Determination of Chlorine in Crude Oil by High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry Using AlCl, InCl, and SrCl Molecules

Abstract

In this work, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) using AlCl, InCl, and SrCl molecules was proposed for direct Cl determination in crude oil. Crude oil analysis was performed by pipetting masses of crude oil directly on the graphite platform. Calibration was performed using aqueous standard solutions containing chlorine. A solution containing Sr2+ ions should be used to increase the sensitivity for AlCl and InCl molecules. For SrCl, only Sr2+ solution was used and the graphite platform should be covered with a Zr permanent modifier. Accuracy was evaluated using certified reference material (NIST 1634c, fuel oil) and also by comparison of results obtained with HR-CS GF MAS to those obtained by microwave-induced combustion (MIC), microwave-assisted extraction (MAE), ASTM D6470-99, and neutron activation analysis (NAA). Significant differences were not observed by comparison of results obtained by HR-CS GF MAS to the certified reference value and the other methods for Cl determination (95% confidence level). The AlCl molecule provided the lowest characteristic mass (0.28 ng). Limits of detection (LODs) of 1.4 and 0.5 mg kg–1 of Cl were obtained for AlCl and SrCl molecules, respectively. Sample preparation was minimized using direct analysis of crude oil combined with HR-CS GF MAS providing better LOD when compared to conventional methods for Cl determination. HR-CS GF MAS using AlCl and SrCl molecules was suitable for quality control of crude oil for Cl determination in compliance with the requirements of crude oil industries.

Development of a fast screening method for the direct determination of chlorinated persistent organic pollutants in fish oil by high-resolution continuum source graphite furnace molecular absorption spectrometry

“…It was applied for the direct determination of total chlorine in biological samples using Zr as permanent chemical modifier and a PIN-platform tube. Later studies have adapted successfully this methodology for the direct determination of chlorine in coal (Pereira et al, 2015), crude oil (Enders et al, 2016) and milk (Ozbek & Akman, 2016), also using direct analysis.…”

Determination of Chlorine in Crude Oil Emulsified via the MgCl Molecule by HR‑CS MAS

“…16,17 Chlorine determination by high-resolution continuum source molecular absorption spectrometry (HR-CS MAS) has been accomplished by detection of several diatomic molecules. 16,18 The most widely reported in the literature is AlCl [19][20][21][22][23][24][25] due to its high energy bond and well separated band heads, making it effective the background correction. 17,26 Strontium monochloride (SrCl) was applied for chlorine determination in different types of samples (coal, milk, animal organs and tissues, and wheat flour).…”

“…This molecule is monitored at 635.862 nm and displays detection limits that are similar to certified values. 21,[27][28][29] A method for chlorine determination through CaCl molecule at the wavelength of 621.146 nm was developed by Guarda et al 30 and applied it to different types of certified reference materials (coal, iron oxide, polyethylene, human hair, pine needles, rice flour and milk). The same molecule was used by Bechlin et al 31 for chlorine quantification in cement samples at wavelength 621.145 nm, employing direct solid sampling analysis.…”

“…Chlorine determination in crude oil by HR-CS MAS through several molecules, AlCl, InCl and SrCl, and direct introduction of the sample, was accomplished by Enders et al 21 The obtained results were compared with those obtained by microwave-induced combustion (MIC), microwave-assisted extraction (MAE), ASTM D6470-99 6 and neutron activation analysis (NAA) and no significant difference was found. 21 The use of MgCl molecule for analytical purposes was investigated by Dittrich and Vorberg 15 and published in 1982, but no application for Cl determination in real samples was reported since then, even after introduction of the HR-CS AAS instrumentation in the early 2000s.…”

“…21 The use of MgCl molecule for analytical purposes was investigated by Dittrich and Vorberg 15 and published in 1982, but no application for Cl determination in real samples was reported since then, even after introduction of the HR-CS AAS instrumentation in the early 2000s. The molecule wavelength, based on literature data, is 377.010 nm, which corresponds to the transition bands of the A2π -X2Σ+ system, visible region, whose molecular spectrum presents broad bands, with two of them exhibiting higher intensities.…”