Jeff Cunningham and Lynn Jordan
Caliper Life Sciences Inc., Applications Laboratory, Hopkinton, Massachusetts, USA
The ability to continuously dispense reagents across multi-well plates and into individual columns (secondary dispensing) is of great importance to high throughput laboratories. Equally important, however, is the precision that can be achieved during a series of dispenses. Therefore, the bulk reagent dispensing performance of the Sciclone Advanced Liquid Handler Workstation was tested for precision. Using the absorbance properties of various tartrazine solutions, we found average variation coefficients (CV's) of <1%, 1%, 1.2% and 2.2% for volumes of 80, 40, 20 and 10μL respectively. Our data exemplifies the capabilities of the Bulk Reagent Dispenser at various microliter ranges.
Materials and Methods
All testing was performed using a Sciclone Advanced Liquid Handler (ALH) and a Bulk Reagent Dispenser (Sciclone pipetting head option). Absorbance was measured at 450nm with a Wallac Victor2 1420 Multilabel Counter (PerkinElmer Wellesley, MA).
Tartrazine (SIGMA) solutions (1.25, 1, 0.16 and 0.08g/L) corresponding to 10, 20, 40 and 80μL dispenses were prepared with deionized H2O and degassed with Helium.
To facilitate the removal of any compressible gasses, at least three 2.5mL volumes of system fluid (in this case degassed tartrazine) are primed into a waste reservoir. Then, manual methods are used to force residual air pockets that collect at the top of the syringes into the lines by three cycles of additional priming.
Tartrazine volumes (10, 20, 40 or 80μL) were d ispensed twice into a waste reservoir then secondary dispensed into each column of a NUNC (Denmark) 96 well, clear bottom, untreated plate with the Bulk Dispenser (Fig.1). Deionized/degassed water was then dispensed into each well to provide a final volume of 200μL (Fig.2). Absorbance was measured and the resulting data exported to Excel for CV determination. The entire process was repeated 5 times for each volume of tartrazine dispensed.
Utilizing the programs depicted in Fig.1 and Fig.2, five plates of each volume (80, 40, 20 and 10μL) were prepared, absorbance measured and the data exported to ExcelTM For CV determination (Table 1).
In this study, we demonstrate the high level of precision that can be expected of the Sciclone ALH Bulk Reagent Dispenser. This device permits non-contact delivery of 10-2500μL volumes to specified columns or all columns of multiwell plates (secondary dispensing). Moreover, serial dilutions are easily formatted because the volume dispensed is selectively variable for any column.
The Sciclone ALH can accommodate up to six (Four if configured with the Z8 option) bulk reagent dispensers each with its own fluid path using either a syringe pump (this study) or a peristaltic pump. Our results clearly demonstrate that the bulk reagent dispenser can easily dispense a wide range of volumes with an exceptional degree of precision.