Negative-ion chemical ionization gas chromatography-mass spectrometry assay for enantioselective measurement of amphetamines in oral fluid: application to a controlled study with MDMA and driving under the influence cases.
In the last few years, oral fluid has become increasingly important in drug analysis. Its main advantage is the relatively easy and noninvasive sample collection, which can be closely supervised, thus preventing adulteration or substitution of samples (9,10). A number of reports have recently been published on analysis of AM, MA, MDA, MDMA, and/or MDEA in oral fluid samples using immunoassays (11-13), gas chromatography-mass spectrometry (GC-MS) (14-21), liquid chromatography with fluorescence detection (22), or liquid chromatography-tandem mass spectrometry (23-25). Although information on enantiomer composition in clinical and forensic samples can help interpret analytical results, the chirality of the above drugs has been neglected. The S-(+)-enantiomers of the drugs are known to be more potent than the respective R-(-)-enantiomers, and their toxicokinetics are known to be different (2,26-30). Furthermore, not only are AM and MA abused as stimulants, but both are also metabolites of several (racemic or optically pure) therapeutic drugs, or are even used as such themselves (27, 31). Hence, their enantioselective analysis can provide the information needed for differentiation of illicit and therapeutic drug use. In the case of MDMA, enantiomer ratios (R vs S) in plasma samples increase steadily over time, which might be useful for estimating the time since ingestion (26, 30). Numerous procedures have been published for enantioselective analysis of these analytes in various biological matrices, but so far not in oral fluid. The only exception is a method by Matin et al. (32) that was limited to analysis of AM enantiomers and based on now-outdated analytical equipment.
Therefore, the first aim of this study was to develop and validate an assay for simultaneous measurement of concentrations and ratios of AM, MA, MDA, MDMA, and MDEA enantiomers in oral fluid. The second aim was to apply the assay to samples from a controlled study with MDMA and from authentic DUID cases and compare the results to published plasma data (28, 30).
Materials and Methods
Chemicals and reagents. We obtained methanolic solutions (1000 mg/L) of racemic AM-[d.sub.11] and MA-[d.sub.5] and methanolic solutions (100 mg/L) of racemic MDA-[d.sub.5] and MDMA-[d.sub.5] from Promochem; racemic hydrochlorides of AM, MA, MDA, MDMA, and MDEA from Lipomed; sodium bicarbonate from Fluka; and all other chemicals from E. Merck. All chemicals were of analytical grade or the highest purity available. The derivatization reagent S-heptafluorobutyrylprolyl chloride (S-HFBPCI) was synthesized as described (29).
Biosamples. We collected blank oral fluid samples used for validation experiments from drug-free volunteers. Residual oral fluid samples (n = 33) previously collected for DUID testing were used in this study. All personally identifying information was removed from the samples. The oral fluid samples from the controlled study had been collected from 12 study participants 1, 2, 3, 4, and 5 h after administration of 75 mg racemic MDMA (33). Oral fluid samples were not available from all volunteers at each sampling time; the numbers of samples were as follows: n = 10 (1 h), n = 10 (2 h), n = 11 (3 h), n = 12 (4 h), and n = 11 (5 h). All samples were unstimulated oral fluid samples (0.2-0.5 mL) collected by spitting into a dry polypropylene tube. They were frozen immediately after collection and stored without preservatives at -20[degrees]C until achiral analysis. After thawing, the oral fluid samples were centrifuged to eliminate food residues and cell debris, and the clean supernatant was recovered for analysis. The remainder of these clean oral fluid specimens was stored at -20[degrees]C until enantioselective analysis.
We diluted 50-[micro]L aliquots of oral fluid with 200 [micro]L aqueous carbonate buffer (35 g/L sodium bicarbonate and 15 g/L sodium carbonate, pH 9). After adding 25 [micro]L methanolic solution of the racemic internal standards (IS) MDA-[d.sub.5] (0.2 mg/L), AM-[d.sub.11] MA-[d.sub.5] and MDMA-[d.sub.5] (1.0 mg/L each), and 6 [micro]L derivatization reagent (0.1 mol/L S-HFBPCI in dichloromethane), we sealed the reaction vials and left them on a rotary shaker at ambient temperature for 30 min. We added 100 [micro]L cyclohexane to the reaction vials, resealed them, and placed them on a rotary shaker for 1 min. After phase separation by centrifugation (10 000g for 1 min), we transferred the cyclohexane phase to autosampler vials. We injected 3-[micro]L aliquots into the GC-MS system. Samples with concentrations exceeding the highest points of the calibration curves were reanalyzed using 10-[micro]L volumes. If the results still exceeded the calibration interval after this reduction of sample volume, approximate concentrations were estimated by extrapolation.
