What is the difference between standard adjust and user calibration?
Standard adjust and user calibation
Standard adjust maintains the shape of the factory calibration curve, but the whole curve is adjusted slightly so that the instrument reads the exact value of a standard solution. Typical limits for calibration curve adjustment are 10-20 percent. These limits ensure that if a standard were prepared incorrectly, the instrument would reject the adjustment. User calibration puts an entirely new calibration curve into the instrument, and does not have rejection limits if standards are prepared incorrectly. User calibration is not recommended for this reason, however it may be required by regulations.