Hsiu-Chuan Liu 1, Hsi-Tzu Lee 1, Ya-Ching Hsu 2, Mei-Han Huang 2, Ray H. Liu 3, Tai-Jui Chen 4 and Dong-Liang Lin 1 *

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1 Journal of Analytical Toxicology 2015;39: doi: /jat/bkv041 Advance Access publication May 2, 2015 Article Direct Injection LC MS-MS Analysis of Opiates, Methamphetamine, Buprenorphine, Methadone and Their Metabolites in Oral Fluid from Substitution Therapy Patients Hsiu-Chuan Liu 1, Hsi-Tzu Lee 1, Ya-Ching Hsu 2, Mei-Han Huang 2, Ray H. Liu 3, Tai-Jui Chen 4 and Dong-Liang Lin 1 * 1 Department of Forensic Toxicology, Institute of Forensic Medicine, Ministry of Justice, Taipei, Taiwan, 2 Department of Medical Laboratory Science and Biotechnology, Fooyin University, Kaohsiung, Taiwan, 3 Department of Justice Sciences, University of Alabama at Birmingham, Birmingham, AL, USA, and 4 Department of Psychiatry, E-Da Hospital, Kaohsiung, Taiwan *Author to whom correspondence should be addressed. dllin@mail.moj.gov.tw A rapid and sensitive liquid chromatography tandem mass spectrometry (LC MS-MS) method was developed, validated and applied to simultaneous analysis of oral fluid samples for the following 10 analytes: methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), buprenorphine, norbuprenorphine, morphine, codeine, 6-acetylmorphine, 6-acetylcodeine, amphetamine, and methamphetamine. The oral fluid sample was briefly centrifuged and the supernatant was directly injected into the LC MS-MS system operated under reverse-phase chromatography and electrospray ionization (ESI). Deuterated analogs of the analytes were adopted as the internal standards and found to be effective (except for buprenorphine) to compensate for potential matrix effects. Each analytical run took <10 min. Linearity range (r 2 > 0.99) established for buprenorphine and the other nine analytes were and ng/ml. Intraand interday precision (% CV) ranges for the 10 analytes were % and %, while the corresponding accuracy (%) ranges were % and %. Limits of detection and quantitation established for these 10 analytes were in the ranges of and ng/ml (5 ng/ml for buprenorphine). The method was successfully applied to the analysis of 62 oral fluid specimens collected from patients participating in methadone and buprenorphine substitution therapy programs. Analytical results of methadone and buprenorphine were compared with data derived from GC MS analysis and found to be compatible. Overall, the direct injection LC MS-MS method performed well, permitting rapid analysis of oral fluid samples for simultaneous quantification of methadone, buprenorphine, opiate and amphetamine drug categories without extensive sample preparation steps. Introduction Urine has long been a well-established, low cost and widely adopted test specimen in workplace (1, 2), pain management (3) and substitution therapy (4) drug-testing programs. On the other hand, oral fluid, as the test specimen, is advantageous in certain applications. For example, since only blood (not urine) drug concentration can reflect the drug s influence on the specimen donor, at the time the specimen was collected, analysis of oral fluid can be extremely valuable if the analytical findings can be related to the drug s equivalent concentration in blood (5, 6). For physicians prescribing methadone and buprenorphine in pain management and substitution therapy programs, oral fluid can be much more easily collected; analytical findings are also valuable in (i) more precisely reflecting the patient s compliance Parts of this work were presented at the annual SOFT meeting in Orlando These authors contributed equally. status; and (ii) providing patients pharmacokinetic/pharmacogenetic parameters, helpful to successful medication. Oral fluid, as the test matrix, has certain limitations and disadvantages as well. Concerning factors include shorter drugs detection windows (compared with urine), effects of ph variation and potential oral contaminations (7, 8). Furthermore, drugs present in oral fluid are usually at lower concentrations than that found in urine (9); together with the small volume of oral fluid available for collection, detecting drug that are present at lower concentrations can become a significant challenge. Consequently, highly sensitive and specific tandem mass spectrometric methodologies are essential analytical approaches. With advances in the interface technology, permitting the use of a liquid mobile phase for chromatographic analysis without the derivatization step, liquid chromatography tandem mass spectrometry (LC MS-MS) methodologies are now widely applied to the identification and quantification of a wide range of compounds in biological samples (10). Unlike LC MS-MS analysis of urine (11 15) and plasma (16, 17), whereby direct injection of neat samples has been extensively reported, report on direct analysis of oral fluid is rare (18, 19). Four categories of sample preparation methodologies applied to toxicological analysis of oral fluid by LC MS-MS are as follows: protein precipitation (9), solid-phase extraction (20, 21), liquid liquid extraction (22 24) and Toxi-Tubes w A extraction (25). Simultaneous detections of amphetamines, opiates and cocaines by direct analysis of diluted oral fluid samples using LC quadrupole-time-of-flight MS, with electrospray ionization (ESI), has been reported (19). Unfortunately, interferences were introduced by the collection devices, resulting in poor reproducibility of the detection (18). In support of the substitution therapy program, involving the use of methadone or buprenorphine as treatment agents that have been implemented in Taiwan since 2006, we have studied and reported our findings on GC MS analysis of methadone in oral fluid and blood samples (26). This report presents further progresses in our efforts; specifically, the development and validation of an analytical methodology for the direct injection LC MS-MS method for simultaneous analysis of methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), buprenorphine, norbuprenorphine, morphine, codeine, 6-acetylmorphine, 6-acetylcodeine, methamphetamine and amphetamine in oral fluid following a simple sample preparation step. Materials and methods Standards, internal standards, reagents and samples Standards of all analytes (methadone, EDDP, buprenorphine, norbuprenorphine, morphine, 6-acetylmorphine, codeine, 6-acetylcodeine, # The Author Published by Oxford University Press. All rights reserved. For Permissions, please journals.permissions@oup.com

