4.1 This document provides guidance for the implementation of procedures for the preparation, testing, and documentation of an in-house reference material (hereafter called an iRM) to be used for a number of purposes, enumerated in the following document, associated with development, validation, and control of chemical and physical measurement processes.

4.2 This guide is primarily concerned with characterization of the chemical compositions of metals, ores, and related materials. For all these materials, there is a continuing, strong demand for reference materials (RMs) that is difficult for metrology institutes and private certified reference material (CRM) developers to meet because CRM development requires substantial investments of time and money. The metals and mining industries consume RMs and create new product and by-product compositions at high rates. They use analytical methods that provide rapid and accurate determinations, and both quality assurance and quality control can be maintained using efficient procedures provided appropriate iRMs are available.

4.3 The user of this guide must recognize that development of an iRM for any purpose carries with it the responsibility to design and execute the development process correctly, and to document the process thoroughly. In addition, the user of an iRM bears the responsibility for correct use of the iRM material within its design limitations.

4.4 This guide contains discussions on material selection and sampling for RMs with some attention given to conversion to the final forms.

4.5 The use of iRMs is appropriate for control chart procedures to demonstrate that chemical measurement processes are under statistical control. This function requires demonstration of sufficient homogeneity of a material, but it does not require assignment of chemical and physical property values with associated, exhaustively evaluated uncertainties.

4.6 The use of iRMs is appropriate for calibration of test methods and evaluation of calibrations in several ways, including checking for bias, systematic testing of corrections for matrix effects, and testing of sample preparation procedures. See Section 6. This guide provides explanations of general cases in which an iRM can be used as part of a validation process (see Guide E2857).

4.7 Because this document is a standard guide, it is intended to educate those who are involved in laboratory operation, quality system development and maintenance, and accreditation of laboratory operations within the scope of a quality system. However, this guide does not constitute requirements for assessment and accreditation.