A Rapid Sample Preparation for Quantitative Analysis of Cortisol in Saliva and Urine by LC-MS/MS
Summary of MSACL 2015 Poster Presentation by: Daniel Zhou and Run-Zhang Shi, Clinical Chemistry and Immunology of Clinical Laboratories, Stanford Health Care
Reduce manual sample preparation time
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.
|Pretreatment||Add 50 μL internal standard and 500 μL acetonitrile to 250 μL of patient saliva and urine samples. Vortex and incubate at room temperature for 10 minutes|
|Extraction||Aspirate and Dispense 3x with WAX-S-XTR tips|
|Elution||Transfer 300 μL organic upper layer|
|Prep for injection||Solvent evaporate and reconstitute in 120 μL of H2O/MeOH|