LIQUID HANDLER PERFORMANCE continued
l-Pak Division aboratory 013
Figure 2 – MVS performance at 10–20 nL in 384- well MVS Verifi cation Plates.
Figure 3 – MVS performance at 20–300 nL in 384-well MVS Verifi cation Plates.
test solution of approximately 75–80% DMSO created using DMSO and aqueous MVS Stock 1 Sample Solution. While this capability permitted for volume verifi cation with a DMSO solution, it did not provide for testing pipetting performance of a truly 100% DMSO-based solution.4
A 100% DMSO Sample Solution has been developed for use with the MVS. DMSO Range E Sample Solution is capable of measuring down to
AL1307
Figure 4 – MVS performance at 100–999 nL in 96-well MVS Verifi cation Plates.
10 nL. As with all MVS Sample Solutions, results are traceable to inter- national standards.
Evaluating the performance of 100% DMSO Range E
Sample Solution The DMSO Range E Sample Solution was developed to be compatible with all existing MVS materials, including MVS Diluent and the Artel character- ized microwell MVS Verifi cation Plates. Integration of this DMSO solution into MVS allows for easy comparison and standardization between various liquid handlers, no matter their location or whether they are dispensing aqueous or DMSO-based solutions.
In order to demonstrate the performance of the 100% DMSO dye solution, a comparison was made between a gravimetrically calculated volume and a volume measured using the MVS. For this experiment, representative gravimetric dilutions were prepared for specifi ed volumes of DMSO Range E Sample Solution diluted into aqueous MVS Diluent. This test procedure was also followed for aqueous-based Range E Sample Solution to provide a performance comparison of the two solutions (DMSO vs aqueous Range E). Using a calibrated automated liquid handler, 200 µL of each prepared dilution was dispensed into every well of a 96-well Verifi cation Plate, or 55 µL into a 384-well Verifi cation Plate. The total volume of solution dispensed into each plate was measured gravimetrically, and the result was used to calculate the average volume dispensed into each well. The volumes dispensed into each well were then measured using the MVS. The volumes calculated from the gravimetric measurements were then compared to the volumes measured using the MVS.
Figures 2–4 display the performance of Aqueous Range E and DMSO Range E as compared to gravimetry, in both 96- and 384-well MVS Verifi cation Plates. The data in these graphs show good agreement between gravi- metric and MVS results, illustrating that the MVS performs equally well for both aqueous and DMSO Range E Sample Solutions in both plate types.
Furthermore, Figure 2 demonstrates the capability of the MVS to measure down to 10 nL in a 384-well plate. This represents an extended volume range for the MVS, which previously had a lower measurement limit of 30 nL.
AMERICAN LABORATORY • 32 • JUNE/JULY 2013
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