c50 ( 8 3 4 )
TIC
537
565 579
593 607
I
l
I
~
0
l
52
l
/
I l 1
100
I
l
l
I
I
l
15C
SCAN NO
Flgure 7. Identification of TG types of C48,C49,Cs0,C5,, C5*, CS3,CS4 TG in milk fat by chemical ionization mass chromatography usin m l e 607, 593, 579, 565, and 537 ions, which are [MH - RCO,H]' ions
and CB TG were obtained, between the Scan No. 150 and Scan No. 190 shown in Figure 5. Also, the CI mass spectra of C36, and the peak top of the mle 225 (C15:0), which is C37, were obtained. These spectra are shown in Figure 6. It can be seen from the QM' ion t h a t the C36 and C38 T G are large in quantity and, hence, there is no interference of other components. T h e peak of the CBi T G which is quite small in quantity, is interfered with by the c 3 6 and CS8T G . In the case of CI mass spectra, because of the high intensity of the QM' ion, the mle 670 ion which corresponds to C3i TG can be distinguished from the mle 656 and 684 ions which correspond to c36 and CS8TG, respectively (Figure 6 middle chromatogram). T h e [MH-RCO2H]+ion group, however, gives a rather complicated spectrum due to the interference of C36T G and C38TG. T h e spectrum shows the existence of odd-carbonnumber fatty acids such as Cg, Cg, Cll, C13 CIS, CI;, and C19. Figure 7 shows the CI-mass chromatograms of the [MH R C 0 2 H ] ion of Cd8,Cd9,Cjo, CS1,Cjz, Cj3, and Cjd T G in milk fat. T h e TIC, which is also shown in Figure 7, shows no odd-carbon-number T G such as Cd9,CS1,or Cj3 TG. The MC,
by contrast, shows clearly how even-carbon-number T G and odd-carbon-number T G overlap each other. On detailed study of the mass chromatograms, we found t h a t the Cj4 T G has a molecular weight of 890 and, also we knew from the MC peaks of the m/c>607 ion that [E-18- 1' ion exists. I t can be concluded from these data t h a t the CS4 T G is of 18-18-18 type. T h e Cj2 T G has a molecular weight of 876 and gives MC peaks of mle 607 and mle 579 ions. Calculation on [MH RCOzH]+ shows t h a t the mle 607 ion corresponds t o [18-18-1' ion and mle 579 ion t o [B8-16- 1' ion. I t can be concluded t h a t the Cjz T G is of the 18-18-16 type. T h e Cjo T G has a molecular weight of 834 and gives MC peaks of mle 607 and mle 579. These ions corresponds t o [18-16- 1' and [18-18- 1' ions. Thus it can be concluded that the Cjo T G is of 18-16-16 and 18-18-14 types. T h e C4ET G has a molecular weight of 806 and gives MC peaks of mle 607 and mle 579 ions. These ions correspond t o [18-16- 1' and [18-18- 1' ions and suggest the existence of T G of 18-16-14 and 18-18-12 types. As for the odd-carbon-number T G , the Cj3 T G has a molecular weight of 876 and gives the MC peak of mle 593 ion. This ion corresponds to [18-17- 1' ion and, therefore, suggests that the CS3T G is of the 18-18-17 type. The Cjl TG has a molecular weight of 848 and gives MC peaks of mle 593 and mle 565 ions, which indicate the existence of [E-18- 1' ion and [ 18-15 1' ion, and that the Cjl TG is of the 18-1&15 type. T h e Cd9T G has a molecular weight of 820. T h e MC peaks of mle 607, mle 565, and mle 537 ions show the existence of [ 18-15- ]+, [ 18-18- ]+, and [ 16-15- ]' ions and that the C4gTG is of the 18-18-13 and 18-16-15 types. In Figure 7, only the important types of T G are shown; it is possible to identify trace-quantity TG, through suitable selection of [MH-RCO,H]+ ions. Odd-carbon-number triglycerides can be identified by effective use of EI-MC, CI-MC, and CI-MS.
LITERATURE CITED (1) T. Murata and S.Takahashi, Anal. Chem., 45, 1816 (1973). (2) T. Murata and S.Takahashi, Anal. Chem., 49, 728 (1977). (3) M. Bugaut and J. Bezard, J . Chromatogr. Sci., 8,380 (1970). (4) J. Bezard, M. Bugaut. and G. Clement, J . Am. OilChem. SOC.,48,134
(1971). (5) J. Bezard, Lipids, 8, 9 (1971).
