323
Table 11. Comparison of LSD Mass Spectra LSD"
323 (1004°C)
... ...
223 222 221 207 196 181
...
(26%) (24%) (32%) (22%) (16%) (26%)
... ... 111 (12%)
...
...
(15'56)
(15%) (12%) (10%)
... 57 (14%)
...
...
;a222 , (39%) (28%) 221 207 196 iai 167 154
... ...
...
97 a3 71 69
323 (100%)
(70%)
(40%) (20%) (38%) (15%) (12%)
... ...
... ... ... ... ...
... ... ...
LSob
80
~
I
I
323 251 235
!
L 'Ol 60
... ...
221 207 196 181 167 154 139 127 111 100
100
Figure 5. Mass spectrum of
200 w e
3:'
300
irradiated L S D extract (residue B)
the irradiated product shows no appreciable absorption a t 313 nm, the characteristic absorption maximum for LSD, hence indicating that the hydration reaction was complete. These findings, i.e., ultraviolet and mass spectral analyses of both LSD and the acid catalyzed photochemically induced hydration product of LSD, provide unequivocal confirmation of the presence of lysergic acid diethylamide in illicit preparations.
...
83
...
... 62 60
...
42
From the data of Nigam and Holmes (9). Relative intensities determined from published spectrum. Only m / e peaks greater than 140 were presented. From the data of Finkle, Foltz. and Taylor ( 1 5 ) . Relative intensity data not available.
LITERATURE CITED
a
acid catalyzed photochemical hydration product. Mass spectral analyses confirm the hypothesized hydration reaction of Stoll and Schlientz. Observation of a molecular ion a t mle = 341 (42.4%) confirms the addition of H20 (mol wt = 18) to LSD (mol wt = 323). Figure 5 depicts the mass spectrum of the irradiated product. The base peak is observed a t v i l e = 323. Alcohols are known to exhibit base peaks of mass M - 18 arising from loss of the neutral molecule H20 (16). The loss of HzO can occur both before or after ionization. The loss before ionization occurs through thermal modes. It is apparent that the peak a t mle = 323 arises from the hydrated product and not from residual LSD in the reaction mixture. The ultraviolet spectrum of
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16)
A. Stoll and W. Schlientz, Helv. Chem. Acta, 71, 585 (1955). D. Anderson, J. Chromatogr., 41, 491 (1969). T. Niwaguchi and T. Inoue, J. Chromatogr., 59, 127 (1971). K. Genest and C. Farmillo, J. Pharm. Pbarmacol., 16, 250 (1964). C. Radecka and I. Nigam, J. Pharm. Sci., 55, 861 (1966). M. A . Katz, G. Tadjer, and W. A. Aufrecht, J. Chromatogr., 31, 545 (1967). A. Sperling, J. Chromatogr., 12, 265 (1974). T. M. Hopes, Microgram, Vol. I, No. 4 (1968). I. Nigam and J. Holmes, J. Pharm. Sci., 58, 506 (1969). M. D. Cunningham, Microgram, Vol. V1, No. 2 (1973). M. Barber, J. A. Weisbach, B. Couglas. and G. 0. Dudock, Chem. lnd., 1072 (1965). R. Martin and T. G. Alexander, J. Ass. Offic. Anal. Chem., 50, 1362 (1967). A. Sperling, J. Forensic Sci., 15, 86 (1970). J. ILook, Microgram, Vol. I, No. 4 (1968). B. Finkle, R. Foltz, and D. Taylor, J. Chromatogr., 12, 304 (1974). H. C. Hill, "Introduction to Mass Spectrometry," 2nd ed., Heyden and Son Ltd., Spectrum House, London, 1972, p 71.
RECEIVEDfor review July 8, 1974. Accepted November 18, 1974.
