Laser-excited atomic fluorescence in a flame as a high-sensitivity detector for organomanganese and organotin compounds following separation by high-performance liquid chromatography

Abstract

The coupling of a high-performance liquid chromatograph with a sensitive and selective laser-excited atomic fluorescence spectrometry (LEAFS) detector is described. In connection with this, a study of the signal and noise characteristics of instrumentation for dispersive, nondispersive, and front surface LEAFS is reported together with a comparison of the sensitivity and selectivity achieved with high-performance liquid chromatography (HPLC)-flame LEAFS, HPLC-ultraviolet (UV), and HPLC-continuum source excited flame atomic fluorescence spectrometry (AFC) instrumentation. The HPLC-flame LEAFS instrumentation was applied to an investigation of the Mn species responsible for (methylcyclopentadienyl)manganese tricarbonyl (MMT) toxicity in rats. The detection limits for various organomanganese species by HPLC-flame LEAFS ranged from 8 to 22 pg of manganese. Recovery of these compounds from rat urine varied between 80% and 100%, with a reproducibility of between 4% and 8% relative standard deviation. Preliminary data for the HPLC-flame LEAFS determination of toxic alkyltin compounds are reported.

Speciation of Methylcyclopentadienyl Manganese Tricarbonyl by High-Performance Liquid Chromatography−Diode Laser Atomic Absorption Spectrometry

“…A modest increase in laser power is expected to cause a significant improvement in the signal-to-noise ratio and detection limit by reducing the shot noise . However, even with the less sensitive line and the limited laser power employed here, our detection power is sufficiently high to allow measurement of inorganic and organic manganese compounds at concentration levels present in environmental and toxicological studies 2 Comparison of Analytical Figures of Merit of DLAAS to Those of Other Techniques for Determination of Inorganic Manganese, CMT, and MMT figure of merit DLAAS a HCLAAS b, ICPOES c ,9 ICPMS d, Mn detection limit, ng/mL 1 3 0.3 0.0005 CMT/MMT detection limit, ng(as Mn)/mL 1 NR e NR e NR e linear dynamic range 4.7 3 5 8 a This work; DLAAS = diode laser atomic absorption spectrometry.…”

“…At the present time, most techniques for speciation involve relatively complicated, expensive instrumentation. For example, Walton et al determined MMT and related compounds by high-performance liquid chromatography (HPLC) with laser-excited atomic fluorescence spectrometry (LEAFS) detection using a flame as the atom cell and obtained a detection limit of 0.5 ng/mL (10 pg). This system used an expensive and unreliable excimer laser pumped dye laser system, which limits the practicality of the technique.…”

Determination of trace elements by chromatographic methods employing atomic plasma emission spectroscopic detection

“…However, sub-ng levels for Sn, Se and Pb have been achieved [28]. For HPLC interfacing a promising approach is in laser-excited atomic fluorescence in a flame (LEAFS) where quantitative results for oragnomanganese and organotin compounds was achieved at the sub-ppm level [29]. …”

Other Modes of Detection

“…For atomic emission, atomization tech niques include inductively coupled plasma, atomic fluoresence [202], DC plasma, radio-frequency-discharge helium plasma [203], microwave induced plasma, and flame emission. These atoms are excited and either the absorption (AAS) or the emission (AES) of light is monitored.…”