RECEIVED for review July 13, 1977. .Accepted September 13, 1977.
Gas Chromatographic Determination of 6-Hydroxyethylhydrazine in the Presence of Its Synthesis By-products Philip J. Palermo Norwich Pharmacal Company, Division of Morton-Norwich Products, Inc., Norwich, New York
A rapid programmed temperature gas chromatographic analysis using thermal conductivity detection Is presented for water, hydrazine, P-hydroxyethylhydrazine (HEH), and high-boilers, which are the products of the reaction between hydrazine and ethylene oxide. The HEH assay has an accuracy of f1.3% at the 95% tolerance level. The other major reaction products are also identified and quantitated. The
138 15
detection limits of the minor constituents are: water, 0.05 % and hydrazine, 0.1 YO.
For some time a fast and accurate analysis of P-hydroxyethylhydrazine ( H E H ) and other components within its formation mixture has been lacking. Most laboratories use ANALYTICAL CHEMISTRY, VOL. 49, NO. 14, DECEMBER 1977
2213
h
I'
I,
INJECTION
Figure 1. Typical chromatogram of technical grade HEH; 1 1 L injected
a tedious vacuum distillation procedure, which employs the weighing of collected fractions. This procedure takes several hours and the components are not well separated. T h e first fraction contains both water and hydrazine, one of which must then be determined by another procedure. T h e second fraction contains HEH and small amounts of the other components, while the third fraction contains a mixture of high-boilers (HB) which are inseparable by distillation. Although an NMR procedure is also available ( 1 ) its precision is in doubt and NMR analysis is usually not preferred because of its expense. A colorimetric procedure has been presented (2) for H E H alone b u t the high boiling 1,l-bis(P-hydroxyethy1)hydrazine and hydrazine itself would react with cinnamaldehyde, resulting in an interference. A paper chromatography system has been reported for the detection of the reaction products but no quantitation was attempted (3). Gas chromatography has also been applied to these and related compounds without quantitation ( 4 ) . (3-Hydroxyethylhydrazine is an important intermediate in the synthesis of nitrofuran antibacterial agents, especially furazolidone. Because of its effect on synthesis yields, the exact composition of the technical grade HEH used is of economic importance. HEH has also been used as a growth regulator ( 5 ) and pesticide ( 3 ) . A gas chromatographic approach was desired for simultaneous determination of all the components including water, and therefore thermal conductivity detection was necessary since water is not quantitated by a flame ionization detector.
EXPERIMENTAL Apparatus. A Hewlett-Packard Model 5750A Gas Chromatograph equipped with a thermal conductivity detector was used with a 10-pL Hamilton Model 701-N syringe. A Moseley Model 7127 Strip Chart Recorder with a Model 229 Disc Chart Integrator was used to integrate peak areas. The column was '/4-inch X 11/2-foot type 316 stainless-steel tubing filled with 100/120 mesh Chromasorb 101 installed for on-column injection. The tubing was prewashed in dilute nitric acid, followed by 25% sodium hydroxide. A glass column showed no differences in elution or peak areas. The column was conditioned overnight at 220 "C and 50 mL/min helium flow. The reference column was the same as the analytical column. The instrument parameters are: helium flow A and B, 60 mL/min; detector block temperature, 220 "C; detector filament temperature, 220 "C; detector transfer zone temperature, 220 "C; injection port temperature, 220 "C; initial column temperature, 85 "C; final column temperature, 230 "C; program rate, 30°/min; post injection time, 0; hold at limit, 4 min; bridge current, 150 mA; and injection volume, 1.0 pL. Procedure. Technical grade HEH is a highly viscous liquid with strong reducing properties. A separate syringe was washed with HEH several times and kept for this analysis only. Because of its high viscosity, highly reproducible (2% or less) injection volumes are difficult to achieve. For this reason, an internal normalization technique was found preferable to comparison with a standard. Since HEH is very hygroscopic, care must be taken 2214
