ASTM E958-93(2005)

This practice should be used by a person who develops an analytical method to ensure that the spectral bandwidths cited in the practice are actually the ones used.

Note 1—The method developer should establish the spectral bandwidths that can be used to obtain satisfactory results.

This practice should be used to determine whether a spectral bandwidth specified in a method can be realized with a given spectrophotometer and thus whether the instrument is suitable for use in this application.

This practice allows the user of a spectrophotometer to determine the actual spectral bandwidth of the instrument under a given set of conditions and to compare the result to the spectral bandwidth calculated from data given in the manufacturer’literature or indicated by the instrument.

Instrument manufacturers can use this practice to measure and describe the practical spectral bandwidth of an instrument over its entire wavelength operating range. This practice is highly prefered to the general practice of stating the limiting or the theoretical spectral bandwidth at a single wavelength.

1.1 This practice describes a procedure for measuring the practical spectral bandwidth of a spectrophotometer in the wavelength region of 185 to 820 nm. Practical spectral bandwidth is the spectral bandwidth of an instrument operated at a given integration period and a given signal-to-noise ratio.

1.2 This practice is applicable to instruments that utilize servo-operated slits and maintain a constant period and a constant signal-to-noise ratio as the wavelength is automatically scanned. It is also applicable to instruments that utilize fixed slits and maintain a constant servo loop gain by automatically varying gain or dynode voltage. In this latter case, the signal-to-noise ratio varies with wavelength. It can also be used on instruments that utilize some combination of the two designs, as well as on those that vary the period during the scan. For digitized instruments, refer to the manufacturer's manual.

1.3 This practice does not cover the measurement of limiting spectral bandwidth, defined as the minimum spectral bandwidth achievable under optimum experimental conditions.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.