Summary of MSACL 2015 Poster Presentation by: Daniel Zhou and Run-Zhang Shi, Clinical Chemistry and Immunology of Clinical Laboratories, Stanford Health Care

For determining saliva and urine cortisol levels LC-MS/MS is the measurement method of choice with high sensitivity and specificity. However, the conventional LC-MS/MS approach requires lengthy manual sample preparation by liquid-liquid extraction [LLE] or solid phase extraction [SPE], and patient samples are processed in a batch mode. To shorten sample preparation time, Stanford investigated dispersive pipette XTRaction tips that contained weak anion exchange (WAX) sorbent and salt (S) necessary for SALLE (Salting-out Assisted Liquid-Liquid Extraction) as a quick alternative. Stanford validated this improved LC-MS/MS method in a clinical chemistry laboratory. Assay characteristics such as sensitivity, specificity, linearity, and precision are presented. We conclude that the improved LC-MS/MS method is rapid and as sensitive as the conventional LC-MS/MS approach making it much more suitable for clinical diagnostic use.