These include absolute values, percentage limits, ranges of values and, for precision, standard and relative standard deviations. Inclusion in an NLM database does not imply endorsement of, or agreement with, the contents by NLM or the National Institutes of Health. It is obvious that erroneous data reported to a physician may adversely affect patient welfare. Currently, acceptable limits of accuracy and precision are poorly. A spectrophotometer, as an analytical tool is used in almost every type of chemical, biological or life science laboratory. Some such. The first requirement for a valid measurement is a representative sample which has been sufficiently characterized that the concomitants of the unknown are understood, interferences characterized, and thermal and chemical history adequately documented. As the selection of standards can be somewhat challenging, we have prepared an overview of options that are. A set of NIST traceable standards have been measured on a wide range of commercially available instruments and comparative results are presented for Unity Scientific SpectraStarTM XT, SpectraStarTM XL, Bruker Tango, Büchi NIRFlex N-500 & FOSS NIRSTM DS2500. pharmacopoeial monographs or internationally recognised control standards, includes the need to specify requirements for absorbance accuracy.