A minimal sample preparation for the determination of Ni and V in crude oil samples by LA-ICP-MS

Abstract

This work demonstrates the feasibility of using minimalist strategies for crude oil analysis using filter paper as a solid support for performing the analytical curves to determine Ni and V in such samples by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) using aqueous standards with a minimal sample preparation. Aliquots (4 µL) of the standards and samples were added directly to the surface of the filter paper and dried at 37 °C. Three calibration curves in the range 0.5–30 mg kg⁻¹ were evaluated using oil-based standards, aqueous standards and with or without ¹³C as an internal standard for both curves to normalize the Ni and V results. Better results were obtained with an aqueous curve without normalization. The accuracy of this method was checked against microwave system decomposition and determination by inductively coupled plasma mass spectrometry (ICP-MS). For analysis, were used 110 µm spot size, 110 µm s⁻¹ scan speed and 60 % (6.99 J cm⁻² of fluency) laser intensity for ablation conditions and 1.2 L min⁻¹ nebulizer gas, 1.6 L min⁻¹ auxiliary gas and 1200 W for ICP-MS conditions. All the results are in accordance with the microwave digestion method, and are in the range 80–120 %.