Aliquot from well-mixed 24 hour urine collected without a preservative.
Adjust aliquot to pH 7.5 - 8.5.
Aliquot tubes containing sodium carbonate are available from Marshfield Labs which provide automatic adjustment of pH.
Indicate the collection time.
The total volume collected must be measured, recorded, and included with the test request.
See Aliquotting of 24-Hour Urines for Multiple Tests.