The Pre-Collaborative Study of AOAC Method Efficiency Evaluation

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

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/55.3.549 ◽

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.

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Comparison of Two Methods for Determination of Total Solids Content of Milk: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/72.5.712 ◽

1989 ◽

Vol 72 (5) ◽

pp. 712-718 ◽

Cited By ~ 6

Author(s):

Jenny L Clark ◽

David M Barbano ◽

Chapman E Dunham

Keyword(s):

Collaborative Study ◽

Raw Milk ◽

Preliminary Evaluation ◽

Oven Method ◽

Total Solids ◽

Relative Standard ◽

Aoac Method ◽

Standard Deviations ◽

Forced Air ◽

Solids Content

Abstract Ten laboratories analyzed 9 pairs of blind duplicate raw milk samples for total solids. A direct forced air oven method (4 h at 100°C) and a modification of the AOAC predry method (16.032) were used. Preliminary evaluation of the modified AOAC method indicated that blank determinations were necessary. Total solids content ranged from 12.0 to 14.6%. Average repeatability standard deviations (sr) of the direct forced air oven and modified AOAC methods were 0.019 and 0.017, respectively. Average reproducibility standard deviations (SR) of the direct forced air oven and the modified AOAC methods were 0.042 and 0.047, respectively. Average repeatability relative standard deviations (RSDr) for the direct forced air oven and the modified AOAC methods were 0.149 and 0.136%, respectively; average reproducibility relative standard deviations (RSDR) were 0.327 and 0.370%, respectively. Mean repeatability values (r) and reproducibility values (R) were 0,054 and 0.118 for the direct forced air oven method and 0.049 and 6.133 for the modified AOAC method, respectively. The mean test result of the direct forced air oven method (12.7293%) was comparable to that for the modified AOAC method (12.7273%). The modification of AOAC method 16.032 and the direct forced air oven method have been approved interim official first action.

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Collaborative Study of the Determination of Phosphorus in Gelatin, Dessert Preparations, and Mixes

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/55.3.581 ◽

1972 ◽

Vol 55 (3) ◽

pp. 581-582

Author(s):

Roger G Burkepile

Keyword(s):

Collaborative Study ◽

Official Method ◽

Standard Samples ◽

Preliminary Work ◽

Aoac Method ◽

Standard Deviations

Abstract A collaborative study of the proposed method for phosphorus in gelatin, dessert preparations, and mixes has been conducted. The present AOAC method for phosphorus in fertilizers, 2.023–2.025(a), was modified for this study. Preliminary work by the Associate Referee involving 4 phosphorus standard samples compared the proposed method with the official final action AOAC method for gelatin, 23.004. Additionally, phosphorus standard spikes in gelatin at the 1 and 10 mg P2O5, levels were determined by the proposed method. The proposed method is faster and more sensitive than the official method and is as accurate. Five collaborators and the Associate Referee analyzed 4 prepared samples containing various levels of phosphorus by the proposed method. The standard deviations varied from 0.005 for a 225 Bloom gelatin containing an average of 0.273% P2O5 to 0.016 for a strawberry-flavored commercial gelatin with added lecithin containing an average of 0.110% P2O5. The proposed method has been adopted as official first action to replace 23.004, which was repealed, official first action.

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Determination of Geotrichum Mold in Comminuted Fruits and Vegetables: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/65.5.1095 ◽

1982 ◽

Vol 65 (5) ◽

pp. 1095-1096

Author(s):

Stanley M Cichowicz ◽

Ruth Bandler ◽

◽

R Bandler ◽

G Dzidowski ◽

...

Keyword(s):

Crystal Violet ◽

Fruits And Vegetables ◽

Collaborative Study ◽

Green Beans ◽

Aoac Method ◽

Tomato Products

Abstract The official AOAC method for determination of Geotrichum mold in canned fruits and vegetables (44.079) requires a series of 3 sieves, Nos. 8, 16, and 230, to separate the packing liquid from the product and the mold from the packing liquid. Although this method has been successful for whole or coarsely chopped products (e.g., green beans, potatoes, carrots, and beets), finely divided products such as fruit purees and tomato products tend to clog the sieves. A method was developed in which the product is centrifuged, diluted by volume, stained with crystal violet, and counted with the sieving steps eliminated. The proposed method was adopted official first action.

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Determination of Starch, Including Maltooligosaccharides, in Animal Feeds: Comparison of Methods and a Method Recommended for AOAC Collaborative Study

Journal of AOAC International ◽

10.1093/jaoac/92.1.42 ◽

2009 ◽

Vol 92 (1) ◽

pp. 42-49 ◽

Cited By ~ 242

Author(s):

Mary B Hall

Keyword(s):

Dry Matter ◽

Collaborative Study ◽

Ease Of Use ◽

Acetate Buffer ◽

Sample Handling ◽

Animal Feeds ◽

Heat Stable ◽

Replacement Method ◽

Aoac Method

Abstract Starch is a nutritionally important carbohydrate in feeds that is increasingly measured and used for formulation of animal diets. Discontinued production of the enzyme Rhozyme-S required for AOAC Method 920.40 invalidated this method for starch in animal feeds. The objective of this study was to compare methods for the determination of starch as potential candidates as a replacement method and for an AOAC collaborative study. Many starch methods are available, but they vary in accuracy, replicability, and ease of use. After assays were evaluated that differed in gelatinization method, number of reagents, and sample handling, and after assays with known methodological defects were excluded, 3 enzymaticcolorimetric assays were selected for comparison. The assays all used 2-stage, heat-stable, -amylase and amyloglucosidase hydrolyses, but they differed in the gelatinization solution (heating in water, 3-(N-morpholino) propanesulfonic acid buffer, or acetate buffer). The measured values included both starch and maltooligosaccharides. The acetate buffer-only method was performed in sealable vessels with dilution by weight; it gave greater starch values (26 percentage units of sample dry matter) in the analysis of feed/food substrates than did the other methods. This method is a viable candidate for a collaborative study.