2 amphetamine and methamphetamine) and their deuterated analogs (adopted as internal standards (ISs)) were purchased from Cerilliant Corporation (Round Rock, TX) as methanol solutions (1.0 or 0.1 mg/ml). HPLC-grade methanol and formic acid were obtained from J. T. Baker Inc. (Phillipsburg, NJ) and Sigma-Aldrich Chemicals (Milwaukee, WI). Deionized water was generated by a PURELAB TM Ultra water purification system from ELGA LabWater VWS Ltd (Bucks, UK). Blank oral fluid was provided by a healthy volunteer, confirmed negative (by LC MS-MS) for the analytes of interest, for the preparation of working standard and controls. Ten blank oral fluid samples, obtained from 10 different individuals, were used to assess method specificity. A total of 62 oral fluid specimens were collected from 62 patients participating in the substitution therapy programs administered by E-Da Hospital (Kaohsiung, Taiwan). IRB protocols established by E-Da were followed for sample processing (collection, storage and disposition) and information management. Sample preparation Oral fluid samples were collected without stimulation. Patients were asked to rinse with the water provided, make tongue and lip movements for about 30 s, then spit (through a large-diameter straw) into a clean centrifugation tube. Oral fluid samples were stored at 2208C until analysis, typically within 1 month (26). For analysis, each specimen was allowed to thaw, then centrifuged (12,000 rpm for 10 min). A precise volume (40 ml) of clear supernatant phase was removed and mixed with 10 ml of 10-IS solution (0.1 mg/ml for each compound), then briefly vortex-mixed. The mixture was extracted with hexane/isopropanol (8:1, v/v) for GC MS analysis following the procedure described elsewhere (26). For LC MS-MS analysis, each specimen was centrifuged (10 min at 12,000 rpm); 10 ml of supernatant were injected onto the LC MS-MS system (described below). Instrumentation for LC MS-MS analysis The LC MS-MS system, used in this study, included an Agilent 6,410 Triple Quadrupole Mass spectrometer (Santa Clara, CA) Table I Retention Times, Transitions and MS MS Parameters for Each Analyte and Internal Standard fitted with an electrospray interface and an Agilent 1,200 RRLC system (Santa Clara, CA). Chromatographic separation was achieved using an Agilent Zorbax SB-Aq (2.1 mm 100 mm, 3.5 mm particle) analytical column operated at 508C. The flow rate of the mobile phase was 0.35 ml/min using gradient elution of solvent A (0.1% formic acid in water, v/v) and solvent B (0.1% formic acid in methanol, v/v) as follows: held for 2 min at the initial gradient composition (90% A and 10% B); decreased to 0% A in 10 min; then increased to 90% A in 1 min. The initial gradient composition was allowed to equilibrate for 5 min to regenerate the column. The electrospray source was operated at 3508C with ionization set at 4,000 V in positive mode. Nitrogen gas, produced by an Agilent nitrogen gas generator, was used for nebulization and desolvation. Nebulizer gas pressure and drying gas flow rate were set at 40 psi and 10 L/min. Identification and quantification of each analyte was performed in positive mode using dynamic multiple reaction monitoring (MRM) of a quantifier and an additional qualifier ion. To meet the criterion for a positive identification, the ratio between the quantitative transition and the qualifying transition ions must fall within +20% of that established by the calibration standards. Parameters of the mass spectrometric method are summarized in Table I. Typical chromatograms of the monitored product ions are shown in Figure 1. Instrumentation for GC MS analysis An Agilent 6890 N gas chromatograph/5975 mass selective detector system operating at 70 ev with ion source temperature set at 2308C was used for this study. The injector temperature and GC MS interface temperature were maintained at 2808C. The sample was introduced into the gas chromatograph in splitless mode and the helium carrier gas flow rate was set at 1.0 ml/min. For buprenorphine and norbuprenorphine analysis, the gas chromatograph was equipped with a 12 m HP-5 (Wilmington, DE, USA) capillary column cross-linked 5% phenyl methyl siloxane with 200 mm ID and 0.33 mm film thicknesses. For the analysis of the acetyl derivatives, the initial oven temperature was held at 2008C for 1 min, then raised to 3008C at 308C/min and held for 5 min. Data derived from these full-scan mass spectra were used to select the following Analyte RT (min) Precursor ion (m/z) Fragment (V) Target ion (m/z) CE (V) Qualifier ion (m/z) CE (V) Dwell time (ms) Morphine-d Morphine Amphetamine-d Amphetamine Methamphetamine-d Methamphetamine Codeine-d Codeine Acetylmorphine-d Acetylmorphine Acetylcodeine-d Acetylcodeine Norbuprenorphine-d Norbuprenorphine EDDP-d EDDP Buprenorphine-d Buprenorphine Methadone-d Methadone Direct injection LC MS-MS Analysis of Drugs in Oral Fluid 473

