Dilution automated workstation

Dilution. It is important to be aware that the dilution process utilized by the automated workstation may differ from a manual process. Adjustments in dilution factors may be required and considerations of the density value of the diluting solvent and sample filtrate are valuable. In some cases the dilution step can be avoided when designing the automated sample preparation through initial volume adjustment whenever possible and/or through changes in the injection loop size to achieve proper column loading. 

The focus of automation is not solely on HPLC anymore (since it is automated), but also includes the sample preparation procedure for drug products since it involves many labor intensive steps (weighing, addition of sample solvent, extraction procedure, mixing, filtration, additional dilutions, second mixing, etc.). So, if the sample preparation procedures are automated and combined with HPLC, then the entire analysis is said to be fully automated whether it is for assay, CU, blend analysis, or even for dissolution testing. Such automated workstations are currently available from number of vendors (Caliper Life Science, SOTAX Inc.), but their ability to integrate with HPLC or UV spectrophotometer is left to the end users. This open-ended option depends on the end user requirements. 

A comparison of automated pipetting with manual pipetting, by Weltz [16]. demonstrates a difference of approximately one order of magnitude 0.4% RSD for automatic sample introduction versus 3.2% RSD for manual sample introduction. To achieve optimum results for trace elements in biological materials, the use of dedicated automated samplers is recommended. The Hquid-handhng capabihties of a pipetter/diluter workstation have been evaluated at Ortho Pharmaceutical (Haller et al. [17]). Four different volumes of each of three solvents were dispensed 20 times. Actual volumes... 

Recently, automated sample preparation approaches utilizing parallel sample processing have been described for SPE [10], LLE [9], simple dilutions [11], and protein precipitation [8]. These procedures utilize commercially available workstations for liquid handling in a 96-well multichannel plate format. These workstations are evolving rapidly and are constandy gaining additional capabilities. A recent article has reviewed the most common types and describes the major advantages of each [36]. 

---