Bacillus stearothermophilus Disk Assay for Determining Ampicillin Residues in Fish Muscle

1991 ◽  
Vol 74 (6) ◽  
pp. 910-912 ◽  
Author(s):  
Steven M Plakas ◽  
Angelo DePaola ◽  
Michael B Mox
Keyword(s):  
Striped Bass ◽  
Bacillus Stearothermophilus ◽  
Fish Muscle ◽  
Control Fish ◽  
Official Method ◽  
Limit Of Determination ◽  
Cultured Fish ◽  
Aoac Official ◽  
The Mean

Abstract The Bacillus stearothermophilus disk assay for penicillin in milk (AOAC official method) was adapted for the determination of ampicillin in fish muscle. The method was evaluated in 2 species of cultured fish: channel catfish and striped bass. Recoveries of ampicillin ranged from 99 to 104% when muscle specimens from both species were spiked at concentrations of 0.025-1.00 μg/g. The lower limit of determination (LOD) was 0.025 μg/g. The assay was applied to monitor the elimination of ampicillin from the muscle of striped bass after intravascular administration (dosage of 10 mg/kg body weight). The mean concentrations in the muscle declined from 1.160 μg/g at 2 h to 0.063 μg/g at 18 h. The half-life of ampicillin in the muscle was 3.6 h. Ampicillin concentrations were below LOD at 24 h. No inhibitory activity was observed in the muscle of control fish.

Adaptation of the AOAC Fluorine Method for Determining Fluoride in Fish Protein Concentrate

1970 ◽  
Vol 53 (1) ◽  
pp. 3-6
Author(s):  
R. Bruce Klemm ◽  
Mary E. Ambrose Klemm
Keyword(s):  
Steam Distillation ◽  
Silica Sand ◽  
Official Method ◽  
Protein Concentrate ◽  
Fish Protein ◽  
Direct Titration ◽  
Modified Method ◽  
Aoac Official ◽  
Aoac Official Method

Abstract The AOAC official method, 24.029–24.035, for the determination of fluorine in foods was modified slightly to o btain quantitative recoveries of fluorine from samples of fish protein concentrate (FPC). The most important alterations include the use of steam distillation, the addition of finely ground silica sand in the distillation, a decrease in the distillation temperature, and the utilization of direct titration. Recoveries of fluoride added to FPC before ashing, using this modified method, averaged 96.0 ± 3.0%. Our results are in agreement with those of several other analysts who used a variety of methods.

Allyl Isothiocyanate in Mustard Seed

1970 ◽  
Vol 53 (1) ◽  
pp. 1-3 ◽  
Author(s):  
Donald L Andersen
Keyword(s):  
Allyl Isothiocyanate ◽  
Mustard Seed ◽  
Official Method ◽  
Average Recovery ◽  
Aoac Method ◽  
Aoac Official ◽  
Mustard Seeds ◽  
Column Preparation ◽  
Aoac Official Method

Abstract A new GLC method for the determination of allyl isothiocyanate in mustard seed was compared to a method of the Midwest Research Institute and to a combination of the AOAC official method and the proposed method. Twelve collaborators compared the AOAC method and the GLC method, using whole mustard seeds. Each collaborator assayed three seed portions by both methods. The range, standard deviation, and coefficient of variation are less for each seed portion by the proposed than by the official method. The average recovery value of allyl isothiocyanate in the prepared standard solutions is lower, using the proposed GLC procedure, but seed assay values are significantly and consistently higher for each seed portion when compared with the results for the AOAC method. Reports from the collaborators also indicate that the proposed method is rugged, as the GLC column preparation was subjected to many changes. It is recommended that the GLC method be adopted as official first action.

scholarly journals Comparison of Babcock and Ether Extraction Methods for Determination of Fat Content of Cream: Collaborative Study

1996 ◽  
Vol 79 (4) ◽  
pp. 907-916 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Extraction Method ◽  
Collaborative Study ◽  
Extraction Methods ◽  
Fat Content ◽  
Official Method ◽  
Ether Extraction ◽  
Aoac Official ◽  
The Difference ◽  
Aoac Official Method

