaminated test portions were spiked at 1.0, 3.0, and 5.0 mg/kg total fumonisins (B1, B2, and B3). Average recoveries of total fumonisins were 120, 100, and 90%, respectively. The relative standard deviations for repeatability ranged from 13.3 to 23.3% and the relative standard deviations for reproducibility ranged from 15.8 to 30.3% across all levels tested. HORRAT values, calculated for each individual sample, ranged from 1.24 to 1.94. This method demonstrated acceptable intra- and interlaboratory precision at the levels tested.

Liquid Chromatographic Determination of Penicillin V Potassium in Tablets: Collaborative Study

1989 ◽  
Vol 72 (6) ◽  
pp. 883-884
Author(s):  
Barry Mopper
Keyword(s):  
Collaborative Study ◽  
Potassium Phosphate ◽  
Internal Standard ◽  
Photometric Detection ◽  
Penicillin V ◽  
Relative Standard ◽  
Repeatability And Reproducibility ◽  
Standard Deviations ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method for the determination of penicillin V potassium in tablets was collaboratively studied by 7 laboratories. The method uses an octadecyl silane reverse-phase column, a mobile phase of acetonitrile-methanol-O.OlM potassium phosphate monobasic (21 + 4 + 75 v/v/v), photometric detection at 225 nm, and sulfadimethoxine as an internal standard. Each collaborator received 6 samples: powdered composites of 2 commercial tablet preparations and 1 synthetic tablet powder mixture, each with blind duplicates. The mean repeatability and reproducibility relative standard deviations for commercial samples were, respectively, 1.10 and 1.46% (250 mg dosage), and 0.84 and 2.82% (500 mg dosage). The average standard recovery from the synthetic formulation was 99.1%, with repeatability and reproducibility relative standard deviations of 1.30 and 3.66%, respectively. The method has been adopted official first action.

scholarly journals Visual and Semiquantitative Spectrophotometric ELISA Screening Method for Aflatoxin Bi in Corn and Peanut Products: Follow-up Collaborative Study

1989 ◽  
Vol 72 (4) ◽  
pp. 638-643
Author(s):  
Douglas L Park ◽  
Brinton M Miller ◽  
Stanley Nesheim ◽  
Mary W Trucksess ◽  
Alan Vekich ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Screening Method ◽  
Test Sample ◽  
The United States ◽  
Roasted Peanut ◽  
Screening Assay ◽  
Test Portion ◽  
Relative Standard ◽  
Standard Deviations

Abstract A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, The Netherlands, Switzerland, Tunisia, and the United States. Twelve raw and roasted peanut and corn portions containing various concentrations of natural aflatoxins and supplemented when appropriate with aflatoxin Bi were distributed to participating laboratories for testing. The assay is based on competition between an enzyme-conjugated aflatoxin Bj and (free) aflatoxins in the test sample for aflatoxin-specific antibodies coated onto interior surfaces of microtiter wells. After a wash step to remove all unbound aflatoxins, a substrate added to each well is catalyzed from a colorless to a blue solution by any bound enzyme-conjugated aflatoxin Bj present. The intensity of the color decreases as the amount of free aflatoxin Bt in the test portion increases. Final determination of aflatoxin concentrations can be made by either visual comparison with standard solutions or spectrophotometric comparisons (at 650 nm) to knowns. Overall correlation was good between ELISA and thin-layer chromatographic results for corn and roasted peanut products, with 93 and 98% correct responses for visual and instrumental determinations, respectively. For instrumental determinations of aflatoxin in corn and roasted peanuts in the <20 ng/g range, the relative standard deviations for repeatability (RSDr) were 14.9 and 41.4%, respectively, and the relative standard deviations for reproducibility (RSDR) were 45.7 and 43.5%, respectively. For instrumental determination of >20 ng/g, the respective RSDr and RSDR values were 19.4 and 52.7% for corn and 23.3 and 23.3% for roasted peanuts. For visual determinations in the <20 ng/g range, the respective RSDr and RSDR values for corn were 38.5 and 60.7% and for roasted peanuts 73.7 and 73.7%. The respective RSDr and RSDR values for determinations of >20 ng/g for corn were 13.5 and 59.5% and 24.3 and 57.3% for roasted peanuts. The ELISA method has been approved interim official first action as a screening method to determine the presence or absence of aflatoxin Bt at a concentration of ≥ 20 ng/g in corn and roasted peanuts.

scholarly journals Determination of Total, Saturated, and Monounsaturated Fats In Foodstuffs by Hydrolytic Extraction and Gas Chromatographic Quantitation: Collaborative Study

1997 ◽  
Vol 80 (3) ◽  
pp. 555-563 ◽  
Author(s):  
Stephen D House ◽  
M Lawson ◽  
T Hammill ◽  
R Mazal ◽  
K Meyer ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Internal Standard ◽  
Nutrition Labeling ◽  
Ether Extraction ◽  
Monounsaturated Fats ◽  
Standard Deviations ◽  
Total Fat ◽  
Education Act ◽  
Sample Set

