CYANIDE ION MINISENSOR BASED ON METHEMOGLOBIN INCORPORATED IN METAL SUPPORTED SELF-ASSEMBLED BILAYER-LIPID MEMBRANES AND MODIFIED WITH PLATELET-ACTIVATING-FACTOR

The present paper reports the development of an electrochemical minise nsor for the detection of cyanide ions based on methemoglobin, which i s incorporated into self-assembled bilayer lipid membranes (s-BLMs) on a metal support. The presence of cyanide in solution was found to mod ulate the ion permeability of BLMs containing methemoglobin, when usin g a lipid composition containing egg phosphatidylcholine (egg PC) and semisynthetic platelet-activating factor (PAF; -O-alkyl-2-acetyl-sn-gl yceryl-3-phosphorylcholine, AGEPC). The cyanide ion sensor exhibited g ood mechanical stability and longevity (routinely over 48 h) and const ant sensitivity and response to a given concentration of cyanide ion i n solution. Incorporation of hemoglobin or methemoglobin into s-BLMs w as examined, and methemoglobin was found to provide lower (by five-fol d) detection limit for cyanide ion determination. The effects of prote in concentration and composition of BLMs on sensitivity of response we re examined. Selectivity studies of cyanide detection were done in the presence of oxygen, carbon monoxide and dioxide. and other anions. Th e present cyanide ion sensor based on thin lipid film technology provi des advantages of fast response times (in the order of 10 s) to altera tions of cyanide ion concentration, low detection limits (ca. 4.9 nM, 0.317 mu g l(-1)), and the capability of analyzing small volumes of sa mples. Furthermore, a device can now simply and reliably be fabricated at low cost, and therefore can be used as a disposable sensor. (C) 19 97 Elsevier Science B.V.