What are the basic principles of process analyzer calibration?

Analyzer calibration establishes relationship between analyzer output and actual concentration using known standards. Key elements: zero calibration (zero gas/solution establishes baseline), span calibration (standard at typical measurement range), linearity check (multiple points if required), and validation (independent verification sample). Calibration frequency depends on analyzer type, process conditions, and regulatory requirements. Document calibration procedures, standards used, and results. Automatic calibration systems (AutoCAL) reduce manual intervention but require reliable calibration gas/solution supply.