Diagnostic assay of chromium (VI) in the ex vivo fluid of the urine of a smoker using a fluorine‐doped handmade sensor

A voltammetric diagnosis of a chromium (VI) ion was investigated using a fluorine‐doped graphite pencil electrode. Square wave (SW) stripping working conditions were attained at a high range of 0.051–0.45 mg L −1 and a microrange of 0.05–0.4 µg L −1 in a 0.1 M NH 4 H 2 PO 4 electrolyte solution, at a relative standard deviation of 1.68% (RSD, n =15), using 10.0 µg L −1 Cr(VI). A fast experimental time was used only for the 120 sec SW accumulation time. An analytical detection‐limit (DL) of 0.008 µg L −1 was attained. DL appeared to be more sensitive than common voltammetric and spectrophotometric assays. The developed sensor was applied to tap water and the urine of a smoker. It was found that the methods can be applicable for in vivo fluid or medicinal diagnosis. J. Clin. Lab. Anal. 23:82–87, 2009. © 2009 Wiley‐Liss, Inc.