Mercury Determination at Ultra-trace Level in Eye Shadow by a New Electrothermal Vaporization System Coupled to ICP-MS

Solid sampling-electrothermal vaporization inductively coupled plasma mass spectrometry (SS-ETV-ICP-MS) was proposed for ultra-trace determination of Hg in eye shadow samples. The ETV system was optimized using a heating program, consisting of drying at 80 °C for 20 s and vaporization at 800 °C for 10 s, followed by cooling for 120 s, without a pyrolysis step. The carrier gas flow rate was set to 1.10 L min-1, and sample mass up to 4 mg was analyzed. An alternative external calibration strategy using a standard solution of Hg and magnesium silicate for matrix matching demonstrated good linearity (R2 0.9983) in the range of 5 to 100 pg of Hg. Magnesium silicate enhances analyte transport and acts as a modifier, enabling calibration with aqueous standard solutions and presenting an alternative to certified reference material (CRM). Despite the differences in signal profiles for Hg observed in the eye shadow samples, CRM MESS-3 (Marine Sediment), and the standard solution, the method has good accuracy when the signal was integrated using peak area. Compared to cold vapor inductively coupled plasma mass spectrometry, which needs acid digestion and a ten-fold dilution with a limit of quantification (LOQ) of 0.1 µg g-1 Hg, the SS-ETV-ICP-MS provided a significantly lower LOQ (0.001 µg g-1) and a simplified analytical approach for Hg determination. This approach presents a practical alternative for determining Hg in eye shadows at ultra-trace levels.