W. C. Cunningham

Application of an instrumental neutron activation analysis procedure to analysis of food

The capabilities of a relatively simple instrumental neutron activation analysis procedure were demonstrated by performing multielement analyses of 240 Food and Drug Administration Total Diet Studies food composites. The analytical results provide a comprehensive database for a wide range of food types. The procedure incorporates only two irradiations and counts, polyethylene packaging and no sample transfer after irradiation. Concentrations were determined for 19 elements, 16 of which were found in most composites. Detection limits were calculated for all food groups and are given for the 22 elements included in the quantitative analysis scheme. In a qualitative search for 18 additional elements for which no standards were run, none were detected in any of the composites. Specific factors such as interferences from the blank are discussed in regard to their effects on the uncertainties associated with the experimental data and the detection limits. Modifications to the procedure are also suggested for lowering the detection limits for specific elements.

Multielement analysis of foods by neutron capture prompt γ-ray activation analysis

A method is described for the determination of H, B, Cl, K, Na, S, Ca, and Cd in foods using in-beam neutron capture prompt γ-ray activation analysis. Special calibration procedures were necessary because of matrix-related thermal neutron scattering-induced sensitivity and background enhancements. Detection limits and sensitivities are presented for best-case and worst-case irradiation conditions. The method was applied to multielement analysis of 41 foods and to B, Cl, and K analysis of 13 orange juice produts in conjunction with analysis by inductively coupled plasma atomic emission spectrometry. The purpose of the latter application was to study B losses during acid digestion.

Analysis of foods for iodine by epithermal neutron activation analysis

Epithermal-neutron activation analysis (ENAA) was applied to the analysis of foods for iodine. The procedure involves irradiation of wet foods in a boron nitride, vessel, followed by direct counting of the 442.9 keV gamma ray of128I without any processing of the sample. Three research reactors were evaluated for use in determining iodine by ENAA. The University of Virginia reactor at Charlottesville was chosen for this study because the reactor facilities minimized thermal heating of the boron nitride vessel, enabling irradiation of larger, more representative analytical portions. Iodine concentrations ranging from <0.003 to 0.74 μg/g are reported for 17 different food matrices.

Trace element levels in tissues from cattle fed a sewage sludge‐amended diet

The levels of 20 elements (Al, Ca, Cd, Cl, Co, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Se, V, and Zn) are reported for kidney, liver, muscle, spleen, and brain tissues taken from two groups of six steers per group in a feeding study conducted at Colorado State University. The control group was fed a normal feedlot cattle ration and the test group was fed the same ration amended with 12% (by weight) air-dried municipal sewage sludge. Elemental levels are also reported for the control and test diets, control and test feces, and sewage sludge added to the diet. All samples were analyzed by inductively coupled plasma emission spectroscopy and neutron activation analysis. Brief descriptions of the analytical methods are included. The levels of all metals determined were elevated in the test diet (as much as 19-fold for Cd) compared with the control diet. The levels of Pb and Cd in kidney and of Pb, Cd, and Cu in liver in the test animals were high enough to cause concern from a toxicological standpoint if these tissues were consumed regularly by humans. None of the levels of any of the other elements in the control and test animal tissues were high enough to cause similar concern with respect to human consumption.

MULTIELEMENT ANALYSIS BY NEUTRON ACTIVATION OF TISSUES FROM SWINE ADMINISTERED COPPER SUPPLEMENTED DIETS

Instrumental neutron activation analysis was used to determine Co, Cu, Fe, Mg, Mn, Se and Zn in tissues from swine fed copper supplemented diets.