title: Microchip capillary electrophoresis with a boron-doped diamond electrochemical detector for analysis of aromatic amines.
abstract: The attractive features of a boron-doped diamond (BDD) thin-film detector for microchip capillary electrophoretic (CE) separations of dye-related amino-substituted aromatic compounds are described. The diamond electrode was employed in the end-column amperometric detection of 4-aminophenol (4-AP), 1,2-phenylenediamine (1,2-PDA), 2-aminonaphthalene (2-AN), 2-chloroaniline (2-CA), and o-aminobenzoic acid (o-ABA), and its attractive behavior was compared to commonly used screen-printed carbon and glassy-carbon electrodes. These conventional electrode materials exhibit a significant degree of passivation and low sensitivity to the above-mentioned environmental pollutants. The diamond-based electrochemical detection system displayed a favorable analytical performance, including lower noise levels, higher peak resolution with enhanced sensitivity, and improved resistance against electrode passivation. Factors influencing the on-chip analysis were assessed and optimized. The diamond detector displayed detection limits of 2.0 and 1.3 microM for 4-AP and 2-AN, respectively, and a wide linear response for these compounds over the 2-50 microM range. The enhanced stability was demonstrated by relative standard deviation (RSD) values of 1.4% and 4.7% for 100 microM 1,2-PDA and 200 microM 2-CA, respectively, for repetitive detections (n = 7). Besides, the simultaneously observed current decrease was 2.4 and 9.1% for 1,2-PDA and 2-CA, respectively (compared to 21.8 and 41.0% at the screen-printed carbon electrode and 28.3 and 34.1% at the glassy carbon electrode, respectively). The favorable properties of the diamond electrode indicate great promise for environmental applications in CE and other microchip devices.
authors.affiliation: Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan.
authors.forename: Dongchan
authors.initials: D
authors.lastname: Shin
authors.forename: Donald A
authors.initials: DA
authors.lastname: Tryk
authors.forename: Akira
authors.initials: A
authors.lastname: Fujishima
authors.forename: Alexander
authors.initials: A
authors.lastname: Muck
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Joseph
authors.initials: J
authors.lastname: Wang
mesh_terms: D000588:Amines / Q000737:chemistry / Q000302:isolation & purification*; D001895:Boron; D018130:Diamond; D004563:Electrochemistry / Q000379:methods; D046209:Electrophoresis, Microchip / Q000295:instrumentation / Q000379:methods*; D006841:Hydrocarbons, Aromatic / Q000737:chemistry / Q000302:isolation & purification*; D012680:Sensitivity and Specificity
chemical_list: D000588:Amines; D006841:Hydrocarbons, Aromatic; D018130:Diamond; D001895:Boron