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

Abstract

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.

Manganese accumulation in bone following chronic exposure in rats: Steady-state concentration and half-life in bone

“…Environmental exposure to this toxic metal has also been linked to the consumption of Mn-containing pesticides and contamination in drinking water and food (Bouchard et al, 2011). Addition of Mn to gasoline as the anti-knocking reagent, methylcyclopentadienyl Mn tricarbonyl (MMT) further raises concerns about health risks associated with a potential increase in environmental levels of Mn (Butcher et al, 1999; Sierra et al, 1995). Recently, increasing numbers of cases of Mn-induced Parkinsonism have been observed among drug addicts using ephedrone (Sikk et al, 2011).…”

Customized compact neutron activation analysis system to quantify manganese (Mn) in bonein vivo

“…Workers in those industries are at high risk of elevated Mn exposure, including Mn miners who are continuously engaged in Mn production and processing. In addition, the general population can be exposed to this toxic metal by environmental routes, such as Mn-containing pesticides, contaminated water and food (Bouchard et al 2011), and organic Mn compounds in gasoline (Butcher et al 1999). Moreover, there have been reports on excessive Mn intake among ephedron drug abusers (Yildirim et al 2009), as well as in patients who are injected with Mn-based contrast probes for magnetic resonance imaging (MRI) screening (Zhen and Xie 2012).…”

A compact DD neutron generator–based NAA system to quantify manganese (Mn) in bonein vivo

“…Environmental exposure to Mn has been reported in the uses of Mn-containing products (e.g. Mn-based pesticides), contamination in drinking water and food (Bouchard et al, 2011), and the use of Mn compounds in gasoline (Butcher et al, 1999). There are also reports of excessive Mn exposure among ephedron drug abusers (Yildirim et al, 2009).…”