Cloud point extraction of lead in saliva via use of nonionic PONPE 7.5 without added chelating agents

A new micelle-mediated phase separation of metal ions to preconcentrate tra ce levels of lead as a prior step to its determination by flame atomic spec troscopy has been developed. The methodology is based on the cloud point ex traction of lead with PONPE 7.5 in the absence of chelating agent. The chem ical variables affecting the sensitivity of the extractive-spectrometric pr ocedure were evaluated in detail, optimised and successfully applied to the determination of lead in saliva samples. Under the optimal conditions, a % E higher than 99.9 was achieved. The proposed method showed linear calibrat ion within the range: 0.6-4 mu g ml(-1) Pb(II). The sensitivity was 0.053 m u g ml(-1). The method has been applied to the determination of lead in hum an saliva. The nature of the extracting species as well as the location of lead in the micelle were studied. The analytical performance of the propose d method clearly satisfies the typical requirements for control processes. (C) 2000 Elsevier Science B.V. All rights reserved.