Table I. Per C e n t Correct Classifications (Training Set/Evaluation Set) Preprocessing technique
Classification method
I. Linear classifier a) Least-squares b) Negative feedback 11. 3-Nearest Neighbor 111. Multiclass classifier a ) Least-squares b) Negative feedback
Autoscale
Weighted autoscale
Optimum linear transformation
83/83
83/83
83/83
56/83 80/60
77/70 89/80
74/87 92/97
91/87
91/87
91/87
94/90
93/90
78/90
method is invariant to all linear transformations, the resuks are the same for the three preprocessed sets of mass spectral data. The second classification method used in this study was the K-Nearest Neighbor Classification Rule ( 4 ) with K
equal to three. This method is a multiclass method that does not depend upon linear separability. Hence, classification performance is improved in the last two sets of preprocessed data. The attributes and limitations of this method can be found in the chemical literature ( 4 ) . The results of the multiclass classifier (III) introduced in this paper are also found in Table I. Here again, the least squares procedure ( a ) and the error correction feedback procedure ( b ) were used to calculate the necessary weight vectors. The multiclass procedure performed very well. The overall performance indicates that the least squares procedure for calculating the weight vector is best. Again, note that least squares solutions are unique and are invariant to all linear transformations of the data. These attributes recommend the least squares multiclass procedure for applications which involve more than two classes. The method is a t least as effective as other linear classifiers and comparable in accuracy to the more expensive K-Nearest Neighbor Rule. Received for review February 26, 1973. Accepted August 27, 1973. Work performed under the auspices of the U. S. Atomic Energy Commission.
Identification of Heroin and Its Diluents by Chemical Ionization Mass Spectroscopy Jew-Ming Chao, Richard Saferstein, and John Manura N2.w Jersey State Police, Forensic Science Bureau, West Trenton, N.J. 08625
Forensic laboratories currently use a variety of techniques to identify illicit seizures of heroin (diacetylmorphine). These methods include color and microcrystal tests, absorption spectrophotometry, thin-layer and gas chromatography ( I ) , as well as electron impact (EI) mass spectroscopy (2). However, no one of the above techniques in itself combines the speed, accuracy, and sensitivity that is necessary for an identification of heroin and its organic diluents. The possible presence of numerous organic components in an illicit heroin mixture, will almost always preclude the examination of the powder directly in the E1 mass spectrometer and therefore necessitates interfacing the mass spectrometer to a gas chromatograph. Increasingly, forensic laboratories are being required to identify all the components of an illicit drug mixture. This analysis may provide investigating authorities with valuable intelligence information regarding the illicit material's synthesis and origin. The application of chemical ionization (CI) mass spectroscopy to drug identification has recently been reported (3-7). This technique has now been utilized as a rapid C. Clarke, "Isolation and Identification of Drugs," Pharmaceutical Press, London, 1969. (2) G . R . Nakamura, T. T. Noguchi, D. Jackson, and D. Banks, Anal. Chem., 44, 408 (1972). (3) G. W. A . Milne. H. M. Fales, and T. Axenrod, Anal. Chem., 43, (1) E. G.
1815 (1971). (4) H . M . Fales. G. W. A. Milne, and T. Axenrod, Anal. Chem., 42, 1432 (1970). ( 5 ) D. F. H u n t and J . F. Ryan, Anal. Chem., 44, 1306 (1972) (6) R . L. Foltz, M. W. Couch, M . Geer. K. N. Scott, and C. M . Williams, Biochem. Med., 6, 294 (1972) (7) R . Saferstein and J. Chao. J. Ass. Offic. Anal. Chern., 56, 1234 (1973).
296
and sensitive means of identifying heroin and its common diluents. The procedure requires no sample preparation or prior chromatographic treatment, and its sensitivity permits a direct and rapid identification of microgram quantities of illicit heroin preparations. EXPERIMENTAL Apparatus. A Du Pont 21-490 single focusing mass spectrophotometer equipped with a dual EI/CI source was used. The instrument has a resolution of 600 with 10% valley, a 90" magnetic sector, and is equipped with differential pumping. The ,reagent gas was isobutane 199.9% ourel. The source was operated a t a pressure of 0.5-1 Torr and at a temperature of 200 f 10 "C. The ionizing voltage was set a t 300 eV in the CI mode. Procedure. Approximately a microgram of the illicit powder was added to a capillary tube. The tube was introduced by the direct probe of the mass spectrometer and the probe temperature was raised to 200 "C. Scans were taken at a rate of 10 sec/decade after 1and 2 minutes.
