Color and transparency are determined from visual observation of the sample. Normal urine is straw yellow to amber in color. Abnormal colors include bright yellow, brown, black (gray), red, and green. These pigments may result from medications, dietary sources, or diseases.
limulus amebocyte lysate test. limulus amebocyte lysate test. LAL test. A test used to detect minute quantities of bacterial endotoxins and to test for pyrogens in various materials; it is also used to detect septicemia due to gram-negative bacteria. Limulus amebocyte lysate is formed from the lysed circulating amebocytes of the horseshoe crab (Limulus polyphemus).
Bubble Point Test. The most widely used non-destructive integrity test is the bubble point test. Bubble point is based on the fact that liquid is held in the pores of the filter by surface tension and capillary forces. The minimum pressure required to force liquid out of the pores is a measure of the pore diameter (see formula).