. 2015 Dec 31;2015:210503. doi: 10.1155/2015/210503

Table 5.

Stability and dilution integrity data of PTB.

Stability	Nominal conc. (ngmL⁻¹)	Plasma			Urine
Stability	Nominal conc. (ngmL⁻¹)	Measured conc. (ngmL⁻¹ ± SD)	Precision (CV %)	Accuracy (R %)	Measured conc. (ngmL⁻¹ ± SD)	Precision (CV %)	Accuracy (R %)
Bench top (6 h)	50	46.01 ± 0.42	0.913	92.01 ± 0.84	47.67 ± 0.40	0.848	95.35 ± 0.81
Bench top (6 h)	100	92.08 ± 0.68	0.736	92.08 ± 0.68	95.63 ± 1.53	1.605	95.63 ± 1.53

Freeze thaw (3 cycles)	50	50.67 ± 0.31	0.606	101.34 ± 0.61	50.00 ± 1.00	2.016	100.0 ± 2.02
Freeze thaw (3 cycles)	100	100.47 ± 1.08	1.071	100.47 ± 1.08	100.0 ± 1.07	1.074	100.0 ± 1.0

14 days at −80°C	50	42.94 ± 0.91	2.108	85.87 ± 0.91	47.20 ± 0.953	2.019	94.40 ± 1.91
14 days at −80°C	100	86.67 ± 0.68	0.788	86.67 ± 0.68	94.11 ± 1.26	1.343	94.11 ± 1.26

Dilution integrity	45	43.54 ± 0.61	1.393	96.76 ± 1.35	44.48 ± 0.59	1.337	98.84 ± 1.32
Dilution integrity	90	90.21 ± 1.66	1.835	100.23 ± 1.84	88.27 ± 0.73	0.824	98.08 ± 0.81