Cost-effective flow cell for the determination of malachite green and leucomalachite green at a boron-doped diamond thin-film electrode.
An electrooxidation and a cost-effective flow-based analysis of malachite green (MG) and leucomalachite green (LMG) were investigated at a boron-doped diamond thin-film (BDD) electrode. Cyclic voltammetry as a function of the pH of the supporting electrolyte solution was studied. Comparison experiments were performed with a glassy carbon electrode. A well-defined cyclic voltammogram, providing the highest peak current, was obtained when using phosphate buffer at pH 2. The potential sweep-rate dependence of MG and LMG oxidation (peak currents for 1 mM MG and LMG linearly proportional to v 1/2, within the range of 0.01 to 0.3 V/s) indicates that the oxidation current is a diffusion-controlled process on the BDD surface. In addition, hydrodynamic voltammetry and amperometric detection using the BDD electrode combined with a flow injection analysis system was also studied. A homemade flow cell was used, and the results were compared with a commercial flow cell. A detection potential of 0.85 V was selected when using a commercial flow cell, at which MG and LMG exhibited the highest signal-to-background ratios. For the homemade flow cell, a detection potential of 1.1 V was chosen because MG and LMG exhibited a steady response. The flow analysis results showed linear concentration ranges of 1-100 microM and 4-80 microM for MG and LMG, respectively. The detection limit for both compounds was 50 nM.
Ngamukot
Passapol
P
Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok 10330, Thailand.
Charoenraks
Thiraporn
T
Chailapakul
Orawon
O
Motomizu
Shoji
S
Chuanuwatanakul
Suchada
S
D000814:Aniline Compounds / Q000032:analysis*; D001895:Boron / Q000737:chemistry*; D003365:Costs and Cost Analysis / Q000379:methods; D018130:Diamond / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012394:Rosaniline Dyes / Q000032:analysis*; D012680:Sensitivity and Specificity
D000814:Aniline Compounds; D012394:Rosaniline Dyes; C005095:malachite green; D018130:Diamond; C015320:leucomalachite green; D001895:Boron