Kinetic catalytic determination of trace Cu(II) in water samples with the thioglycolic/thiolactic acid–chromate reaction
- 77 Downloads
- 3 Citations
Abstract
The use of two novel similar indicator reactions as applied to the kinetic determination of Cu(II) in water is investigated. The methods rely on the catalytic effect of the analyte on the oxidation of thioglycolic (TGA) and thiolactic (TLA) acids by chromate in acidic media. The extent of the reactions was followed spectrophotometrically at 345 nm. Pseudo-first-order rate coefficients, kobsd, were determined as a function of catalyst concentration. Interference of Fe(III) and Pb(II) was suppressed by complexation with pyrophosphate. For the reaction of TGA, a linear regression for kobsd versus [Cu(II)] was obtained for the entire concentration range considered. Although the plot corresponding to TLA oxidation exhibits a sharp change of slope at approximately 1.8×10−5 M Cu(II), it can still be described effectively by two linear regressions with different slopes. The reaction of TGA is more sensitive than that of TLA at low Cu(II) concentration. The opposite is true for higher catalyst contents. The detection limits were 65 μgL−1 for TGA and of 80 μgL−1 for TLA oxidation, respectively. The relative standard deviations, of 0.4% for TGA and 1.1% for TLA oxidation, respectively, were obtained for five replicate runs at 1000 μg L−1. Samples of river and wastewater from the mining region of Baia-Mare, Northern Romania were analyzed using the more sensitive reaction of thioglycolic acid. Results were compared to those obtained by the officially standardized methods. Good agreement was obtained, even for an untreated sample. Measurements did not require prior separation of interfering species.
Keywords
Kinetic catalytic method Thiol oxidation Cu(II) determination Water analysis Slope techniqueNotes
Acknowledgements
This study was carried out with the financial support of the CNCSIS—Romania Ministery of Education, Grant No 33965/8.07.2003, code no. 37/31. We also gratefully thank Dr. Onorica Meteş from the Water Management Office—Baia-Mare, Maramureş County, Romania for her kind advice and for the AAS determinations.
References
- 1.Pérez-Bendito D (1998) In: Kellner R, Mermet JM, Otto M, Widmer HM (eds) Analytical chemistry. Wiley–VCH, Weinheim, Ch 6Google Scholar
- 2.Crouch SR (2004) In: Proc 8th Int Symp on Kinetics in Analytical Chemistry (KAC 2004), July 8–10, Rome, Italy, p 21Google Scholar
- 3.Rustoiu-Csavdari A (2000) PhD Thesis. Babeş-Bolyai University, Babeş-Bolyai, RomaniaGoogle Scholar
- 4.Rustoiu-Csavdari A, Bâldea I, Mihai D (2002) Mikrochim Acta 140:1–7Google Scholar
- 5.Rustoiu-Csavdari A, Bâldea S, Mihai D (2002) Anal Bioanal Chem 374:17–24Google Scholar
- 6.Wei J, Teshima N, Ohno S, Sakai T (2003) Anal Sci 19:731–735Google Scholar
- 7.Teshima N, Katsumata H, Kurihara M, Sakai T, Kawashima T (1999) Talanta 50:41–47Google Scholar
- 8.Prasad S, Halafihi T (2003) Mikrochim Acta 142:237–244Google Scholar
- 9.Katayama A, Ithoh K, Furukawa M, Kamidate T, Watanabe H (1992) Nippon Kagaku Kaishi 3:318–321; Chem Abstr (1992) 116:187113tGoogle Scholar
- 10.Kachur AV, Koch CJ, Biaglow JE (1999) Free Radical Res 31:23–34Google Scholar
- 11.Hanaki A, Kinoshita T, Ozawa T (2000) B Chem Soc Jpn 73:73–80Google Scholar
- 12.Bagiyan GA, Koroleva IK, Sorokova NV, Ufimtsev AV (2003) Russ Chem Bull 52:1135–1141Google Scholar
- 13.Bâldea I (1987) Studia Univ Babeş-Bolyai Chem 32:42–49Google Scholar
- 14.Bâldea I (1994) Studia Univ Babeş-Bolyai Chem 39:138–147Google Scholar
- 15.Bâldea I, Niac G (1986) Studia Univ Babeş-Bolyai Chem 31:41–48Google Scholar
- 16.Niac G, Schön S, Bâldea I (1986) Studia Univ Babeş-Bolyai Chem 31:31–40Google Scholar
- 17.Bâldea I, Niac G (1968) Inorg Chem 7:1232–1234Google Scholar
- 18.Bâldea I, Niac G (1970) Inorg Chem 9:110–114Google Scholar
- 19.Niac G (1996) Studia Univ Babeş-Bolyai Chem 41:3–8Google Scholar
- 20.Perez-Benito JF, Saiz N, Amat E (1998) J Mol Catal A-Chem 135:1–10Google Scholar
- 21.Přibil R (1982) Applied complexonometry. Pergamon Press, Oxford, Ch 3 and 6Google Scholar
- 22.Rustoiu-Csavdari A, Bâldea I (2000) Studia Univ Babeş-Bolyai Chem 45:107–117Google Scholar
- 23.Bâldea I (1989) Studia Univ Babeş-Bolyai Chem 39:80–88Google Scholar
- 24.Bridgart GJ, Fuller MW, Wilson IR (1973) J Chem Soc Dalton 1274–1280Google Scholar
- 25.Bridgart GJ, Fuller MW, Wilson IR (1973) J Chem Soc Dalton 1281–1285Google Scholar
- 26.Analytical Method Committee (1987) Analyst 112:199–204Google Scholar
- 27.Water Management Office (2000–2003) Annual reports. Water Management Office, Baia-Mare, Maramureş County, RomaniaGoogle Scholar