to consider Be loss in the vapor phase when pretreating for The impinger analyses are quite important from an industrial hygiene standpoint since beryllium was found in all the samples past the Millipore filters and appeared to be concentrated in the traps. This the contention that do exist and that they are present in the vapor state in facilities where beryllium is machined. These findings are environmentally significant since such volatile beryllium compounds may conceivably pose a previously unrecognized threat.
ACKNOWLEDGMENT We wish to thank Noel deNevers of the Environmental protectionAgency, Office of ~i~ programs,for providing impinger and cold trap samples and his helpful suggestions. The valuable assistance of Michael Taylor and Mason Hughes of the Aerospace Research Laboratories in spectrometric analyses is very much appreciatthe VU.
Received for review October 11, 1972. Accepted March 28, 1973.
Determination of Degree of Substitution in Sodium Carboxymethylcellulose by a Reverse Dye Partition Technique Sailes Mukhopadhyay,’ Bhairab Ch. Mitra,2 and Santi R. Palit D e p a r t m e n t of Physical Chemistry, Indian Association for
the Cultivation of Science, Jadavpur, Calcutta-32, India
Various analytical procedures (1-3) for the determination of carboxylate groups present in carboxymethylcellulose (CMC) and its sodium salt have been proposed from time to time to determine the degree of substitution (DS), i. e . , the average number of sodium carboxymethyl groups substituted per anhydroglucose unit. A reverse dye partition (RDP) technique (4, 5 ) is described in this note as an alternative method for the determination of DS.
EXPERIMENTAL Reagents. Disulfine blue VN 150 (I.C.I.) was recrystallized from a mixture of methanol and acetone. n-Dodecylamine hydrochloride was prepared by passing dry hydrogen chloride gas through a n alcoholic solution of n-dodecylamine. The hydrochloride was recrystallized from carbon tetrachloride using diethyl ether as the precipitant. Procedure. Four representative samples of Na-CMC with different degrees of substitution were prepared by the treatment of chloroacetic acid on cellulose. The resulting substituted cellulose samples were rigorously purified by repeated washing with 80 and 95% ethanol alternately and then drying the samples a t 50 “C. Aqueous solutions having concentrations in the range of 1.0 to 2.5 X g/l. were prepared with these samples. The pH’s of all the solutions were brought to exactly 6 . 5 by titration with the help of a pH meter. The matching of the pH of the control and the sample before partition is very critical. Buffering should be avoided. R D P Technique. A “dye reagent” was prepared by equilibrating an equal volume of a 0.005% w/v chloroform solution of ndodecylamine hydrochloride and a 0.01% w/v solution of disulfine blue VN 150 in 0.005N HC1. After partition, the deep blue colored chloroform layer was separated by centrifugation and stocked as “dye reagent.” Exactly equal volumes ( 5 ml) of the “dye reagent” and the aqueous solution of Na-CMC were shaken in a centrifuge tube. Present address, St. Stephen’s College, Delhi-7, India. Present address, Shri Ram Institute for Industrial Research, Delhi, India. R. S. Eyler, E. D. Klug, and F. Diephuis, Anal. Chem., 19, 24 (1947). K . Wilson,Sv. Papperstidn., 59, 218 (1956). A. Z. Conner and R. W. Eyler, Ana/. Chern.. 22, 1129 (1950). S. Mukhopadhyay. 6. C. Mitra, and S. R. Palit, Makromol. Chern., 141, 55 (1971). (5) D. K. Vidyarthi, S. Mukhopadhyay, and S. R. Palit, Makromol. Chern., 148, 1 (1971).
Table I . Determination of DS from RDPT Equiv
of carboxyl Concn of Corresponding per g ( A ) Na-CMC Diff in concn of of Na-CMC, Sample solution, absorbance Na-laurate, (l;)(i;l) no. g/l. X lo2 at 630 nm moi/l. X l o 5 (1)
( 1 1)
1 2 3 4
1.50 2.09 1.15 2.12
(111)
0.700 0.731 0.358 0.547
DS
(IV)
3.10 3.25 1.60 2.40
2.07 1.56 1.39 1.13
0.38 0.28 0.25 0.20
Some dye was transferred to the aqueous layer, leaving behind a less intense blue colored chloroform layer. After complete partition, the tubes were centrifuged and the absorbance of the chloroform layer was measured a t 630 nm. A “blank” test was done by shaking a n equal volume of “dye reagent” and distilled water (pH 6 . 5 ) in a centrifuge tube, and the absorbance of the chloroform layer was measured. The difference in absorbance of the test and blank solutions was determined and compared with a calibration curve to find out the concentration of COO- ions (mol/l.) in the respective solutions. The calibration curve was obtained by plotting the difference in absorbance between blank and test us. different concentrations of sodium laurate ( 4 , 5 ) . Calculation.
DS = 162A/1 - 58A
(1)
where A is the equivalents of total carboxyl per gram of the sample.
RESULTS AND DISCUSSION The disulfine blue, which carries a SO3- group, forms a n ionic complex with the n-dodecylammonium chloride. The complex is soluble in the organic layer. When the blue complex is shaken with water, it dissociates to liberate the free dye which passes into the aqueous layer. This dissociation is enhanced with the presence of any polymer bearing negatively charged groups in the aqueous layer. The opposite effect is observed in the presence of -NH3+ groups. Other groups such as -OH, -SH, >C=O, or -CONH2 have no effect on the dye partition.
