When performing a Standard Adjust why will the instrument not accept the concentration being entered?
The instrument does not accept the concentration entered for a Standard Adjust
Most likely the adjustment is outside the acceptable limits for the program. Limits are programmed into the instrument to reject adjustments that are unreasonably far from the measured value. For example, if a 1.00 mg/L standard solution was placed in the instrument and the displayed value was 0.77 mg/L, the instrument may not allow forcing it to read 1.00, because that would change the concentration by more than 20%. Typical limits for standard adjustment are 10-20%, but will vary depending on the method. These limits ensure that if a standard solution was prepared incorrectly, the instrument would reject the adjustment. If this happens, prepare a fresh standard solution and make sure to follow the procedure correctly. Note that the standard solution must first be mixed with reagents and any reaction time must be observed as specified in the procedure.