(1 1) A. Ringbom, "Complexation in Analytical Chemistry", Interscience, New York, 1963,p 315. (12)J. Stary in "MTP International Review of Science, Physical Chemistry, Series One", Vol. 12,Butterworths,London, 1973,p 279. (13)A. Wyttenbach and S. Bajo. Anal. Chem., 47, 2 (1975). (14) P. D. LaFleur, J. Radioanal. Chem., 19, 227 (1974). (15) H. J. M. Bowen. J. Radioanal. Chem., 19, 215 (1974).
(16) International Laboratory of Marine Radioactivity, Principality of Monaco,
Progress Report No. 13,June 1976. (17)F. J. Flanagan, Geochim. Cosmochim. Acta, 37, 1169 (1973). (18) K. J. R. Rosman and J. R. De Laeter, Chem. Geol., 13,69 (1974).
RECEIVEDfor review May 3,1976. Accepted September 30, 1976.
Thin-Layer Chromatographic Determination of Hydrazine in Aqueous and Alcoholic Media Maria Bordun,* Joseph M. O'Connor, Gandharva R. Padmanabhan, and Joseph A. Mollica Ciba-Geigy Corporation, Pharmaceuticals Division, Analytical Research and Development, Suffern, N. Y. 1090 1
A rapid and efficient procedure for the determination of hydrazine as an azlne derivative has been developed. Hydrazine may be readily detected down to 0.002% in aqueous and aicoholic media.
Recent studies on evaluation of recovered solvents in our laboratory required the development of a rapid and efficient method of analysis for hydrazine a t low levels. A thin-layer chromatographic method of analysis which consists of reacting hydrazine and p -dimethylaminobenzaldehyde for a specified time and chromatographing the resulting derivative satisfied this need. The method is fast, simple, sensitive, and relatively free from intaferences. A survey of the literature showed that hydrazine has been analyzed extensively by a variety of methods including spot tests (1-7), colorimetry (8-15), titrimetry (16-18), and chromatography (19-21). The existing methodology was not applicable to our needs, being either too time consuming, complicated, or lacking the required sensitivity. The p -dimethylaminobenzaldehyde reacts preferentially with hydrazine and hydrazine compounds substituted in only one amino group to form the corresponding derivative as described by F. Feigl (21). The thin-layer chromatographic method described herein is based on this reaction and is specific for the detection of hydrazine and may be used for the determination of hydrazine or related compounds in water or other solvents. The lower limit of detection of hydrazine by this method was found to be 0.2 bg. The solubility of hydrazine and its salts and the rate of formation of the azine derivatives were studied in the solvents of interest. The compounds under investigation were dissolved in water, 95%ethanol, and methanol. These solvents were of immediate interest and do not react with p-dimethylarninobenzaldehyde. Hydrazine and its salts react in the same manner towards the derivatizing reagent. Because of its insolubility in alcohols, the sulfate salt was analyzed only in water (Table I).
EXPERIMENTAL Equipment. Analtech precoated Silica Gel GF plates with a 250-p layer thickness were used for the investigation. Reagents and Solutions. p-Dimethylaminobenzaldehyde was obtained from K & K Laboratories. Hydrazine and hydrazine acetate were obtained from Eastman Organic Chemicals. Hydrazine sulfate and dihydrochloride salts were obtained from Fisher Scientific. The chemicals were used without further purification. Preparation of p-Dimethylaminobenzaldehyde Derivatization Solution. p-Dimethylaminobenzaldehyde, 1.0 g, is dissolved in 100 ml of 6 N hydrochloric acid.
Procedure. Add 3.0 ml of the 1%p-dimethylaminobenzaldehyde solution to a 10-ml volumetric flask containing 10 mg of hydrazine and make up to volume with the appropriate solvent (95% ethanol, methanol, or water). The standard solution is then shaken thoroughly and allowed to stand for 20 min. Concomitantly, add 3.0 ml of the 1%p-dimethylaminobenzaldehyde solution to a 10-ml volumetric flask containing 7.0 ml of sample, shake thoroughly, and allow to stand for 20 min. Ten p1 of the standard and sample solutions are spotted 2 cm from the bottom of the plate, dried under a stream of nitrogen, and developed in a chloroform-methanol-ammonium hydroxide (85:15:1) solvent system. The chamber is saturated for 1h prior to use. After developing the solvent front to 15 cm, the plate is removed and air dried for 15 to 30 min. Detection. The hydrazine derivative, p-dimethylaminobenzalazine, is detected in visible light and appears as a yellow spot against the white background; after the plate is sprayed with the Dragendorff's reagent, the color changes to an intense orange, which facilitates detection of the derivative a t low levels. The derivative may also be detected by long and short UV light.
