MEASUREMENT OF STRONTIUM IN SERUM, URINE, BONE, AND SOFT-TISSUES BY ZEEMAN ATOMIC-ABSORPTION SPECTROMETRY

To study the possible accumulation of Sr in chronic renal failure pati ents, methods were developed for the determination of the element in s erum, urine, bone, and soft tissues by using Zeeman atomic absorption spectrometry. Serum samples were diluted 1:4 with a Triton X-100-HNO3 mixture, whereas urine samples were diluted 1:20 with HNO3. Bone sampl es were digested with concentrated HNO3 in stoppered polytetrafluoroet hylene (Teflon(R)) tubes, whereas soft tissues were dissolved in a tet ramethylammonium hydroxide solution in water. For serum and urine we u sed matrix-matched calibration curves, whereas bone and tissue samples were measured against aqueous calibrators. Atomization was performed from the wall of pyrolytically coated graphite tubes for all of the ma trices under study. Both inter- and intraassay CVs were <6% (n = 12, n = 10, respectively), and the recovery of added analyte was close to 1 00% for all of the biological matrices under study. Detection limits w ere 1.2 mu g/L (serum), 0.3 mu g/L (urine), 0.4 mu g/g (bone), and 2.2 ng/g (soft tissues), whereas the sensitivity determined by the slope of the calibration curve, i.e., the amount of Sr producing a 0.0044 in tegrated absorbance change in signal, was 2.4 pg, 2.4 pg, 3.9 pg, and 2.6 pg for these matrices respectively. We conclude that the present m ethods are precise and accurate and easily applicable for both routine use and research investigations. They will allow us to study the meta bolism of the element in chronic renal failure patients and shed some light on the association that was recently noted between increased bon e Sr concentrations and the development of osteomalacia in these indiv iduals.