products was carried out and chromium was back-extracted with 0.01M nitric acid. Ruthenium did not accompany chromium through extraction and stripping. Clear separation was achieved. This is shown by the y-spectra in Figure 10. Since iron, cobalt, nickel, and manganese(I1) are also inextractable, the separation of chromium from steel can also be effected. T h e decontamination factor would improve considerably when the extraction process is carried out in a manner such that there is a high degree of saturation of the organic phase with Cr(V1).
ACKNOWLEDGMENT
M. Saeed and Riaz Joseph gave valuable assistance with the measurement/counting of radioactive samples and the calculations on D values. LITERATURE CITED
when the original aqueous Cr(V1) concentration exceeds 10 g/l. T h e extraction of a number of metal ions including the important fission products was checked a t this acidity. T h e data presented in Table I show that Cr(V1) can be separated from a number of elements. Separation of spiked W r ( V 1 ) (the concentration of chromium in the initial aqueous phase was 2.55 g/l) from four-month-old fission
(1) M. lqbal and M. Ejaz, J. Radioanal. Chem., 23, 51 (1974). (2) H. M. A. Karim, Int. J. Appl. Radiat. /sot., 24, 599 (1973). (3) A. S. Solovkin, M. I. Konarev. and D. P. Adaev, Zh. Neorg. Khim. 5, 1861 (1960). (4) M. Ejaz, Radiochim. Acta, in press. ( 5 ) M. Ejaz, Radiochim. Acta, in press. 16) M. S. Faddeva. O.N. Panlov. and V.V. Bakunina. Zh. Neora Khim.. 3, 165 (1958). (7) J. Ying-Peh Tong and E. L. Prue, J. Am. Chem. SOC.75, 6180 (1953). (8)G. P. Haight, D. C.Richardson, and N. H. Coburn, horg. Chem. 3, 1777 11964\ -- I \
(9) K. A. Muirhead, G. P. Haight, Jr., and J. K. Beattie, Inorg. Chem., 12, 1116 (1973). (10) I. Baldea and G. Niac, Inorg. Chem., 9, 110 (1970).
RECEIVEDfor review July 10, 1974. Accepted January 14,
1975.
Extraction and Spectrophotometric Determination of Vanadium(V) with N-Phenyl-2-naphthohydroxamic Acid Y. K. Agrawal' Department of Chemistry, Indian Institute of Technology, Bombay, Powai, Bombay 400 076, India
Hydroxamic acids are the potential reagents for the determination of vanadium(V) (1-20). T h e parent acid Nphenylbenzohydroxamic acid (PBHA) (I) is a selective and
H
- N-OH I
@J-c=o @-!-OH e c
N-OH
@ - L O
= o (I)
sensitive reagent for vanadium(V) having a maximum absorbance a t 530 nm; t = 4650 of chloroform extract of vanadate complex ( 4 ) . However, Zr, Ti, Mo, and W interfere in the determination of vanadium with PBHA. Several other acids such as N-phenylcinnamo- ( 5 ) ,disubstituted (9) and unsaturated (6, 7) hydroxamic acids have been reported for the determination of vanadium. Bass and Yoe have proposed 2-naphthohydroxamic acids(II), as a reagent for vanadium which gives in methanol an intense red-orange color with vanadium(V) a t a wavelength of 450 nm ( c not reported) (10). Sometimes an introduction of substituent group in the ring increases the reactivity of the reagent. Present address; E n v i r o n m e n t a l Studies Section, H e a l t h P h y s ics Division, B h a b h a A t o m i c Research Centre, T r o m b a y , B o m b a y 400 085. India.
