Flow‐injection determination of carbaryl and carbofuran based on KMnO₄–Na₂SO₃ chemiluminescence detection

Abstract

A flow-injection method is described for the determination of carbaryl and carbofuran. It was found that a strong chemiluminescence (CL) signal was generated when these pesticides were mixed with Na(2)SO(3) and KMnO(4) in acidic medium. Under the optimum experimental conditions, the enhanced CL intensity was linear, with the concentrations in the range 0.1-2.0 microg/mL (r(2) = 0.9996 and 0.9993, n = 6) with relative standard deviation (n = 4) in the range 1.0-2.3%. The limits of detection (3sigma blank) were 10 and 50 ng/mL, respectively, with a sample throughput of 180/h. The proposed method was applied to determine carbaryl and carbofuran in freshwaters with satisfactory results. Most metal and non-metal ions and some pesticides, such as carbophenothion and aldicarb, do not interfere with the determination. Dinoseb, diazinon and malathion calibration graphs (in the range 0.2-2.0 microg/mL, r(2) = 0.9966-0.9988, n = 6) were also established with relative standard deviations (n = 4) in the range 1.2-2.0% with limits of detection (3sigma blank) in the range 100-300 ng/mL.

Analysis of Pesticides by Flow Injection Coupled with Chemiluminescent Detection: A Review

“…Although most of organophosphorus determinations were carried out using luminol reaction, in a few of them, as buminafos (López Malo 2008), diazinon and malathion (Waseem 2007b), CL was obtained by the direct oxidation with permanganate in acidic medium. In the first case, the method involved the on-line photo-degradation of the analyte (stopped flow, 5 s) and its subsequent chemiluminescent oxidation by the potassium permanganate.…”

“…In the first case, the method involved the on-line photo-degradation of the analyte (stopped flow, 5 s) and its subsequent chemiluminescent oxidation by the potassium permanganate. CL from diazinon and malathion (Waseem 2007b) was sensitized by sulfite. Finally, the tris(2,2´bipyridine)ruthenium(II) system was used by Adcock et al (Adcock 2004) for glyphosate determination.…”

“…In some cases the carbamate itself was directly oxidized, such was the case of carbaryl (Waseem 2007b) (Murillo Pulgarin 2006), carbofuran (Waseem 2007b) (Xie 2005) and tsumacide (Liu 2007a). In those cases, CL emission was sensitized by the use of substances such as rhodamine 6 G or sulfite.…”

“…Carbaryl can also inhibit that CL from luminol when Co (II) as catalyst, and hydrogen peroxide as oxidant are present. Taking advantage of it, a fast method (120 injections h -1 ) has been developed for its determination in water (Waseem 2007b). Apart from carbaryl and carbofuran, pirimicarb can also enhance CL from luminol, when it is present together with hydrogen peroxide and horseradish peroxidase (HRP).…”

“…The role of the inclusion complexes formed between β-cyclodextrin and certain organic molecules as enhancers of luminescence quantum yield is well known (Santana-Rodríguez 2006). Sulphite and quinine were the sensitizers of choice in the dinoseb (Waseem 2007b) (Sa 2007), chlorsulfuron (Mervartova 2005) and diphenamid (Czescik 2007). The PICL of this latter pesticide was predicted by applying molecular connectivity.…”