Manufacturers have based their tests on the color response of chemical indicators that detect the presence of adulterants. The administrator would use this test to determine its integrity prior to testing.\r\rCreatinine reacts with a creatinine indicator to form a purplish-brown color complex. The color intensity is directly proportional to the concentration of creatinine which is a waste by-product produced by the body. Urine samples with creatinine concentrations of less than 20 mg/mL are dilute, which may be an indication of contamination.\rNitrites react to form a pink-red/purple color complex. Urine samples containing nitrate at levels higher than 15 mg/dL are considered adulterated.\rTesting the pH value of the urine sample is based on a color change in the indicator. The standard urine pH ranges from 4 to 9. Urine pH below 4 or above 9 indicates contamination of the specimen with acids or alkalines.\rBleach or other oxidizing agents react with an oxidant indicator to form a blue-green, brown, or orange color which indicates adulteration with bleach or other oxidizing agents.\rSpecific Gravity testing relies on the pKa change of certain pretreated polyelectrolytes about the ionic concentration. The indicator will show color changes from dark blue to blue-green in the urine of low ionic strength to green and yellow-green in the urine of higher ionic concentration. Specific gravity below 1.005 or above 1.025 is considered abnormal, which may indicate adulteration.