Which PC Spectrophotometer Calibration Filter Replaces My Current Liquid Filter?

NIST Standards For Calibrating Spectrophotometers Consist Of The Following Parts:

Performance of standards (mandatory to follow for a customer wishing to be in compliance with NIST) must be equal or better standard liquid Neutral Density (ND) standards.   Our Premium spectrophotometer calibration standards are entirely in compliance with NIST guidelines.

Reoccurrence requirements for ND standards’ verification and recalibration is mandatory to follow for a user wishing to be in compliance with NIST.  NIST requires ND standards’ verification and recalibration at least every two years. Many customers choose to conduct ND standards’ verification and recalibration every year. The reason being – spills of samples and some finger-prints are invisible by eye and, most importantly, some spills cannot be fully removed by swabbing with alcohol etc. Thus, NIST strongly recommends that ND standards are NOT cleaned with any liquids and only particles-free dry air or nitrogen are allowed to remove dust from standards. Following NIST requirements, in the event there are signs of spills or fingerprints on an ND standard this standard must be immediately recalibrated.

Usually liquid standards have shelf-life up to three years because performance of liquid mixtures degrade with time. PC's solid-state ND standards have unlimited shelf-life as long as they are taken care of properly.

The answer to the question of which liquid filters does the PC filters replace is impossible to answer.  NIST provides a guide for the liquid materials that the calibration standards can be made of.  At the same time, NIST does not limit the standards’ manufacturers to use the only materials NIST provides as a the guide as long as the ND standards perform at least as good as the liquid standards provided in the NIST’s guidelines.  Important note: When the ND NIST standards were developed the solid-states’ standards technology was not yet available.  The same NIST provisions is applicable to all other type standards used for spectrophotometers’ calibration. 

While periodic verification of ND performance of spectrophotometers is required by all reputable manufacturers of spectrophotometers, verifications of performance of spectrophotometers for wavelengths accuracy, resolution, etc. are required only by SOME manufacturers of spectrophotometers. At the same time, NIST requires that wavelength accuracy of spectrophotometers to be verified at least every two years.  This testing is mandatory. The discrepancy between the NIST position and position of some manufacturers on verification of wavelength accuracy and wavelength resolution of spectrophotometers is driven by the belief of the manufacturers that liquid filters can cause change of wavelength performance.

Therefore, every researcher has to decide whether they wish to strictly follow NIST requirements or just go by the manufacturers’ user manual. Either way the PC spectrophotometer calibration standards are a one time investment that completely comply with NIST guidelines.  Check out these awesome calibration standards today