Using gas chromatography (GC), 10 collaborating laboratories measured total, saturated, and monounsaturated fats in 8 blind duplicate pairs of foodstuffs. The method involves a hydrolysis/ether extraction of fat followed by quantitative GC analysis versus an internal standard. Calculations were designed to comply with federal regulations as specified in the Nutrition Labeling and Education Act of 1990. The range of fat contents was about 150%. Collaborators received and analyzed (in triplicate) a pre-collaborative sample of known fat content as a practice sample. After satisfactory results were obtained, participants received the 16-sample set. The repeatability standard deviations (RSDr) for total fat ranged from 2.04 to 10.6%; the reproducibility standard deviations (RSDr) for total fat ranged from 3.74 to 15.8%. The hydrolytic extrac- tion-GC method for determination of fat (total, saturated, and monounsaturated) in foodstuffs has been adopted first action by AOAC INTERNATIONAL.

Determination of Vitamin E and Vitamin A in Infant Formula and Adult Nutritionals by Normal-Phase High-Performance Liquid Chromatography: Collaborative Study, Final Action 2012.10

2016 ◽  
Vol 99 (1) ◽  
pp. 223-241 ◽  
Author(s):  
Adrienne McMahon ◽  
S Christiansen ◽  
F-F Chee ◽  
A Chua ◽  
H Braddock ◽  
...  
Keyword(s):  
Vitamin E ◽  
Vitamin A ◽  
Infant Formula ◽  
Collaborative Study ◽  
Retinyl Palmitate ◽  
Normal Phase ◽  
Retinyl Acetate ◽  
Total Vitamin ◽  
Normal Phase Hplc

Abstract The main objective of the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) project is to establish international consensus methods for infant formula and adult nutritionals, which will benefit intermarket supply and dispute resolution. A collaborative study was conducted on AOAC First Action Method 2012.10 Simultaneous Determination of 13-cis and All-trans Vitamin A Palmitate (Retinyl Palmitate), Vitamin A Acetate (Retinyl Acetate), and Total Vitamin E (α-Tocopherol and D-α-tocopherol acetate) in Infant Formula and Adult Nutritionals by Normal-Phase HPLC. Fifteen laboratories from 11 countries participated in an interlaboratory study to determine 13-cis and all-trans vitamin A palmitate (retinyl palmitate), vitamin A acetate (retinyl acetate), and total vitamin E (α-tocopherol and D-α-tocopherol acetate) in infant formula and adult nutritionals by normal-phase HPLC and all laboratories returned valid data. Eighteen test portions of nine blind duplicates of a variety of infant formula and adult nutritional products were used in the study. The matrixes included milk-based and soy-based hydrolyzed protein as well as a low fat product. Each of the samples was prepared fresh and analyzed in singlicate. As the number of samples exceeded the recommended number to be prepared in a single day, analysis took place over 2 days running 12 samples on day one and 10 samples on day two. The reference standard stock was prepared once and the six-point curve diluted freshly on each day. Results obtained from all 15 laboratories are reported. The RSDR for total vitamin A (palmitate or acetate) ranged from 6.51 to 22.61% and HorRat values ranged from 0.33 to 1.25. The RSDR for total vitamin E (as tocopherol equivalents) ranged from 3.84 to 10.78% and HorRat values ranged from 0.27 to 1.04. Except for an adult low fat matrix which generated reproducibility RSD >40% for some isomers, most SPIFAN matrixes gave results within the acceptance criteria of <16% RSD as stated in the respective Standard Method Performance Requirements.

Enzymatic-Ultraviolet Method for Measuring Lactose in Milk: Collaborative Study

1984 ◽  
Vol 67 (3) ◽  
pp. 637-640 ◽  
Author(s):  
David O Biltcliffe ◽  
Dick H Kleyn ◽  
J Richard Trout ◽  
◽  
D Azzara ◽  
...  
Keyword(s):  
Food Industry ◽  
Collaborative Study ◽  
Skim Milk ◽  
Gravimetric Method ◽  
T Test ◽  
Enzymatic Method ◽  
Commercial Laboratory ◽  
Aoac Method ◽  
Standard Deviations

Abstract Collaborators in 8 dairy and food industry laboratories performed one lactose determination on each of 8 unknown samples of milk, lowfat milk, or skim milk, as 3 pairs of blind duplicates. Two known samples were provided to gain experience prior to analysis of the unknown samples. All of the above samples were also analyzed for lactose content by the official AOAC gravimetric method (16.507) by a commercial laboratory. From the overall mean of results on all samples, determinations by the enzymatic method averaged 0.49% lower than by the AOAC method. This difference was significant by the t-test (P = 0.05), which indicated a lack of agreement between the compared methods in determining lactose content. Standard deviations were similar for the 3 sets of blind duplicates which ranged between 3.67 and 4.55% lactose content. F-values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has been adopted official first action.

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