The prepared samples were analyzed using an Agilent Technologies 6890 Series GC system combined with an Agilent 5973 network mass selective detector, an Agilent 7683 series injector, and an Agilent enhanced Chem Station G1701CA, v. C.00.00 21-Dec-1999. GC conditions were as follows: splitless injection mode, split vent opened after 1.5 min; 5% phenylmethyl siloxane column (HP-5Mh; 30 m x 0.25 mm internal diameter, 250 run film thickness); injection port temperature, 280[degrees]C; carrier gas, helium; flow rate, 1 mL/min; column temperature, 100[degrees]C raised to 190[degrees]C at 30[degrees]C/min, to 230[degrees]C at 5[degrees]C/min, to 245[degrees]C at 30[degrees]C /min, to 260[degrees]C at 5[degrees]C /min, and to 310[degrees]C at 30[degrees]C/min. Negative-ion chemical ionization (NICD-MS conditions were as follows: transfer line heater, 280[degrees]C; NICI, methane (2 mL/min); source temperature, 150[degrees]C; solvent delay, 7.5 min; selected-ion monitoring mode. The time windows, selected ions, and electron multiplier voltage offsets are listed in Table 1.
Quantification was performed via peak area ratios (analyte vs IS) using linear weighted (1/[chi square]) least-squares calibration curves. For all analytes except S-(+)-MA and the 2 enantiomers of MDEA, the corresponding enantiomers of the deuterated analogs were used as IS. R-(-)MA-d, was also used as IS for S-(+)-MA, and the enantiomers of MDMA-d, were also used as IS for the corresponding enantiomers of MDEA.
We validated the method with respect to selectivity, linearity, analytical recovery, precision, stability, and limit of quantification. A detailed description of the validation experiments is provided in the supplemental data [see Text 1 in the Data Supplement that accompanies the online version of this article at http://www.clinchem.ort/content/vo153/issue4].
The 54 samples from the controlled study and the 33 samples from authentic DUID cases were assayed as described above. We compared the oral fluid concentrations of the R-(-)- and S-(+)-enantiomer, of MDMA in individual study samples visually and by 2-tailed paired t tests at each sampling time. We compared the mean enantiomer ratios (R vs S) for MDMA at each sampling time to the theoretic ratio of 1.0 for racemic mixtures by 1-tailed t tests. In addition, we compared the concentrations and ratios of the analytes in the oral fluid samples to the corresponding reported results in plasma samples (28, 30). We studied correlations between the enantiomer concentrations and their ratios (R vs S) by plotting the results for the oral fluid samples against those obtained for plasma samples.
SAMPLE PREPARATION AND GC-NICI-MS QUANTIFICATION
We achieved baseline separation of the S-heptafluorobutyrylprolyl (S-HFBP) derivatives of all 5 enantiomer pairs within a 16-min program. The peaks corresponding to S-(+)-MDMA and R-(-)-MDEA were not fully resolved but could be differentiated because of their different MS properties. The observed noise was generally low, allowing detection of all enantiomers, even for sample volumes [less than or equal to]50 [micro]L. Supplemental data Fig. 1 shows the merged selected ion chromatograms of a derivatized and extracted blank sample and a derivatized and extracted calibration sample containing 50 [micro]g/L of each enantiomer of MDA and 250 [micro]g/L of each enantiomer of AM, MA, MDMA, and MDEA.
A detailed description of the validation studies and observed analytical properties of the assay is provided in supplemental data, Text 2 and Tables 1-3.