RESULTS AND DISCUSSION The application of CI mass spectroscopy to forensic identification lies in the ability of the operator to control the complexity of the spectra that are generated through the choice of the CI reagent gas. The ionization process can occur through a charge or proton transfer processes, depending on the nature of the reagent gas. The former results in spectra resembling that of conventional E1 spectroscopy, the latter produces spectra that are generally less complex. As the present study has as its objective the identification of heroin in the presence of its diluents, isobutane was the reagent gas of choice. This gas has previously been demonstrated as having yielded the least
ANALYTICAL CHEMISTRY, VOL. 46, NO. 2, FEBRUARY 1974
Table I. Isobutane CI Mass Spectra of Heroin and Common Di1uentsa.b Peaks Compound
Mol wt
1
2
3
Heroin Acet ylcodeine Quinine Caffeine Procaine Methapyrilene Mannitol Sorbitol Glucose Fructose Galactose Mannose Sucrose Lactose
369 34 1 324 194 236 261 182 182 180 180 180 180 342 342
310 282 325 195 237 262 183 183 163 163 163 163 163 163
370 (33%) 342 (15%) 326 (25%)
268 (14%)
100 (16%)
99 (10%)
165 (20%) 165 (20%) 145 (85%) 145 (85%) 145 (85%) 145 (85%) 145 (85%) 145 (85%)
147 (10%) 147 (10%) 127 (25%) 127 (25%) 127 (25%) 127 (25%) 127 (25%) 127 (25%)
All peaks are listed in descending order of intensity with their abundancea in parentheses. shown.
4
136 (20%)
307 (10%)
129 (10%) 129 (10%)
Only those peaks with abundance of 10'; or g r e ~ t e rare
17 Y
I
DO
N) G
Figure 1. Mechanism for the fragmentation of heroin complex CI spectra (8). The simplicity of an isobutane CI spectra suggests its application to the characterization of multicomponent mixtures as those most frequently encountered in illicit drug determinations. The isobutane CI spectra of drugs generally display only one to three ions with abundances greater than 10% (3, 7). The majority of these drugs show an (M 1) peak as the predominant ion; the presence of other ions can generally be accounted for by mechanisms common to carbonium ion chemistry. The isobutane CI spectra of heroin and its common diluents are listed in Table I. The CI spectrum of heroin has its base peak at m / e 310. This ion is attributed to the protonation of the acetyl group on the C-6 carbon and its subsequent loss as acetic acid (Figure 1).Loss of the acetic acid from C-3, is unlikely as it would result in a highly unstable aryl ion. Heroin usually contains 06-monoacetylmorphine and acetylcodeine (9). The former is a degradation product and the latter is a by-product of the heroin synthesis. Acetylcodeine has its major peak at m / e 282; this peak also represents the loss of acetic acid from the (M + 1) ion. Its presence in a heroin preparation is illustrated in Figure 2 . Though a standard 06-monoacetylmorphine was not available for analysis, it is assumed that its predominant ion would be the MH-CH3COOH ion at.m/e 268, a (M + 1) ion would also be present at m / e 328; its presence in illicit heroin preparations is shown in Figure 3. The spectra of the heroin diluents that were examined are characterized by their simple fragmentation patterns. Caffeine and methapyrilene have only ( M + 1) ions a t m / e 195 and 262, respectively. Quinine and procaine, while exhibiting other ions, show strong (M + 1) ions as their base peaks at m / e 325 and 237, respectively.
:i D
+
(8) M . S . 5. Munson , A n a / . Chem., 43, (13). 28A (1971) (9) J. M. Moore, Micrograms, 5, 38 (1972).
