Acid digestion, hydride evolution atomic absorption spectrophotometric method for determining arsenic and selenium in foods: collaborative study. tpart I.

The hydride evolution atomic absorption spectrophotometric (AAS) method for determining As and Se in foods developed and evaluated by the Food and Drug Administration and Agriculture Canada laboratories was subjected to collaborative study, Twenty-four laboratories provided results for As and 23 provided results for Se levels in 13 different samples consisting of tuna, swordfish, flounder, oyster, liver, flour, skim milk poweder, spinach, kale, and apple containing natural levels of As and Se in the ranges 0-15,000 and 0-4000 ng/g, respectively. Reference materials formed a substantial segment of samples, and a number of other laboratories using fluorometry, colorimetry, neutron activation, spark source mass spectrometry, and graphite furnace AAS provided confirmative reference values for the remaining samples. A variety of hydride generation instruments were used, ranging from commercially available devices to semiautomated and fully automated custom-made instruments. Although the accuracy of the method was fairly good, between-laboratory and between-determination (hydride evolution AAS measurement) precisions were not favorable. The main advantage of the hydride AAS method is the rapidity of the determinative step.