A simple microfluidic electrochemical HPLC detector for quantifying Fenton reactivity from welding fumes

Abstract

Development and characterization of a simple microfluidic electrochemical flow cell that can be coupled with HPLC to enable dual absorbance/electrochemical detection is described. Coupling absorbance and electrochemical detection increases the information that can be gathered from a single injection, but a second (typically expensive) detection system is required. Here, an inexpensive, customizable microfluidic electrochemical detector is coupled in series with a commercial HPLC/UV system. The microfluidic device is made from poly(dimethylsiloxane) and contains carbon paste electrodes. To demonstrate the utility of this dual-detection system, the reaction products of the radical scavenging agent salicylic acid and hydroxyl radical generated by Fenton chemistry were analyzed. The dual-detection system was used to quantify 2,5-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, and catechol produced by the addition of H2O2 to filter samples of welding fumes. Measurement recovery was high, with percent recoveries between 97-102%, 92-103%, and 95-103% for 2,5-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, and catechol, respectively, for control samples. The methods described in this work are simple, reliable, and can inexpensively couple electrochemical detection to HPLC-UV systems.

A Concentric Ring Electrode for a Wall‐jet Cell in a Microfluidic Device

“…This standard curve exhibits a wide dynamic range of more than five orders of magnitude, although its slope changed at around 10 μmol/L. The detection limit (LOD) of catechol was determined to be 6.2 nmol/L (S/N=3), while the LODs of most of electrochemical detectors in a conventional flow‐injection system are on the sub‐μmol/L level . In addition, this LOD for catechol was comparable or superior to those of microfluidic analytical systems with electrochemical detection (Table S1) .…”

Separation of Nucleobases Using High‐performance Liquid Chromatography Coupled with Voltammetric Scanning

“…Similarly but for another purpose Pluangklang et al. used UV detector coupled to HPLC‐ED in order to increase selectivity and specificity of analysis .…”

“…To accomplish this task, the volume gap between UV and ED, resulting in a constant delay between retention times registered by both detectors is taken into account to control the starting of the electrochemical scan cycles on the ED. Similarly but for another purpose Pluangklang et al used UV detector coupled to HPLC-ED in order to increase selectivity and specificity of analysis [21].…”

An Original HPLC Method with Coulometric Detection to Monitor Hydroxyl Radical Generation via Fenton Chemistry

“…Some published papers describe assays for the detection of •OH formation via Fenton’s reaction [20,27] and •OH production evaluation through HPLC-ED determination of hydroxylated salicylic acid [27,29,30,31,32] or tyrosine [33]. The method that uses tyrosine derivatives was, however, not characterized in detail (method validation results are mostly missing; method details are insufficient to allow replication) [33].…”

“…Among the papers that determine hydroxylated salicylic acid derivatives, some of them only include 2,3-DHBA and 2,5-DHBA [30,31,32]. Among those that include catechol as well [27,29,33], just A. Puppo et al tested the •OH-scavenging effect of a narrow selection of compounds belonging to the class of flavonoids [33]; importantly, none of these papers included the study of Cu(I)-mediated Fenton’s reaction. Regarding the analytical technique, most published methods use amperometric detection, which is usually less selective and sensitive than coulometric detection [27,29,31,32,33].…”