Optimization of compound‐specific chlorine stable isotope analysis of chloroform using the Taguchi design of experiments
| Autor: | Kaori Sakaguchi-Söder, Christoph Schüth, Berhane Abrha Asfaw, Hagar Siebner, Anat Bernstein |
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| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
Chloroform
Chromatography 010401 analytical chemistry Organic Chemistry Extraction (chemistry) Fractionation 01 natural sciences 0104 chemical sciences Analytical Chemistry chemistry.chemical_compound Dwell time Taguchi methods chemistry Selected ion monitoring Gas chromatography Quadrupole mass analyzer Spectroscopy |
| Popis: | Rationale Chloroform, a probable human carcinogen, is commonly detected in various concentration levels in many surface water and groundwater sources. Compound-specific chlorine stable isotope analysis (Cl-CSIA) is significant in investigating the fate of chlorinated contaminants in the environment. Analytical conditions should, however, be thoroughly examined for any isotopic fractionation. In this study, we simultaneously optimize three analytical parameters for a robust online Cl-CSIA of chloroform using the Taguchi design of experiments. Methods For Cl-CSIA, a purge-and-trap autosampler coupled to a gas chromatograph in tandem with a quadrupole mass spectrometer, with electron ionization in selected ion monitoring (SIM) mode, was used. Using the Taguchi method, the dominant parameter affecting the results of Cl-CSIA for chloroform was identified through concurrent investigation of the signal-to-noise ratios (S/N) of three parameters, each at three levels: purging time (5, 10, 15 min), transfer time (80, 120, 160 s), and dwell time (20, 60, 100 ms). Moreover, the optimum combination of the levels was identified. Results The purging time, with a maximum S/N, resulted in the highest influence on the isotope ratios determined. It was further refined through additional experiments to sufficiently extract chloroform from the aqueous phase. Accordingly, 8 min of purging time, 120 s transfer time and 100 ms dwell time were the optimum conditions for Cl-CSIA of chloroform. Post-optimization, a precision of ±0.28 ‰ was achieved for 8.4 nmol of chloroform (equivalent to 0.89 μg or approx. 25 nmol Cl-mass on column). Conclusions A simple online method for Cl-CSIA of chloroform was optimized with the Taguchi design of experiments. The Taguchi method was very useful for the optimization of the analytical conditions. However, the purging conditions should be fine-tuned and selected so that sufficient extraction of a target compound is confirmed to acquire a stable and higher precision of the method. |
| Databáze: | OpenAIRE |
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