Abstract A modified Mojonnier ether extraction method for determination of the fat content of cream was developed based on the method for milk (AOAC Official Method 989.05). The cream Babcock method (AOAC Official Method 920.111 B-C) was modified to harmonize with the milk Babcock method (AOAC Official Method 989.04) and to clarify procedural details. Using the AOAC collaborative study format, 10 laboratories tested 9 pairs of blind duplicate heat-treated cream samples with a fat range of 30-45% using both methods. The statistical performance (invalid and outlier data removed) was as follows: mean % fat = 37.932, sr = 0.125, sR = 0.151, RSDr = 0.330, RSDR = 0.398, r = 0.354, and R = 0.427 for the ether extraction method. For the Babcock method, mean % fat = 38.209, sr = 0.209, SR = 0.272, RSDr = 0.548, RSDR = 0.712, r = 0.592, and R = 0.769. Average test results for fat from the Babcock method were 0.277% (absolute fat) greater than for the Mojonnier ether extraction method. The difference between methods, as a percentage of the average fat content of the samples, was 0.73%. This agrees with differences observed between the 2 methods for milk when 10 to 17 laboratories tested 7 milk samples in blind duplicate at bimonthly intervals over a 4-year period (average difference 0.029% fat, 0.78% as a percentage of average fat content). The Mojonnier ether extraction and Babcock methods for fat in cream have been adopted by AOAC INTERNATIONAL. The new Babcock method replaced the AOAC Official Method 920.111 B-C.

Determination of Maleic Hydrazide Residues in Tobacco and Vegetables

1973 ◽  
Vol 56 (5) ◽  
pp. 1164-1172
Author(s):  
Milan Ihnat ◽  
Robert J Westerby ◽  
Israel Hoffman
Keyword(s):  
Standard Deviation ◽  
Present Method ◽  
Maleic Hydrazide ◽  
Collaborative Study ◽  
Official Method ◽  
Sample Weight ◽  
Relative Standard ◽  
The Mean ◽  
Pipe Tobacco

Abstract The distillation-spectrophotometric method of Hoffman for determining maleic hydrazide has been modified to include a double distillation and was applied to the determination of 1–30 ppm maleic hydrazide residues in tobacco and vegetables. Recoveries of 1–23 μg added maleic hydrazide were independent of weight of maleic hydrazide, but did depend on sample and sample weight. The following recoveries were obtained from 0.5 g sample: pipe tobacco, 84%; commercially dehydrated potato, 83%; cigar tobacco, 81%; dried potato, 76%; fluecured tobacco, 73%; dried carrot, 71%. In the absence of sample, the recovery was 82%. When appropriate standard curves were used, maleic hydrazide levels determined in tobacco samples were essentially independent of sample weight in the range 0.1–3 g. The mean relative standard deviation for a variety of field-treated and fortified tobacco samples containing 1–28 ppm maleic hydrazide was 3%. The precision and sensitivity of this procedure seem to be substantial improvements over official method 29.111–29.117. It is recommended that the present method be subjected to a collaborative study.

Microbiological Determination of Neomycin in Feeds: Collaborative Study

1989 ◽  
Vol 72 (2) ◽  
pp. 237-241
Author(s):  
Gerald L Stahl ◽  
D Dal Kratzer ◽  
Charles W Kasson
Keyword(s):  
Statistical Analysis ◽  
Confidence Interval ◽  
Salt Concentration ◽  
Agar Medium ◽  
Collaborative Study ◽  
Tris Buffer ◽  
Official Method ◽  
The Mean ◽  
Swine Feed

Abstract A modification of the AOAC microbiological determination of neomycin in feeds was collaboratively studied by 12 laboratories. The official method was modified by substituting a constant salt concentration diluent for the feed extract diluent, preparing the agar medium in tris buffer, and performing the test with a monolayer plating system. Each laboratory performed single assays on 8 samples in a randomized sequence. The samples included duplicates of a cattle and swine feed at 2 different marketed concentrations. The mean recovery across all laboratories was 110.7% of theory with a range of means of 69.4-128.6 across the 12 laboratories. The results of one laboratory and 2 additional values from different laboratories were deemed outliers and excluded from statistical analysis. The statistical analysis gave a confidence interval of ± 26% for individual assays.

