Development of a liquid chromatography-tandem mass spectrometry method to address the increased utilization of umbilical cord in the assessment of in utero drug exposure

Objectives: The method described supports the detection of drugs and drug metabolites in the assessment of in utero drug exposure. The presented method employs liquid chromatography-tandem mass spectrometry (LC-MS/MS) as an alternative to a previously validated method using liquid chromatography-time-of-flight mass spectrometry (LC-TOF/MS). A reduction in required chromatographic time and consolidation from two injections to one injection per sample was desired to reduce turnaround time while maintaining the high specificity required. Design and methods: Homogenized and extracted umbilical cord samples were analyzed using LC-TOF/MS and LC-MS/MS. The LC-MS/MS chromatographic method used a 3.5 min gradient with an injection-to-injection time of 5 min. Dynamic multiple reaction monitoring was utilized. Results: A 55% reduction in total analytical time was achieved by incorporating positive and negative mode acquisition in a single injection with the LC-MS/MS (5 min cycle time) compared to the LC-TOF/MS method that required two total injections (one for positive mode, one for negative mode) and a combined similar to 11.5 min cycle time. 514 patient samples were analyzed by both methods over 20 days. Of the 260 LC-TOF/MS negative samples, 259 were LC-MS/MS negative. Inter-assay imprecision conducted over 20 days using the 50% and 150% QC samples yielded $_amp_$gt; 97% qualitative acceptance and an average percent deviation from the target of 12% and 21%, respectively, using a single point calibration strategy. Conclusions: In comparison to the existing LC-TOF/MS method, the LC-MS/MS method delivered the required specificity in a single injection with a 55% reduction in instrument time. Use of a single-point calibration standard and eight representative internal standards provided adequate accuracy for the quantitative assessment of quality control results with qualitative reporting of patient results. (C) 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.