Anal. Chem. 1987, 59, 899-903
optical background noises since the signal is a coherent laser beam. In addition, the phase-conjugation property of DFWM could be used effectively in analytical studies of samples when a probe beam needs to propagate through a beam distorting medium or material or for remote diagnostic studies where the probe (and thus the signal) beam is required to travel long distances, especially through fiber-optic cables. Furthermore, sensitivity of DFWM can be improved significantly since it is feasible to generate a conjugate wave that is stronger than the incident probe wave (Le., amplification, with reflectivity greater than unity) (29). DFWM provides not only high spectral resolution but also high spatial resolution since the nonlinear interaction zone (the diameter of the laser beam) can be minimized. Based on the unique properties and potential applications of resonant DFWM, this novel laser spectroscopic technique is expected to become a valuable analytical spectroscopic tool.
899
Tan-no, N.; Kawauchi, K.; Yokoto, K. J . Opt. SOC. Am. B: Opt. Phys. 1986, 3 , 60-64. Vanherzeele, H.; Van Eck, J. L. Appi. Opt. 1981, 20,524-525. Nilsen, J.; Yariv, A. Appl. Opt. 1979, 18. 143-145. Liao, P. F.; Bloom, D. M.; Economou, N. P. Appl. Phys. Lett. 1978, 32. - - , 813-815. - .- - . -. (13) Lam, J. F. Opt. Eng. 1982, 21,219-223. (14) Fu, T.-Y.; Sargent, M., I11 Opt. Lett. 1960, 5 , 433-435. (15) Liao, P. F.; Economou, N. P.; Freeman, R. R. Phys. Rev. Lett. 1977,
39. 1473-1476. (16) Steel, D. G.; Lind, R. C.; Lam, J. F. Phys. Rev. A 1981, 23, 2513-2524. (17) Haueisen, D. C. Opt. Commun. 1979, 28, 183-185. (18) Hoffman, H. J.; Perkins, P. E. I€€€ J. Quantum Electron. 1986, QE22, 563-568. .. 1986, (19) Diels, J. C.; McMichael, I. C. J. Opt. SOC.Am. 6 : 0 . ~ tPhys. 3 , 535-543. Betin, A. A.; Zhukov, E. A.; Mitropol'skii, 0.V. Sov. J . Quantum Electron. (Engl. Trans/.) 1985, 15, 1248-1251. Wu, C.; Li, X.; Wang, 2. Chin. Phys. 1985, 5 , 990-993. Pender, J.; Hesselink, L. Opt. Lett. 1965, IO, 264-266. Ewart, P.; O'Leary, S.V. Opt. Lett. 1986, 1 7 , 279-281. Ramsey, J. M.; Whitten, W. B. Anal. Chem. 1987, 59, 167-171. i25;, Tona. ". W. G.: Yeuna. E. S. Talanta 1984. 37. 659-665. (26) Abrams, R. L.; LaG,'J. F.; Lind, R. C.; Steel,'D. G.; Liao, P. F. Optical Phase Conjugation; Fisher, R. A.; Ed.; Academic: New York, 1983; pp 211-284. (27) Sobolev, N. N. Spectrochim. Acta 1956, 11, 310-317. (28) Tong, W. G.; Yeung, E. S.Anal. Chem. 1985, 57,70-73. (29) Yariv, A.; Pepper, D. M. Opt. Lett. 1977, 1 , 16-18. (30) Tong. W. G.; Chen, D. A. Appl. Spectrosc., in press. I
LITERATURE C I T E D (1) Optical Phase Conjugation; Fisher, R. A,, Ed.; Academic: New York.