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Comparison of Methods for Determining Sodium in Fertilizers

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/64.3.704 ◽

1981 ◽

Vol 64 (3) ◽

pp. 704-708

Author(s):

Luis F Corominas ◽

Víctor M Boy ◽

Pedro Rojas

Keyword(s):

Phosphate Rock ◽

Collaborative Study ◽

Ammonium Oxalate ◽

Selective Electrode ◽

Accuracy And Precision ◽

Flame Emission ◽

Aoac Method ◽

Aoac Official ◽

Aas Method

Abstract The AOAC official first action method, 2.147-2.150, for flame emission spectrophotometry (FES) determination of sodium in fertilizers was compared with the atomic absorption spectrophotometric (AAS) method and the sodium selective electrode (SSE) method. Ammonium oxalate, which was previously compared with water, H2SO4, HC1, and HNO3, was used to extract the sample for all 3 methods. Three synthetic NPK samples, 3 commercial samples (urea, normal superphosphate, and neutrophos), 1 phosphate rock, and 2 Magruder check samples were used for the study. Statistically significant differences were obtained in averages for most of the samples, but few differences were found in standard deviations. The AAS method showed the best accuracy and precision. Accuracy of the AOAC method is acceptable. The SSE method showed the highest deviations from the theoretical values. A collaborative study is recommended to compare the AOAC with the AAS method.

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Comparison of AOAC and Atomic Absorption Spectrophotometry Methods for Determining Sodium in Fertilizers: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/66.5.1234 ◽

1983 ◽

Vol 66 (5) ◽

pp. 1234-1241

Author(s):

Luis F Corominas ◽

Roberto A Navarro ◽

Pedro Rojas ◽

◽

M Aihara ◽

...

Keyword(s):

Atomic Absorption ◽

Collaborative Study ◽

Atomic Absorption Spectrophotometry ◽

Sodium Content ◽

Matched Pairs ◽

High Potassium ◽

Absorption Spectrophotometry ◽

Low Sodium ◽

Aoac Method ◽

Aas Method

Abstract A collaborative study was carried out to compare AOAC method 2.147-2.150 for determining sodium in fertilizers with the atomic absorption spectrophotometric (AAS) method. Twelve synthetic NPK samples, 6 pairs of blind duplicates (0.06-8.5% Na), were sent to 22 collaborators; a total of 13 sets of results were received and evaluated by the modified matched pairs technique. The AAS method showed better performance in samples with low sodium content and high potassium content. The AAS method has been adopted official first action for determining sodium in fertilizers.

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Gas Chromatographic Methods for Determination of γ-BHC in Technical Emulsifiable Concentrates and Water-Dispersible Powder Formulations and in Lindane Shampoo and Lotion: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/67.4.834 ◽

1984 ◽

Vol 67 (4) ◽

pp. 834-837

Author(s):

James W Miles ◽

Dwight L Mount ◽

◽

T J Beckmann ◽

S K Carrigan ◽

...

Keyword(s):

Coefficient Of Variation ◽

Collaborative Study ◽

Internal Standard ◽

The Other ◽

Water Dispersible ◽

Coefficients Of Variation ◽

Aoac Method ◽

Liquid Chromatographic ◽

Gas Chromatographic Separation

Abstract Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.

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Extraction of Light Filth from Tea: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/64.2.287 ◽

1981 ◽

Vol 64 (2) ◽

pp. 287-290

Author(s):

Faith F Lim ◽

◽

J Barnett ◽

A Bright ◽

M P Chaput ◽

...

Keyword(s):

Sample Preparation ◽

Collaborative Study ◽

Tween 80 ◽

Mineral Oil ◽

Plant Residue ◽

Official Method ◽

Existing Problems ◽

Aoac Method ◽

Filter Papers ◽

Wet Sieving

Abstract The present AOAC method for determining insect and rodent filth in tea is time-consuming because it produces filter papers which are heavy in plant residue and therefore requires long paper-reading times. Anew method for the analysis of light filth in tea was developed to remedy existing problems and to improve recoveries. The method consists of the following steps: sample preparation, wet sieving, dilution with 40% isopropanol, extraction with Tween 80-Na4EDTA-40% isopropanol, flotation with mineral oil-heptane, and trapping off in a Wildman trap flask. In an interlaboratory collaborative study, analysts reported combined insect fragment recoveries of 99.2% for the proposed method and 93.0% for the AOAC method; the same analysts recorded combined rodent hair recoveries of 92.2% for the proposed method and 47.6% for the official method. Average times for reading individual subsamples were 9 min for the proposed method and 27 min for the AOAC method. The proposed method has been adopted official first action.

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