A new scheme for trace determination of chromium using electrothermal atomization-laser induced fluorescence spectrometry

The determination of chromium (Cr) in water, gastrointestinal perfusates an d serum samples by laser induced fluorescence in an electrothermal atomizer (ETA-LIF) has been investigated. Laser radiation used to excite Cr at 236. 471 nm is generated by frequency doubling the output of a tunable dye laser . Fluorescence emissions are observed at 302.2 nm or 357.9 nm. Due to the l ow transition probability of the Cr excitation transition, excitation is pe rformed using laser pulse energies of approximately 100 muJ per pulse. Atom ization is performed in a commercial graphite furnace using pyrolytically c oated graphite tubes without L'vov platforms. The optimized temperatures fo r ashing and atomization have been found to be 1300 degreesC and 2500 degre esC, respectively. The limit of detection for Cr in water by the ETA-LIF te chnique is 80 fg, which corresponds to 4 pg mL(-1) in 20 muL sample volumes . The analytical approach has been utilized for the determination of Cr in biological fluids. Prior to analysis, gastrointestinal perfusate solutions and serum samples were diluted 1 + 1 and 1 + 49, respectively, using 18 M O mega deionized water. The analysis of these samples has been evaluated usin g two different matrix modifiers [25 mug per 10 muL Mg(NO3)(2) and 2% Trito nX- 100] and without a matrix modifier.