The Effects of Pipette Tip Production & Sterilization Methods on the Retention of Liquids


Plastic pipette tips are ubiquitous pieces of labware commonly used in life science, pharmaceutical, chemistry and many other types of laboratories. Because of their use in such diverse fields, certain qualities have been implemented to meet specific needs. Some of these qualities include sterilization of the tips for biological work, the addition of filters inside the tip to reduce aerosol contamination of the pipette cavity, and reducing the volume of drops retained by the tip’s surface.

While lab personnel may be accustomed to selecting tips based on their particular needs, certain tip types may possess unexpected characteristics. One quality that may be commonly overlooked is the degree of liquid retention associated with a particular tip type versus another, or from one manufacturer versus another.

Initiated by an observation that Artel dye solutions were ‘sticking’ to, or remaining in, pipette tips after a dispense from a liquid handler, an investigation into the various properties of these tips and their interaction with different solutions was conducted. The presence of remaining droplets of dye solution in/on the tips, along with a high degree of variability in the dispensed volume prompted Artel to undertake this study.

The goal of this tip evaluation study was to determine if the observed droplet retention was due to some chemical/physical property of solution or of the tips. The types of tips tested herein included commercially available tips as well as some non-sterile samples which are currently unavailable for purchase. Using an electronic pipette to imitate an ALH dispense method, solution retention was measured by; i) the Artel PCS® Pipette Calibration System, and ii) a gravimetric method. A selection of tips was purchased from different manufacturers, including sterile, non-sterile, filter and low retention tips. The same experimental protocol was conducted for each tip type using aqueous dye solution, deionized water and DMSO. Experimental testing focused on tip sterilization as a possible factor affecting droplet retention.

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