Unacceptable tolerances 6. Quality Control 6.1 QC materials used 6.2 Preparation and handling of QC materials 6.3 Frequency QC is run 6.4 Acceptance limits for controls 6.5 Corrective actions when QC is out of limits 6.6 Recording and storage of QC data 6.7 Alternatives if controls unavailable 7. Urine Extraction - Obtain a creatinine value on a well mixed urine. Add 1 mL DNPH reagent to the tube. Mix and let stand for 10 minutes.
Positive result is a white chalky precipitation.
A positive patient will require an additional derivatization procedure called Oxime. Adjust the pH to less than 1.0 with 6N HCl. If urine volume used is greater than 5 mL, split samplea t this step into two tubes, perform the extraction on each tube and combine all supernatants. Do not pull off any aqueous phase. Cap and mix well, place into a 60 C heating block for 30 minutes.