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Biomedical subjects

K W Boyer

Publications and source records attributed to K W Boyer.

6 recordsLinked to original sources
PubMed1979

Sample homogenization procedure for determination of lead in canned foods.

To improve the homogeneity of canned foods before Pb determination, composited samples or single can contents (150--500 g) are treated with an equal weight of dilute nitric acid, and then thoroughly blended in a high efficiency, probe-type Polytron homogenizer; subsamples are then either dry-ashed or wet-ashed in preparation for analysis. Within-can variability is reduced from the 20--50% coefficient of variation range obtained with conventional blending procedures to a coefficient of variation of less than 5% by using the proceudre described. Precision data for Pb, using both the probe-type and conventional blade-type homogenizers, are compared. The procedure described for Pb determination was used to analyze a number of canned products. Data indicate that the Polytron plus dilute acid procedure improves overall Pb homogeneity for subtle as well as severe initial Pb heterogeneity.

Food Analysis↗
PubMed1977

Fortification variability in rat diets fortified with arsenic, cadmium, and lead.

Eleven rat diets fortified with 200 ppm Pb as lead acetate, and/or 50 ppm Cd as cadmium chloride, and/or 50 ppm As as sodium arsenate or p-arsanilic acid for use in a feeding study to determine the interactive effects of the three elements in rats were analyzed to confirm the fortification levels. Gross inhomogeneity was found. After remixing, variability within and among diets was improved but was still unacceptable. Fortification levels of Pb and of As as sodium arsenate could be accurately determined only by taking a very large sample and homogenizing the diet subsamples with a Polytron homogenizer. A review of the recent literature indicates that no standard procedures exist for fortification, mixing, or analysis of animal feeding study diets. Such procedures should be developed and analysis of the diets before and at intervals during a feeding study should be adopted as standard procedure.

Animal Feed↗
PubMed1977

Dry ash-voltammetric determination of cadmium, cooper, lead, and zinc in foods.

An analytical method is presented for determining cadmium, copper, and lead by differential pulse anodic stripping voltammetry and zinc by cathodic scan differential pulse voltammetry. Food samples are dry ashed using a sulfuric acid ashing aid, dissolved in dilute nitric acid, buffered at pH approximately 4.3 with an acetate buffer, and quantitatively analyzed using the technique of standard additions at a hanging mercury drop electrode. The quantitation limits (5 times the estimated detection limits) are approximately 5 ng/g for Cd, Cu, and Pb, and 50 ng/g for Zn. Accuracy of the method is established by (a) analysis of NBS Standard Reference Material No. 1577 Bovine Liver, (b) comparison of results obtained by the method described with those obtained by independent analytical methods, and (c) quantitative recovery of analyte metals from fortified, noncanned food samples. Results from an interlaboratory method trial indicate that the method is suitable for the analysis of a variety of food types.

Cadmium↗
PubMed1976

A simplified method for the gas-liquid chromatographic determination of methyl mercury in fish and shellfish.

A simple acetone wash of the fish sample which removes lipids and other organic materials replaces the cystein cleanup specified in other methods. Methyl mercury is freed by hydrochloric acid, extracted into benzene, and determined with a gas-liquid chromatograph equipped with an electron capture detector. The method is quantitative for methyl mercury levels as low as 0.10 ppm in fish and shellfish. Ethyl mercury chloride may be used as an internal standard to detect unsuspected error or instrumental parameter variation.

Animals↗