Calibration

17.1 Calibration - Instruments/ Equipment

Instruments/ equipments must be properly calibrated as per NABL 142.
Where equipment used for tests, including equipment used for subsidiary measurements, have a significant effect on the accuracy or validity of the test results, that equipment shall be calibrated or

otherwise verified before being put into service and shall be subjected to a programme of recalibration and/ or re-verification.

Note:

Laboratories can also refer to other NABL specific criteria to follow the calibration interval (e.g.NABL 103). These intervals are considered as maxima and can vary depending upon equipment

capability, usage, staff expertise. Thus, it is necessary to make intermediate check of equipments /instruments.

The programme for the calibration of equipment in forensic science laboratories must ensure that, where the concept is applicable, all significant measurements are traceable, through certificates of calibration held by the laboratory, to the national standards of measurements.

Where a laboratory performs in-house calibrations, by means of comparisons between reference standards and working/measuring instruments, the calibration procedure must be documented. Calibration records (e.g. calibration certificates, calibration data) must be maintained. The laboratory must have a mechanism that alerts staff when calibrations and subsidiary checks fall due and indicates the nature of work required.

17.2 Calibration – Chemical Analysis

Quality testing in a testing laboratory, particularly in the case of its assessment, highlights the need to consider closely the question of the accuracy of its measurements and analytical results and to ensure that the principles necessary to establish demonstrated accuracy have not been omitted. 

The calibration of the parameters associated with chemical analyses and material tests deserves particular attention, because major errors can occur by neglecting or ignoring the basic principles of metrology which also apply to these areas.