Robotic stations

Compatibility between sensors and automatic and automated analytical systems is crucial as it allows two Analytical Chemistry trends to be combined (see Fig. 1.1). Probe-type and planar sensors can be used in automated batch systems including robot stations, as well as in continuous (mixed in-line/on-line) systems. On the other hand, flow-through sensors are only compatible with continuous configurations. 

Figure 2.17 compares the different ways of regenerating flow-through sensors with the normal procedure for probe sensors the probe is successively immersed in the sample and buffer solution and removed from it prior to immersion into the next sample, which hinders automated functioning unless a robot station is lised (Fig. 2.17.A). On the other hand, on-line coupled flow-through sensors in continuous configurations lend themselves readily to convenient, automated regeneration.

In this chapter we will discuss current approaches for analytical characterization of combinatorial libraries in a pharmaceutical industry environment. Recently, several analytical groups have presented very similar strategies for analysis of libraries [7-9]. As will be shown later, the key to successful analytical characterization of a combinatorial library is to perform analytical and chemical work in parallel with the library development. The accumulation of data and analytical experience during this process results in an assessment of library quality with a high level of confidence, even if as little as 5-10% of the library components are analyzed. Utilization of the strategy will be demonstrated using two examples analysis of a library synthesized on a robotic station in spatially addressed format and analysis of a library synthesized in accordance with split-and-mix technology. 

An example of a scheme for analysis of a library synthesized on a robotic station in 96-well microtiter plates is shown in Figure 10.1. The milestones that need to be reached during the library development process are presented on the left side of the figure, and the goals to be achieved in order to surpass the corresponding milestone are on the right. 

Finally, the development of automated methods for wet decomposition of solid samples without human participation can only be achieved with the use of a robotic station [183]. Nevertheless, a number of auxiliary energies and commercially available modules can facilitate and/or accelerate this time-consuming step of the analytical process (i.e., obtain the analyte(s) from a solid sample in the form of a solution). 

An alternative method, avoiding filtration completely, employs aspiration of the liquid from the surface (42,99). This technology was automated and a robotic station was built that can process up to 72 microtiter plates (6912 compounds) in one batch (100). A robotic arm moves microtiter plates into stations into which the delivery of reagents is performed by 96-channel distributors and solvent aspiration is achieved by lifting the plate against an array of needles attached to a vacuum source. 

Because of their special features, workstations and robotic stations are dealt with separately (in Chapter 10) from the techniques in the previous two groups. 

As noted earlier, not all open-vessel systems (viz. those that operate at atmospheric pressure) are of the focused type. A number of reported applications use a domestic multi-mode oven to process samples for analytical purposes, usually with a view to coupling the microwave treatment to some other step of the analytical process (generally the determination step). Below are described the most common on-line systems used so far, including domestic ovens (multi-mode systems) and open-vessel focused systems, which operate at atmospheric pressure and are thus much more flexible for coupling to subsequent steps of the analytical process. On the other hand, the increased flexibility of open-vessel systems has promoted the design of new microwave-assisted sample treatment units based on focused or multi-mode (domestic) ovens adapted to the particular purpose. Examples of these new units include the microwave-ultrasound combined extractor, the focused microwave-assisted Soxhlet extractor, the microwave-assisted drying system and the microwave-assisted distillation extractor, which are also dealt with in this section. Finally, the usefulness of the microwave-assisted sample treatment modules incorporated in robot stations is also commented on, albeit briefly as such devices are discussed in greater detail in Chapter 10. 

Because robotic technology continues to have some magical connotations in relation to laboratory automation, a number of manufacturers and users still use the words robot and robotic indifferently to refer to both robotic stations and workstations. In addition, any instance of automation is also indiscriminately associated with robotics by many. One case in point is the Internet page http //www.lab-robotics.org/manufact.htm, where... 

The most salient difference between robotic stations and workstations is that, whereas a workstation can only be used for the tasks (all or some) for which it was constructed, robotic stations can be modified by changing their software, modules or peripherals as required to undertake one or more specific tasks, or even a whole analytical process. As a result, describing a workstation is as simple as listing its intended functions, whereas characterizing a robotic station includes stating the type of arm it uses and the equipment that helps the arm perform its tasks. 

Fig. 10.1. Fields of application of workstations and robotic stations according to task complexity and throughput.

The Presto Microplate Labeler, a fast, reliable workstation for printing and applying adhesive bar code labels to microplates which is available as either a standalone workstation, integrated into a robotic station or loaded using the Twister Universal Microplate Handler. 

One of the most important features of a robot, which determines its work envelope (i.e. the maximum extent and reach of the robot) is its position in the robotic station, which can be fixed or variable. The former is used in circular robotic stations, which are typical of Zymark s Py technology. In this configuration, the robotic arm is in the centre of a circle and the different peripherals are included in a work envelope radius as removable pieces of a pie. The work envelope of the arm in this case is 360° and the radius equal to, or shorter than, the extent of the arm (see Fig. 10.3 A). 

A mobile arm in a robotic station is supported in a track (Fig. 10.3B), which allows displacement of the arm in a length that varies, depending on the particular station, from... 