Oral fluid samples from the controlled study. We applied the described GC-MS method to 54 oral fluid samples collected during a controlled study with 12 volunteers. Fig. 1 shows plots of MDMA enantiomer concentrations (A) and ratios (B) vs sampling time for the 9 volunteers from whom samples were collected at all time points. Concentrations of R-(-)-MDMA for all participants and sampling times (including those excluded in Fig. 1) were from 26.9-2273 [micro]g/L, and those of S-(+)-MDMA were from <25-1567 [micro]g/L. Peak oral fluid concentrations were reached 1-4 h after ingestion. In all samples, concentrations of R-(-)-MDMA exceeded those of S-(+)-MDMA, with statistically significant differences at all sampling times (P <0.05). The enantiomer ratios (R vs S) were from 1.04-1.92, increased steadily over time, and were >1.0 for all sampling times (P <0.001).
The concentrations of R-(-)-MDA were <5 [micro]g/L in 42 of 54 samples, with a maximum concentration of 21.4 [micro]g/L. S-(+)-MDA was present at concentrations <5 [micro]g/L in only 15 samples. For this enantiomer, the maximum concentration was 74.7 [micro]g/L. Because of the numerous missing values for R-(-)-MDA, enantiomer ratios (R vs S) could be calculated for only 12 samples, in which they were 0.29-0.87.
[FIGURE 1 OMITTED]
Oral fluid samples from authentic DUID cases. We applied the described GC-MS method to 33 oral fluid samples collected during routine road patrols. In Fig. 2, merged selected ion chromatograms are shown for 2 derivatized and extracted oral fluid samples from DUID cases. The 1st sample (A) contained AM, MDA, and MDMA, whereas the 2nd sample (B) contained MDA, MDMA, and MDEA. AM was present in 11 samples. Concentrations of R-(-)-AM were 47.8 to --7300 [micro]g/L, with a median of 400 [micro]g/L. Concentrations of S-(+)-AM were 49.3 to -6700 [micro]g/L, with a median of 386 [micro]g/L. The AM enantiomer ratios (R vs S) were 0.97-1.33, with a mean of 1.10. MA was detected in only 1 oral fluid sample. Concentrations of R-(-)-MA and S-(+)-MA were 104 and 84.7 [micro]g/L, respectively, with the enantiomer ratio (R vs S) being 1.23. MDA was present in 30 samples. In 4 samples, concentrations of R-(-)-MDA were <5 [micro]g/L. The highest measured concentration and the median concentration for this enantiomer were 336 and 30.9 [micro]g/L, respectively. Concentrations of S-(+)-MDA were <5 [micro]g/L (in 3 samples) to 979 [micro]g/L, with a median concentration of 104 [micro]g/L. The enantiomer ratios (R vs S) for MDA were 0.26-0.52, with a mean of 0.31. MDMA was detected in 30 oral fluid samples. The minimum concentration of R-(-)-MDMA was 40.2 [micro]g/L and the maximum concentration was ~37 000 [micro]g/L, with a median concentration of 2523 [micro]g/L. S-(+)-MDMA concentrations were 36.8 to -26 000 [micro]g/L, with a median concentration of 1749 [micro]g/L. After exclusion of the results from the 3 samples for which only approximate concentrations were measured, the R vs S ratios of MDMA enantiomers were 1.09-1.98. MDEA was detected in only 1 sample. The merged selected ion chromatogram of this sample, after derivatization and extraction, is shown in Fig. 2B. The concentrations of R-(-)-MDEA and S-(+)-MDEA were -840 and 540 [micro]g/L, respectively, with an enantiomer ratio of -1.6.
Comparison of plasma and oral fluid data. We studied correlations between enantiomer concentrations and their ratios (R vs S) by plotting the results for oral fluid samples against those for corresponding plasma samples (28, 30). In Fig. 3, plots are shown for the concentrations of R-(-)-AM (A), S-(+)-AM (B), and their R vs S ratios (C), after exclusion of the results of 1 sample for which only approximate values were available. The ratio of the concentrations in oral fluid vs plasma were 2.4-43.2 for R-(-)-AM and 3.0-42.6 for S-(+)-AM. In Fig. 4, the oral fluid concentrations of R-(-)-MDMA (A), S-(+)-MDMA (B), and their R vs S ratios (C) are plotted against the corresponding data obtained from plasma samples. The correlation was too weak to allow reliable estimations of plasma concentrations from oral fluid concentrations. Oral fluid/plasma ratios were 2.6-46.3 for R-(-)-MDMA and 3.5-49.8 for S-(+)-MDMA. As can be seen in Fig. 4C, the correlation of enantiomer ratios (R vs S) was good as long as enantiomer ratios in plasma were [less than or equal to]2, but above this ratio the scatter increased considerably.