1983. (2) Hellwarth, R . W. J. Opt. SOC. Am. 1977, 67, 1-3. (3) Bloom, D.M.; Bjorklund, G. C. Appl. Phys. Lett. 1977, 31,592-594. (4) Giuliano, C. R. Phys. Today 1981, 34 (April), 27-35. (5) Yariv, A,; Fekete, D.; Pepper, D. M. Opt. Lett. 1979, 4 ,52-54. (6) Martin, G.; Lam, L. K.; Hellwarth, R. W. Opt. Lett. 1980, 5 , 185-187. (7) Levenson, M. D.; Johnson, K. M.; Hanchett, V. C.; Chaing, K. J. Opt. SOC.Am. 1981. 71,737-743. (8) White, J. 0.; Yariv, A. Appl. Phys. Left. 1980, 37, 5-7.
RECEIVED for review August 18, 1986. Accepted December 1, 1986.
Flow Injection Spectrophotometric Determination of Aluminum in Natural Water Using Eriochrome Cyanine R and Cationic Surfactants Oddvar Roryset Norwegian Forest Research Institute, P.O. Box 61, N-1432 AS-NLH, Norway
A flow InJectlonanalysis spectrophotometrlc method for determination of aluminum In water uslng erlochrome cyanine R and cetyltrlmethylammonlum bromide (ECRXTA) Is described. The measurements are performed at a pH of 7.5, and the Interference from phosphate and fluoride Is greatly reduced compared to the Interference at a pH of 6.0. Dlssolved organk carbon up to 20 mg L-' C can be tolerated. Of 40 elements tested, only Iron, berylllum, lanthanum, and cerlum cause strong Interference. The effect of Iron can be masked (24 mg L-' C), while the other aliphatic carboxylic acids, oxalic, maleic, lactic, and pyruvic acid, do not. For oxalic acid, citrate, and the fulvic and humic acids, the interference is lower at pH 7.5 than at pH 6.1; for citrate and oxalic acid the tolerable concentration increases by more than 1 order of magnitude. The general trend in the results presented in Table I1 is that organic compounds with a majority of carboxylic acid functional groups cause lower interference at pH 7.5 than at pH 6, presumably due to the fact that the stability of carboxylic acid aluminum complexes decreases (same pattern as for fluorides and phosphates). The phenolic compounds on the other hand (benzene-1,2,3-triol and 8-hydroxyquinoline) dissociate more when the pH increases, which in turn facilitates formation of more stable aluminum-organic complexes.
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ANALYTICAL CHEMISTRY, VOL. 59, NO. 6, MARCH 15, 1987
Table 11. Interference from Organic Compounds in the FIA-ECR/CTA Method for Determination of Aluminum at pH 6.1 and pH 7.5"
interfering compound
tolerable concnb pH 7.5 mM[ DH 6.1 mM (mg L-' C) 0
benzene-1,2,4,5-tetracarboxylicacid benzene-1,2,4-tricarboxylic acid benzene-1,3,5-tricarboxylic acid benzene-l,2-dicarboxylicacid
8 (960) 10 (1080)* 10 (1080)* 10 (960)*
benzene-2-hydroxycarboxylic acid benzene-3-hydroxycarboxylic acid benzene-4-hydroxycarboxylic acid benzene-2,3-dihydroxycarboxylicacid 8-hydroxyquinoline benzene-1,2,3-triol citric acid EDTA
5 (420) 10 (840)* 10 (840)* 0.4 (32) 0.04 (4) 0.06 (4)
NTA
oxalic acid tartaric acid maleic acid lactic acid
puruvic acid fulvic acid humic acid
I
10* 10* 5 10* 10*
" 20 40 60 Dissolved organic carbon
0.4 10* 10*
10' -
(20)
-
(10)
I 80 mg
c
a
-
-I
Figure 7. Calibration graphs for the FIA-ECRICTA method (pH 7.5) for determination of aluminum: (A) 200-pL injection loop, concentrations given in pg L-': (B) 10-pL injection loop, concentrations given in mg L-'.
0.005 0.005 0.005 0.08
LT
-
I
0.4 0.06 1.0
0
m 9
0
"The interference was tested with a sample containing 1.0 mg L-' A1 by adding increasing amounts of interfering compound, up to 10 mM. bTolerableconcentration (
