Certified reference material (CRM) is characterized by a metrologically valid procedure for one or more specified properties, accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability. 

European Reference Materials (ERM) is a trademarked term for CRMs produced by European Reference Material consortium.

Environmental Reference Material can be defined as natural soil, water, or biota that have been homogenized and well characterized for a specific set of analysis by multiple techniques. These types of material standards are usually more representative of laboratory samples and are useful for site-specific PE (Performance Evaluation) standards development, method detection level determination, and as natural blank matrices for use as method blanks or as a basis for preparing fortified matrix standards. A vast majority of matrix Environmental Reference Materials are suitable for method validation, quality assurance and quality control, but not for instrument calibration.

Internal quality control is a set of procedures undertaken by laboratory staff for the continuous monitoring of operation and the results of measurements in order to decide whether results are reliable enough to be released.

Matrix reference material is a natural substance more representative of laboratory samples that has been chemically characterized for one or more elements, constituents, etc. with a known uncertainty. Most of the times matrix RMs are sufficient for method validation, quality assurance and quality control purposes, but not for calibration.

Method validation is the process of establishing the performance characteristics and limitations of a method and the identification of the influences that may change these characteristics and to what extent. Which analytes can it determine in which matrices in the presence of which interferences? Within these conditions what levels of precision and accuracy can be achieved? The process of verifying that a method is fit for a purpose, i.e. for solving a particular analytical problem.

Proficiency testing is a periodic assessment of the performance of individual laboratories and groups of laboratories that is achieved by the distribution by an independent testing body of typical materials for unsupervised analysis by the participants.

Quality is a totality of characteristics of an entity that bears on its ability to satisfy stated and implied needs.

Quality assurance comprises of all those planned and systematic actions undertaken by the organization necessary to provide adequate confidence that a product or service will satisfy given requirements for quality.

Quality control are operational techniques and activities that are used to fulfill requirements for quality.

Quality Control Material (QCM) is a in-house Reference Material that is used as a supplement to CRMs for internal laboratory quality control.

Reference Material (RM) is a material that is sufficiently homogeneous and stable with respect to one or more specified properties, which has been established to be fit for its intended use in a measurement process. 

Standard Reference Material (SRM) is a certified reference material issued by United States National Institute of Standards and Technology (NIST) that meets additional criteria assigned by NIST. The terms "Standard Reference Material" and the diamond-shaped logo which contains the term "SRM," are registered with the United States Patent and Trademark Office.