[FIGURE 2 OMITTED]
We measured the concentrations and ratios (R vs S) of AM, MA, MDA, MDMA, and MDEA enantiomers in oral fluid samples and compared the concentrations to those reported for plasma (28, 30). The availability of sufficient sample volume is critical in oral fluid analysis. Sample volumes of 50 [micro]L or less were sufficient to perform our assay, comparable to the volume required for the nonenantioselective liquid chromatography-tandem mass spectrometry method published by Wood et al. (23) and less than the sample volumes of 100-1000 [micro]L required by other nonenantioselective chromatographic methods (1421, 24, 25). The sample preparation was simple, consisting of direct derivatization without any previous extraction steps. This was possible because oral fluid samples consist mainly of water and contain only low concentrations of protein and mucin, and because derivatization with SHFBPCl works well under aqueous alkaline conditions (28, 29). With the described temperature program, enantioseparation of all analytes was achieved within a runtime of only 16 min, which is relatively short for separation of 5 enantiomer pairs. This is -1 min longer than our method for analysis of AM and MA enantiomers in plasma (29) and shorter than our method for analysis of MDA, MDMA, and MDEA enantiomers in plasma (28). S-(+)-MDMA could not be fully resolved from R-(-)MDEA, however, precluding the use of MDEA-d, as an IS. The fragment ions of MDEA-d5, with the exception of the molecular ion, had the same m/z values as those of MDMA, causing interference with the quantification of the latter. While the alternative use of MDMA-[d.sub.5] as an IS for MDEA worked well for enantioselective analysis of MDEA in plasma samples (28), it did not work in the present method, as illustrated by the unacceptable analytical recovery and precision data for MDEA [see Tables 2 and 3 in the online Data Supplement]. Extending the chromatographic run-time or choosing a different GC column with respect to phase material or dimension might solve this problem; however, we decided not to modify the assay because of the low prevalence of MDEA (34) and the inconvenience of an extended analysis time or the need to change the column, which can be used for enantioselective analysis of the same analytes in plasma samples.
[FIGURE 3 OMITTED]
[FIGURE 4 OMITTED]
As previously observed (28, 29), the ionization properties of the S-HFBP derivatives of the primary amines were better than those of the secondary amines. We adjusted for this difference by modifying the electron multiplier voltage during the run (Table 1). The chosen calibration intervals were in good agreement with the calibration intervals of nonenantioselective chromatography-based methods for analysis of the same analytes in oral fluid (14-17,20-25) and covered the majority of observed concentrations in real samples, as determined in the present study and reported in the literature (24, 34-36). Much higher oral fluid concentrations have also been reported, however, particularly for AM and MDMA. The ability to use reduced sample volumes to achieve analyte concentrations within the intervals of the calibration curves was demonstrated using 10 [micro]L of a quality control sample with a concentration above the calibration interval.
Freeze-thaw stability is usually tested over 3 cycles (37). We tested it over 6 cycles [see Text 1 and 2 in the online Data Supplement], because oral fluid samples are sometimes deliberately frozen and thawed before analysis to reduce viscosity, which markedly facilitates handling (9).
The findings of oral fluid concentrations of R-(-)MDMA significantly exceeding those of S-(+)-MDMA at all sampling times during the controlled study, and steadily increasing enantiomer ratios (R vs S) are similar to results reported for plasma samples (26, 28, 30, 38). The low concentrations of MDA enantiomers, particularly R-(-)-MDA, in these oral fluid samples are in agreement with plasma data, in which R-(-)-MDA was also the minor MDA enantiomer (26, 28, 30, 38). This is also in agreement with low concentrations of AM, the corresponding demethylation product of MA, after controlled administration of MA (16, 35).
