Candidate reference measurement procedure for determination of urea in serum by liquid chromatography-tandem mass spectrometry

This study investigated a candidate RMP (cRMP) for detecting serum urea directly via ID-liquid chromatography (LC)-MS/MS, without derivatization, which simplifies pre-processing samples. The cRMP was developed and evaluated relative to the recognized RMP, inter- and intra-laboratories. The intra-precisions were 1.35%, 1.98% and 1.47% at 4.95, 24.74 and 31.36 mmol/L, respectively; inter-precision was 2.10%, 2.60% and 2.10%. The relative bias for the measurement of standard human serum (SRM 909c) was –0.49%. The relative biases were 0.41% and 0.02% for IFCC-RELA (International Federation of Clinical Chemistry and Laboratory Medicine-External Quality Assessment Scheme [EQAS] for reference laboratories) 2015 A and 2015B. The linearity response between 2.4 mmol/L and 53.7 mmol/L was R2 = 0.9989. No carryover, ion suppression, or interference was detected. Correlation was acceptable with the reference spectrophotometry (R2 = 0.9985, P <  0.0001). Between our laboratory and other reference laboratories, the absolute deviation range for IFCC-RELA 2016A and 2016B was from –0.63 to 1.52 mmol/L. This well-characterized cRMP for urea can provide a base of accuracy for the traceability of clinical systems.
Source: Journal of Pharmaceutical and Biomedical Analysis - Category: Drugs & Pharmacology Source Type: research