scholarly journals Determination of Total Dietary Fiber in Selected Foods Containing Resistant Maltodextrin by a Simplified Enzymatic-Gravimetric Method and Liquid Chromatography: Interlaboratory Study in China

2008 ◽  
Vol 91 (3) ◽  
pp. 614-621 ◽  
Author(s):  
Boqiang Fu ◽  
Jing Wang ◽  
Jean Michel Roturier ◽  
Zhiyu Tang ◽  
Huan Li ◽  
...  
Keyword(s):  
Dietary Fiber ◽  
Interlaboratory Study ◽  
National Standard ◽  
Official Method ◽  
Total Dietary Fiber ◽  
Modified Method ◽  
Resistant Maltodextrin ◽  
Aoac Official ◽  
Aoac Official Method

Abstract An interlaboratory study was conducted in China to validate the modified AOAC Official Method 2001.03 for the determination of total dietary fiber (TDF) in foods containing resistant maltodextrin (RMD), which will be adopted as the National Standard Method of China. The kind of buffer solution, the volume of filtrate evaporation, the volume of eluent for desalting and residual solution after evaporation, etc. were modified, which had been proved to have acceptable accuracy and precision in the routine assay. TDF contents in 3 representative foods and 2 kinds of RMD ingredient (i.e., NUTRIOSE 06 and NUTRIOSE 10) were measured using the modified method in 6 eligible laboratories representing commercial, industrial, and governmental laboratories in China. The results of the interlaboratory study indicated that the intralaboratory repeatability, interlaboratory reproducibility, and precision of the modified method are adequate for reliable analysis of TDF in food containing RMD, as well as resistant dextrin. Compared to AOAC Official Method 2001.03, the modified method is time- and cost-saving.

Analysis of Cocoa Flavanols and Procyanidins (DP 1–10) in Cocoa-Containing Ingredients and Products by Rapid Resolution Liquid Chromatography: Single-Laboratory Validation

2014 ◽  
Vol 97 (1) ◽  
pp. 166-172 ◽  
Author(s):  
Philip R Machonis ◽  
Matthew A Jones ◽  
Catherine Kwik-Uribe
Keyword(s):  
Original Method ◽  
Degree Of Polymerization ◽  
Official Method ◽  
Response Factors ◽  
Rapid Resolution ◽  
Different Types ◽  
Aoac Official ◽  
Single Laboratory ◽  
Cocoa Flavanols

Abstract Recently, a multilaboratory validation (MLV) of AOAC Official Method 2012.24 for the determination of cocoa flavanols and procyanidins (CF-CP) in cocoa-based ingredients and products determinedthat the method was robust, reliable, and transferrable. Due to the complexity of the CF-CP molecules, this method required a run time exceeding 1 h to achieve acceptable separations. To address this issue, a rapid resolution normal phase LC method was developed, and a single-laboratory validation (SLV) study conducted. Flavanols and procyanidins with a degree of polymerization (DP) up to 10 were eluted in 15 min using a binary gradient applied to a diol stationary phase, detected using fluorescence detection, and reported as a totalsum of DP 1–10. Quantification was achieved using (-)-epicatechin-based relative response factors for DP 2–10. Spike recovery samplesand seven different types of cocoa-based samples were analyzed to evaluate the accuracy, precision, LOD, LOQ, and linearity of the method. The within-day precision of the reported content for the samples was 1.15–5.08%, and overall precision was 3.97–13.61%. Spike-recovery experiments demonstrated recoveries of over 98%. The results of this SLV were compared to those previously obtained in the MLV and found to be consistent. The translation to rapid resolution LC allowed for an 80% reduction in analysis time and solventusage, while retaining the accuracy and reliability of the original method. The savings in both cost and time of this rapid method make it well-suited for routine laboratory use.

