Biomedical subjects

R H Albert

Publications and source records attributed to R H Albert.

3 recordsLinked to original sources

PubMedDate not supplied

Time required to achieve homogeneity of test substances added to dog feed.

The homogeneity of test substances in a carrier (animal feed) is a critical factor in conducting long-term feeding studies in laboratory animals. A method for determining the adequate amount of mixing to achieve homogeneity by a mixer of the type described has been determined when 2 distinctly different compounds are added to ground dog feed. Nicotinic acid and butylated hydroxyanisole at a concentration of 1% were separately mixed with the dog feed for 15, 30, 45, 60, and 120 min to determine optimum mixing time. Test portions were taken from 4 different sampling sites at each time period and analyzed in duplicate for the added substance. Four batches were prepared and the results were aggregated. Very little interbatch variability was observed. The variance of the average values from the 4 sampling sites at each time period was calculated and used as a simple, crude, but effective numerical quantity to monitor the approach to homogeneity of the mixture.

Animal Feed↗

PubMedDate not supplied

Immunoaffinity column coupled with solution fluorometry or liquid chromatography postcolumn derivatization for determination of aflatoxins in corn, peanuts, and peanut butter: collaborative study.

An AOAC/IUPAC (International Union of Pure and Applied Chemistry) collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column for the determination of aflatoxin. The test portion is extracted with methanol-water (7 + 3), filtered, diluted to less than 30% methanol with water, and applied to the affinity column. The column is washed with water and the concentrated aflatoxins are eluted with methanol. Total aflatoxins are determined by solution fluorometry with bromine (SFB), and individual toxins are determined by reverse-phase liquid chromatography with postcolumn derivatization with iodine (PCD). Corn naturally contaminated with aflatoxins, and peanuts, peanut butter, and corn containing added aflatoxins (B1:B2:G1:G2 = 7:1:3:1) were sent to 24 collaborators in the United States, France, Canada, and the Republic of South Africa. Twelve collaborators used the SFB method, 9 used the PCD method, and 3 used both SFB and PCD methods. Twenty collaborators completed the study (10 used the SFB method, 7 used the PCD method, and 3 used both SFB and PCD methods). Test portions were spiked at 10, 20, and 30 ng/g. For SFB analyses, recoveries of total aflatoxins were 123, 105, and 107%, respectively; the relative standard deviation for repeatability (RSDr) ranged from 11.75 to 16.57%, and the relative standard deviation for reproducibility (RSDR) ranged from 10.97 to 33.09%. For PCD analyses, recoveries were 81, 81, and 83%, respectively; the RSDr ranged from 5.20 to 17.22%, and the RSDR ranged from 4.68 to 50.77%. The RSDr for aflatoxins B1 and G1 for spiked test portions ranged from 5.45 to 23.55%, and the RSDR ranged from 4.21 to 57.28%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxins↗

PubMedDate not supplied

Atomic absorption spectrophotometric determination of tin in canned foods, using nitric acid-hydrochloric acid digestion and nitrous oxide-acetylene flame: collaborative study.

Twenty-six collaborators participated in a study to evaluate an atomic absorption spectrophotometric (AAS) method for the determination of tin in canned foods. The 5 foods evaluated were meat, pineapple juice, tomato paste, evaporated milk, and green beans, each spiked at 2 levels. The concentration range of tin in the samples was 10-450 micrograms/g, and each level was sent as a blind duplicate. Statistical treatment of results revealed no laboratory outliers and 6 individual or replicate-total outliers, accounting for 3.3% of the data. Repeatability (within-laboratory) coefficient of variation (CVo) ranged from 2.2 to 48%, depending on the tin level and food evaluated. For samples containing greater than or equal to 80 micrograms/g of tin, repeatability CV averaged 5.6% including outliers and 3.7% after their rejection. Overall among-laboratories coefficient of variation (CVx) varied from 3.3 to 58%; at levels greater than or equal to 80 micrograms/g, it averaged 7.3% with outliers and 5.3% after their rejection. Recovery of tin, based on spiking levels, ranged from 100.0 to 112.8% and averaged 105.4%. Detection limit range is 2-10 micrograms/g, and lower quantitation limit is 40 micrograms/g. This method has been adopted official first action.

Acetylene↗