4. Review the calibration of the test instrument.
- What was the date of the last calibration?
- Test instruments need to be calibrated according to the manufacturer's instructions or more frequently if necessary.
- Federal requirements call for analytical tests to be recalibrated, or calibration verification performed, at least every six months to verify the accuracy of the testing procedure. (Additional verification must be performed whenever there has been a major change/repair/software update to the analyzer or test system.)