940
I
a-I
ANALYTICAL CHEMISTRY, VOL. 47, NO. 6, MAY 1975
With this object in view, a new acid has been synthesized by replacing the H atom from 11, by a benzene ring (111). In the present communication, N-phenyl-2-naphthohydroxamic acid (P-2-NHA) (III), is shown to be the most selective and sensitive reagent, surpassing 2-naphthohydroxamic acid. I t gives an intense violet colored complex with vanadium (extracted with chloroform from 3-8M HC1) molar absorptivity being 7.1 X lo3 a t 545 nm. T h e advantage of the proposed reagent lies in the fact that a satisfactory separation from many common metal ions is easily accomplished and it can be used for the extraction of trace amounts of vanadium. T h e effects of acidity, reagent concentration, and diverse ions on the absorbance of the vanadium(V)-P-2-NHA system have been studied. An attempt has been made to elucidate the stoichiometry of the extracted species.
Table I. Spectral Characteristic of Vanadium-NPhenyl-2-NaphthohydroxamicClored System in Chloroform Concn
Color of
chloroform extract
absorbance, nm
tivity, E
4.00
Violet Violet Violet Reddish violet Reddish violet Amethyst
545 545 545 530 510 480
7100
2.00 1:oo
0.10 0.01
I
~
500
I
I
540
580
I
I
62 0
... 7085 6500
... 5200
Table 11. Extraction of Vanadium(V)-P-2-NHA Complex as a Function of pH
W A V E L E N G T H , nm Figure 1. Absorption spectra of (I) vanadium(V)-P-2-NHA complex and (11) P-2-NHA in chloroform
c
Molar absorp-
of acid Y
3 .OO
?I,
Wavelength of maximum
PH
% E
Distribution ratio
0.3
100 100 100 85 70 45 20
a
0.5
1.0 1.5 2.0 2.5
I
3 .O a
a
a 10.55 4.80 1.oo 0.25
Too high to measure.
solution [1.0 X 10-4M], 5 ml of concd HC1, S ml of P-2-NHA solution and (10 - S ) ml of chloroform solutions were taken. The ratio of vanadium(V) to reagent was varied with the former held constant.
RESULTS AND DISCUSSION
0
0
2.0
1.0
3.0
PH Figure 2. Effect of acidity in extraction of vanadium(\/)
EXPERIMENTAL Apparatus. The spectra of vanadium complexes were scanned on a Hilger and Watts spectrophotometer and measurements at constant wavelength were performed on a Beckman DU Quartz spectrophotometer using 10-mm quartz cells. Reagent and Solutions. P-2-NHA was prepared freshly from N-phenylhydroxylamine and 2-naphthoylchloride (21),mp 156'. A 0.1 w/v solution in ethanol-free chloroform was used for extraction. Standard vanadium solution was prepared from AR ammonium metavanadate, and the vanadium concentration was determined titrimetrically using potassium permanganate solutibn (22). Procedure. Extraction and Determination of Vanadium(V). An aliquot of vanadium(V) solution (5 ml of 5 X 10-4M) was transferred into a separatory funnel followed by 5 ml of hydrochloric acid ( 7 M ) . Then 5 ml of 0.1 w/v chloroform solution of P-2-NHA was added, and the contents were vigorously shaken for 5-10 minutes. The violet colored organic layer was separated, dried over anhydrous sodium sulfate, and collected into a 25-ml volumetric flask. The extraction was repeated with 2 ml of the reagent solution to check the complete extraction of vanadium(V) from aqueous layer. The anhydrous sodium sulfate was washed with chloroform, and the washings were collected. The extracted layer was diluted by adding chloroform to the mark, and the absorbance was measured at 545 nm vs. the reagent biank. The composition of the extracted species was examined with the following sets of solutions. Stoichiometry. In the 100-ml separatory funnel, R ml of vanadate solution [1.0 X 10-4M], (10 - R ) ml of water, 5 ml of concd HC1, R ml of chloroform, and (10 - R ) ml of P-2-NHA [1.0 X 10-4M] solutions were taken. The violet complex formed was extracted into chloroform and absorbance was measured. Molar Ratio. In the 100-ml separatory funnel, 10 ml of vanadate
