Optimized Configuration of Fixed-Tip Robotic Liquid-Handling Stations for the Elimination of Biological Sample Cross-Contamination

Abstract

R obotic liquid-handling stations (RLHSs) are the mainstay of high-throughput biomedical/forensic DNA sample processing facilities. These liquid-handling systems can be alternatively tooled with either disposable or fixed-tip pipetting heads. The use of disposable tips is often perceived as the best tip configuration to eliminate cross-contamination between biological samples processed on liquid-handling stations. However, this suppression can be effectively achieved on instruments equipped with fixed tips with optimally designed tip wash station (WS) configurations. Fixed-tip instruments offer many significant sample processing advantages with respect to precision, pipetting of liquids that may contain aggregates, and operational cost. This report discusses how cross-contamination suppression was achieved for the reliable processing of forensic casework samples on specially configured fixed-tip TECAN Genesis RSP/ Freedom EVO RLHSs. A critical analysis of the major components involved in tip washing, as well as the specifications of a redesigned tip-washing routine that increases wash effectiveness and significantly reduces processing time and cost is also presented. ( JALA 2007;12:339-54

Development of Standard Test Procedures for Quantifying Carry over from Fixed Pipetting Tips in Liquid-Handling Systems

“…Despite widespread use of fixed tips in these systems, we are not aware of systematic studies on procedures to quantify CO in such liquid-handling systems for analytes other than nucleic acids. The CO of nucleic acids has been investigated by several groups (Fre´geau et al 15 and references therein). Together with a consortium of three liquid-handling system suppliers, we have therefore established and validated test procedures for measuring the CO of three model substances, a small organic molecule, a protein, and a lipid protein complex.…”

Mammalian Genotyping Using Acoustic Droplet Ejection for Enhanced Data Reproducibility, Superior Throughput, and Minimized Cross-Contamination

“…In addition, this body of work demonstrates the ability of ADE devices to assemble PCR and qPCR reactions with an impressive amount of contamination reduction. There are various sources of potential contamination in an automated laboratory; samples can become contaminated during DNA extraction, 31 while reaction assembly takes place, 32 or even during thermal cycling. 33 It is possible that if we had used a classical liquid handler with disposable pipette tips, rather than fixed tips, we could observe different or reduced patterns of contamination in the above experiments.…”

New incompatibilities uncovered using the Promega DNA IQ™ chemistry

“…The Royal Canadian Mounted Police (RCMP) National Forensic Laboratory Services implemented automated DNA extraction with DNA IQ™ paramagnetic beads (Promega Corporation) for biological samples in 2004-2005 [1][2][3]. This resulted in an enhanced throughput and capacity to produce high quality STR profiles.…”

“…Lysates were transferred robotically (with 700 µL of Promega Lysis Buffer; Promega Corporation, Madison, WI) with a TE-Shake Unit, a TE-VacS Unit and Teflon-coated stainless steel tips; TECAN US, Research Triangle Park, NC)[1][2][3]. The DNA was eluted from the beads at 65°C in a final volume of 52 or 60 μL of low Tris-EDTA (10 mM Tris pH 8.0, 0.1 mM EDTA) and stored at 4°C.For Experiments #3, 6, 9 and 10, DNA extraction was performed using a modified protocol based on the DNA IQ™ Casework Pro Kit and the Maxwell® 16 System (Promega Corporation).…”