Long-Term Stability of Hydromorphone in Human Plasma Frozen at −20°C for Three Years Quantified by LC-MS/MS

Table 1

Interassay accuracy and precision of the applied analytical method.

QC sample	Nominal concentration (ng/mL)	Mean ± SD (ng/mL)	%RSD	%RE	n
High concentration	20.0	19.98 ± 0.33	1.63	−0.10	15
Middle concentration	2.50	2.49 ± 0.14	5.45	−0.53	15
Low concentration	0.31	0.35 ± 0.052	14.9	10.9	15

SD: standard deviation; %RSD: relative standard deviation; %RE: relative error from nominal concentration.