Large‐Volume Injection and Assessment of Reference Standards for n ‐Alkane δD and δ 13 C Analysis via Gas Chromatography Isotope Ratio Mass Spectrometry
Year: 2024
Type: article
Abstract: ABSTRACT Rationale Compound‐specific stable isotope analysis of hydrogen (δD) and carbon (δ 13 C) in organic compounds is a valuable tool in biogeochemical research. A key limitation of this method is the relatively large amount of sample required to achieve desirable precision. Methods We developed a large‐volume (20 μL) injection method that allows for high throughput analysis of less concentrated samples and tested it for δ 13 C and δD measurements of n ‐alkanes. We also conducted a comparison of reference standards and assessed several methods to normalize and correct n ‐alkane δD and δ13C measurements. Results The mean precision of the δD method based on 233 environmental n ‐alkane samples (two to three replications per sample) is 4.0‰ (1σ, estimated from the weighted mean of the pooled unbiased standard deviations) and 0.46‰ (1σ) for δ 13 C from 37 environmental samples (two to three replications per sample). The evaluation of reference standards shows that the use of n ‐alkane standards with large offsets in δD values in adjacent n ‐alkane chains can lead to biases in measurement correction. Conclusions The large‐volume injection method shows good reproducibility of δ 13 C and δD measurements of n ‐alkanes and reduces the required sample concentration by about 80%. We propose that for δD measurements, a reference standard set should be used in which each reference standard has a limited range of δD values and no adjacent n ‐alkane chains, to minimize memory effects.
DOI: 10.1002/rcm.9943
Language: English
Topic: Isotope Analysis in Ecology
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,840
OpenAlex ID: W4404720618