Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/1999
Publication Date: 6/15/2001
Citation: Miller-Ihli, N.J., Baker, S.A., Bradshaw, D. 2001. Trace element determinations in food and biological samples using icp-ms. Journal of Food Composition and Analysis. 14:619-629.
Interpretive Summary: A method for the determination of 13 elements (Na, Mg, P, K, Ca, V, Cr, Fe, Mn, Co, Ni, Zn and Cu) in digested food and biological samples is presented. Samples were acid digested and then analyzed using inductively coupled plasma mass spectrometry which provides sub-ppb detection capability. Five elements (Sc, Ga, Ge, Y, and In) were evaluated as internal standards and we found that Ga provided superior results. A total of 5 well- characterized reference materials were used to evaluate accuracy and precision. The measurement precision for individual digests was typically better than 0.5% RSD (n=3) and analyte concentrations compared favorably (+/- 10%) with mean reference concentrations. Looking to the future, this method will prove useful to colleagues generating food composition data in industrial, contract, and government labs because it is a very sensitive, rapid and robust method which will continue to be useful as the number of elements required on labels increases beyond the 3 current mandatory elements (Ca, Na, Fe).
Technical Abstract: A method for the determination of 13 elements (Na, Mg, P, K, Ca, V, Cr, Fe, Mn, Co, Ni, Zn, and Cu) in digested food and biological samples is presented. Five internal standards (Sc, Ga, Ge, Y, and In) were investigated in this work and both Ga and Ge were determined to be effective in compensating for matrix-induced signal suppression. A single internal standard could be used to accurately determine the concentration of all of the analytes, even though they differed significantly in mass and ionization potential. Results for five reference materials using Ga as the internal standard were in good agreement with the reference values. Average recoveries were 102 % - range of 91-112 % (SRM 1548), 96 % - range of 74-106 % (SRM 1549), 102 % - range of 89-110 % (SRM 1577a), 100 % - range of 89- 130 % (RM 8431), and 100 % - range of 89-112 % (QC Bread) based on the mean reference concentration. The measurement precision for individual digested samples was typically better than 0.5 % RSD (n = 3). In addition, the average difference (duplicate sample preparations) between measured concentrations for all analytes in the five matrices was only 3%.