3 Figure 1. Chromatograms and ion ratio confirmation for 10 analytes and their deuterated internal standards, observed in a blank oral fluid sample that was fortified with 10 ng/ml of each analyte and internal standard. The dotted lines set the acceptable intensity range limit of the qualifier ions. 474 Liu et al.

4 ions for designating buprenorphine/buprenorphine-d 4 and norbuprenorphine/norbuprenorphine-d 3 : m/z420, 408, 452/424,412, 456 and m/z 440, 441, 422/443, 444, 425. For methadone and EDDP analysis, the gas chromatograph was equipped with a 30-m HP-5 (Wilmington) capillary column cross-linked 5% phenyl methyl siloxane with 250-mm ID and 0.25-mm film thicknesses. The initial oven temperature was held at 1608C for 4 min, then raised to 2508C at 108C/min and held for 1 min. Selected ion monitoring was done at m/z 72, 223, 294/78, 226, 303 for methadone/methadone-d 9, and m/z 262, 276, 277/265, 279, 280 for EDDP/EDDP-d 3. The ions italicized were used for quantitation. Method validation for LC MS-MS analysis Calibration and linearity Five standard solutions over the ng/ml range (1, 10, 20, 50 and 100 ng/ml), incorporating each analyte s deuterated analog as IS, were analyzed. Peak-area ratios of the target analytes and their respective ISs were calculated automatically using Mass Hunter software. For calibration, data were fit to a linear least-squares regression curve with a 1/x weighting and was not forced through the origin. Precision and accuracy Precision and accuracy were evaluated over the linear dynamic range at five different concentrations (1, 10, 20, 50 and 100 ng/ ml). Intra- and inter-day precision were assessed by five determinations per concentration on one and five consecutive days, respectively. Limits of detection and quantitation Limits of detection (LOQ) and quantitation (LOQ) were assessed using oral fluid samples fortified with decreasing concentrations of the analytes. LOD and LOQ were defined using commonly accepted criteria, i.e., reasonable agreements with regard to retention time and ion ratio information as derived from standard and test specimens in the same analytical batch. Specifically, each analyte s retention time, found in test specimens, must be within +2% of that established by the standard. Method LOD was defined as the lowest concentration at which ion ratio pairs monitored for a particular analyte fell within +20% of that observed in the standard; while LOQ was defined as the lowest concentration at which LOD requirements were met and the observed concentration also fell within +20% of the expected value. Matrix effects Ion suppression was evaluated by comparing the analyte/is peak-area ratios observed from standards prepared in drug-free oral fluid and the same ratios observed in standards prepared in the initial mobile phase composition. Five replicates, with each analyte at three concentrations (10, 20 and 50 ng/ml), were used for this evaluation. Results and discussion A GC MS methodology, as established in our earlier study (26), was also used to analyze the clinical specimens for comparison purpose (see the Comparison of LC MS-MS and GC MS Data section). However, the focus of this report is concerned with the establishment, validation and application of the LC MS-MS methodology for the analysis of the 10 analytes included in this study. All data discussed below, unless specifically indicated otherwise, are pertaining to this LC MS-MS study. Evaluation of common analytical parameters The adopted reversed-phase chromatographic method, with gradient elution, was able to