Specimen collection:
After first morning void collect 24 hour urine with 25.0 mL 6N HCl, to maintain pH below 3. Last sample collected should be first morning void at the same time as the previous mornings first void. Mix urine well, record total volume on aliquot and requisition and send a 10.0 mL aliquot in a screw capped urine cup.

Alternate collection:
Preservative may be added within 4 hours after collection is completed instead of prior to collection.