The retention time of cyanocobalamin was stable during the
analyses, irrespective of the sample matrices. The 30-day average
retention time was 3.27 min with a narrow change from 3.25 to
3.29 min over the study period. The UHPLC analysis was faster
with a total run time of 10 min compared with over 30 min that
was required for the HPLC methods (Heudi et al., 2006; Marley
et al., 2009). An external calibration curve of excellent linearity
(R2 > 0.999) was achieved by injecting a series of cyanocobalamin
standard solutions (0.015–0.75 ng/lL). The instrumental LOD and
LOQ were 0.075 ng/inj and 0.225 ng/inj, respectively, for a 5 lL