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Methylcyclopentadienyl manganese tricarbonyl (MMT) is a fuel additive that has been marketed for use in unleaded gasoline since December 1995. The widespread use of this additive has been suggested to cause health risks, but limitations in data regarding its degradation products and their toxicity prevent an accurate evaluation. To monitor the organomanganese compounds, it is clearly advantageous to employ low-cost, high-sensitivity, manganese-specific instrumentation to perform speciation. In this work, instrumentation fitting these criteria was obtained by the combination of high-performance liquid chromatography (HPLC) with diode laser atomic absorption spectrometry (DLAAS) and was used to determine MMT, its nonmethylated derivative, cyclopentadienyl manganese tricarbonyl (CMT), and inorganic manganese. DLAAS was shown to be a versatile analytical technique for total Mn determination, with a detection limit of 1 ng/ mL and a linear dynamic range (LDR) of almost 5 orders of magnitude. Analytical figures of merit for HPLC-DLAAS included a detection limit of 2 ng(as Mn)/mL, a LDR of 3 orders of magnitude, and an analysis time of three minutes. The organometallic compounds are characterized by rapid photolysis in sunlight, and hence, experiments were performed to evaluate whether normal laboratory lighting is suitable for their determination. Our results showed that normal laboratory protocols may be employed except that the organomanganese compounds should be stored away from light except during sample introduction procedures. The ability of the instrumentation to selectively preconcentrate organomanganese compounds while removing inorganic manganese was demonstrated. Sufficient resolution was obtained to determine a 20-fold excess of CMT compared with MMT. The ability of the system to do practical analysis was demonstrated by the accurate determination of MMT in spiked samples of gasoline, human urine, and tap water. These results demonstrate the suitability of HPLC-DLAAS for the speciation of MMT and its derivatives in industrial, toxicological, and environmental samples.

A simple, compact, and powerful instrument for metal speciation in the ppt range is described. The instrument includes a HPLC module for separation and a diode laser for element-selective detection by wavelength modulation absorption spectrometry in an analytical flame. The high detection power for metal species is due to a two-beam arrangement with logarithmic amplification of the normalized signal, which compensates the laser residual amplitude modulation noise, the offset, and its fluctuation. The analytical figures of merit are demonstrated by measurements of very low concentrations of Cr(VI) in tap water.

A quantitative metal-free high-performance liquid chromatographic/electrothermal atomic absorption spectrometric (HPLC/ETAAS) technique allowing an adequate separation of the proteins and of the inorganic/organic metal species of interest was developed. A silica-based scavenger was placed proximal to the injection valve retaining any remaining Al and Fe originating from buffer solutions and recipients. ETAAS instrumental conditions and matrix modifiers were carefully selected to eliminate interferences occurring due to the salt gradient elution. The postelution Al recovery (143-1428 micron g L to the -1; 100-micron L sample volume) was found to be 100.1 + or - 15.3% (N = 50) whereas that of Fe was 97.3 + or - 2.0% (N = 20; 442-2653 micron g L to the -1). The protein recovery varied between 95 and 105%. The HPLC/ETAAS intraassay CV (N = 3) was 8.0% for Al (eluted amount of Al bound to transferrin (Tf), 7.3 ng) whereas that of Fe was 1.4% (eluted amount of Fe bound to Tf, 124.8 ng). The intraassay CV of the HPLC Tf determination was 1.6%. The proposed method is sensitive and accurate, allowing for the first time quantitative evaluation of the competition between Al and Fe for protein binding at clinical relevant concentrations. The technique will also be used for studying the protein binding of elements other than Al and Fe.

A hydrogen fueled flexible microatomization interface capable of handling 100 percent aqueous high pressure liquid chromatography (HPLC) mobile phases is discussed. Flow injection and HPLC-atomic absorption spectroscopy modes were used to detect cadmium in mussels and animal tissues to optimize the system. The approach was found to provide a unique combination of advantages over alternate techniques in the determination of cadmium in aqueous samples.