Proteins, nucleic acids are best example of natural polymers. Similarly cellulose is also a natural polymer which acts as main structural component of plants. Usually natural polymers are composed by condensation polymerisation with the elimination of water molecule.
Drug-Laboratory Test Interactions. False-positive urine immunoassay screening tests for phencyclidine (PCP) and amphetamine have been reported in patients taking venlafaxine. This is due to lack of specificity of the screening tests. False positive test results may be expected for several days following discontinuation of venlafaxine therapy. Confirmatory tests, such as GC/MS will clear that misconception up asap...or if you are not using pcp and your dr is sceptical.
Finding bubbles in urine is probably not something you need to be overly concerned about since various normal and abnormal conditions can cause urine to bubble. Bubbles in urine can be indicative of a normal or abnormal finding. Because bubbles inurine can result from something as minor as urine mixing with cleaning chemicals found in the toilet to a sign of something more significant like kidney disease. It is always a good idea to discuss this symptom with your physician.