Microdetermination of Nitrogen by Means of a Thermal Conductivity Detector. Application to the Determination of Nitrogen in Tin-Nitrogen and Germanium-Nitrogen Compounds Jean-Claude Remy and Yves Pauleau Thermodynamics and Mineral Physico-Chemistry Laboratory, U.E. R. Sciences, et Techniques, Faculte des Sciences, Boulevard Lavoisier, 49045 Angers Cedex, France
Research in our laboratory relating to metal-nitrogen compounds prepared in the form of thin films by reactive cathodic sputtering ( I ) has involved the determination of nitrogen in such compounds. A comparative study carried out by Healy and Parker ( 2 ) showed that conventional methods of nitrogen determination on metallic nitrides
(Kjeldahl method, alkaline fusion. . .) are only efficient when this element is a t oxidation state -3. Surveys (3-6) have established, however, that the hydrolysis of some nitrides will produce ammonia, hydrazine, and even molecular nitrogen, suggesting that nitrogen, in these compounds, is not entirely a t its oxidation state -3. The Dumas method A N A L Y T I C A L C H E M I S T R Y , VOL. 47, NO. 3, M A R C H 1975
583
Figure 1. Experimental apparatus (A) argon cylinder, (6)flow regulator, (C)and (D) flowmeters, (E) thermal conductivity detector, (F) power supply and bridge-control, (G)recorder, (H),(I), (J), and (K) three-way taps, (L) sample valve, (M) mercury manometer, (N) vacuum pump, (0) nitrogen cylinder, (P) dissociation tube inside oven, R,, R2, and R3, one-way taps
and its variants are being used currently in the determination of the total amount of nitrogen, but they require larger samples to allow the measurement of volume to be made with small relative error limits. Moreover, the oxidation of metallic nitrides by oxygen does not always produce exclusively molecular nitrogen (formation of nitrogen oxide with BN ( 7 ) ) .The method used by Hynek and Nelen ( 7 ) presents the same disadvantages, though the final nitrogen determination by gas chromatography has a greater sensitivity than Dumas's conventional method. Because of this, we have developed a method that enables us to determine the total amount of nitrogen in samples weighing only a few milligrams. Our method consists of thermally dissociating the nitride into metal and molecular nitrogen, in a static vacuum atmosphere; then, the newly formed nitrogen is carried by an argon flow into a previously calibrated thermal conductivity detector.
Figure 2. Various argon circuits used for the experiment
I
EXPERIMENTAL Apparatus. Figure 1 shows the arrangement of the components used in the system; each of them is described separately as follows. Gases. Argon is used as carrier and nitrogen is used for calibration, both of which are produced by Air Liquide Cy at 99.995% purity. A Brooks (8844) regulator controls the argon flow and keeps it a t constant 3 Iph rate, visualized on a Sho Rate 150 flow meter. Thermal Conductiuity Detector. The detector used is a GowMac of the Pretzel type with a semi-diffusion cell having an internal volume of 2.2 ml. It is immersed in an oil-bath, thermoregulated a t 90 f 0.05 "C. Pou:er Supply a n d Bridge-Control. The detector is equipped with four W2X filaments, with a stabilized supply from a GowMac generator, allowing changes in voltage ranging from 0 to 40 volts and of 0 to 500 mA in current. Sample Value. A Perkin-Elmer variable-loop sample valve is used to obtain quantities of known volumes of nitrogen, for detector calibration. Recorder. A Sefram potentiometric recorder (Servotrace P E 1IO) records the Wheatstone bridge unbalanced potential difference. Dissociation Tube. The dissociation tube is made of transparent quartz. The volume included between taps R1 and R:, is roughly 50 ml. Gas Circuits. The gas circuits are of stainless steel or borosilicate glass, thus reducing the risk of leakage or contamination due to the porosity of tubing. We shall below refer to three different argon circuits, respectively C1, Cz, C3, as shown in Figure 2 by thick lines. The C1 circuit allows the direct passage of argon from the reference side to the measuring side of the detector, the C2 circuit allows the passage of argon through the sample valve, and the C3 circuit lets argon through the dissociation tube. Procedure. Establish an argon flow at 3 lph in C:, and when the thermoregulated oil bath has reached constant temperature, supply the detector filaments with a 10-V voltage and a 62-mA current 584
ANALYTICAL
(