In the 33 oral fluid samples collected during routine road patrols, AM as well as MDMA and its metabolite MDA were most frequently detected, with 11 and 30 occurrences, respectively. There was a large distribution of total AM, MDMA, and MDA concentrations in these samples, which is in accordance with the findings of Wylie et al. (34). In some of the samples, the concentrations of AM and MDMA enantiomers were so high they did not fall within the calibration interval after using reduced sample volumes, so only approximate concentrations could be measured.
Navarro et al. (21) studied oral fluid vs plasma ratios for total MDMA and concluded that oral fluid concentrations might be helpful to estimate plasma concentrations, but also cautioned that these conclusions were obtained under controlled conditions that might be different for authentic samples. When we compared the enantiomer concentrations and ratios of the above analytes in oral fluid samples to plasma samples taken at the same time from the same individuals (28, 30), very large ranges of oral fluid:plasma ratios were observed. In our opinion, these wide ranges for oral fluid:plasma ratios preclude any reliable prediction of plasma concentration from oral fluid data. In the case of AM, the same is true for the enantiomer ratios (R vs S), for which only a weak association could be found. Therefore, the only real interpretative value of enantioselective analysis of AM in oral fluid samples should be the possibility to differentiate between illegal or legitimate ingestion of AM and/or one of its precursor compounds, as has been described previously for other matrices (27, 29, 31, 39, 40). For MDMA, enantiomer ratios (R vs S) in plasma have been described as being potentially helpful for assessing the time since ingestion of MDMA (26, 30). Unfortunately, the correlation between the enantiomer ratios of MDMA in oral fluid and plasma samples was not strong enough to draw similar conclusions for the enantiomer ratios of MDMA in oral fluid samples. As can be seen in Fig. 4C, the correlation is rather good as long as enantiomer ratios in plasma are [less than or equal to]2. Above that, the scatter increases, making reliable estimations impossible.
We thank Gabi Ulrich, Armin A. Weber, and Andreas H. Ewald for their help. The controlled study was supported financially by the Dutch Ministry of Transport, Transportation Research Center AW. No financial disclosures declared.
Received October 10, 2006; accepted January 23, 2007. Previously published online at DOI: 10.1373/clinchem.2006.081547
(1.) Logan BK. Amphetamines: an update on forensic issues [Review]. J Anal Toxicol 2001;25:400-4.
(2.) Kalant H. The pharmacology and toxicology of "ecstasy" (MDMA) and related drugs [Review]. CMAJ 2001;165:917-28.
(3.) McCann UD, Ricaurte GA. Amphetamine neurotoxicity: accomplishments and remaining challenges [Review]. Neurosci Biobehav Rev 2004;27:821-6.
(4.) Easton N, Marsden CA. Ecstasy: are animal data consistent between species and can they translate to humans? [Review]. J Psychopharmacol 2006;20:194-210.
(5.) Gouzoulis-Mayfrank E, Daumann J. The confounding problem of polydrug use in recreational ecstasy/MDMA users: a brief overview [Review]. J Psychopharmacol 2006;20:188-93.
(6.) Moeller MR, Kraemer T. Drugs of abuse monitoring in blood for control of driving under the influence of drugs [Review]. Ther Drug Monit 2002;24:210-21.
(7.) Logan BK. Methamphetamine and driving impairment [Review]. J Forensic Sci 1996;41:457-64.
(8.) Logan BK, Couper FJ. 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) and driving impairment [Review]. J Forensic Sci 2001;46:1426-33.
(9.) Kintz P, Samyn N. Use of alternative specimens drugs of abuse in saliva and doping agents in hair [Review]. Ther Drug Monit 2002;24:239-46.
(10.) Maurer HH. Advances in analytical toxicology: Current role of liquid chromatography-mass spectrometry for drug quantification in blood and oral fluid [Review]. Anal Bioanal Chem 2005;381: 110-8.
(11.) Cooper G, Wilson L, Reid C, Hand C, Spiehler V. Validation of the Cozart Amphetamine Microplate EIA for the analysis of amphetamines in oral fluid. Forensic Sci Int 2006;159:104-12.