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The degree of substitution of the samples of Na-CMC was also determined by acid wash (1) and Wilson’s method (2) and tabulated in Table II. The results from RDPT were found to be in close agreement with the results obtained by these two other methods.
Table II. Comparison of the Results of DS from Different Methods, Degree of Substitution Sample no.
Acid wash method
Wilson’s method
1
0.43 0.31 0.30 0.25
0.37 0.26 0.27 0.23
2 3 4
RDPT
0.38 0.28 0.25 0.20
The concentration of COO- ions in each solution of the Na-CMC sample was estimated by the RDP technique and the equivalents of total carboxyl per gram ( A ) of the sample were calculated. From this procedure, the DS was calculated using Equation 1, and the data are presented in Table I.
CONCLUSIONS This study suggests that the quicker and simpler RDP technique may be recommended as an analytical method for the determination of the degree of substitution in CMC. This technique can also be used for the estimation of acid groups present in traces in other types of watersoluble polymers. Received for review October 24, 1972. Accepted January 18, 1973.
Analysis of Polynuclear Aromatic Hydrocarbons, Some Heterocyclics, and Aliphatics with a Single Gas Chromatograph Column D. A. Lane, H. K. Moe, and Morris K a t z l Centre for Research on Environmental Quality, York University, Downsview, Ontario, Canada
The combustion of fossil fuels for heat, power, and transportation, including internal combustion engines of automobiles and the diesel engines of buses, produce most of the organic fraction of the atmospheric particulate matter commonly found in urban centers. Many of the compounds constituting this organic fraction are known to produce cancers in the experimental animal. Hence, it is of interest to know what compounds exist and in what concentrations they occur. The currently accepted method of Sawicki et al. (1) uses column chromatography to separate the organic fraction of the particulate matter into about 50 subfractions. Each subfraction is spectrophotometrically analyzed for its polynuclear aromatic hydrocarbon content. Other methods such as fluorescence ( Z ) , thin layer chromatography ( 3 ) ,paper chromatography ( 4 ) , and high-pressure liquid chromatography ( 5 ) have been used with varying degrees of success. It has long been recognized that gas chromatography is, in principle, an ideal method for the qualitative and quantitative determination of air pollutants. By nature, 1 To whom a l l correspondence should
be directed
(1) E. Sawicki, R . C. Corey, A. E. Dooley, J. B. Gisclard, J. L. Monkman, R . E. Neligan, and L. A . Ripperton, Health Lab. Sci., 7, 31 (1970). (2) E. Sawicki, R . C. Corey, A. E. Dooley, J. €3. Gisclard. J. L. Monkman, R . E. Neligan, and L. A. Ripperton, Health Lab. Sci.. 7, 45 (1970). (3) E. Sawicki, R . C. Corey, A. E. Dooley, J. B. Gisclard. J. L. Monkman, R. E. Neligan, and L. A. Ripperton, Health Lab. Sci., 7, 60 (1970). (4) T. M. Spotswood, J. Chromatogr.. 2, 90 (1959). (5) G. J. Fallick and J. L. Waters, Amer. Lab., 1972 (8),p 21. 1776
gas chromatography is a simpler and more direct method for the separation and quantitative determination of compounds than are the spectrophotometric methods, provided, however, a suitable column can be found. Columns for specific compounds or narrow ranges of compounds have been developed (6-11). However, these columns cannot separate, for example, a mixture of benzo[k]fluoranthene, benzo[a]pyrene, and perylene, or a mixture of benzo[lz]fluoranthene, benzo[e]pyrene, and perylene. One packed column (12) achieves partial success but is unsatisfactory for the lower molecular weight compounds such as phenanthrene and anthracene. Carugno and Rossi (13) achieved fairly good separation of these compounds on a capillary glass column. Since a splitter was used, they could not carry out quantitative determinations accurately. A description is given below of a packed column, capable of being used for quantitative determination, which exhibits separations comparable to those obtained by Carugno and Rossi (13). Not only is this column suitable for the determination of polynuclear aromatic hydrocarbons, but it has been found suitable for the separation of some heterocyclics and aliphatics. It is, therefore, highly suited to the analysis of organic atmospheric pollutants. (6) R . M . Duncan, Amer. Ind. Hyg. Ass., J.. 30,624 (1969). (7) L. DeMaio and M .Corn, Anal. Chem., 38,131 (1966). (8) A. Liberti, G . P. Cartoni, and V. Cantuti, J. Chromatogr.. 15, 141 (1964). (9) A. Zane, J. Chrornatogr., 38,130 (1968). (10) J. Frycka,d. Chromatogr., 65, 341 (1972). (11) J. Frycka, J. Chromatogr., 65, 432 (1972). (12) K. Bhatia,Ana/. Chem., 43,609 (1971). (13) N. Carugnoand S.R0ssi.J. Gas Chrornatogr.. 5 , 106 (1967).
ANALYTICAL CHEMISTRY, VOL. 45, NO. 9, AUGUST 1973
