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

Table 2

Intra-assay 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	19.8 ± 0.47	2.35	−0.90	5
Middle concentration	2.50	2.54 ± 0.055	2.16	1.60	5
Low concentration	0.31	0.32 ± 0.045	14.0	2.40	5

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