Determination of phosphine in plant materials: method optimization and validation in interlaboratory comparison tests
Thomas M Amrein1, Lara Ringier, Nathalie Amstein
1COOP Central Laboratory, Head Quarters, Gottesackerstrasse 4, 4133 Pratteln, Switzerland.
Journal of Agricultural and Food Chemistry
|February 26, 2014
Summary
This study optimized a phosphine determination method in plants using headspace sampling. Standard addition is crucial for accurate results due to matrix effects, though interlaboratory results show analysis remains challenging.
Area of Science:
- Agricultural Chemistry
- Analytical Chemistry
Background:
- Phosphine (PH3) is a toxic gas relevant in agriculture and environmental monitoring.
- Accurate quantification of phosphine in complex matrices like plant material is challenging.
Purpose of the Study:
- To optimize and validate a robust method for phosphine determination in plant samples.
- To identify critical parameters influencing method accuracy and reliability.
Main Methods:
- Headspace sampling coupled with heating in 5% sulfuric acid.
- Investigated sample amount, equilibration, quantitation methods, and matrix effects.
- Utilized standard addition for quantitation due to significant matrix effects.
Main Results:
- Grinding samples is necessary for standard addition but does not lower phosphine content.
- Flame photometric and mass spectrometric detection yielded comparable results.
- High reproducibility was observed within laboratories, but interlaboratory comparisons revealed significant variability (approx. 50% uncertainty).
Conclusions:
- The developed method is reproducible within a single laboratory.
- Significant challenges remain in achieving consistent interlaboratory phosphine analysis in plant materials.
- Further proficiency testing is recommended to improve analytical accuracy and reliability across different labs.
