CTI provides chemical analysis services for hazardous substances related to quality control samples, which are mainly used for method verification and confirmation, quality assurance of the testing process, etc., which can be used for blind samples for on-site review, supervisory review, re-assessment and unannounced inspections by regulatory agencies. Charge samples or blind samples used for laboratory internal audit, daily quality supervision, quality assessment, personnel assessment, method comparison, personnel comparison, equipment comparison, etc.