Aliquoting liquids from one plate or position to another is a very common step in automated liquid handling workflows. An aliquot can be a simple transfer from a source plate (i.e., one that already contains some mixtures) to another plate, or a transfer from a previously simulated workflow to a new destination plate. This technical note outlines a workflow that transferred liquids from one plate to another using the Aliquot element. The workflow was executed on three liquid handlers: a Gilson PIPETMAX 268, a Hamilton Microlab STAR and a Tecan Freedom EVO.

This technical note has been used to validate liquid handling accuracy for the volumes of liquid (tartrazine) transferred when aliquoting, and provides a starting point for any liquid handling optimization should it be required.

Within this workflow (Figure 1), the liquid handler of choice aspirated and dispensed a 0.1mM tartrazine solution from one plate to another.

Figure 1: Aliquot workflow in Synthace. This workflow describes a method for aliquoting liquids to 2 plates. The Define Liquids And Plates element describes the reagents to be used in the experiment. This is connected to the Aliquot 1st Plate element, which enables the user to select tartrazine as the liquid to use and set the different volumes to be dispensed across the plate. The liquid information and the plate layout to use from this element flows through to the Aliquot 2nd Plate element by wiring the two elements together.

Aliquot volumes were specified at 200 µl, 175 µl, 100 µl and 75 µl with multi-channelling enabled. To demonstrate intra- and interplate variability, each aliquot was performed in triplicate on two replicate plates, generating 24 replicates per volume per plate, 48 replicates in total (Figure 2). This workflow was executed over three devices: a Gilson PIPETMAX 268, a Hamilton Microlab STAR and a Tecan Freedom EVO.

Figure 2: Execution Details Preview in Synthace. Users can simulate, preview and verify their experiments in silico prior to physical execution demonstrated here on the Hamilton Microlab STAR.

Labware information and estimated execution run times for each of the liquid handling devices is shown in Table 1. The workflow was run on all three devices on the same day. Tartrazine absorbance was measured using a BMG Labtech CLARIOstar microplate reader at 425 nm (Tartrazine 𝜆max), and baseline subtraction performed with absorbance at 620 nm. Data was processed and graphs were generated by a python script in Jupyter Notebook and can be accessed from the Downloads section at the end of this article.

Table 1: Liquid handling information

Independent measurements, and intra- and interplate variability for aliquots at different volumes of tartrazine, were calculated for samples prepared across the different devices tested (Figure 3).

With multi-channeling enabled and using the Water liquid policy that is readily available within Synthace, high precision and low variability could be demonstrated across all devices for all aliquots (Figure 3). The average intraplate coefficient of variance (CV) was 0.93% (Gilson PIPETMAX 268), 2.04% (Hamilton Microlab Star), and 1.18% (Tecan Freedom EVO). The average interplate CV was 0.35% (Gilson PIPETMAX 268), 0.52% (Hamilton Microlab STAR) and 0.15% (Tecan Freedom EVO)).

Figure 3: Absorbance data for aliquots prepared across three devices. Corrected absorbance values of tartrazine at different volumes for (A) Gilson PIPETMAX 268, (B) Hamilton Microlab STAR and (C) Tecan Freedom EVO. Each data point represents an individual replicate. Coefficient of variation (% CV) for each set of replicates on each plate, (D) intraplate variation, and across both plates, (E) interplate variation. Dashed horizontal lines represent Synthace internal validation standards for % CV maximum thresholds.

The following file contains the workflow that was discussed in this technical note. To download the file, right-click the button, then select Save as.

After you download the file, complete the following steps.

The following file contains the raw data that was discussed in this technical note. To download the file, right-click a button, then select Save as.

If you want to process the raw data in the way that was discussed in this technical note, download the Jupyter Notebook or Python scripts. You must edit the scripts to point at the directory that contains the raw data.