Thin‐Layer and Wall‐Jet Arrangement of Amperometric Detector with Boron‐Doped Diamond Electrode: Comparison of Amperometric Determination of Aminobiphenyls in HPLC‐ED

Abstract

The performance of a microcrystalline boron-doped diamond electrode in a thin-layer and wall-jet amperometric detection cell for HPLC was compared with the spectrophotometric detection. Comparison of peak parameters of 2-, 3-, and 4-aminobiphenyl after their separation revealed satisfactory repeatabilities of signal responses for all detection modes and regarding electrochemical detection higher current densities and higher noise for the thin-layer arrangement, and a slightly wider linear dynamic range of calibration dependencies and lower quantitation limits in the 10 À8 mol L À1 concentration range for the wall-jet arrangement. This detection mode was further employed for the determination of studied aminobiphenyls in model samples of the synthetic colorant tartrazine. Using solid phase extraction for the preliminary separation and preconcentration of the analytes the limit of quantitation was lowered to nanomolar concentrations.

Voltammetric and Amperometric Determination of Mixtures of Aminobiphenyls and Aminonaphthalenes Using Boron Doped Diamond Electrode

“…The detection potentials E det higher than +900 mV provided similar peak heights, nevertheless, destabilization of the baseline occurred at E det higher than +1000 mV, complicating the evaluation. Further, a slight increase of the peak‐to‐peak noise was observed at potentials higher than +1100 mV, in concordance with our previous study utillizing wall‐jet arrangement of amperometric detection cell with BDD as an indicator electrode 11. Therefore, detection potential +1000 mV was selected as optimum based on stable background current and satisfactory peak heights.…”

“…The easier oxidation of 4‐AB in comparison with the other two ABs was observed also in our previous voltammetric and amperometric studies at BDD electrodes 11, and in HPLC‐ED with platinum tubular detector in acidic media 26,41 and was ascribed to the easier accessibility of the tail‐placed amino group of 4‐AB for the initial oxidation reaction – the loss of one electron forming a radical cation at the nitrogen atom. 1‐AN and 2‐AN could not be incorporated in the mixtures, because the difference of the oxidation potential is low with respect to each other and all tested aminobiphenyls.…”

“…This work is connected with our previous ones, devoted to voltammetric and amperometric determination of aminobiphenyls 8,10,11,14 using nanocrystalline and microcrystalline anodically pretreated BDD and its objective is to study the possibilities of simultaneous detection of 2‐aminobiphenyl (2‐AB), 3‐aminobiphenyl (3‐AB), 4‐aminobiphenyl (4‐AB), 1‐aminonaphthalene (1‐AN), and 2‐aminonaphthalene (2‐AN) by means of BDD electrodes. For this purpose, batch voltammetry and amperometric detection coupled to HPLC were used and after optimization of separation and detection conditions the model samples of the food colorant dye sunset yellow (E‐110) were analyzed.…”

“…It should be mentioned at this point that between the particular HPLC measurements on‐line electrochemical activation had to be carried out due to passivation of the electrode surface. We had not any problems of that kind in our previous studies dealing with HPLC‐ED of aminobiphenyls 8,11 and our experimental tests revealed that the fouling is caused by aminonaphthalenes. For seven consecutive injections, a drop of about 23 % was observed for their peak heights.…”

“…Limits of determination reached values between 0.06 µmol L −1 for 2‐AN and 0.20 µmol L −1 for 2‐AB. Other amperometric methods offer similar quantitation and detection limit in the 10 −7 mol L −1 to 10 −8 mol L −1 concentration ranges: Amperometric detection of 2‐AB and 4‐AB with platinum tubular detector 26 or with BDD as an indicator electrode in thin‐layer 8 or wall‐jet arrangement 11 or detection of 1‐AN and 2‐AN at carbon paste electrode 42, platinum microcylindrical electrode 44, or thin‐layer arrangement using glassy carbon electrode and BDD for the determination of 1‐AN and 2‐AB 45.…”