Determination of Reference Concentrations of Strontium in Urine by Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

Objective: The aim of this study was to establish reference concentrations of urinary strontium by inductively coupled plasma atomic emission spectrometry (ICP-AES). Methods: For the determination of strontium, urine samples were collected from healthy Japanese (n=146; 115 males, 31 females; mean age, 33±9 years; age range, 18 to 58 years). The urine samples stored at or below −20°C were thawed with incubation at 40°C for 30 min and sediments were dissolved by vigorous shakings. Then, the samples were centrifuged at 3000 g for 5 min, and the supernatant was directly aspired into a P-5200-3600/1200 ICP-AES system from Hitachi Ltd., Tokyo, Japan. Results: A steeper increase in the S/N ratio and a good effective linearity of the calibration line was obtained at 407.771 nm in the range of 0-300 μg/L strontium standard solution. Urine samples having the same background signal as that of 18 MΩ cm ultrapure blank water, a good correspondence of the single peak pattern of the spectra, accuracy and precision of spike recovery were also confirmed. Urinary strontium concentrations showed a log-normal distribution and a geometric mean concentration of 143.9 μg/L, with 5-95% confidential interval of 40.9-505.8 μg/L. Conclusion: The results of this study will be useful as guidelines for the biological monitoring of strontium in normal subjects and in individuals therapeutically or environmentally exposed to strontium.

An Overview of Boron, Lithium, and Strontium in Human Health and Profiles of These Elements in Urine of Japanese

“…Kurtosis is a measure of the "peakedness" of the probability distribution and higher kurtosis values indicate that more of the variance is due to infrequent extreme deviations, as opposed to frequent moderately sized deviations. The obtained kurtosis values indicate that the urinary boron concentration fluctuates more frequently and shows higher volatility than the urinary concentrations of lithium and strontium (12,48).…”

“…The quality assurances of these techniques have been amply described in several reports (10)(11)(12).…”

“…The reported urinary boron (10,(77)(78)(79), lithium (11,78,80) and strontium (12,(81)(82)(83) concentrations are summarized in Table 1. These results suggest that urinary boron concentration is on the order of several hundred μg/l with a mean value of approximately 1000 μg/l, that urinary lithium concentration is on the order of μg/l with a mean value of approximately 20 μg/l, and that urinary strontium concentration is on the order of 10-100 μg/l with a mean value of approximately 150 μg/l.…”

“…Urine sampling is simple, non-invasive and can be performed in a routine manner (12). We recommended that our obtained GM with CI reference values could be used as practical biological benchmarks for the prevention and early diagnosis of exposure to these three elements.…”

“…Being part of one of the major excretion routes for trace elements, urine is frequently utilized for monitoring occupational and environmental exposures (8,9). Consequently, we carefully optimized the conditions for using ICP-AES to analyze urine samples for boron, lithium and strontium concentrations in the Japanese population and determined the urinary reference values for these elements (10)(11)(12). In this review article, we summarize the role of boron, lithium and strontium in human health and the reference values of these elements in the urine of Japanese people.…”