engleski

Determination of Penicillamine by Batch and Flow-injection Potentiometry with AgI-based sensor

Potentiometric determination of penicillamine (pen) is described based on batch experiment and flow-injection analysis (FIA) by using a chemical sensor with AgI-based membrane. The membrane was prepared by pressing silver salts (AgI, Ag2S) and powdered Teflon. This membrane was incorporated in the multipurpose electrode body for batch measurements, and in the tubular flow-through sensor body for FIA measurements. For batch measurements the equilibrium potential recorded with continuous addition of standard penicillamine solution were considered in relation to log c(pen). Linear response with 60 mV {p(pen)}-1 was obtained in the concentration range from 2.5×10-5 mol L-1 to 1.8×10-2 mol L-1. In using the tubular sensor with a membrane of the same composition for FIA measurements the linear response with 59 mV {p(pen)}-1 slope was recorded in the concentration range from 1×10-4 mol L-1 to 1×10-1 mol L-1. The response of the applied chemical sensor to penicillamine (designated as RHS) is explained by the formation of sparingly soluble RSAg in the reaction solution and/or on the exposed surface of the sensor. The solubility product Ksp(RSAg) was determined using experimental values recorded both with batch measurements and with the continuous-flow experiment. The mean value obtained with different measurements and using a membrane of the same composition is Ksp(RSAg)=1.4 ą0.1×10-20 mol2 L-2.

batch potentiometry; flow-injection analysis; membrane electrode; tubular sensors; penicillamine

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