Multiresidue Analysis of Pesticides in Environmental Waters by Capillary Electrophoresis Using Simultaneous UV and Electrochemical Detection

Abstract

A rapid multiresidue method has been developed for the analysis of eight pesticides (triazines, triazinones and ureas) in environmental waters. A simple end-column electrochemical detector was used in combination with an available commercial capillary electrophoresis instrument with UV detection. The determination of these pesticides using micellar electrokinetic capillary chromatography (MEKC) with dual electrochemical and UV detection is the first time reported. In both detection systems, a linear range was obtained for the eight pesticides, concentrations lower than 5.0 Â 10 À5 mol L À1, in 0.020 mol L À1 boric acid at pH 8.3 and containing 0.025 mol L À1 of sodium dodecylsulfate, to obtain selectivity in the additional separation by micellar distribution process. Under these conditions a lower detection limit than 2.0 Â 10 À6 mol L À1 (0.15 pmol of pesticide) was achieved for the most of them. The eight pesticides are resolved in less than 14 min.

Automated determination of asulam by enhanced chemiluminescence using luminol/peroxidase system

“…Enhancement of the base reaction by means of asulam is a novel method for a procedure for the determination of asulam by an automated method using standard instrumentation. [28] Tap water 10 μg/mL 86 6.50 MECK-UV detection [29] Tap water 10 μg/mL 88 5.80 MECK-electrochemical detection [24] Tap water 0.04 ng 90-118 1.13 HPLC with derivatization [25] Natural water 10.9 μg/mL 98 <5.3 CE-UV detection [27] Natural water 0.9 μg/mL 99 <6.5 CE-electrochemical detection [27] Water Samples 40 μg/mL -4.1 Photochemiluminometric [22] Water Samples 5 μg/mL -1 FIA-fluorescence [21] Soil 1 mg/mL --TLC [26] Peaches 0.043 μg/mL 85-106 1.6 Synchronous fluorescence with derivatization [23] …”

“…Asulam has been determined in several matrices by fluorescence [20] and photo-CL [21] determination using flow injections systems, derivatization methods, [22] UV and electrochemical detection, [23] HPLCfluorescence, [24] thin-layer chromatography [25] and electrophoretic detection. [26] In a previous paper [27] a stopped flow chemiluminescence determination of asulam, based on its inhibition action over the system luminol-H 2 O 2 -HRP in the first instants of the reaction, has been proposed. The aim of this work was to develop a simple and fast procedure for determining asulam in freshwater, which involves an enhanced effect in the CL signal of the HRP reaction.…”

Ionic liquid based microextraction combined with derivatization for efficient enrichment/determination of asulam and sulfide

“…Compared with the presented asulam determination method, the methods in Table 5 show some disadvantages in the limit of detection, 1,4,5,7,8,12,37 linear dynamic range [3][4][5]10 , and the range of the sample analyzed. [1][2][3][4][5][6][7][8][9][10]12,37 Moreover, the analytical characteristics of the presented sulfide determination method were compared with the others as shown in Table 6. Compared with the presented sulfide enrichment/determination method, the others show some limitations in the limit of detection, 19,20,38−44 linear dynamic range, 20,42 and the range of the sample analyzed.…”

Fluorescence Determination of the Pesticide Asulam by Flow Injection Analysis

“…[13][14][15][16] Capillary electrophoresis has been applied to Asulam determination by simultaneous spectrophotometric and electrochemical detection. 17,18 Other authors have investigated isotachophoresis along with conductimetric or UV-vis detection 19 or micellar electrokinetic capillary chromatography. 20 For complex matrices, combinations of these methods have been employed: one of them for the sample pretreatment; preparative capillary isotachophoresis for humic matrices 21 and HPLC; or, sample pretreatment for soil samples followed by capillary electrophoresis.…”