Calibration establishes the relationship between instrument measurements and known standard values through a series of steps. Key aspects of calibration include identifying instruments and sources, following calibration procedures, documenting results, accounting for sources of error, and ensuring traceability to national standards. Calibration procedures vary based on instrument type, but generally involve evaluating instrument performance, establishing calibration curves using certified reference materials at multiple concentration levels, and quantifying samples based on the calibration curves.

1. Calibration
Pradeep Kumar. G.T

2. Definition
Calibration is the set of operations that
establish, under specified conditions,
the relationship between values
indicated by a measuring instrument,
a measuring system or values
represented by a material measure,
and the corresponding known
values/standard value of a
measurand.

3. Steps
1. Identify instruments/glassware
2. Identify sources of calibration
facility/procedures
3. Calibration procedure
4. Documentation
5. sources of error
6. correction

4. 1. Identify instruments/glassware
• Instruments /glassware which
–Directly influence the results
–Measure physical quantities
–Detect the residue
–Used for CRM preparation
–Used for reconstitution

5. 2. Identify sources of calibration
facility/procedures
• Calibration procedures
• IS, ASTM, BS
• Manufacture’s
instruction
•GC, GC-MS, LC-MS

6. • NABL accredited calibration
laboratories
•SCTIMST, Poojappura,
Trivandrum
•STIC, CUSAT, Cochin
•FCRI, Palakkad

7. 3. Calibration procedure
• General rules
• One-point calibration
• Volumetric glassware
• Two-point calibration
• pH meter
• Multi-point calibration
• GC,GC-MS, LC-MS

8. CRMs/Standards for
calibration
• Certified Reference Material
• Certificate
• Correction in the reading
• Calibration Curves
• graph which relates reference
value to the instrument’s output

9. Documentation
• Name of equipment and identification
number
• Observed reading/value
• Reference value
• Difference between reference value
and observed value
• Corrective action may include
servicing, labeling, or disposal

10. Sources of error
• Stabilisation
• Normal position
• Avoid sources of interference
• Avoid traces of leftover
• Calibration accuracy should be 3
to 10 times the accuracy required
for the measurement .

11. Traceability
• Traceable to a national
standards.
• In India it is with National
Physical Laboratories, New Delhi
• SI system

12. Uncertainty

13. Calibration of balance
• Stabilization
• Accuracy test
• Repeatability test
• Eccentricity or off-centre loading
• Acceptance criteria

14. Calibration of GC, LC
• Calibration of Instrument
performance
–Flow calibration using flow meter
–Temperature calibration
–Detector signal/sensitivity
–Mass calibration for mass
spectrometer

15. • External/Internal calibration
using CRMs
– Find out the retention time. (RT,
compound parameters and spectrum
for MS)
– Prepare the pesticide CRM
mixture (min 5 levels)
– Inject this mixture in GC or LC
» Cont.

16. –Give the names, retention
time, compound parameters
and concentration
–Draw the calibration curves.
–This calibration curve can be
used for the quantitation of
pesticides.