Voltammetric determination of 2-nitrobiphenyl and 4-nitrobiphenyl using a mercury meniscus modified silver solid amalgam electrode
Abstract
Direct current voltammetry (DCV), differential pulse voltammetry (DPV), and differential pulse adsorptive stripping voltammetry (DPAdSV) at a mercury meniscus modified silver solid amalgam electrode (m AgSAE) were used for the determination of trace amounts of carcinogenic 2-nitrobiphenyl (2 NBP) and 4-nitrobiphenyl (4 NBP) in buffered aqueous-methanolic solutions (for 2 NBP: 0.01 mol L-1 LiOH (pH 12.0) - methanol (9:1), for 4 NBP: 0.25 mol L-1 acetate buffer (AB) of pH 4.8 - methanol (7:3)). Both nitrobiphenyls (NBPs) can be determined by DCV and DPV in the concentration range 0.2 - 100 μmol L-1 (limit of quantification (LQ) of both NBPs for DCV is 0.2 μmol L-1, LQ of 2 NBP and 4 NBP for DPV is 0.1 and 0.2 μmol L-1, respectively).
An attempt to decrease the LQ using DPAdSV was not successful, probably due to some competitive adsorption. The optimal medium for the simultaneous determination of 2 NBP and 4 NBP by DPV at the m AgSAE was: 0.10 mol L-1 AB of pH 6.0 - methanol (7:3).
The dependences of the peak current on the concentration of individual NBPs in the mixture were linear in the 10-6 and 10-7 mol L-1 concentration ranges. The practical applicability of the newly developed methods was verified using model samples of drinking and river water.