T h e absorption spectra of t h e reagent and of vanadium complex in chloroform are shown in Figure 1. It can be seen that t h e reagent has no absorbance at t h e wavelength of maximum absorbance (545 nm) of its vanadium complex. T h e characteristic absorption and distribution ratio data are given in Tables I and 11, respectively. Effect of Acidity, Time, and Temperature. Maximum color intensity was obtained with 3 t o 8M HC1 ( p H u p t o 1.2) but, as t h e concentration of acid decreases, t h e intensit y also decreases ( p H 1.2 and above). T h e color is stable up t o 6 days and is not affected by temperature. T h e effect of p H is shown in Figure 2. T h e optimum p H is 1.0 at the absorbance 545 nm. Beer's Law. T h e system obeys Beer's law over t h e range 0.3 t o 9.0 pg per ml vanadium at 545 nm. T h e sensitivity of t h e reagent as defined by Sandell (23) is 0.008 wg V/cm2 using a 10-mm cell a n d t h e molar absorptivity worked out t o be 7.1 X lo3 a t t h e 545 nm. Stoichiometry of the Complex. T h e ratio of vanadium(V) t o P-2-NHA in extracted species was determined by t h e modified method of Job's continuous variation ( 2 4 ) . It indicates t h a t t h e complex consists of 2 molecules of P2-NHA for each atom of vanadium. T h e J o b curves show maxima a t a molecular ratio 1 : 2 of metal : ligand. However, t h e molar ratio method (Figure 3) shows no such sharp break but a rather gradual sloping off t o become parallel to t h e molar ratio axis at a higher ratio. Results obtained by extrapolation show t h e molecular ratio 2 : 1 : : ligand : vanadate. Effect of Diverse Ions. T h e recommended procedure was followed t o study t h e interference due to various diverse ions in t h e direct spectrophotometric determination of vanadium(V) with P-2-NHA. Seventy-five pg of vanadiu m in 25 ml of aqueous solution was determined in t h e presence of t h e following ions: Ba2+(25 mg), Ca2+(25 mg), Cd2+(25 mg), Co2+(25 mg), Cu2+(30 mg), Hg2+(30 mg), ANALYTICAL CHEMISTRY, VOL. 47, NO. 6, MAY 1975
941
Table IV. Analysis of NBS and BCS Standard Samples NO.
Sample
Manganese steel (NBS) Ferrotitanium (NBS) Steel (NBS) Cr-V steel (BCS) High speed (BCS) a Average of 4 determinations. 67 117 132 224 241/1
2.0
6.0
4.0
8.0
1
MOLES LIGAND PER MOLE VANADIUM
Figure 3. Mole ratio method
Table 111. Analytical Data on Extraction of Vanadium(V) Std dev
Vanadium(V),
(6 deter-
u g / 2 5 m l of
Vanadium(V)
chloroform
found, u g
Error
minations)
5.01 9.99 20.00 50.00 99.98 200.03
io.01 -0.01 0.00
io,01
5
10 20 50 100 2 00
New
method0
0.17-0.19 0.05-0.08 1.60-1.68 0.240 1.570
0.186 0.062 1.695 0.241 1.568
Table IV show that vanadium can be determined precisely and accurately.
021
0 0
Standard value vanadium
0.00 -0.02 +0.03
10.02 10.02 10.01 10.01 10.03
Mn2+(30 mg), Zn2+(25 mg), Pb2+(30 mg), Ni2+(25 mg), M004~-(10 mg), u0z2-(25 mg), wo42-(15 mg), Ti3+(25 mg), A13+(30 mg), Ti4+(15 mg), Zr4+(30 mg), and 0s6+(60 mg). T h e complexing ions such as citrate, tartrate, phosphate, and fluoride had no effect on extraction and determination of vanadium. T h e analytical data on extraction of vanadium(V) in the presence of all the above diverse ions are given in Table 111. Determination of Vanadium in Steel. T o test the reliability of the method, 5 samples from the U S . National Bureau of Standards and the Bureau of Analyzed Samples Ltd. were analyzed for vanadium. The results presented in
ACKNOWLEDGMENT T h e author expresses his deep sense of gratitude to A. B. Biswas, Department of Chemistry, Indian Institute of Technology, Powai, Bombay 400 076 for his sustained interest in the execution of this work and his invaluable criticism.