RESULTS AND DISCUSSION The procedure described above is specific for hydrazine. It is based on the reaction of hydrazine with p-dimethylaminobenzaldehyde to form an intensely orange to orange-yellow colored azine solution. Akio Tsuji reported a spot-test procedure for hydrazine using a modification of this reaction (4). In the system developed herein, the azine travels as a yellow spot and is easily detectable. The following materials were screened by us for interference and found to be unreactive with p-dimethylaminobenzaldehyde: alcohols, water, methyl isobutyl ketone, and primary, secondary, and tertiary aliphatic amines (Table I). Some aromatic amines, urea, and adrenaline were reported to react to some extent (6); but the distinctive orange colored solution is produced only with hydrazine (4,6). The screening results are shown in Table I. The lower limit of detection and the optimum reaction time were determined experimentally. In these experiments, the volume of derivatizing reagent-1% p-dimethylaminobenzaldehyde solution-was kept constant while varying the quantity of hydrazine in the system. Solutions of the derivatizing reagent and hydrazine (0.02,0.2,1.0, and 10 mg) were prepared in 95% ethanol, thoroughly mixed and allowed to stand for 15,20,30,and 60min. The resulting solutions were spotted and developed as described in the Experimental section. The rate study showed that formation of the azine derivative at these concentrations was optimized at a reaction time of 20 min; similar reaction times have been reported by Akio Tsuji (4)and by M. Pesez and A. Petit (6). In the above experiments the azine derivative was detected ANALYTICAL'CHEMISTRY, VOL. 49, NO. 1, JANUARY 1977
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Table I. & Values and Formation of p Dimethylaminobenzalazine Formation of p -DimethylaminobenzalCompound Hydrazine0 Methylamineb Diethylamine Triethylamine Methyl isobutyl ketoneb 95% Ethanol Methanol Water
azine
R/ x 100
Positive Negative Negative Negative Negative Negative Negative Negative
79
4 14 26 0.7
...
...
...
Hydrazine, hydrazine acetate, and hydrazine dihydrochloride were analyzed in 95% ethanol, methanol, and water. Hydrazine sulfate, which is insoluble in alcohol, was analyzed only in water. bThe amines and ketone were dissolved in 95% ethanol and methanol. a
,
by using long and short wave UV light and Dragendorff‘sspray reagent. A direct relationship was observed between the amount of azine derivative spotted and the intensity of the spot detected on the plate with Dragendorff‘s reagent. The minimum amount of hydrazine detectable by the described procedure is dependent upon the method of detection. The least sensitive method is visual observation o$ the yellow spot where levels of 0.5 pg are readily detected. The use of Dragendorff‘s spray reagent increases the sensitivity to allow for detection of 0.2 pg. Maximum sensitivity is achieved using long and short wave UV light where the minimum detectable amount of hydrazine as the azine derivative is 0.1 pg. At this level, visual detection is not possible as the color of the spot has diminished and tends to blend into the background. The azine derivative exhibits a strong fluorescence in long and short UV radiation, which decreases as the hydrazine concentration decreases to 0.005 mg/ml when fluorescencewas no longer observed. The fluorescence of the spot correlates very well with the color of the solutions. The method described is more convenient, sensitive and semiquantitative for the determination of hydrazine than most other procedures available in the literature. The literature survey showed that while several chromatographic
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methods employed spray reagents for the detection of hydrazine, none derivatized the hydrazine prior to chromatography. Spot-tests depend in most cases on color development only. The colorimetric methods, which are time consuming, do not always give consistent results. Furthermore, the colorimetric personal dosimeters are not capable of high accuracy or of reliable quantitative interpretation of the color developed (2;15).The titrimetric methods are time consuming and often involve complicated procedures not suitable for routine testing of hydrazine. The development of this method was made feasible due to the fact that alcohols and water do not react with p-dimethylaminobenzaldehyde. The method provides for the determination of low levels of hydrazine in recovered alcohols or feed and waste water and when these solvents are treated according to the method described, hydrazine can easily be detected by visual means at a concentration of 0.002% (0.2 CLg). LITERATURE CITED (1) L. L. Legradi, Fresenius’ 2.Anal. Chem., 239, 29-30 (1968). (2)C. A. Plantz, P. W. McConnaughey, and C. C. Jenca, J. Am. lnd. Hyg. Assoc.,
29, 162-164 (1968). (3) L. M. Kul’berg and A. I. Cherkesov, Zh. Anal. Khim., 6,364-370 (1951). (4)Akio Tsuji, Bunseki Kagaku, 11, 996-997 (1962). (5) B. R. Sant, Microchim. Acta, 169-170 (1958). (6) M. Pesez and A. Petit, Bull. SOC.Chim. f r . , 122-123 (1947). (7) Mine Safety Appliances Co., Brit. Patent 1,151,594(Cl. G O h ) 07 May 1969. (8) Jean Barlot and Simone Marsaule, Mem. Poudres, 35 7-13 (1953). (9) Vera Spinkova, Pharm. Acta Helv., 46,643-648 (1971). (IO) N. M. Kalinina, Energetik, 12 (ll),41-42 (1964). (11)Jarmila Prazenska and Jaroslav Zika, Chem. Prum., 10, 343-346 (1960). (12)E. Yu. Kostrikina, Energetik, 17 (12),27-29 (1969). (13) “Kirk-Othmer Encyclopedia of Chemical Technology”, 2d ed. rev., Interscience, New York, N.Y., 1966,p 184. (14)A. Aleksandrov, P. Vasileva-Aleksandrova,and E. Kovacheva, Mikrochim. Acta, 5, 1007-1012 (1968). (15) E.L.ArnoldandR.F.Rakowski, U.S. C.F.S.T.l.,ADRep.,AD679527,29 (1968). (16)H. E. Malone, and D. M. W. Anderson, Anal. Chim. Acta, 47, 363-366 ( 1969). (17)R. N. Aksel’rud, and G. P. Berezyuk, €lek. Stn., 40 (3),79-80 (1969). (18) H.E. Malone and R. E. Barron, U.S. Dept. Commer., Off. Tech. Serv., AD 278,499,13 (1962). (19)V. Spinkova, Cesk. Farm., 16, 138-142 (1967). (20)J. M. Bremner, Analyst (London)79 198-201 (1954). (21) Fritz Feigl, Spot Tests in Organic Analysis”, 7th ed., 1966, pp 277278.
RECEIVEDfor review August 5, 1976. Accepted September 24, 1976.
