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.
Urine drug test results can be attributed to human error and urine sample contamination. In addition, there are a number of controlled and uncontrolled substances that will cause a false positive result; these are some of the reasons why labs will immediately split your urine drug test specimen into two samples.ational laboratories state that the EMIT test is wrong 25% to 30% of the time, and can result in false during a urine drug test positives from legal substances up to 38% of the time!