Standardisation: What is it and How is it Done? Part 1

The term "standardise" appeared in 1881 in Nature where it was advised that, "This other mode of measurement should be standardised (sic) ... by comparison with Mr. Harcourt's air-gas flame, which should alone be taken as the official standard."1 The term was first applied to instrument standardisation in 1889 in the Daily News which stated, "The supply of electrical energy under statutory powers could not be effectively carried out unless there was some method of standardising (sic) the meters and other instruments."1 These quotations from the late 19th century show that the problem of standardisation is as old as analytical chemistry, and has had varying definitions since its inception. In the first cas·e, a standard method was proposed against which all newer methods would be tested, while in the second instruments were being required to give the same response. It should be no surprise, then, that the problem of standardisation and its ambiguous definition have grown along with analysis and includes a set of related problems. This paper describes the scope of standardisation and gives a description of the methods associated with standardisation. Part 2 will cover the advantages and disadvantages of each approach . According to Webster's Dictionary standardisation means: "1 . to compare with a standard 2. to bring into conformity with a standard."2 The fundamental problem of standardisation is making an instrument response conform to a "standard" instrument response. The current formulation of the standardisation problem can be seen by examining the aspects of a generic instrument response, in the hope of defining the important aspects of a "standard" instrument respo111se . The first aspect of the standard instrument response is the instrument. The methods of Shenk et al. and those of Wang et al.3-f3 have mathematically modified the instrument response function of a second instrument to match the instrument response function of a primary instrument. They succeeded to varying degrees by correcting spectra of the same samples, taken with different instruments. Shenk has shown that instrument differences can be corrected between similar instruments, such as correcting a near infrared reflectance