Abstract
This work describes the development and optimization of a sequential injection method to automate the determination of paraquat by square-wave voltammetry employing a hanging mercury drop electrode. Automation by sequential injection enhanced the sampling throughput, improving the sensitivity and precision of the measurements as a consequence of the highly reproducible and efficient conditions of mass transport of the analyte toward the electrode surface. For instance, 212 analyses can be made per hour if the sample/standard solution is prepared off-line and the sequential injection system is used just to inject the solution towards the flow cell. In-line sample conditioning reduces the sampling frequency to 44 h−1. Experiments were performed in 0.10 M NaCl, which was the carrier solution, using a frequency of 200 Hz, a pulse height of 25 mV, a potential step of 2 mV, and a flow rate of 100 µL s−1. For a concentration range between 0.010 and 0.25 mg L−1, the current (i p, µA) read at the potential corresponding to the peak maximum fitted the following linear equation with the paraquat concentration (mg L−1): i p = (−20.5 ± 0.3)C paraquat − (0.02 ± 0.03). The limits of detection and quantification were 2.0 and 7.0 µg L−1, respectively. The accuracy of the method was evaluated by recovery studies using spiked water samples that were also analyzed by molecular absorption spectrophotometry after reduction of paraquat with sodium dithionite in an alkaline medium. No evidence of statistically significant differences between the two methods was observed at the 95% confidence level.
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References
Bismut C, Hall AH (1995) Paraquat poisoning, prevention, treatment. Dekker, New York
Syngenta Crop Protection (2009) Paraquat information center. http://www.paraquat.com/. Accessed 30 Jun 2009
Ministério da Agricultura, Pecuária e Abastecimento (2009) Sistema de agrotóxicos fitossanitários. http://agrofit.agricultura.gov.br/agrofit_cons/principal_agrofit_cons. Accessed 30 Jun 2009
Office of Water, US Environmental Protection Agency (2006) Drinking Water Standards and Health Advisories, EPA 822-R-06-013. Office of Water, US Environmental Protection Agency, Washington
Schmitt GC, Paniz C, Grotto D, Valentini J, Schott KL, Juarez Pomblum V, Garcia SC (2006) J Bras Patol Med Lab 42:235–243
Serra A, Domingos F, Martins Prata M (2003) Acta Med Port 16:25–32
Guijarro EC, Sedeño PY, Diez LMP (1987) Anal Chim Acta 199:203–208
Infante CMC, Masini JC (2007) Spectrosc Lett 40:3–14
Infante CMC, Morales-Rubio A, de la Guardia M, Rocha PRP (2008) Talanta 75:1376–1381
Munch JW, Bashe WJ (1997) Determination of diquat and paraquat in drinking water by liquid-solid extraction and high performance liquid chromatography with ultraviolet detection, method 549.2, revision 1.0. US Environmental Protection Agency, Cincinnati
Snyder LR, Glajch JL, Kirkland JJ (1997) Practical HPLC method development, 2nd edn. Wiley, New York
Zen JM, Jeng SH, Chen HJ (1996) Anal Chem 68:498–502
De Oliveira UMF, Lichtig J, Masini JC (2004) J Braz Chem Soc 15:735–741
De Souza D, Machado SAS (2005) Anal Chim Acta 546:85–91
De Souza D, Machado SAS, Pires RC (2006) Talanta 69:1200–1207
Lopes IC, De Souza D, Machado SAS, Tanaka AA (2007) Anal Bioanal Chem 388:1907–1914
El Mhanunedi MA, Bakasse M, Chtaini A (2007) Electroanalysis 19:1727–1733
Felix FS, Maciel JM, Brett CMA, Angnes L (2006) Tecnol Santa Cruz do Sul 10:9–22
Simões FR, Vaz CMP, Brett CMA (2007) Anal Lett 40:1800–1810
Dos Santos LBO, Abate G, Masini JC (2004) Talanta 62:667–674
Dos Santos LBO, Masini JC (2008) Anal Chim Acta 606:209–216
Dos Santos LBO, Masini JC (2007) Talanta 72:1023–1029
Abate G, Lichtig J, Masini JC (2002) Talanta 58:433–443
Dos Santos LBO, Silva MSP, Masini JC (2005) Anal Chim Acta 258:21–27
Monk PMS, Turner C, Akhtar SP (1999) Electrochim Acta 44:4817–4826
Heyrovský M, Pospísil L (1998) J Electroanal Chem 255:291–296
Walcarius A, Lamberts L (1996) J Electroanal Chem 406:59–68
De Souza D, Machado SAS (2006) Electroanalysis 18:862–872
De Souza D, Machado SAS (2005) Anal Chim Acta 546:85–91
Zen J-M, Jeng S-H, Chen H-J (1996) Anal Chem 68:498–502
Bird CL, Kuhn AT (1981) Chem Soc Rev 10:49–82
El Mahmmed MA, Bakasse M, Bachirat R, Chtaini A (2008) Food Chem 110:1001–1006
Wang C-K, Chen S-M, Hsu J-F, Cheng S-G, Lee C-K (2008) J Chromatgr B 876:211–218
Empresa Brasileira de Pesquisa Agropecuária (2008) Controle de plantas invasoras em pastagens cultivadas nos cerrados. http://www.cnpgc.embrapa.br/publicacoes/doc/doc117/07herbicidas.html. Accessed 10 Dec 2008
Teófilo RF, Reis EF, Reis C, Da Silva GA, Kubota LT (2004) J Braz Chem Soc 15:865–871
López-Paz JL, Catulá-Icardo M, Antón-Garrido B (2009) Anal Bioanal Chem 394:1073–1079
Acknowledgements
The authors express their gratitude to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB), and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support and fellowships.
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dos Santos, L.B.O., Infante, C.M.C. & Masini, J.C. Development of a sequential injection–square wave voltammetry method for determination of paraquat in water samples employing the hanging mercury drop electrode. Anal Bioanal Chem 396, 1897–1903 (2010). https://doi.org/10.1007/s00216-009-3429-x
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DOI: https://doi.org/10.1007/s00216-009-3429-x