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.
Item: DOA-154. Specificity. The following table lists substances that are detected positive in urine by the One Step 5-Panel Drug Test: THC-COC-OPI-AMP-PCP at 5 minutes. Cutoff represents, in nanograms per milliliter (ng/ml), the concentration of the substance required to yield a positive reading. A lower Cutoff indicates greater sensitivity to the substance.