Evaluation of Direct Saponification Method for Determination of Cholesterol in Meats

1986 ◽  
Vol 69 (5) ◽  
pp. 844-846 ◽  
Author(s):  
Mark L Adams ◽  
Darryl M Sullivan ◽  
Randall L Smith ◽  
Earl F Richter
Keyword(s):  
Lipid Extraction ◽  
Meat Products ◽  
Internal Standard ◽  
Meat Sample ◽  
Official Method ◽  
Flame Ionization ◽  
Aoac Method ◽  
Aoac Official ◽  
Meat Samples

Abstract A gas chromatographic (GC) method has been developed for determination of cholesterol in meats. The method involves (a) ethanolic KOH saponification of the sample material, (b) homogeneous-phase toluene extraction of the unsaponifiables, (c) derivatization of cholesterol to its trimethylsilylether, and (d) quantitation by GC-flame ionization detection using 5-α-cholestane as internal standard. This direct saponification method is compared with the current AOAC official method for determination of cholesterol in 20 different meat products. The direct saponification method eliminates the need for initial lipid extraction, thus offering a 30% savings in labor, and requires fewer solvents than the AOAC method. It produced comparable or slightly higher cholesterol results than the AOAC method in all meat samples examined. Precision, determined by assaying a turkey meat sample 16 times over 4 days, was excellent (CV = 1.74%). Average recovery of cholesterol added to meat samples was 99.8%.

A Rapid 13C/12C Test for Determination of Corn Syrups in Honey

1991 ◽  
Vol 74 (4) ◽  
pp. 627-629 ◽  
Author(s):  
Steven T Brookes ◽  
Andrew Barrie ◽  
Jonathan E Davies
Keyword(s):  
Isotope Ratio ◽  
Fold Increase ◽  
Official Method ◽  
Corn Syrup ◽  
Sample Throughput ◽  
Straight Line ◽  
High Fructose ◽  
Isotope Ratio Mass Spectrometer ◽  
Aoac Official

Abstract The AOAC official method for detection of corn syrup products in honey measures the 13C/12C ratio (δ13C) (978.17). In the official method, a suspect honey is combusted off-line to C02 gas for analysis on a dual-inlet isotope ratio mass spectrometer (IRMS). The procedure is manual, requires liquid N2, and takes 20-50 min/sample. In the present study, we examine a recently developed alternative, automated 15N 13C analysis mass spectrometry (ANCA-MS). This procedure combusts and analyzes 66 samples in a batch and takes only 5 min/sample. We used both ANCA-MS and IRMS with offline combustion to analyze 6 honeys containing from 0 to 100% high fructose corn syrup (HFCS). δ13C values by both methods agreed within 0.2%o and gave an excellent straight line fit (slope = 0.991; R = 1). As an alternative to IRMS, ANCA-MS is automated and provides a 5-fold increase in sample throughput.

scholarly journals Determination of Methylcellulose and Hydroxypropyl Methylcellulose Food Gums in Food and Food Products: Collaborative Study

2007 ◽  
Vol 90 (3) ◽  
pp. 786-793 ◽  
Author(s):  
Robert G Harfmann ◽  
Balasaheb K Deshmukh ◽  
Jerry Conklin ◽  
Maciej Turowski ◽  
Stephanie Lynch ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Hydroxypropyl Methylcellulose ◽  
Collaborative Study ◽  
Food Samples ◽  
Size Exclusion ◽  
Official Method ◽  
Relative Standard ◽  
Aoac Official

Abstract A collaborative study was performed to determine the reproducibility of a method for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) in food. These widely used food gums possess unusual solubility characteristics and cannot accurately be determined by existing dietary fiber methods. The new method uses the enzyme-digestion procedure of AOAC Official Method 991.43. Digestate solutions must be refrigerated to fully hydrate MC or HPMC. The chilled solutions are filtered and analyzed by size-exclusion liquid chromatography. Collaborating laboratories received 28 samples containing MC or HPMC in the range of 0100%. The sample set included blind duplicates of 5 food matrixes (bread, milk, fish, potato, and powdered juice drink). Cochran and Grubbs tests were used to eliminate outliers. For food samples containing MC, values for within-laboratory precision, repeatability relative standard deviation (RSDr), ranged from 4.2 to 16%, and values for among-laboratories precision, reproducibility relative standard deviation (RSDR), ranged from 11 to 20%. For HPMC samples, RSDr values ranged from 6.4 to 27%, and RSDR values ranged from 17 to 39%. Recoveries of MC and HPMC from the food matrixes ranged from 78 to 101%. These results show acceptable precision and reproducibility for the determination of MC and HPMC, for which no Official AOAC Methods exist. It is recommended that this method be adopted as AOAC Official First Action.

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