LITERATURE CITED (1)G. A. Brydon and D. E. Ryan, Anal. Chim. Acta, 35, 190 (1966). (2) U. Priyadarshini and S. G. Tandon, Chem. hd. (London), 931 (1960). (3)D. E. Ryan, Analyst(London), 85,569 (1960). (4)U. Priyadarshini and S. G. Tandon, Anal. Chem., 33, 435 (1961). (5) U. Priyadarshini and S. G. Tandon, Analyst, (London). 88, 379 (1961). (6)D. C. Bhura and S. G. Tandon, Anal. Chim. Acta, 53, 379 (1971). (7)D. C. Bhura and S. G. Tandon, lndian J. Chem., 8, 1036 (1970). (8)J. P. Shukla and S. G. Tandon, J. lndian Chem. SOC.,49,83 (1972). (9)R. M. Cassidy and D. E. Ryan, Can. J. Chem., 46,327 (1967). (10)V. C. Bass and J. H. Yoe, Anal. Chlm. Acta, 35, 337 (1967). (11) A. K. Majumdar and G. Das, J. indlan Chem. SOC.,42, 189 (1965). (12)W. M. Wise and W. W. Brandt, Anal. Chem., 27, 1392 (1955). (13)S.G. Tandon, and S.C. Bhattacharyya, Anal. Chem.. 33, 1267 (1961). (14)A. S.Bhaduri and P. Ray, Z.Anal. Chem., 151, 109 (1956). (15)A. K. Majumdar and G. Das, Anal. Chlm. Acta, 31, 147 (1964). (16)R. L. Dutta, J. lndian Chem. SOC.,35,243 (1958). (17)U. Priyadarshini and S.G. Tandon, J. lndian Chem. Soc., in press. (18)V. K. Gupta and S.G. Tandon, J. lndian Chem. Soc., in press. (19)Y. K. Agrawal, Anal. Lett., 5, 863 (1972). (20) R. L. Dutta, J. lndian Chem. Soc., 36,285 (1959). (21)Y. K. Agrawal and S. G. Tandon, J. Chem. Eng. Data, 16,495 (1971). (22)W. F. Hillebrand, G. E. F. Lundel. H. A. Bright, and J. I. Hoffman, "Applied Inorganic Analysis," 2nd ed., Wiley, New York, N.Y.. 1953. (23)E. B. Sandell. "Colorimetric Determination of Traces of Metals", 3rd ed.. Interscience, New York, N.Y., 1959. (24)W. C. Vosburgh and G. R. Cooper, J. Am. Chem. Soc., 63,437 (1941).
RECEIVEDfor review October 11, 1974. Accepted January 21, 1975. A Senior Fellowship was awarded by C.S.I.R., New Delhi.
Determination of Carbon Disulfide in Industrial Atmospheres by an Extraction-Atomic Absorption Method B. M. Kneebone and Henry Freiser Chemistry Department, University of Arizona, Tucson, AZ 8572 1
T h e accurate measurement of ambient carbon disulfide vapor concentrations in industrial atmospheres, such as those in viscose fiber plants, is necessary to protect the health of workers, as required in the Occupational Safety and Health Act of 1970, Public Law 91-596. Among the deleterious effects of chronic CS2 intoxication are vitamin B6 deficiency, depletion of levels of essential trace metals such as Cu and Zn, and intensification of the development of atherosclerosis ( I , 2). 942
ANALYTICAL CHEMISTRY, VOL. 47, NO. 6, MAY 1975
T h e current methodology includes gas-liquid chromatography of samples collected on charcoal and desorbed with toluene or benzene ( 3 ) or the classical spectrophotometric determination of copper diethyldithiocarbamate formed by the absorption of CS2 in scrubbers containing diethylamine, triethanolamine and cupric acetate (4-7). Truhaut et al. (8) used diethanolamine as described by Cullen (9) and designed a portable apparatus to be worn by workers which collects CS2 vapors on activated charcoal.