ANALYTICAL CHEMISTRY, VOL. 49, NO. 14, DECEMBER 1977
Table I. Composition of Synthetic Mixture Samples Sample No. HEH,g HB,g N,H,,g H,O,g 1 4.2270 0.8074 0 0 2 3.9280 0.8361 0.0463 0.0260 0.8361 3 3.9280 0.1370 0.0772 4 4.5222 0.7484 0.0272 0.0154 5 4.5259 0.7961 0.0906 0.0508 6 4.0094 0.9864 0.1620 0.0910 Table 11. Normalized Peak Area Synthetic Mixtures Sample No. H,O N,H, 1 0.46 0.04 2 1.33 1.07 3 2.82 3.89 4 0.67 0.75 5 1.97 1.91 6 3.40 3.55
Percentages for the HEH 87.21 84.06 82.36 87.84 84.72 79.13
HB 12.29 13.54 10.93 10.74 11.40 13.93
to inject as quickly and reproducibly as possible. A delayed syringe withdrawal of about 3 s was used to ensure complete vaporization of the sample from the syringe and thereby minimize the possibility of differential vaporization within the needle. A typical chromatogram of a technical grade HEH sample is shown in Figure 1. The approximate retention times are: air (0.1 min), H20 (0.4 rnin), N2H4(2.0 min), ethylene glycol (3.4min), HEH (4.5 rnin), high-boilers (5.8 and 6.7 min). Since HEH is the major component, it is advantageous to change attenuations to give reasonable peak areas for all components. Thus, after elution of hydrazine, the attenuation is increased by a factor of four. For an internal normalization technique, both the linearity of response of each component over the expected concentration range and the relative detector response factors were established. This was accomplished by obtaining both pure HEH and pure high-boilers (HB) from the distillation technique. The purity was established by the lack of any extraneous gas chromatographic or NMR peaks. Synthetic mixtures of HEH, HB, and pure hydrazine hydrate of known concentrations were prepared to typify technical grade samples by weighing each. The HEH used was double distilled and showed only a minor water peak (less than 0.05%). GC and NMR data both indicated high purity. The HB used showed only the ethylene glycol (EG) peak and the high-boilers. No HEH peak was present in the high-boilers. The 100% hydrazine hydrate (HH) used showed no other GC peaks. The composition of the samples is shown in Table I. The normalized peak area percentages are shown in Table 11. To simplify the calculation, the EG peak is included with the high-boilers. Although ethylene glycol elutes before HEH, most of it stays back with the high-boilers in the distillation procedure. When the peak percentage is plotted vs. the actual percentage of each component, the slope of the line gives the response factor of that component. Also when linear regression is performed on these data the linearity is reflected in the correlation coefficient. Table I11 shows these data for the six samples. According to the slope for the four components the calculations are:
area area area area
HzO peak N2H4peak HEH peak HB peak
t t t t
1.83 = 1.13 = 1.02 = 0.73 =
corrected area H 2 0 corrected area NzH4 corrected area HEH corrected area HB total corrected area
The percentage of each component is its (corrected area/total corrected area) X 100. To establish the precision of the method, a technical-grade HEH sample was analyzed six times by this method. The results are shown in Table IV. From the chromatogram (Figure l ) ,the limit of detection of water is estimated to be about 0.05% and hydrazine about 0.1 %.
Table 111. Linear Regression Analysis
Component
Slope
Correlation Coefficient
HZO
1.83 1.13 1.02 0.73
0.979 0.992 0.989 0.963
%% HB
Standard Error of Estimate 0.198 0.153 0.437 0.331
Table IV. Anaiysis of a Technical Grade HEH Sample Run H,O,% N,H,,% H E H , % H B , % 1 2
0.64
3 4 5 6 X
S
RSD,%
0.70 0.86 0.63 0.61 0.66 0.68 0.09 13.4
0.39 0.42 0.38 0.50 0.49 0.40 0.43 0.05 11.1
83.95 83.76 83.55 82.95 82.92 83.12 83.38 0.44 0.52
15.02 15.09 15.21 15.92 15.97 15.81 15.50 0.44 2.9
Table V . Analyses of Synthetic Samples Component Av % Recovery Water 113 Hydrazine hydrate 107 HEH 99.4 HB 102.6 Five synthetic samples composed of hydrazine hydrate, phydroxyethylhydrazine,and high-boilers were analyzed for water (range 0-2%), hydrazine (range 0-3%), HEH (range 75-85%), and high-boilers (range 14-19%). These mixtures represent the normal variation in yields. The results are shown in Table V.
