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.
Quick Answer. The results from a urine test can take from a few days to a week for a positive screen, while negative results are usually found in a single day. Additionally, if a rapid test is requested, the results are received on the same day. Some drugs are detectable in urine from a couple days to three or four weeks with chronic use, such as marijuana. To reduce the chances of a false-positive, provide an up-to-date history of all prescription, over-the-counter and herbal drug use prior to taking the urine test.