OXY Analysis
Analysis of OXY was conducted using a validated reversed phase LC-MSMS method. Reversed phase chromatography was performed using a Waters XSelect CSH C18 column (2.1 x 50 mm, 2.5 µm particle size) and a 0.1% formic acid / acetonitrile gradient at 0.5 mL/min flow rate. The injection volume was 8 µL and the total run time was 6 minutes. Quantitation was performed on a Shimadzu LCMS-8060 instrument in positive ESI mode using multiple reaction monitoring (MRM). Parent/daughter transitions acquired for quantitation were 1007.4>723.3 (single charge) and 504.3>285.2 (double charge). The validated range was 20 – 100 ng/mL OXY using external standard quantitation. It should be noted that a LC-MSMS method was used in preference to pharmacopoeial methods to provide the necessary sensitivity to quantify the low concentrations of OXY present when ampoules are further diluted in preparations for infusion use.