This application note describes a method based on high-performance liquid chromatography (HPLC) coupled to inductively-coupled plasma mass spectrometry (ICP-MS) for the separation and determination of methyl and ethyl mercury. Because the different chemical forms of mercury exhibit different toxicities, separating elemental mercury from the alkylated forms provides vital information on the actual risk posed by a sample. The HPLC-ICP-MS method is applied to the analysis of water and soil samples. The method detection limits in water for MeHg, EtHg, and Hg2+ are better than 10 ng/L, and recoveries between 80% and 120% were obtained for the Hg species extracted from the soil samples.
This document presents an application note detailing a method for the simultaneous determination of inorganic and organic mercury species, specifically methylmercury (MeHg) and ethylmercury (EtHg), in environmental samples. The method combines high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) to separate and quantify these toxic compounds.
The study utilizes an Agilent 1100 HPLC system interfaced with an Agilent 7500a ICP-MS. Key operating parameters, including column specifications (ZORBAX Eclipse XDB-C18), mobile phase composition, and ICP-MS settings (RF power, nebulizer flow), are provided. The method achieves detection limits better than 10 ng/L in water and demonstrates recoveries between 80% and 120% for soil samples. The note also discusses the use of compound-independent calibration and the method's suitability for high-matrix samples like seawater.
| Column | ZORBAX Eclipse XDB-C18, 2.1-mm id x 50 mm, 5 um |
|---|---|
| Mobile Phase | 0.06-mol/L ammonium acetate, 5% v/v methanol, 0.1% 2-mercaptoethanol, pH = 6.8 |
| Flow rate | 0.4 mL/min |
| RF power | 1550 W |
| Nebulizer | PFA concentric 100 L/min |
| Spray chamber | Quartz, Scott double pass, chilled to-6 C |
The method uses an Agilent 1100 HPLC interfaced to an Agilent 7500a ICP-MS.
The Provisional Tolerable Weekly Intake (PTWI) for methyl mercury is 1.6 micrograms per kilogram of body weight per week.
The HPLC flow rate is set to 0.4 mL/min.