Method development for the selective determination of some organometallic compounds by headspace single drop micro extraction and graphite furnace atomic absorption spectrometry

In this study, headspace single drop microextraction (HS-SDME) method in combination with electro thermal atomic absorption spectrometry (ETAAS) with Zeeman-effect background correction method was developed and validated for separate determinations of methylmercury (MeHg) and tributyltin (TBT) in tap water, bottled water, waste water and mussel tissue samples. Besides organometallic forms in the presence of inorganic mercury and tin selectivity of the method was performed as well.Methylmercury or tributyltin species were converted to their hydrides in the presence of NaBH4 and trapped onto 3-4 µL drop of trapping agent in the tip of a microsyringe. Thiourea and APDC for MeHg and hexadecane and APDC for TBT were selected as the acceptor phases. When the equilibrium was reached between the hydrides in the headspace and microdrop suspended above the 5-10 mL solution the drop was retracted back into the syringe and injected manually into graphite furnace for the determination. The analytical parameters of the method such as microextraction time, sampling temperature, NaBH4 concentration, trapping agent concentration, pH of the medium, possible interference effects have been investigated. Regarding the method validation analytical figures of merits such as; precision in terms of inter-batch and intra-batch repeatability, limit of detection (LOD) and limit of quantitation (LOQ), linearity and interference effects have been evaluated. Accuracy of the method has been verified by analyzing certified reference materials (CRM) and spiked samples.The precision of the method was adequate enough for analytical purposes and relative standard deviations for the recovery studies are lower than 10%. Methylmercury and tributyltin have been determined in the samples with a relative error less than 10 %.