(12.) Laloup M, Tilman G, Maes V, Boeck GD, Wallemacq P, Ramaekers J, et al. Validation of an ELISA-based screening assay for the detection of amphetamine, MDMA and MDA in blood and oral fluid. Forensic Sci Int 2005;153:29-37.
(13.) Crouch DJ, Walsh JM, Flegel R, Cangianelli L, Baudys J, Atkins R. An evaluation of selected oral fluid point-of-collection drug-testing devices. J Anal Toxicol 2005;29:244-8.
(14.) Scheidweiler KB, Huestis MA. A validated gas chromatographicelectron impact ionization mass spectrometric method for methylenedioxymethamphetamine (MDMA), methamphetamine and metabolites in oral fluid. J Chromatogr B Analyt Technol Biomed Life Sci 2006;835:90-9.
(15.) Fucci N, De Giovanni N, Chiarotti M. Simultaneous detection of some drugs of abuse in saliva samples by SPME technique. Forensic Sci Int 2003;134:40-5.
(16.) Schepers RJ, Oyler JM, Joseph RE Jr, Cone EJ, Moolchan ET, Huestis MA. Methamphetamine and amphetamine pharmacokinetics in oral fluid and plasma after controlled oral methamphet amine administration to human volunteers. Clin Chem 2003;49: 121-32.
(17.) Gunnar T, Ariniemi K, Lillsunde P. Validated toxicological determination of 30 drugs of abuse as optimized derivatives in oral fluid by long column fast gas chromatography/electron impact mass spectrometry. J Mass Spectrom 2005;40:739-53.
(18.) Yonamine M, Tawil N, Moreau RL, Silva OA. Solid-phase microextraction-gas chromatography-mass spectrometry and headspace-gas chromatography of tetrahydrocannabinol, amphet amine, methamphetamine, cocaine and ethanol in saliva samples. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 789:73-8.
(19.) Toennes SW, Steinmeyer S, Maurer HJ, Moeller MR, Kauert GF. Screening for drugs of abuse in oral fluid: correlation of analysis results with serum in forensic cases. J Anal Toxicol 2005;29: 22-7.
(20.) Mancinelli R, Gentili S, Guiducci MS, Macchia T. Simple and reliable high-performance liquid chromatography fluorimetric procedure for the determination of amphetamine-derived designer drugs. J Chromatogr B Biomed Sci Appl 1999;735:243-53.
(21.) Navarro M, Pichini S, Farre M, Ortuno J, Roset PN, Segura J, et al. Usefulness of saliva for measurement of 3,4-methylenedioxymethamphetamine and its metabolites: correlation with plasma drug concentrations and effect of salivary pH. Clin Chem 2001;47:1788-95.
(22.) Concheiro M, de Castro A, Quintela 0, Lopez-Rivadulla M, Cruz A. Determination of MDMA, MDA, MDEA and MBDB in oral fluid using high performance liquid chromatography with native fluorescence detection. Forensic Sci Int 2005;150:221-6.
(23.) Wood M, de Boeck G, Samyn N, Morris M, Cooper DP, Maes RA, et al. Development of a rapid and sensitive method for the quantitation of amphetamines in human plasma and oral fluid by LC-MS-MS. J Anal Toxicol 2003;27:78-87.
(24.) Wood M, Laloup M, Fernandez MM, Jenkins KM, Young MS, Ramaekers JG, et al. Quantitative analysis of multiple illicit drugs in preserved oral fluid by solid-phase extraction and liquid chro matography-tandem mass spectrometry. Forensic Sci Int 2005; 150:227-38.
(25.) Wylie FM, Torrance H, Anderson RA, Oliver JS. Drugs in oral fluid Part I. Validation of an analytical procedure for licit and illicit drugs in oral fluid. Forensic Sci Int 2005;150:191-8.
(26.) Fallon JK, Kicman AT, Henry JA, Milligan PJ, Cowan DA, Hutt AJ. Stereospecific analysis and enantiomeric disposition of 3,4-methylenedioxymethamphetamine (Ecstasy) in humans. Clin Chem 1999;45:1058-69.