M/€
Figure 2. CI mass spectrum of heroin, acetylcodeine, quinine, and glucose
V E
Figure 3. CI mass
spectrum of heroin, caffeine, and rnonoa-
cetylrnorphine Mannitol and sugars are popular diluents for illicit heroin. The isomeric hexahydric alcohols of mannitol and sorbitol cannot be distinguished by CI mass spectroscopy.
ANALYTICAL CHEMISTRY, VOL. 46, NO. 2, FEBRUARY 1974
297
Table 11. C I Mass Spectra of Salts and Corresponding Free Basesasb Peaks Compound
Heroin free base Heroin hydrochloride Quinine free base Quinine hydrochloride Quinine sulfate Quinine gluconate
Mol wt
369 423 324 396 782 520
1
2
3
310 310 325 325 325 325
370 (33%) 370 (33%) 326 (25%) 326 (25%) 326 (25%) 326 (25%)
268 (14%) 268 (14%) 136 (20%) 136 (20 % ) 136 (20%) 136 (20 % )
4
307 307 307 307
(10%) (10%) (10%) (10%)
*
All peaks are listed in descending order of intensity with their abundance in parentheses. Only those peaks with abundance of 10% or greater are shown.
+
2Hz0 and (M 1)-3H20, respectively. The disaccharides examined, sucrose and lactose, all exhibit CI spectra similar to those of the monosaccharides; this is attributed to their decomposition in the CI source prior to ionization. Identical CI spectra are produced by a compound in both the salt and free-base form (Table 11). This observation therefore precludes the necessity of any sample preparation prior to the insertion of the illicit powder in the direct probe of the mass spectrometer. Similar observations have previously been made regarding the E1 spectra of barbiturates in both the salt and free-acid forms ( I O ) . The CI spectra of illicit heroin preparations are shown in Figures 2-4. Though a definitive forensic identification of the components of a heroin mixture cannot be made by isobutane CI spectroscopy alone, its utilization for screening or for confirmation of other testing procedures is quite apparent. Additionally, the spectrum will yield a "fingerprint'' pattern of the powder, that could be useful in characterizing the production and source of the illicit material. The technique is both rapid and sensitive. Microgram quantities of powder can be analyzed in three minutes.
X Y
510
Figure 4. CI mass
spectrum of heroin, quinine, and mannitol
+
Both show (M 1) ions at 183; the 165, 147, and 129 ions correspond to the loss of one, two, and three water molecules from the (M + 1) ion, respectively. The monosaccharides, glucose, fructose, galactose, and mannose all have the same CI spectra. The base peak is that of (M 1)-H20 at m/e 163. The 145 and 127 ions are (M 1)-
+
+
Received for review June 18, 1973. Accepted August 13, 1973. (10) J. D. McChesney, D. K. Beal, and R. M. Fox, J. Pharm. So., 61, 310 (1972).
Spectrometric Assay of Aldehydes as 6-Mercapto-3-substituted-s-triazolo(4,3-b)-s=tetrazines N. W. Jacobsen and R. G. Dickinson Department of Chemistry, University of Queensland, St. Lucia, 4067, Queensland, Australia
The formation of magenta and. violet colored 6-mercapto-3-substituted-s-triazolo(4,3-b)-s-tetrazine derivatives (11) from 4-amino-3-hydrazino-5-mercapto1,2,4-triazole (I) has been described as the basis of a sensitive and specific qualitative test for aliphatic and aromatic aldehydes ( I ) . The intense colors which were produced in these tests by the absorption of light by the anion of the 6-mercapto-s-triazolo(4,3-b)-stetrazine system were recognized as being the basis of a new and useful quantitative test for aldehydes. (1) R. G. Dickinson and N. w. Jacobsen, Chem. Commun., 1970,1719.
298
'
1
NH, NH2
?N""
I N-N I
?' i? OH-/O, H S y N y N RCHO
N-N
n
Encouraged by the interest shown by a u m b e r of chemical industries needing to measure and control the level of small quantities of formaldehyde in their processes, we sought to exemplify a quantitative method by
ANALYTICAL CHEMISTRY, VOL. 46, NO. 2, FEBRUARY 1974
