Improved Thyreostatic Drug Detection in Animal Tissues
Using Liquid Chromatography–High-Field Asymmetric Waveform
Ion Mobility Spectrometry–Mass Spectrometry
posted on 2022-01-21, 14:33authored byRandy W. Purves, Kim Souster, Michelle West, Azhar M. Huda, Caleb M. E. Fisher, Michael W. Belford, Bryn O. Shurmer
Thyreostatic
drugs (thyreostats) interfere with thyroid function
and have been used illegally in animals slaughtered for food. Thyreostat
use leads to poorer quality meat, and the drug residues can cause
adverse effects in humans. These drugs, with the exception of thiouracil,
do not occur naturally and require sensitive methodologies for their
detection in animal tissues. Because thyreostats are low-molecular-weight
polar analytes, liquid chromatography–mass spectrometry (LC–MS)
is typically used for detection and, in particular, triple quadrupole
mass spectrometry with selective reaction monitoring (i.e., LC–SRM).
However, LC–SRM thyreostat methods suffer from chemical background
noise and endogenous interferences arising from the complex tissue
matrix. An improved high-field asymmetric waveform ion mobility spectrometry
interface (FAIMS Pro), which separates ions based on differential
ion mobility, was combined with LC–SRM to minimize these interferences.
Using the same samples and conditions, LC–FAIMS–SRM
showed improvements in the signal-to-noise ratio (S/N) of up to 50
times compared with our validated LC–SRM method. In addition,
wider linear ranges, including substantial improvements in the lower
limit of quantification (approximately an order of magnitude for tapazole
and methylthiouracil), were observed with LC–FAIMS–SRM.