Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2018
Publication Date: N/A
Interpretive Summary: .
Technical Abstract: Quantitation of contaminants in food animal products by regulatory officials is mostly conducted using hyphenated mass spectrometry (MS) technologies. While hyphenated MS approaches can be used for multi-residue sample analysis in an effective manner, it is time consuming, expensive, and labor intensive. In the last decade, several ambient ionization techniques including desorption electrospray ionization (DESI) and atmospheric solid analysis probe (ASAP) have been introduced that have the potential for direct, real-time analysis of target analytes in complex biological matrices. Here, we demonstrate the use of ASAP and DESI-like MS in an existing commercial heated electrospray ionization (HESI) probe for conducting high throughput screening of zilpaterol in real time with little or no sample preparation. A total of 244 urine and 72 tissue samples were analyzed for zilpaterol concentration in a blinded study with respect to sample identity. In ASAP, limits of detection (LoD) and limits of quantitation (LoQ) of urine samples were 1.1 and 3.7 ng/mL while in DESI they were 1.3 and 4.4 ng/mL respectively. The LoDs of kidney, muscle, liver and lung were 0.1, 0.2, 0.3 and 0.35 ng/mL in ASAP, and 0.5, 0.15, 0.25 and 0.6 ng/mL respectively in DESI. The LoQs of kidney, muscle, liver and lung in ASAP were 0.36, 0.64, 1.1 and 1.15 ng/mL, and 1.6, 0.48, 0.85 and 2.1 ng/mL respectively in DESI. Slight variation in signal intensity was observed in day-to-day analysis but linearity of the standard curve (r2 0.9931 ± 0.003 & 0.9954 ± 0.003 in ASAP and DESI, respectively) was not affected. For both techniques, triplicate samples were analyzed in under a minute. However, manual sample introduction and individual data collection limited the number of samples analyzed in an hour to forty. Animals treated with trace levels of zilpaterol (0.1% to 10% of label dose) were correctly identified via urine analysis; tissue analysis correctly identified animals treated with a 10% zilpaterol dose and slaughtered with a 0-day withdrawal period.