Abstract:

Matrix effect is an important interfering factor in LC-MS quantitative analysis. In this paper, matrix effects and retention efficiencies of 33 veterinary drugs spiked in river water were studied on hydrophilic-lipophilic balance (HLB) cartridges of 3 brands (Waters, Supelco, and CNW), using LC-MS/MS for detection and reverse osmosis (RO) water as the control under 500-fold concentration. In RO water, only the exogenous matrix effects were observed on three brands of HLB cartridges. Most quinolones and tetracyclines showed positive matrix effects. Estrogens showed negative matrix effects on two brands of HLB cartridges. Sulfonamides were not obviously affected by matrix effects. Chloramphenicols showed negative matrix effects on one brand of HLB cartridge. In river water, matrix effects were different from those of the RO water due to the combined exogenous and endogenous interfering substances. Sulfonamides showed slight matrix effects as those in RO water. Most quinolones and tetracyclines showed positive matrix effects. Chloramphenicols and estrogens showed negative matrix effects. Compared to the external standard method, matrix matched calibration method effectively overcame the matrix effects with better quantitative results. The recoveries of 33 target veterinary drugs spiked in river water at 50 ng/L and 200 ng/L levels were in the ranges of 40.3%-146.0% (Waters), 37.8%-104.2% (Supelco), and 52.9%-150.1% (CNW) with RSDs (n=4) of 0.2%-14.6%. The results indicated that there was no significant difference in the retention efficiency between the 3 HLB cartridges with the matrix matched calibration method. This study provided supporting data for the HLB cartridge selection in multi-residual determination of the veterinary drugs in river water samples.

Key words: hydrophilic-lipophilic balance (HLB) cartridges, liquid chromatography-mass spectrometry, matrix effect, retention efficiency, river water, veterinary drug