ABSTRACT
AIM: A bioanalytical method using inductively-coupled plasma-mass spectrometry to measure endogenous levels of strontium in human serum was developed and validated. RESULTS & METHODOLOGY: This article details the experimental procedures used for the method development and validation thus demonstrating the application of the inductively-coupled plasma-mass spectrometry method for quantification of strontium in human serum samples. The assay was validated for specificity, linearity, accuracy, precision, recovery and stability. Significant endogenous levels of strontium are present in human serum samples ranging from 19 to 96 ng/ml with a mean of 34.6 ± 15.2 ng/ml (SD). DISCUSSION & CONCLUSION: Calibration procedures and sample pretreatment were simplified for high throughput analysis. The validation demonstrates that the method was sensitive, selective for quantification of strontium (88Sr) and is suitable for routine clinical testing of strontium in human serum samples.
ABSTRACT
BACKGROUND: Mucopolysaccharidosis IVA (MPS IVA, Morquio A syndrome) is an inherited lysosomal storage disease caused by deficiency of N-acetylgalactosamine-6-sulfatase (GALNS), an enzyme required for stepwise degradation of keratan sulfate (KS). We have developed a selective, sensitive, accurate and precise LC-MS/MS assay for the KS-derived disaccharides Galß1-4GlcNAc(6S) and Gal(6S)ß1-4GlcNAc(6S) in human urine and plasma using keratanase II digestion. RESULTS: Mean accuracy was 96-106% in urine and 97-108% in plasma. Precision was high, with relative standard deviations of 1-2% (intra-day) and 2-5% (inter-day) in urine and 1-2% (intra-day) and 4-7% (inter-day) in plasma. The lower limit of quantitation was 0.026 µg/ml (plasma) and 0.104 µg/ml (urine), with a quantitation range of 0.026-5 µg/ml (plasma) and 0.104-20 µg/ml (urine). CONCLUSION: Clinical sample analysis in 168 MPS IVA patients and 225 healthy controls demonstrates the clinical utility of this method.
