A number of laboratory settings require the accurate handing of large volumes of samples. In industries such as forensics, clinical monitoring, toxicology, pharmaceutical high throughput screening, environmental toxicology, agricultural pesticide residue analysis, and synthesis and purification during combinatorial chemistry, large numbers of similar samples are processed using an array of methodologies including Solid Phase Extraction (SPE), filtration and derivitization. The large number of samples involved and the perishable nature of some of them makes speed in analysis of the utmost importance. Balanced against this need for speed is the need for accuracy. In some cases tight government regulation of these industries requires that strict standards for accuracy and reproducibility of assays be met.
In answer to these requirements, devices have been developed that allow for the simultaneous processing of multiple samples in automated systems. In standard devices of this type, a well block is provided having either 48 or 96 wells in ordered rows. These wells accommodate a similar number of sample reservoirs for processing and filtration of the samples to be analyzed. The sample reservoirs may take the form of a modified tube with a luer tip. The sample reservoirs may be packed with a resin or filtration media. When assembled in the well block, the reservoirs are typically connected or touching. These devices are used as stand-alone systems or in conjunction with automated robotic fluid handling systems.
The blocks are sized and dimensioned to fit vacuum manifolds necessary for applying vacuum to the luer tips to effect filtration of the processed samples and to be compatible with the automated equipment. The size of the well block is therefore limited by the dimensions of the vacuum manifold and the requirements of the associated equipment. The size of the well block and the ordered arrangement of the wells necessarily places limits on the size of the sample reservoirs that can be used with the well block. Typically, samples reservoirs used with current well blocks have a nominal capacity of 2 mL or less, depending on the filtration media or packing used. Additionally, when installed in the well block, most current sample reservoirs are in physical contact with one another.
The design of the well blocks currently in use presents several problems. Very often in the applications where these devices are used, the samples tested are very dilute or require a large amount of analyte. For this reason, it is very often necessary to fill the small sample reservoirs to near capacity to obtain a sample with sufficient analyte. This combined with the contiguous arrangement of the sample reservoirs often leads to cross-contamination of the samples. Additionally, it is sometimes not possible to introduce enough sample to the sample reservoir to obtain the accuracy or reproducibility required for some assays.
It would be desirable to provide a well block for use with a standard vacuum manifold that overcomes the limitations of the current designs by allowing the use of larger sample reservoirs. It would further be desirable to provide a well block in which the sample reservoirs are not in physical contact when assembled in the well block. It would further be desirable to provide such a well block that is compatible with the instruments and assays currently in use in all laboratory environments. It would still further be desirable to provide such a well block that can be either re-usable or disposable after use.