Introduction
Dimethyl sulfoxide (DMSO) is a powerful organic solvent that can dissolve most organic substances to high loading levels, including carbohydrates, polymers and peptides. Therefore, DMSO is widely used for compound dissolution in pharmaceutical and research laboratories. Even when performed in the low to mid throughput range, compound testing assays require a high degree of standardization and reproducibility. An automated pipetting system can help to meet these requirements. In this report we show that DMSO* can be pipetted with the Eppendorf epMotion automated pipetting system at an excellent accuracy and precision over a broad volume range
The excellent pipetting accuracy of the epMotion automated pipetting system has made it a popular tool for many demanding small volume molecular biology reaction setups[1]. Routine pipetting tasks, like serial dilutions, reagent distributions and sample transfers can equally benefit from automation through increased reproducibility and complete assay standardization. The epMotion pipetting tools work with an air cushion piston stroke system and disposable tips. The unique optical sensor can measure liquid levels contact free, also with non-conducting liquids like DMSO. Liquid type parameters for the tools can be adapted to many different liquids from aqueous solutions to organic solvents. Safe operation is ensured by the completely contained housing that prevents manual interference in the process and possible contact with hazardous substances.
Materials and Methods
When working with pure DMSO, the liquid type class "98 % alcohol" should be set in the epMotion software [2]. With this setting a prewetting step is performed to saturate the air inside the tip with the solvent and the aspiration and dispensing is done at low speed. Water based solutions with low DMSO content should be pipetted with the liquid type class "water". For the accuracy and precision measurement of DMSO the epMotion was equipped with a Mettler SAG high precision balance. The measurements were taken and recorded electronically using the PICASO® Pipette calibration software[3]. Used tools were taken randomly from the training laboratory. The density of DMSO was set to 1.101 mg/μl. For the single channel TS tools the measurements were taken according to EN ISO 8655: 10 measurements each at 10 %, 50 % and 100 % of the maximum volume of the tool. For each volume, the average out of these 10 measurements, the corresponding systematic error (Accuracy) and the random error (Precision) was calculated.
Figure 1: epMotion 5075 LH, Version with PC software dom error (Precision) was calculated.>> Download the full Application Note as PDF
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