The use of a triple quadrupole provides high selectivity and specificity. Two SRM transitions were monitored for each analyte, which improves specificity. For identification, the ratios of the two SRM transitions were compared with those of the standards. The specificity of the method was further confirmed through the analysis of many blank samples (more than 20 samples for some matrices) over a 3-year period of use of this method. For each of the SRM transitions, no peak with a signal-to-noise ratio of at least 3 was detected.