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-mer-
azole (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
capto-3-substituted-s-triazolo(4,3-b)-s-tetrazine derivatives (11) from 4-amino-3-hydrazino-5-mercapto1,2,4-tri-
?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
1.1
Table I. Measured Absorbances f o r K n o w n Concentrations of Formaldehyde
1
Formaldehyde concn, PPm
Absorbance at 549 nm
0.5 1 .o 2 .o 3 .O 4 .O 5 .O
0.16 0.325 0.62 0..95 1.24 1.56
0.16 0.325 0.65 0.95 1.26 1.59
0.16 0.32 0.63 0.96 1.25 1.58
0.165 0.325 0.635 0.95 1.24 1.58
adaptation of the qualitative procedure to suit the assay of this aldehyde in concentrations down to one half part per million by weight.
c’’21 0.1
0
10
Calibration for the Analytical Procedure. Standard solutions of formaldehyde in the range 0.5-5.0 ppm were prepared from a stock solution of formalin assayed independently by the peroxide oxidation method ( 2 ) . The special reagent 4-amino-3-hydrazino-5-mercapto1,2,4-triazole (3) (0.1 gram) as dissolved in N-sodium hydroxide (10 ml) in a 25-ml standard iask (stock solutions of the reagent were not used because of their limited shelf-life). The formaldehyde test solution (10 ml) was then added and the mixture aerated (lo0 ml/min) for 30 minutes at 20 “C by means of a small Pasteur pipet connected to a steady source of clean compressed air. At the end of this period of aeration, the colored solution was immediately made up to 25 ml with distilled water, and the absorbance value of 549 nm measured in 1-cm cells using as referat the ,A,, ence a blank solution prepared in the same manner. RESULTS Table I shows the measured absorbances for known concentrations of formaldehyde. The linear relationship (Beer’s law) that was obtained between the two parameters was represented by the equation:
(1)
Formaldehyde solutions of concentrations 5-20 ppm were also measured within the accuracy limits of 3% by appropriate dilution (after aeration with the reagent) of the test solution and reference with 0.W sodium hydroxide to allow the absorbances to be measured in the most sensitive range of the spectrophotometer. Formaldehyde solutions of concentration greater than 20 ppm were reliably measured by suitable dilution before assay. The major source of error in the analytical procedure was in the delivery of a constant volume of air to the reaction mixture. This error may be reduced by selection of a longer period of aeration (Figure 1) when errors in both time of aeration and rate of delivery of air become less significant. For example, the calibration relationship for an aeration time of 60 minutes was determined as: ( 2 ) U.S.
Pharmacopoeia, 17th revision, Mack Printing Co., Easton. Pa.,
1965, p 260.
30
40
60
50
70
T i m e o f A e r a t i o n (Minutes)
EXPERIMENTAL
Concn (ppm) = 3.16 X Absorbance f 3%
20
(3)R. G . Dickinson and N. W. Jacobsen, “Organic Preparations and Procedures International,”in press.
Figure 1. Graph showing relationship between the time of aeration at 100 rnl/min of a 3-ppm formaldehyde solution and the absorbance at 549 nm as measured in a 1-cm cell
Table 11. Wavelength f o r M a x i m u m Absorption (nm) for 6-mercapto3-substituted-s-triazolo(4,3-b)-s-tetrazine
Xmsx
Aldehyde
Formaldehyde Acetaldehyde Propionaldehyde Butyraldehyde Benzaldehyde
549 537 536 532 540
Concn (ppm) = 2.94 x Absorbance f 2%
(2)
Application to Industrial Samples. In use on industrial samples known to contain varying quantities of formaldehyde in substrates ranging from paper pulp to gelatinous adhesives and frothy detergents, the method gave reproducible results. In practice, samples were filtered where deemed advisable, and aqueous extracts made of paper pulp specimens. SCOPE After preparation of the appropriate calibration equation, this analytical procedure could clearly be used for the assay of other aldehydes. Table 11 lists the wavelength at which maximum absorption occurs for the 6-mercapto3-substituted-s-triazolo(4,3b)-s-tetrazines prepared from the given aldehydes. The absorption maxima, however, are too close to allow the application of the analysis to mixtures of aldehydes. Received for review August, 7, 1972. Resubmitted September 24, 1973. Accepted September 24, 1973. The authors thank the Reserve Bank of Australia for support of this work through a Rural Credits Development Fund Research Grant.
ANALYTICAL CHEMISTRY, VOL. 46, NO. 2, FEBRUARY 1974
299