(27.) Kraemer T, Maurer HH. Toxicokinetics of amphetamines: metabolism and toxicokinetic data of designer drugs, of amphetamine, methamphetamine and their N-alkyl derivatives [Review]. Ther Drug Monit 2002;24:277-89.
(28.) Peters FT, Samyn N, Lamers C, Riedel W, Kraemer T, de Boeck G, et al. Drug testing in blood: validated negative-ion chemical ionization gas chromatographic-mass spectrometric assay for enantioselective determination of the designer drugs MDA, MDMA (Ecstasy) and MDEA and its application to samples from a controlled study with MDMA. Clin Chem 2005;51:181122.
(29.) Peters FT, Kraemer T, Maurer HH. Drug testing in blood: validated negative-ion chemical ionization gas chromatographic-mass spectrometric assay for determination of amphetamine and metham phetamine enantiomers and its application to toxicology cases. Clin Chem 2002;48:1472-85.
(30.) Peters FT, Samyn N, Kraemer T, de Boeck G, Maurer HH. Concentrations and ratios of amphetamine, methamphetamine, MDA, MDMA, and MDEA enantiomers determined in plasma samples from clinical toxicology and driving under the influence of drugs cases by GC-NICI-MS. J Anal Toxicol 2003; 27:552-9.
(31.) Musshoff F. Illegal or legitimate use? Precursor compounds to amphetamine and methamphetamine [Review]. Drug Metab Rev 2000;32:15-44.
(32.) Matin SB, Wan SH, Knight JB. Quantitative determination of enantiomeric compounds. I: Simultaneous measurement of the optical isomers of amphetamine in human plasma and saliva using chemical ionization mass spectrometry. Biomed Mass Spectrom 1977;4:118-21.
(33.) Samyn N, de Boeck G, Wood M, Lamers CTJ, De Waard D, Brookhuis KA, et al. Plasma, oral fluid and sweat wipe ecstasy concentrations in controlled and real life conditions. Forensic Sci Int 2002;128:90-7.
(34.) Wylie FM, Torrance H, Seymour A, Buttress S, Oliver JS. Drugs in oral fluid Part II. Investigation of drugs in drivers. Forensic Sci Int 2005;150:199-204.
(35.) Drummer OH. Review: Pharmacokinetics of illicit drugs in oral fluid. Forensic Sci Int 2005;150:133-42 [Review].
(36.) de la Torre R, Farre M, Navarro M, Pacifici R, Zuccaro P, Pichini S. Clinical pharmacokinetics of amfetamine and related substances: monitoring in conventional and non-conventional matrices [Review]. Clin Pharmacokinet 2004;43:157-85.
(37.) Peters FT, Maurer HH. Bioanalytical method validation and its implications for forensic and clinical toxicology: a review [Review]. Accred Qual Assur 2002;7:441-9.
(38.) Pizarro N, Farre M, Pujadas M, Peiro AM, Roset PN, Joglar J, et al. Stereochemical analysis of 3,4-methylenedioxymethamphetamine and its main metabolites in human samples including the catechol-type metabolite (3,4-dihydroxymethamphetamine). Drug Metab Dispos 2004;32:1001-7.
(39.) Nystrom I, Trygg T, Woxler P, Ahlner J, Kronstrand R. Quantitation of R-(-)- and S-(+)-amphetamine in hair and blood by gas chromatography-mass spectrometry: an application to compliance monitoring in adult-attention deficit hyperactivity disorder treatment. J Anal Toxicol 2005;29:682-8.
(40.) George S, Braithwaite RA. Using amphetamine isomer ratios to determine the compliance of amphetamine abusers prescribed dexedrine. J Anal Toxicol 2000;24:223-7.
 Nonstandard abbreviations: AM, amphetamine; MA, methamphetamine; MDA, 3,4-methylenedioxyamphetamine; MDMA, 3,4-methylenedioxymethamphetamine; MDEA, 3,4-methylenedioxyethylamphetamine; DUID, driving under the influence of drugs; GC-MS, gas chromatography-mass spectrometry; S-HFBPCl, S-heptafluorobutyrylprolyl chloride; IS, internal standard; and NICI, negative-ion chemical ionization.
