Use of synthetic urine as a matrix substitute for standard and quality control materials in the clinical assessment of iodine by inductively coupled plasma mass spectrometry

Objectives: We developed and validated the use of synthetic urine as a matrix substitute for standard and quality control material preparation in the clinical assessment of iodine status in urine.

Design and methods: Measurement of iodine in urine was conducted using inductively coupled-plasma mass spectrometry. Analytical and clinical recoveries were assessed to investigate comparability between synthetic urine and pooled patient urine. Method performance characteristics were determined in accordance with clinical laboratory standards.

Results: Established assay performance characteristics included inter- and intra-assay imprecision <10%, carryover of <0.2%, analytical measurement range of 5 to 1000μg/L, limit of quantification of 5μg/L (coefficient of variation <10%), proportional bias of 0.92 and constant bias of 8.8 in comparison to an outside reference laboratory.

Conclusions: Synthetic urine is an appropriate alternative matrix for standard and quality control material preparation for the measurement of iodine in urine.