Reliability and accuracy of environmental analytical data on moss samples: an interlaboratory comparison

Area of Science:

• Environmental Science
• Analytical Chemistry
• Geochemistry

Background:

• Inter-laboratory comparisons are crucial for validating analytical methods.
• Moss is a valuable biomonitor for environmental heavy metal contamination.
• Standardized sample preparation and analysis are essential for accurate results.

Purpose of the Study:

• To assess the reliability of heavy metal (Cd, Cr, Cu, Fe, Ni, Pb) measurements in mineralized moss samples from two independent laboratories.
• To compare the performance of different analytical techniques, including Atomic Absorption Spectrometry (AAS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and Instrumental Neutron Activation Analysis (INAA).
• To evaluate the impact of different mineralization procedures on analytical accuracy and precision.

Main Methods:

• Ten moss samples, certified reference materials (CRMs), and blanks were analyzed.
• Independent sample mineralization was conducted in two laboratories.
• Analysis employed AAS, ICP-MS, and INAA for target elements.
• Statistical analyses included linear regression, Student t-test, and maximum likelihood estimation.

Main Results:

• Accuracy tests for AAS showed high precision (RSDs 0.2-2.9%) and values close to CRMs, with minor exceptions.
• Statistical analysis revealed high correlation coefficients (>0.750) and slopes not significantly different from one for most regressions.
• ICP-MS demonstrated superior precision for most elements compared to AAS, with both mineralization methods yielding satisfactory results.

Conclusions:

• Both laboratories demonstrated the capability to produce reliable results for heavy metal analysis in mineralized moss.
• ICP-MS is recommended for higher precision in analyzing most target elements in this matrix.
• The study validates the analytical methodologies and inter-laboratory agreement for environmental monitoring using moss.