Challenges in providing standard reference materials for chemical and pharmaceutical process analysis

The NIST Analytical Chemistry Division has supplied transmittance verificat ion and wavelength calibration standard reference materials (SRMs) speciali zed to the needs of chemical and pharmaceutical spectrophotometric analysis since 1970. Growing demand for UV/visible standards stems from the increas ingly routine use of spectrophotometers for pharmaceutical quality control and from the escalation in the documented use of standards for regulatory a nd voluntary quality control purposes. To meet the demand, NIST is studying ways to accelerate standards production. Projects include studies of the o rigin of transmittance drift (which necessitates aging during production), investigations of solid UV filters and of sealed liquid standards, and the devleopment of an NIST-traceable reference material (NTRM(TM)) optical filt ers program to involve the private sector. Recently, we have revised the op tical specifications of our solid filter standards to meet the requirements of reversed-geometry (post-dispersion) instruments. In the near-infrared, spectrochemical process control applications mandate the need for wavelengt h standards to support the stability and instrument-to-instrument transfer capability of multivariate analytical calibration models. We are presently producing one such standard and are investigating others. Finally, we are s tudying algorithms for locating peaks in wavelength standards to find a con sistent means for making wavelength assignments from the UV through the mid -infrared. (C) 1999 Published by Elsevier Science B.V. All rights reserved.