NCCLS Guidelines recommend testing urine within two hours of its collection. However, refrigeration or chemical preservation of urine specimens may be utilized if testing or refrigeration within a two-hour window is not possible. A variety of urine preservatives (tartaric and boric acids being the most common) are available that allow urine to be kept at room temperature while still providing results comparable to those of refrigerated urine. Generally, the length of preservation capacity ranges from 24 to 72 hours. Claims for the length of specific analyte preservation should be obtained from the manufacturer. When a specimen is directly transferred from a collection cup into a preservative tube, it provides a stable environment for the specimen until testing can be conducted and reduces the risk of bacterial overgrowth or specimen decomposition. Non-additive tubes (those not containing any chemical preservatives) can be used for urinalysis, but must be handled following strict timing and refrigeration guidelines.