QA / QC
Quality Assurance/Quality Control
It is essential that clients of X-ray Mineral Services have full confidence in the data produced by our analytical procedures. Our internal quality assurance (QA) and quality control (QC) procedures include:
- Top 10 lab in the Reynolds Cup
- Consistent quantitative mineralogy data
- Weekly validation of 4 diffractometers
- Most minerals quantified within 2 wt.% absolute error
- Certified ICP data
Method documentation
All in-house methods are fully documented, and procedures followed from receipt of samples to issue of the final report. Regular training ensures all staff are familiar with our methods and are kept updated with any changes to procedure.
Cross-check with the use of independent methods
The accuracy and precision of mineral quantification of each batch of samples analysed is confirmed using the following independent methods:
- Rietveld
- Reference Intensity Ratio (RIR)
When available, XRF data is used along with XRD data to cross-check results using a mass balance calculation.
Reference material analysis
The routine performance of our 4 diffractometers is validated on a weekly basis, using mineral standards of known composition. The performance of our XRF spectrometer is monitored by daily analysis of 3 validation beads prepared from certified reference materials (CRMs). The data is checked to ensure that results are within pre-set limits for key elements. If any element is outside these limits the instrument is drift corrected and the analysis repeated to ensure the instrument is within specification.
Analysis of synthetic standard mixtures of known composition
The accuracy and precision of the mineralogical quantification is verified against synthetic mixtures of known composition. These mixtures are prepared from appropriate mineral standards to resemble real rocks. This is the only way to check the accuracy and precision of a technique applied to natural samples.
Most of the minerals are quantified within 2 wt.% absolute error.
Round robin proficiency tests
To assess the accuracy of our XRD and XRF data against external laboratories from around the world XMS participate in a variety of round robin tests including:
- international quantitative phase analysis (QPA) proficiency tests for XRD.
- GeoPT – a major international proficiency test organised by the International Association of Geoanalysts.
Repeat analyses
Regular repeat analyses are an integral part of our QA process to recognise any potential issues during the sample preparation.
Blind checks
Samples with known compositions are randomly processed in the same way as routine samples to maintain performance and reproducibility of the analytical procedure.
ICP certified data
ICP certified to ISO 9001:2015 for fusion and digestion data.