Most pipette tip manufacturers provide documentation to reassure customers that their products have been tested for biological contamination.
The language of “DNA-free”
In the age of PCR and qPCR, even small amounts of foreign DNA can wreak havoc with experiments, assays and forensics work. Beware of manufacturers who claim that their product is “DNA-free,” but provide no documentation to verify that such testing actually occurred. If there is no qualitative or quantitative data provided by a tip manufacturer, their claim of “DNA-free” should be regarded as highly suspect. Occasionally, a manufacturer will provide an image of a gel and claim that the absence of any visual bands is proof that no DNA contamination was present.
This substance is a “lipopolysaccharide” (LPS) derived from the cell wall of gram-negative bacteria (such as common E. coli). All brands appear to test for the presence of endotoxin contamination.
Protein and Protease
Among all pipette tip manufacturers, only Rainin tests for both protein and protease. In order to offer tips that have been thoroughly tested for optimal performance in all applications, including proteomics, quality tests for both protein and protease are required. By ruling out contamination by both protein and protease, Rainin provides tips which are designated as “proteomics qualified.”
The test for ATP contamination is important because ATP can only be derived from living organisms. Therefore, the presence of ATP is a strong indication that the products have been brought into contact with humans, bacteria, etc., either directly or indirectly. ATP serves as an “indicator of biological contact” within the production environment.
This is the only contaminant type for which Rainin does not provide a specification. The reason for this is the “binary nature” of the test and the fact that the test for PCR inhibition is actually being simultaneously carried out during the PCR-based tests for human and bacterial DNA.