resolve the 10 analytes (including methadone, buprenorphine, opiate, methamphetamine and their metabolites) and each analyte s deuterated analogs representing different categories of compounds with retention times ranging from 1.36 (morphine) to 9.18 (methadone) min. Injection of 10 ml of the supernatant following centrifugation of the oral fluid onto the LC MS-MS system proved to be a simple and efficient method for toxicology analysis. Because oral fluid contains a high aqueous content and does not require extensive cleanup prior to LC MS-MS analysis, we were able to eliminate tedious and time-consuming sample preparation steps and ultimately reduce workload and analytical time. Method specificity was assessed by the analyses of 10 blank oral fluid samples of different origin. Figures 2 and 3 are typical MRM chromatograms of standard and blank oral fluid samples. None of the MRM chromatograms (see Figure 3), resulting from the 10 blank oral fluid samples, exhibited interference to any of the target analyte, confirming the specificity of the method. Analytical data for a set of standards, with each analyte s concentration ranging from 1 to 100 ng/ml, used for linearity evaluation, are presented in Table II. Good linearity, with r , was observed for all compounds. Also shown in this table are the LOD and LOQ data that were established based on the criteria noted in the Method validation for LC MS-MS analysis section. Specifically, the LODs and LOQs, for the 10 analytes, established for this analytical protocol were in the and ng/ ml (5 ng/ml for buprenorphine) ranges. Data derived from intra- and inter-day precisions of the analytical procedure, including analytes at five concentrations (1, 10, 20, 50, and 100 ng/ml) and each set with five replicates, are summarized in Tables III and IV. Intra- and inter-day precisions were,13.0%. Method accuracies, expressed as percentages of the target concentrations for these 10 analytes, ranged from 91.9 to 113.0% for the intra- and inter-day study. ESI is susceptible to ion suppression, commonly resulting in reduction of the analyte s signal by co-eluting compounds (10). Stable isotope-labeled ISs were reportedly effective, in most cases, to compensate for the matrix variation among samples from various individuals (27). In this study, the effect of matrix suppression was investigated, at three concentrations, by comparing the analyte/is peak-area ratios, observed from samples prepared in the mobile phase versus samples prepared in drugfree oral fluid. As shown in Table V, the adopted deuterated ISs were effective in compensating for the matrix effect (if any) for all analyses, except for buprenorphine. It is not known why this deuterated analog has not proven effective in compensating for the matrix effect; however, buprenorphine data obtained by LC MS-MS and GC MS were found compatible (see the Comparison of LC MS-MS and GC MS data section). Additional experiments will be conducted to understand this observed phenomenon. Direct injection LC MS-MS Analysis of Drugs in Oral Fluid 475

5 Figure 2. Ion chromatograms observed from direct injection of a blank oral fluid sample that was fortified with 20 ng/ml of the 10 analytes included in this study: morphine (a), amphetamine (b), methamphetamine (c), codeine (d), 6-acetylmorphine (e), 6-acetylcodeine (f), norbuprenorphine (g), EDDP (h), buprenorphine (i) and methadone ( j). 476 Liu et al.

6 Figure 3. Direct injection of drug-free oral fluid (see Figure 2 for ion channels). Direct injection LC MS-MS Analysis of Drugs in Oral Fluid 477

