They can also be disassembled and, in many cases, autoclaved to ensure cleanliness. However, taking pipettors apart and putting them back together after every use can be a laborious and time-consuming process. Dave White perfected the self-sealing filter as a solution to the task of repeated cleaning while he was at Molecular BioProducts. He later introduced a micropore hydrophobic filter, constructed of polypropylene, that kept liquid from being drawn into the pipettor. Although cellulose acetate filters have been substituted for polypropylene in some filter tips, these tend to absorb whole samples in addition to the overflow they are intended to protect against.
Many companies now offer their own brands of filter tips.
Mark Brolaski, lab director of Mo Bio Laboratories Inc., San Diego, Calif., has been testing and certifying pipette tips for over five years. Brolaski agreed to be interviewed in order to dispel some of the myths and correct some of the general misconceptions about pipette tips. One of the most pervasive, and certainly the most inaccurate, of these beliefs is that all tips undergo the same basic inspection process and have the same level of quality. Not so, says Brolaski, who has witnessed a broad range of quality and performance. Brolaski has seen contamination in products that are not regularly tested for DNA, DNAse, RNase, and endotoxins and believes that these products are making their way into laboratories.