||50 mL (10 mL min.) aliquot of random urine. Add 50% HCl drop by drop to bring the pH between 1-2. Do not use concentrated HCl. Ship refrigerated or frozen. Patient should strictly avoid banana, kiwi, walnut, avocado, brinjal, pineapple, plum, tomato & drugs like Fluorouracil, Melphalan, Paracetamol & Acetaminophen, Heparin, L-dopa, Reserpine, Salicylates, Chlorpromazine, Imipramine, Isoniazid, MAO inhibitors, Phenothiazines, Promethazine, alcoholic beverages, caffeine, tea/coffee, tobacco and strenuous exercise at least 72 hrs before and during specimen collection.