7 Table II Linearity, LOD and LOQ Established for the Analysis of 10 Analytes in Oral Fluid Analyte Linear range (ng/ml) Regression line Correlation coefficient (r 2 ) LOD (ng/ml) LOQ (ng/ml) Methadone y ¼ x EDDP y ¼ x Buprenorphine y ¼ x Norbuprenorphine y ¼ x Morphine y ¼ x Acetylmorphine y ¼ x Codeine y ¼ x Acetylcodeine y ¼ x Methamphetamine y ¼ x Amphetamine y ¼ x Table III Intra-day Accuracy and Precision Analyte Intra-day accuracy (% of target, n ¼ 5) Intra-day precision (% CV, n ¼ 5) Analyte concentration (ng/ml) Analyte concentration (ng/ml) 1 (5) a (5) a Amphetamine Methamphetamine Morphine Acetylmorphine Codeine Acetylcodeine Methadone EDDP Buprenorphine Norbuprenorphine a 5ng/mL for buprenorphine. Table IV Inter-day Accuracy and Precision Analyte Inter-day accuracy (% of target, n ¼ 5) Inter-day precision (% CV, n ¼ 5) Analyte concentration (ng/ml) Analyte concentration (ng/ml) 1 (5) a (5) a Amphetamine Methamphetamine Morphine Acetylmorphine Codeine Acetylcodeine Methadone EDDP Buprenorphine Norbuprenorphine a 5ng/mL for buprenorphine. Applications Following the development and validation stages, this method was applied to the analysis of 62 oral fluid specimens collected from patients participating in the substitution therapy programs (57 methadone and 5 buprenorphine cases). Analytical data derived from these 62 subjects are summarized in Table VI. Among the 57 methadone cases, concentrations of methadone and EDDP were found to be in the ,566 and ng/ml ranges; the corresponding data for buprenorphine and norbuprenorphine from the five buprenorphine cases were ,784 and ng/ml. It was noted that amphetamine/methamphetamine, 6-acetylcodeine/6-acetylmorphine and/or codeine/morphine were detected in many samples. According to the analytical results, more than 50% of the 62 program participants appeared to continue using heroin and/or methamphetamine during the treatment period. Comparison of LC MS-MS and GC MS data Seventy-one oral fluid specimens previously analyzed by GC MS (27) were re-analyzed by LC MS-MS for their methadone and buprenorphine contents. Quantification data obtained by these two methods are compared in Figure 4. Linear regression analysis was performed and good correlations were obtained (with r 2 values of for methadone and for buprenorphine), 478 Liu et al.

8 Table V Analyte/IS Response Ratios Obtained from the Analysis of Samples Prepared in Mobile Phase and Oral Fluid Matrix at Three Concentrations, Each with Five Replicates Analyte/deuterated analogs Concentrations of the analytes and their respective deuterated analogs 10 ng/ml 20 ng/ml 50 ng/ml Solvent a /matrix b (%) Solvent a /matrix b (%) Solvent a /matrix b (%) Methadone/methadone-d / / / EDDP/EDDP-d / / / Buprenorphine/buprenorphine-d / / / Norbuprenorphine/norbuprenorphine-d / / / Morphine/morphine-d / / / Acetylmorphine/6-acetylmorphine-d / / / Codeine/codeine-d / / / Acetylcodeine/6-acetylcodeine-d / / / Methamphetamine/methamphetamine-d / / / Amphetamine/amphetamine-d / / / a Analytes and their respective deuterated analogs were prepared in initial mobile phase. b Analytes and their respective deuterated analogs were prepared in blank oral fluid matrix. Table VI Frequency (n) and Concentration Range of Analytes Found in the 62 Oral Fluid Specimens Analyte n (%) Concentration range (ng/ml) Methadone 57 (91.9%) ,566 EDDP 50 (80.6%) Buprenorphine 5 (8.1%) ,784 Norbuprenorphine 2 (3.2%) Morphine 18 (29.0%) Acetylmorphine 5 (8.1%) Codeine 27 (43.5%) Acetylcodeine 6 (9.7%) Methamphetamine 9 (14.5%) ,499 Amphetamine 5 (8.1%) indicating good agreement between LC MS-MS and GC MS data. Correlating slopes were slightly higher than 1 for both analytes, indicating slightly higher LC MS-MS data for the analysis of both buprenorphine and methadone. Limitations of this study The LC MS-MS methodology hereby reported was aimed for direct analysis of oral fluid samples collected by expectoration. With the apparent matrix effect observed for the analysis of buprenorphine, this method would probably be unsuitable for the analysis of samples collected by commercial devices, which may incorporate extraneous materials (such as buffer) or issues (such as absorption/incomplete release). Several issues related to the analytical findings and their interpretations and potential applications that may be of interest to the readers have not been addressed in this study. For example, the stability of drugs in neat oral fluid has not been evaluated, although it had been reported that methadone was stable at 48C for 2 months (28). As reported in our earlier study (26), correlating drug dose and oral fluid drug concentration finding is an area awaiting substantial research efforts. In this study, oral fluid samples were collected immediately after a 30-s rinse (with water). This practice was found effective for collecting adequate volume of samples and was adopted to cope with the limited patience displayed by the sample donor group; however, it remains unknown whether this practice would have affected accurate representation of drug concentrations in the samples collected. Figure 4. Correlation of quantitative data derived from LC MS-MS and GC MS analysis of oral fluid specimens collected from patients participating in buprenorphine (A; n ¼ 20) and methadone (B; n ¼ 51) treatment programs. Conclusion A highly sensitive and rapid LC MS-MS methodology capable of detecting low ng/ml level of methadone, EDDP, buprenorphine, Direct injection LC MS-MS Analysis of Drugs in Oral Fluid 479

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