The primary goal of any laboratory is to collect and analyze data, and it is rare for many samples to be ready for analysis the moment they enter the lab. Samples may need cleanup or purification prior to downstream analysis. Standards and controls may need to be created and analyzed with the samples in order to form a baseline against which the samples will be compared. Samples themselves may need to be modified (pH adjustments, solvent composition, sample derivatization, etc.) in order to make them more amenable to the analysis technique(s) that will be used. It’s clear that obtaining data is generally more complicated than simply inserting a sample into a machine for analysis and getting the desired result at the end.
If you are not convinced already, sample preparation procedures are often among the most time-consuming and labor-intensive functions within the laboratory. Because of this, they are often the prime candidate for introducing error and inefficiencies into the sample analysis process. Sample preparation procedures often consist of a series of monotonous tasks, making it difficult for laboratory personnel to maintain focus and concentration for long periods of time when these procedures are performed manually. Sample preparation procedures require just as much care and attention as the final sample analysis, because small errors can be magnified and propagated throughout the process and skew the final results.
Automation can address many potential bottlenecks and sources of error within the sample preparation process, improving process efficiency, personnel efficiency, and confidence in data obtained. When comparing automated solutions vs. manual methods, the following items should be considered:
The potential throughput of laboratory personnel is limited to the hours present within a workday while automated solutions operate at any time of the day, including unattended operation overnight or over the weekend.
The consistency of work completed by laboratory personnel can vary from person to person, and even from one instance of work to another when finished by the same person. But liquid handling instrumentation can be used to produce reliable and consistent results every time.
Liquid handling instrumentation and software packages provide a level of fine-tuned control over the sample preparation process—a level of control not typically possible when performing procedures using manual methods. Time dependent parameters such as flow rate, or the parallelization of time dependent processes, such as incubations or derivatizations, would be difficult, or nearly impossible, for laboratory personnel to perform on a consistent basis.
In order to highlight the benefits of an automated workflow, an application which involves sample weighing is presented below. This application was performed on a GX-281 Prep Liquid Handler (Gilson, Inc.: Middleton, WI) utilizing a CPA324S Analytical Balance (Sartorius AG: Goettingen, Germany), under software control using TRILUTION® LH v3.0 (Gilson, Inc.). Software control of the balance was achieved using GEARS (Gilson, Inc.), a set of software tools designed to integrate third party devices with TRILUTION LH v3.0. A summary of the liquid handling procedure is below:
- Tare balance, prior to transfer of tube.
- Transfer tube (empty) in specified well from rack to balance, and record the tube weight.
- Transfer specified sample volume to tube, and record total weight.
- Calculate sample weight.
- Transfer tube (with sample) to original rack location.
- Record well, sample volume, tube weight, total weight, and sample weight to spreadsheet for later analysis.
- Repeat steps 1-6, for each sample to be processed.
The liquid handling procedure was programmed in TRILUTION® LH v3.0, by utilizing a sequence of Operators and Tasks which were dragged into the Method Builder Workspace, resulting in a series of actions which mirrored the manual process (Figure 1). A Sample List was then created using the Application Builder of TRILUTION LH v3.0, where a Well and Sample Volume was defined (Figure 1). Finally, the Application was executed, and the instrumentation performed the sample preparation procedure unattended.
During the execution of the Application, data obtained from the balance was recorded to a spreadsheet (in addition to the Well and Sample Volume), which was later used to determine the precision and accuracy of sample delivery performed on the liquid handling system (Table 1).
The procedure described above represents a typical workflow for a laboratory process which requires the transfer of liquid samples from one location to another, coupled with the integration of a balance to record data for auditing purposes (in this case, to provide a means of measuring the volume of sample delivered, gravimetrically). As part of a larger overall sample analysis process, the data obtained in this application could provide a valuable piece of information for auditing purposes, or perhaps could be used as an input into a subsequent part of the process.