Determination of Se at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry

Abstract

A method is proposed for the determination of selenium at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry (CRC-ICP-MS). Samples were decomposed by high pressure microwave-assisted wet digestion (MAWD) using 250 mg of coal, a mixture of 5 mL of 14.4 mol L-1 HNO3 and 1 mL of 40% HF and 70 min of heating program (200 ºC and 40 bar). Hydrogen gas used in the collision/reaction cell was investigated to minimize the argon-based interferences at m/z 77, 78 and 80. The rejection parameter (RPq) and the H2 gas flow rate were set to 0.45 and 4.8 mL min-1 , respectively. The use of H2 in the cell resulted in other polyatomic interferences, such as 76 Ge 1 H + , 79 Br 1 H + and 81 Br 1 H + , which impaired Se determination using 77 Se, 80 Se and 82 Se isotopes, thus Se determination was carried out by monitoring only 78 Se isotope. Selenium determination was performed in certified reference materials of coal (NIST 1635 and SARM 20) and an agreement better than 95% was observed between the results obtained by CRC-ICP-MS and the certified values. Under optimized conditions, the instrumental limit of detection was 0.01 µg L-1 and the method limit of detection was 0.01 µg g-1 , which was suitable for Se determination at very low concentration in coal.

Challenges and trends for halogen determination by inductively coupled plasma mass spectrometry: A review

“…161 In addition to the ID method, other strategies have been 81 Br. 38 The interference of 40 Ar 39 K + (m/z 79) was confirmed in other studies by using a solution containing 1000 μg g −1 K. 97,163 Hence, the 81 Br isotope was chosen in order to minimize 40 Ar 39 K + interferences in bromine determination.…”

“…It is important to emphasize that the last two works cited above evaluated the possibility of polyatomic interference in determination 97,167. Both chlorine isotopes (m/z 35 and 37) present very similar m/z values to Ar isotopes ( 36 Ar,38 Ar, and 40 Ar) and the bromine isotopes (m/z 79 and 81) present similar m/z values to the40…”

“…It is well documented that fluorine suffers major spectral interferences from 38 Ar 2+ , 1 H 18 O, and 1 H 2 16 O 1 H species. 22,25 However, as for other similar cases, 25,31,32 if a molecular ion containing fluorine (MF) + , with high dissociation energy and low first and second ionization energies can be formed in the plasma, inductively coupled plasma mass spectrometry with a triple quadrupole instrument (ICP-QQQ) can be used to minimize interferences.…”

Selenium and tellurium concentrations of Carboniferous British coals

“…Samples were analysed using both standard mode mass spectrometry methods and CRC microwave‐assisted wet digestion methods (Henn et al, ) for better detection of low concentrations.…”

“…Developments in analytical methods for measuring Se and Te using cold plasma and collision/reaction cell (CRC) interface allow the detection of Se and Te down to ultra-low levels of detection in British coals. This study reports new data for Carboniferous coals from across Great Britain (Figure 1) Samples were analysed using both standard mode mass spectrometry methods and CRC microwave-assisted wet digestion methods (Henn et al, 2018) for better detection of low concentrations.…”