Q: Is it acceptable to use water or saline as a negative control for qualitative urinalysis performed by an instrument?
A: Water and saline are generally not acceptable as a negative control for qualitative urinalysis performed by an instrument. Laboratories should follow manufacturer instructions for quality control. Past contact with urine dipstick vendors has shown that they do not recommend use of water or saline as a negative control. The specifications of the commercial controls have been determined by methods traceable to NIST* standards and it would be impractical for most laboratories to demonstrate comparable analysis.
*National Institute of Standards and Technology