The use of certified reference materials (CRMs) to monitor the quality of analytical results as part of a wider quality assurance and quality control (QA/QC) programme is well understood. This is a requirement under the reporting codes for publicly listed companies involved with mineral exploration, resource estimation and mining grade control. The focus on CRMs is around their performance to monitor accuracy and bias relative to the nominal values for the material. This provides a level of confidence in results generated for the unknown samples submitted to a laboratory. However, while CRMs are certified for a few different methods, the methods used to analyse these and the unknown samples needs to be considered in more detail. The use of aqua regia method for base metals has an upper detection limit for key elements copper (Cu), lead (Pb) and zinc (Zn) of 1 per cent. If samples are tested that exceed these values, they will require further analysis by a different method to achieve absolute values. If the CRM also exceeds 1 per cent base metal, can the performance be assessed accurately across the various methods for the surrounding samples? Alternatively, if the CRM does not exceed 1 per cent base metals, and the surrounding samples do, is the CRM accurately assessing the surrounding samples? This issue, of CRM grades being unsuitable for the samples being tested (ie grades outside the detection ranges for method used), was identified at Aurelia Metals in 2022. In co-operation with the partner laboratory, a suitable solution was implemented that resulted in most samples undergoing the same analytical method which streamlined the analytical process. This had the added benefit of reducing turnaround time and costs, while maintaining the quality and confidence in the results.