Fresenius J Anal Chem (1991) 339 :62-63 - © Springer-Verlag 1991

Short communications

Mass spectrometric profile of zopiclone P. Kintz, A. Tracqui, and P. Mangin

Institut de M~decine L6gale, 11, rue Humann, F-67000 Strasbourg, France

Zopiclone is a non-benzodiazepine hypnotic drug that has been shown in insomniac patients to possess rapid onset of action and few associated side-effects [1, 2].

We have previously described a gas-chromatographic proce- dure using nitrogen detection for the quantification of zopiclone [3]. The present paper develops our earlier conclusions, and enhances the specificity of the method using mass spectrometry.

Plasma samples (1 ml) were extracted with dichloromethane (5 ml) after acidification (1 ml potassium dihydrogenophos- phate buffer 1 mol/1, pH 5.5) and addition of diazepam (10 gg/

Offprint requests to: P. Kintz

ml) as an internal standard [3]. After evaporating the extract to dryness, the residue was dissolved in 25 ill methanol and 1 gl injected into a 12.5 m x 0.22 mm i.d.B.P, i capillary column (SGE). The flow of carrier gas (helium, purity grade N55) through the column was 3.2 ml/min and the head pressure on the column maintained at 8 psi. The column oven temperature was programmed from an initial temperature of 60 ° C to 270 ° C at 30°C/min, and held at 270°C for the final 5 min. Splitless injection with a split value off-time of 0.8 min was employed.

The GC system consisted of a Perkin Elmer (8500) chroma- tograph with an ion trap detector (ITD). Data acquisition and manipulation were performed using standard software on an Epson PC AX computer. In electron impact mode, the ITD was operated at 35 eV with an ion source temperature of 220°C; the electron multiplier voltage was set at 1250 V. To produce chemical ionisation, methane (purity N55) was used with an electron multiplier voltage set at 1050 V.

Selected ion monitoring (m/z 149, and m/z 256 for zopiclone and diazepam, respectively) was used to prepare calibration graphs and to calculate concentrations by electron impact mode.

Spectrum # 666 Filena~e: ZOPI Acquired: Jun-19-1998 17:39:m~- ÷ 11:87 Cow~nt : NALADE 24361 Base PR: 149 Int: 9539 Range: 58-354 RIC: 43472 188,88X : 9539

A~C t i m e : 984 188Z 149

I HT 57

. l , . . . . J I , ! , . 3 ,4 Z , I , I , Z , I , Z - I , Z , Z , Z , ~ , I , t - I , i , Z , I , Z - Z , Z , Z . I , Z , Z , Z , I - I , Z , I , I - Z , I , ~ 58 188 158 288 2 5 8 388 358

SPEC >

I N 0 N~C1

A t

SpectEuM # 668 Co~en t : Ba~e PR: 71 Int:

188Z 71

,4L

57 Z l i t

q"7

i . I . . . . . . . .

Filename: ZOPI-Cl Acquired: Jun-19-1998 11:16:41 ÷ 11:81

143 Range: 41-391 RIC: 1378 188.88Z = 143 A~C t i ~ e : 1819

1 4 9

58 SPEC >

Fig. 1 A, B. Mass spectrum of zopiclone obtained from A electron impact mode, B chemical ionization mode

167

398

~45 279 [

, . , . . . . . ,,,.,:£L i I ! I L "1 " f ' l " " t ' i ' l ' z ' l ' l ' l ' l ' l ' l " "1 18e 158 2188 251~ 388 358 488

B

The retention times of zopiclone and diazepam were 11.01 and 12.04 min, respectively. The electron impact and chemical ionization mass spectra of zopiclone are shown in Fig. 1. In order to be considered positive for zopiclone, the selected ion monitoring analysis must show coincident peaks in the m/z 149, 167, and 207 ion current profiles. The molecular weight of zopiclone is 388.8 and the ion M + 1 (m/z 390) is present in chemical ionization.

The detection limit (using SIM) was found to be 0.8 ng/ml. The within-run and day-to-day precisions, studied with plasma samples spiked with zopiclone at concentrations of 50 and 200 ng/ml, were about 4.2 to 7.6%.

The combination of both electron impact and chemical ionization considerably simplifies the identification and

quantification of zopictone, particularly pharmacokinetics studies.

on trace

63

levels in

References

1. Wheathley D (1985) Br J Psychiatry 146: 312 2. Tanaka M, Mizuki Y, Isozakian H, tnanaga K (1983) Eur J Clin

Pharmacol 24: 469 3. Kennel S, Kintz P, Tracqui A, Mangin P, Lugnier AA,

Chaumont AJ (1990) J Chromatogr 527:169

Received August 23, 1990

Fresenius J Anal Chem (t991) 339 :63-64 - © Springer-Verlag 1991

Separation of racemates by capillary zone electrophoresis based on complexation with cyclodextrins Minoru Tanaka i, Satoshi Asano 1, Masanobu Yoshinago t, Yoshihiro Kawaguchi 2, Tadahiro Tetsumi 3, and Toshiyuki Shono 1

Department of Applied Chemistry, Faculty of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565, Japan 2 NTT Opto-Electronics Laboratories, Tokai-mura, Naka-gun, Ibaragi, 3t9-1 l, Japan 3 Faculty of Pharmaceutical Sciences, Setsunan University, Nagaotoge, Hirakata, Osaka 573-01, Japan

Capillary zone electrophoresis (CZE) is a highly efficient method to separate a wide range of charged species. A variation of CZE using a micelle containing buffer has been developed by Terabe et al. [1] and has gained popularity due to its ability to separate neutral species. Cyclodextrins (CDs) were also employed in place of surfactants, carboxymethyl-/?-CD for separations of aromatic isomers [2], ethylenediamine-mono- substituted /%CD for dansylamino acid enantiomers [3] and

Offprint requests to: M. Tanaka

methylated /~-CDs for enantiomers of ephedrine and related compounds [4].

In a previous paper on liquid chromatographic separation of racemates [5], we reported on the enantioselectivity changes in the/~-CD stationary phase after its chemical modifications. In that case, the spacer-arm was also chemically modified besides the CD moiety. This may cause the considerable change in the enantioselectivity. To avoid such suspicion, we have started CZE separation of racemates by using CD derivatives as chirat additives. In this communication, we describe the sepa- ration of dansylamino acids or barbiturates in the presence of unmodified or methylated CDs.

Experimental

A Model 270A CZE system (Applied Biosystems, California, USA) equipped with an UV detector was used under the following conditions: applied voltage, 15 kV; capillary, 50 gm i.d. x 60 cm; detection at 220 nm; buffer, 0.05 mol/1 phosphate- 0.1 tool/1 borate at pH 9.0 containing 0.0t tool/1 of each CD.

Unmodified CDs (c~-, /~- and },-CDs) were obtained from Wako, and dimethylated and trimethylated CDs were prepared by the well-known methods and are denoted by prefixing the unmodified CDs by DM- and TM-, respectively.

Table 1. Enantiomeric separation of dansylamino acids

Dansylamino acid R'-value

fl-CD 7-CD DM-c~-CD T M - c ~ - C D DM-/~-CD TM-/~-CD

Aspartic acid 100 90.3 Glutamic acid 100 100 Leucine 86.9 100 Norleucine c 65.9 97.8 Norvaline 74.2 100 Phenylalanine 38.8 Valine 92.1 95.7

75.1"

24.3 b 100 ~ 70.1 ~ 100" 89.1

24.7 b 75.3 100 ~ 4.3 b t00

47.1 37.1"

L-Isomer migrated fast Two peaks were too close

° Neither isomer was obtained