T h e 95% tolerance level is the '70 RSD (0.52) multiplied by the Student t table value (2.57 for 5 degrees of freedom). Because they are minor constituents and also because HEH is hygroscopic, the error is larger for both H 2 0 and N2H4. T h e major products of the synthesis were also of interest. In the first fraction of the distillation method, a trace of ethanol was found which eluted between H20 and N2H,. The high-boiler residue contained mostly 1,l-his(@-hydroxyethyl)hydrazine, as confirmed by the disappearance of its GC peak ( R , = 6.7 min) upon reaction with cinnamaldehyde in ethanol solution. T h e second high-boiler (R, = 5.8 min) was 1,2-bis(P-hydroxyethyl)hydrazine( I ) . At low attenuation a third peak was barely detectable between these two. This is probably P-(P-hydroxyethoxy)ethyl hydrazine ( I ) . As previously mentioned, ethylene glycol was found. The column used in this method can be prepared in 1 h and conditioned overnight. A typical column showed no signs of deterioration after more than 200 sample analyses. Rapid and accurate analyses of the major components in the synthesis mixture, including calculations, is achieved in about 20 min. Since the relative response of these components to thermal conductivity detection has been shown to be constant (5),the relative response factors given should be appropriate for any gas chromatograph equipped with a thermal conductivity detector. T h e internal normalization technique eliminates the inconvenience of periodically preparing pure HEH for a standard by the distillation technique.
LITERATURE CITED (1) R . G. Haber, Chim. Anal. (Paris), 52, '1394-1396 (1970). (2) M. P. Thomas and H. J . Ackerman, J. Agric. FoodChem., 12,432-433 (1 964). (3) L. Fishbein and M. A. Cavanaugh, J , Chromafcgr., 20,283-294 (1965). (4) L. Fishbein and W.L. Zielinski, Jr., J. Chromafogr.,28,418-421 (1967). (5) A. E. Messner, D. M. Rosie. and P . A. Argabright, Anal. Chem., 31, 230-233 (1949).
RESULTS AND DISCUSSION The linear regression and standard deviation data show that HEH can be assayed to *1.3% a t the 9 5 % tolerance level.
RECEIVED for review July 18, 1977. Accepted September 2 , 1977.
Spectroscopic Element Detector for Gas Chromatography Cyrus Feldman" and Daniel A. Batistoni' Analytical Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
A simple helium glow discharge detector with a stable but Inexpensive power supply has been used to detect individual halogens, S, P, C, and metals in GC effluents. Glow chamber design prevents degradation products from coatlng the observation window. The monochromator Is provided with an internal beam-splitter and a sideexit port. A movable exit dit mounted on the latter permits background corrections to be made at the most suitable distance from the elemental line detected. Selectivity and versatility are greatly improved by this type of background detection.
A need recently arose in this laboratory for an individual element detector for gas chromatography. The type of device desired would be highly specific, but simple and inexpensive Present address, ComisiBn Nacional de Energia AtBmica, Avenida del Libertador 8250, Buenos Aires, Argentina.
t o construct and operate. T h e requirement of specificity confined our search essentially to spectroscopic methods. The spectroscopic methods used to detect specific elements in gas chromatography have been reviewed by Cram and Juvet ( I ) . Almost all of the spectroscopic detectors they mention employed either a microwave discharge or a flame to generate the spectrum. T h e microwave devices were comparatively complex and expensive, however, and the flames not highly specific for a wide range of elements. One detector, the glow discharge tube of Braman and Dynako (2),had the desired simplicity: it consisted of a 50-mm length of 1-mm or 2-mm i.d., 6-mm 0.d. silica tubing, with platinum wire electrodes mounted axially, a 6-18 mm electrode gap, and provision for axial flow of gas (He, Ar or He-Ar mixtures). This device's principal drawback appeared to be coating of the tube walls by decomposition products, thus attenuating the light signal as chromatographic peaks (or, by accident, solvent peaks) passed through the discharge. It appeared to us that certain changes in design and materials might result in a detector with ANALYTICAL CHEMISTRY, VOL. 49, NO. 14, DECEMBER 1977
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