USP chapters that actually reach the vial, not the instrument
Last Tuesday a validated headspace GC method for residual solvents drifted out of tolerance on the calibration check. RSD on the internal standard jumped from 1.8% to 6.4% across six vials from the same tray. The column was fine, the inlet was fine, the method had not changed. The only new variable was a batch of 20 mL crimp-top vials from a supplier we had switched to three weeks earlier to save $0.11 per unit. When you run a validated method, the phrase USP requirements for vial supplier ...
