Analytical error in stable isotope ecology

Area of Science:

• Ecology
• Analytical Chemistry

Background:

• Stable isotope analysis (SIA) is increasingly used in ecological research.
• A gap exists between ecologists and isotope ratio mass spectrometry (IRMS) operators, leading to poor understanding and reporting of methodology.
• Many ecological studies using SIA do not adequately report analytical error, impacting data interpretation.

Purpose of the Study:

• To assess the reporting of analytical error in ecological studies using SIA.
• To highlight the potential for spurious results due to variations in IRMS analysis over time.
• To recommend protocol adjustments for more robust SIA data in ecological research.

Main Methods:

• Survey of 330 ecological research papers to evaluate the reporting of analytical error from IRMS.
• Simulation of standard data to assess the likelihood of false positives in SIA results.
• Analysis of variations in analytical error between internal standards and real ecological samples.

Main Results:

• 19% of surveyed papers failed to report any analytical error associated with IRMS.
• Significant variation exists in how analytical error is quantified and described.
• Simulations showed a 90% likelihood of detecting a false significant difference in nitrogen isotope ratios for a single sample analyzed across different time periods.

Conclusions:

• Inadequate reporting of IRMS analytical error in ecological literature can lead to misinterpretation of data.
• Internal laboratory standards may not accurately reflect the analytical error associated with complex ecological samples.
• Implementing minor protocol changes, such as blind replicates and varied sample repeats, can improve the reliability of SIA in ecological studies.