1. Storage (freezers, appropriate temp), limited access, monitoring 2. Sample handling, chain of custody, extractions, storage, HPLC, LC-MS/MS system, equilibration samples 3. Light sensitivity (if applicable) 4. Assay Validation 5. Sample analysis and reanalysis: Justified? Well documented? 6. QC samples-range curves observed subject concentrations? 7. Standard curve-appropriate range 8. Run acceptance ,Carryover effect/interference 9. ISR ,Audit trails-manual integration 10. Contemporaneous documentation ,Correspondence File 11 Audit report preparation