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A dilute‐and‐shoot flow‐injection tandem mass spectrometry method for quantification of phenobarbital in urine
Author(s) -
Alagandula Ravali,
Zhou Xiang,
Guo Baochuan
Publication year - 2016
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7763
Subject(s) - chemistry , chromatography , phenobarbital , mass spectrometry , tandem mass spectrometry , electrospray ionization , correlation coefficient , selected reaction monitoring , detection limit , coefficient of variation , electrospray , liquid chromatography–mass spectrometry , analytical chemistry (journal) , pharmacology , medicine , statistics , mathematics
Rationale Liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the gold standard of urine drug testing. However, current LC‐based methods are time consuming, limiting the throughput of MS‐based testing and increasing the cost. This is particularly problematic for quantification of drugs such as phenobarbital, which is often analyzed in a separate run because they must be negatively ionized. Methods This study examined the feasibility of using a dilute‐and‐shoot flow‐injection method without LC separation to quantify drugs with phenobarbital as a model system. Briefly, a urine sample containing phenobarbital was first diluted by 10 times, followed by flow injection of the diluted sample to mass spectrometer. Quantification and detection of phenobarbital were achieved by an electrospray negative ionization MS/MS system operated in the multiple reaction monitoring (MRM) mode with the stable‐isotope‐labeled drug as internal standard. Results The dilute‐and‐shoot flow‐injection method developed was linear with a dynamic range of 50–2000 ng/mL of phenobarbital and correlation coefficient > 0.9996. The coefficients of variation and relative errors for intra‐ and inter‐assays at four quality control (QC) levels (50, 125, 445 and 1600 ng/mL) were 3.0% and 5.0%, respectively. The total run time to quantify one sample was 2 min, and the sensitivity and specificity of the method did not deteriorate even after 1200 consecutive injections. Conclusions Our method can accurately and robustly quantify phenobarbital in urine without LC separation. Because of its 2 min run time, the method can process 720 samples per day. This feasibility study shows that the dilute‐and‐shoot flow‐injection method can be a general way for fast analysis of drugs in urine. Copyright © 2016 John Wiley & Sons, Ltd.