Researchers from the French Institute IFPEN have developed a method based on the hyphenated technique GC-ICP-MS/MS for the determination of volatile organochlorides in complex hydrocarbon samples.
Background:Chlorine is naturally present in some process feeds such as crude oil or plastic waste pyrolysis oils, both in the form of inorganic salts or organic species. Unfortunately, these compounds are responsible for numerous industrial issues, such as pipe or heat exchanger fouling, corrosion issues or catalyst poisoning. Whereas inorganic chlorine containing salts can be removed to certain extent by water extraction, the removal of organic chlorine is much more challenging, calling for dedicated processes. As a consequence, adequate analytical techniques for chlorine speciation analysis are required. Existing methods based on GC separation with an electron capture detector (ECD) or quadrupole time of flight mass spectrometry (QTOF/MS) do not fully satisfy due to either poor sensitivity, low selectivity or the need for adequate calibration standards.
The new study:
Researchers from the IFPEN have developed a method for Cl speciation analysis in complex hydrocarbons such as petrol or plastic pyrolysis oils based on GC separation coupled with ICP-MS/MS detection. GC-ICP-MS/MS parameters were carefully optimized to minimize matrix effects.
GC separation was performed on a HP-INNOWax column (60 m, 0.25 mm, 0.5 μm – Agilent JW, USA) using He as the carrier gas and split injection. The column effluent was mixed with argon carrier gas, and Ar/O2 mixture before entering a heated transfer line to the ICP injector. The addition of oxygen to the carrier gas is meant to avoid any carbon build-up on the ICP-MS cones.
H2 was used as the reaction gas, monitoring Cl with the mass shift mode (35Cl → 35Cl1H2+). The carrier gas flows were optimized with respect to minimizing the effect of carbon on the detection of Cl. Under optimized conditions, the influence of carbon was compensated and the Cl response was independent of the structure of the Cl-compound. The relative response factors of 13 Cl-containing compounds were between 0.97 and 1.05, allowing for compound-independent calibration (CIC) using 1,2-dichlorethane as calibration standard.
Satisfactory recoveries (80-120 %) were obtained for most of the 13 compounds spiked to four different petrol samples at spike levels close to 0.2 mg Cl/L. Limits of quantification between 30 and 100 µg Cl/L were obtained for numerous organochlorides in n-heptane. The developed method was applied to four different complex organic samples, including plastic pyrolysis oil petrol cuts. Results obtained in these samples agreed well with respect to the chlorine mass balance between the speciation results and the total Cl content.
The original publication
Vincent Souchon, Marc Maleval, Fabien Chainet, Charles-Philippe Lienemann,
Chlorine speciation in complex hydrocarbon matrices using GC-ICP-MS/MS, J. Anal. At. Spectrom., 38/8 (2023) 1634-1642.
DOI: 10.1039/d3ja00066d
Used Instrumentation:
Agilent Technologies Inc. - 8800 ICP-MS/MS
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last time modified: September 18, 2024
