Instrument calibration index

The analytical instruments a testing laboratory’s results stand on. Calibrated across the parameters that actually move a result, not just switched on and checked.

HPLC and UHPLC

Flow rate, column oven and autosampler temperature, injection volume, wavelength accuracy, UV detector linearity

UV-visible spectrophotometer

Absorbance, transmission, wavelength accuracy

Atomic absorption spectrophotometer

Absorbance and linearity

FTIR spectrometer

Wave number

Flame photometer

Linearity

Polarimeter

Angle of rotation

Karl Fischer titrator

Delivered volume

Bench instruments that read a physical property directly, where a drifting scale reads as a real change in the product.

Brixometer and refractometer

Brix

Viscosity meter

Viscosity

Hydrometer

Density

Lactometer

Density

Butyrometer

Volume

Equipment whose setting is a control point: if the number on the dial is not the number in the chamber, the process record is wrong.

Autoclave

Temperature

Tachometer and RPM equipment, including centrifuges

Rotational speed

Stopwatches, machine timers, HPLC and RPM timers

Time

The measuring tools on the shop floor rather than in the metrology room — the ones that get dropped, and are rarely checked until something is rejected.

Vernier calipers

Length

Micrometers and screw gauges

Length

Height gauges

Length

Measuring tapes

Length

Every calibration produces a certificate stating the measured value at each point, the deviation from nominal, the uncertainty of measurement, the reference standard used and its traceability, and the environmental conditions the work was done under. As-found data is recorded before any adjustment is made, because as-left data tells you the instrument is fine now and as-found data tells you what your last six months of readings were worth.

Where an instrument is found outside its acceptance criteria it is reported immediately rather than quietly adjusted, so you can assess what was measured on it since its last calibration.

An instrument calibration that reports only a pass has told you almost nothing. The number, its deviation and its uncertainty are the product.

This index is a statement of capability, not of accreditation. The laboratory’s accredited calibration scope is defined by the annex to certificate N-C-00592 and by nothing else — it is reproduced line by line on the accreditation page, with the accredited range and CMC for every parameter it covers.

Work outside that annex is done as in-house calibration and is said to be outside the scope before it is commissioned, never after. If your requirement is specifically for accredited calibration, say so at quotation and the reply states plainly whether the instrument falls inside the annex.