Novel quality control strategies for the determination of 25-hydroxyvitamin D by LC-MS/MS

Mass spectrometry analysis has been applied in many important diagnostic fields of laboratory medicine. However, there is little literature to guide quality management systems for LC-MS/MS methods. In this study, LC-MS/MS 25-hydroxyvitamin D (25(OH)D) was used as an example to establish internal quality control strategies to ensure the accuracy of clinical vitamin D results. A total of 141 batches of samples were analyzed. Sample internal standard peak area variability, ion pair ratio, and physical examination population data were monitored as quality control strategies for 25(OH)D results. The analytical performance was evaluated by calculated Sigma metrics. Applying our quality control strategies, several abnormal data were monitored in the routine analysis. The daily peak area CV of 25(OH)D fluctuated within a certain range. By selecting P99 CV as the control target, two abnormal batches were found. The ratio of 25(OH)VD3 ion pairs was relatively stable. Among them, batch20230120 had a high CV value, which may be due to the bias caused by the limited number. According to the physical examination data, batch20220913 and batch20220919 exceeded the alarm limit. Sigma level of 25(OH)VD3 in the laboratory was 6.52, which achieved "excellent" performance. In conclusion, we established comprehensive quality control strategies for the determination of 25(OH)D by LC-MS/MS, which has high analytical performance and can provide more accurate reports for the clinic.