Reliability of geochemical analyses: Deja vu all over again

Area of Science:

• Geochemistry
• Analytical Chemistry
• Geological Sciences

Background:

• Accreditation is standard for commercial labs, with documented quality control (QC) results.
• Customers often rely on lab accreditation and internal QC, potentially neglecting external checks.
• Large-scale geochemical projects require robust data integrity.

Purpose of the Study:

• To demonstrate the necessity and methodology of laboratory-independent, external QC for geochemical projects.
• To highlight potential quality issues missed by internal QC procedures.
• To provide a framework for implementing project-level QC.

Main Methods:

• Utilizing recent project examples from the Geological Survey of Norway.
• Implementing simple graphics for visualizing QC results.
• Providing R scripts for generating QC graphics.

Main Results:

• Detected quality issues including time trends, sample mix-ups, and concentration breaks between batches.
• Identified problems arising from the use of multiple instruments and excessive data rounding.
• Demonstrated that internal QC alone is insufficient to guarantee data quality.

Conclusions:

• Laboratory-independent, external QC is essential for reliable and comparable geochemical datasets.
• Accreditation does not eliminate the need for project-specific QC protocols.
• Implementing external QC procedures is a necessity in modern geochemical mapping and monitoring.