Fig. 10.3. Robotic stations with fixed and mobile arms. (A) Circular, PyTechnology, from Zymark. (B) Linear track, from Hudson. (Reproduced with permission of Zymark Corporation and Hudson Control Group, respectively.)...

The modules of a robotic station are the devices (apparatus, instruments, racks) used by the arm to perform its tasks. In circular configurations, the modules are referred to as peripherals . 

All-purpose hands and syringe hands, available in a variety of designs, are also required elements of a robotic station. Differently sized objects (e.g. sample flasks, test tubes, probes, hold and press push-buttons) call for different types of hand. A syringe hand facilitates the withdrawal of liquids from vessels. Hand design has benefited from innovations devised by academic research groups [10]. 

Additional modules not always required in a robotic station include a cappinguncapping module, used to remove and replace screw caps a bar-code reader, which is usually a laser bar-code scanner combined with a turntable assembly capable of reading a label positioned anywhere around the circumference of a vial and an ultrasonic hath, which is required for sonic mixing or cleaning, but also, occasionally, to facilitate dissolution or leaching. 

Atomic (AAS, DCP-AES) detectors have been coupled to robotic stations either through a continuous system acting as interface [ 11,29] or by direct aspiration into an ICP-AES instrument from a sample vial following treatment by the robot [30]. Mass spectrometric and NMR detectors used in this context are also based on direct aspiration. 

Two essential facts to be considered when purchasing a robotic station are that no single firm builds everything one is bound to need to construct a robotic system tailored to their needs and that not all commercially available equipment operates by the same set of instructions or plays by the same set of rules. Compatibility between modules from different sources should thus be carefully checked prior to purchasing. 

Because workstations can be designed and dedicated to a single, specific task, they are normally simpler mechanically and usually more reliable than are robotic stations. In addition, they can provide a data trail for regulatory compliance and are typically designed to be operated by non-experts. Commercial workstations vary in their level of sophistication, which allows the automation of even the most simple procedures. Economically, automation can benefit anybody running more than 150 samples a day and can justify purchasing a moderately priced workstation. More sophisticated workstations, however, are only profitable with a heavier workload. As a rule, a workstation will replace a 40 000-a-year technician and have a one- to two-year payback period. 

Choosing between a robot plus peripherals and a workstation is a difficult task. From the beginning, automation held the promise of freeing analysts from cumbersome, time-consuming, repetitive tasks. This is especially true with the quality control (QC) laboratory, which must routinely test products such as pharmaceuticals or foods prior to release, often with a well-defined analytical procedure dictated by regulatory requirements. In these laboratories, workstations are typically the best solution as they are often more hardwired and are better in QC laboratories, where the analytical steps are well-understood and this equipment does save laboratories time and money. The best solution for implementing the complex treatments required by some solid samples is the sequential use of two workstations when this is impossible, a robotic station is the next-best choice in most instances. 

Automation of the analytical process by use of robotic equipment (robotic stations and workstations included) can reach from a single step to the whole analytical sequence. The number of steps that are robotized should be dictated by the user s experience and judgement, always as a function of the target process, costs, number of samples to be processed, etc. Straightforward single-task uses of robots, robotic sample preparation procedures and fully robotized methods are discussed below, as are more rational uses in combination with other techniques intended to ensure optimum development of each step of the analytical process. 

Although workstations and even robotic stations commonly perform liquid-liquid and liquid-solid separations, these steps can be implemented in a continuous manner by using a more inexpensive set-up and with shorter development times when the number of... 

USE OE ROBOTIC STATIONS FOR SAMPLE PREPARATION IN ENVIRONMENTAL AND CLINICAL ANALYSIS... 

Most frequently, using a robotic station to develop an entire analytical process is unwarranted. In the mid-1980s, when robotic technology first reached the analytical laboratory, robots were more of a novelty than a useful tool. At that time, conventional manual titrations and similarly easy tasks were entrusted to robotic stations. At present, however, well-established criteria exist to ensure correct use of the potential of robotic technology. 

There are few reported instances of the combined use of an FI manifold and a robotic station operating independently. One is a method for the automatic analysis of used oils by ICP-AES [30]. The robot is used to weigh the oil after the sample is heated, to add the volume of xylene required to obtain a 1 9 weight ratio and to mix the two. The sample thus obtained is used to fill a vial fitted in the autosampler of the FI analyser, which acts merely as a device for automatic insertion of the sample into the ICP spectrophotometer. The link between the two sub-systems [viz. the transfer of both samples and information produced in the robotic operation (dilution of each sample)] is established manually. This approach does not completely dispense with human intervention, although it has been estimated to cut manpower requirements by two-thirds. 

One other application is the automation of a method for the determination of total vitamin C in foods [51]. Here, the robotic station is used for homogenization of the sample, weighing, addition of an extractant, centrifugation, filtration and clean-up through a C j( column. After this treatment, the sample is manually transferred to the FI autosampler. A derivatizing reaction is implemented along the FI manifold to obtain a fluorescent product prior to insertion into the spectrofluorimeter. Although not specifically stated, the information produced is also transferred manually between both systems. 

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