. Author manuscript; available in PMC: 2016 Jul 1.

Published in final edited form as: Anal Bioanal Chem. 2015 May 13;407(19):5615–5624. doi: 10.1007/s00216-015-8733-z

Table 2.

Confirmation ion ratios for a candidate reference measurement procedure for the quantitation of 25(OH)D₂ and 25(OH)D₃ in calibrators and serum samples

	n	Concentration, nmol/L	Mean Ion Ratio^a (range)

25(OH)D₂
Calibrator	40	3.71	0.57 (0.45–0.68)^b
Serum samples	67	LOQ-64.9	0.56 (0.45–0.69)^c
25(OH)D₃
Calibrators	80	10–100	0.57 (0.49–0.66)^d
Serum samples	148	16–183	0.57 (0.51–0.63)^c

Peak area ratios of confirmation (m/z 383.3→105.0) to quantitation (m/z 383.3→365.1) ions

Mean (± 20%) calculated from calibration level 2 in 10 measurement series (2 preparations, 2 injections)

Mean (minimum-maximum) from all serum samples with concentrations >LOQ from 5 measurement series

Mean (± 15%) calculated from all calibration levels in 5 measurement series (4 levels, 2 preparations, 2 injections)