FRANK T. PETERS,  NELE SAMYN,  THOMAS KRAEMER,  WIM J. RIEDEL,  and HANS H. MAURER  *
 Department of Experimental and Clinical Toxicology, Saarland University, Homburg (Saar), Germany.
 National Institute of Criminalistics and Criminology, Brussels, Belgium.
 Experimental Psychopharmacology Unit, Maastricht University, Maastricht, The Netherlands
* Address correspondence to this author at: Institute of Pharmacology and Toxicology, Homburg, D-66421, Germany. Fax +49-6841-16-26051; e-mail email@example.com.
Table 1. Time windows, analytes, selected ions (with relative intensities), and electron multiplier voltage (EMV) offsets used in the selected-ion monitoring method. Analyte Target ion Time window, m/z Relative EMV min intensity, offset, V % (a) 7.50-9.50 R-(-)-AM-[d.sub.11] 399 100 0 R-(-)-AM 388 100 S-(+)-AM-[d.sub.11] 399 100 S-(+)-AM 388 100 9.50-12.00 R-(-)-MA-[d.sub.5] 407 100 400 R-(-)-MA 402 100 S-(+)-MA-[d.sub.5] 407 100 S-(+)-MA 402 100 12.00-13.50 R-(-)-MDA-[d.sub.5] 437 100 600 R-(-)-MDA 432 100 S-(+)-MDA-[d.sub.5] 437 100 S-(+)-MDA 432 100 13.50-16.17 R-(-)-MDMA-[d.sub.5] 451 100 R-(-)-MDMA 446 100 S-(+)-MDMA-[d.sub.5] 451 100 S-(+)-MDMA 446 100 R-(-)-MDEA 460 100 S-(+)-MDEA 460 100 Analyte Qualifier ion 1 Time window, m/z Relative EMV min intensity, offset, V % (a) 7.50-9.50 R-(-)-AM-[d.sub.11] 379 92 0 R-(-)-AM 368 83 S-(+)-AM-[d.sub.11] 379 89 S-(+)-AM 368 76 9.50-12.00 R-(-)-MA-[d.sub.5] 387 49 400 R-(-)-MA 382 45 S-(+)-MA-[d.sub.5] 387 46 S-(+)-MA 382 41 12.00-13.50 R-(-)-MDA-[d.sub.5] 417 111 600 R-(-)-MDA 412 108 S-(+)-MDA-[d.sub.5] 417 114 S-(+)-MDA 412 115 13.50-16.17 R-(-)-MDMA-[d.sub.5] 431 45 R-(-)-MDMA 426 44 S-(+)-MDMA-[d.sub.5] 431 43 S-(+)-MDMA 426 48 R-(-)-MDEA 480 84 S-(+)-MDEA 480 92 Analyte Qualifier ion 2 Time window, m/z Relative EMV min intensity, offset, V % (a) 7.50-9.50 R-(-)-AM-[d.sub.11] 439 44 0 R-(-)-AM 428 45 S-(+)-AM-[d.sub.11] 439 54 S-(+)-AM 428 54 9.50-12.00 R-(-)-MA-[d.sub.5] 447 23 400 R-(-)-MA 442 19 S-(+)-MA-[d.sub.5] 447 20 S-(+)-MA 442 20 12.00-13.50 R-(-)-MDA-[d.sub.5] 477 72 600 R-(-)-MDA 472 61 S-(+)-MDA-[d.sub.5] 477 78 S-(+)-MDA 472 68 13.50-16.17 R-(-)-MDMA-[d.sub.5] 491 28 R-(-)-MDMA 486 22 S-(+)-MDMA-[d.sub.5] 491 27 S-(+)-MDMA 486 25 R-(-)-MDEA 500 28 S-(+)-MDEA 500 24 (a) Relative [intensity.sub.ion] ([intensity.sub.ion]/ [intensity.sub.target ion]) x 100%.
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|Title Annotation:||Drug Monitoring and Toxicology|
|Author:||Peters, Frank T.; Samyn, Nele; Kraemer, Thomas; Riedel, Wim J.; Maurer, Hans H.|
|Date:||Apr 1, 2007|
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