Tandem DART™ MS Methods for Methadone Analysis in Unprocessed Urine

Abstract

Current methods of methadone analysis in untreated urine are traditionally limited to enzyme immunoassays (EIA) while confirmation techniques require specimen processing (i.e., sample clean-up) before analyzing by gas or liquid chromatography coupled with mass spectrometry (GC-MS or LC-MS-MS). EIA and traditional confirmation techniques can be costly and, at times inefficient. As an alternative approach, we present Direct Analysis in Real Time (DART™) coupled with both time-of-flight and triple quadrupole linear ion trap (Q-TRAP™) mass spectrometers for screening and confirming methadone in untreated urine specimens. These approaches require neither expensive kits nor sample clean-up for analysis. More importantly, the total combined analysis time for both screening and confirmation methods was <5 min per sample; in contrast to the 3-5 day process required by traditional EIA, GC-MS and LC-MS-MS techniques. To examine the fundamental protocol and its applicability for routine drug screening, studies were performed that included limits of detection, precision, selectivity and specificity, sample recovery and stability and method robustness. The methods described in this report were determined to be highly specific and selective; allowing for detection of methadone at 250 ng/mL, consistent with cutoffs for current EIA techniques (300 ng/mL). The results reported here demonstrate the DART™ MS platform provides rapid and selective methadone analysis and the potential for providing savings of both time and resources compared with current analysis procedures.

Effect of reducing sample volume on the detection of drugs in urine by transmission mode direct analysis in real time mass spectrometry

“…Each concentration was analyzed with four repeats, and concentrations were classified as detected if at least three of the repeats had signal‐to‐noise ratios greater than 3. As shown in Figures A and B, the LOD for methadone is between 0.05 and 0.1 ng μL −1 with 1 μL volumes and below 0.05 ng μL −1 with 200 nL volumes, which are both comparable with, if not better than, the LOD provided by some immunoassays (0.3 ng μL −1 ) 2 . Although the absolute amount of methadone deposited onto the QS card with 200 nL was less than that of 1 μL, improved sensitivity was achieved with 200 nL.…”

“…First, a screening method, such as an immunoassay, is used to quickly identify specific drugs or classes of drugs present in the urine. Next, a confirmatory method, such as gas chromatography‐ or liquid chromatography‐mass spectrometry (GC/MS or LC/MS), is used to confirm a positive, or in some instances, negative result 2 . Although immunoassays are rapid and inexpensive, the specificity varies based on the assay, and the method can result in high rates of false positives and false negatives.…”

“…Direct analysis in real time mass spectrometry (DART‐MS) enables rapid and confident screening of drugs with limited sample preparation particularly when used with accurate mass and tandem mass spectrometry 2 . This technology requires no chromatographic separation as sample analytes are rapidly desorbed and ionized to generate intact protonated or deprotonated molecules, the mass of which can be accurately measured.…”

Rapid analysis of fentanyls and other novel psychoactive substances in substance use disorder patient urine using paper spray mass spectrometry

“…They predict that mass spectrometry (MS)‐based methods, the current gold standard in laboratory‐based methods, hold great promise in the immediate future . It is with these point‐of‐care harm reduction strategies in mind that some researchers are pursuing ambient ionization with MS methods, suitable for drug testing in real time, such as direct analysis in real time (DART) or paper spray (PS) ionization approaches. DART‐MS offers advantages for the sensitive, qualitative detection of drugs directly from the surfaces of a wide variety of substances, but it is challenging to use for accurate quantitative measurements.…”

“…They predict that mass spectrometry (MS)-based methods, the current gold standard in laboratory-based methods, hold great promise in the immediate future. 17 It is with these point-of-care harm reduction strategies in mind that some researchers are pursuing ambient ionization with MS methods, suitable for drug testing in real time, such as direct analysis in real time (DART) 18,19 or paper spray (PS) [20][21][22] ionization approaches.…”