Dilutor system

The Seralyzer system (Fig. 42) consists of the individual components pipette and dilutor system, reagent carrier, method-specific measurement module, calibrators and a reflection photometer. 

The analysis speed is determined (a) by the ICP or AA system flush-out characteristics and (b) by the mixing and sample-transfer rates of the dilutor. TTie latter can readily be adjusted by increasing the flow-rate of the peristaltic pump tubes. The steady diluted stream can easily be adjusted in order that only a few seconds is required to flush out the previous sample and to set up a steady stable flow. Although peristaltic pumps are... 

Fig. 9.6. Schematic representation of die BEST system (Brnker Biospin see also [21]). 1, Bottle with transport liquid 2, dilutor 402 single syringe (5mL) with 1100 iL tube 3, dilutor 402 3-way valve 4, sample loop (250-500 pL) 5, 6-way valve (standard version) loading sample 6, 6-way valve (standard version) injecting sample 7, injection port 8, XYZ needle 9, rack for sample vials 10, rack for recovering vials 11, rack for washing fluids and waste bottle (3 glass bottles) 12, external waste bottle 13, flow probe with inner lock container 14, inert gas pressure canister for drying process.

Since the Seralyzer system partly requires the use of diluted serum or plasma, a pipette system or a dilutor unit must be kept ready (Fig. 43). The entire system consists of one each 30 pi and 100 pi air displacement micro-pipette, a... 

As throughput needs increase, add additional independent sample dilutors and assay robots. If needed, evaluate customized systems that may offer higher throughput, but be mindful of the difficulty in validating custom software in a GLP environment. 

Sample dilution is one of the most labor-intensive tasks in running an LBA. Add standard curve and quality control dilution (which these systems can easily do) [8], and it becomes over half the effort to run an assay. Depending on the specific practices of a laboratory, samples can be diluted in duplicate, triplicate, at four serial dilutions, at eight serial dilutions, with one or more sample diluents, at different dilutions for each sample, and from different size tubes (e.g., clinical versus nonclinical). Similarly, standard curve and control dilutions can be performed in a variety of ways. For these reasons, it can be challenging to implement an automated dilutor to meet all of these requirements. 

As mentioned in a previous section, one of the goals in implementing an assay robot is to make the manual and automated methods as similar as possible. If this is done successfully, then system qualification becomes a fairly simple proposition. As with automated dilutors, it is recommended to compare to a validated manual... 

Automated sample dilutors and assay robots can independently have a beneficial impact on a laboratory s efficiency and throughput. Further improvements can come from integration of the two types of systems and a LIMS. There are many ways of accomplishing this, based on the needs of an individual laboratory however, two general approaches are described ... 

A representative example of a flexible, single-parameter analyser with final transfer is the Vitatron Akes, depicted In Fig. 8.5. In the aspiration position, the sample meets the reagent or diluent stream and the reaction mixture is subsequently transferred to the measuring cuvette, from which it is flushed by the aspiration system after detection, the cuvette being suitably washed. The instrument includes a linear sample train, sample turntable, sampling head, dilutor, reagent dispenser, data-input keyboard, photometric detection system, computer, printer, evacuation pump and wash solution doser. It is prepared for kinetic measurements. 

Dedicated Analyzers. A wide choice of such systems, with varying degrees of automation, are available for clinical applications. One of the most prevalent is an atomic-emission spectrometer that generates both Na and K concentrations simultaneously on separate readouts a matter of seconds after a sample is aspirated. Automatic dilutors are commonly built in. Auto samplers and printers are generally available as optional attachments. Some of these systems are readily converted to Li assays when needed. 

A modification of this method was proposed by Leroi et al. (77LER1). It is based on time function how solute is eluted (stripped) by inert gas from a mixture in the saturator ( exponential dilutor ). The concentration must be monitored periodically by gas chromatographic analysis. Then, if the detector is properly calibrated, the method may be applied to the determination of limiting activity coefficients in multicomponent systems. The method is rapid and simple. 

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