Validated quantification method for five ephedrines in dietary supplements using LC-MS/MS: Application to 503 cases.

Ephedrines in dietary supplements can arise from herbs or illegal adulteration so a liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for separation and quantification of ephedrine, pseudoephedrine, norephedrine, norepseudoephedrine, and methyl-ephedrine, some of which are isomer pairs of pseudo-structures. This method includes liquid-liquid extraction of ephedrines from three typical dietary supplement matrices-solid, liquid, and oil-as well as liquid chromatographic separation. After liquid chromatographic separation, ephedrines are qualitatively and quantitatively analyzed using triple quadrupole mass spectrometry with positive electrospray ionization in multi-reaction monitoring (MRM) mode. Ephedrine recoveries in a solid matrix ranged from 53.3-91.5%, in a liquid matrix from 56.4-102.3%, and in an oil matrix from 51.7-01.2%. Linearity ranges were 10-1000ng/g in solid and oil matrix and 1-100ng/ml in liquid matrix. Accuracy was -11.5-16.3%. Intra-day and inter-day variation are less than 5.9% and 7.3%, respectively. Expanded uncertainty of quantification is less than 0.123ng/g in a solid matrix, less than 0.139ng/ml in a liquid matrix, and less than 0.158ng/g in an oil matrix. Data collected for more than 500 routine samples are presented and discussed.