Contamination, carry-over

Contamination or carry-over is the process by which materials are carried into a reaction mixture where they do not belong.

Materials can be the sample, the reagent, or ions leaching from the probe metal. Contamination is often a major problem with fixed reusable tips, a complex issue that also involves the instruments pipetting and washing procedures as well as the nature of the liquids and the sensitivity of the tests.

Probe induced contamination can be minimized through the choice of the base material and the best tube drawing technique to minimize the tubing surface roughness. Surface properties may be further enhanced with passivation, electropolishing, coatings or fluoropolymer lining.