To validate the precision of the proposed method, the relative standard deviations (RSDs) of peak areas were calculated for intra-day and inter-day variations.
The intra-day variation was measured by analyzing BAs standards at 0.05 mM in triplicate within one day, and the inter-day variation was tested by analyzing the same BAs standards on three different days.
As shown in Table 2, the intra-day and inter-day precision are in the range of 0.98–2.54% and 2.11–3.87%, separately.
BAs standards at three concentration levels (0.005, 0.05 and 0.5 mM) were subjected to the MASC-derivatization-HPLC–MS/MS procedure to evaluate the accuracy.
The accuracy was expressed as percentage of calculated value to the nominal concentration, and the results are shown in Table 2.
The accuracy for the seven BAs at levels of 0.005, 0.05 and 0.5 mM ranged from 97.9% to 102.1%, from 97.6% to 102.3%, and from 98.7% to 102.5%, respectively.
The results indicated that the described method was sufficiently precise and accurate for routine analysis of BAs.