MicroLiter ITSP (instrument top sample preparation) extraction technique

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ITSP (instrument top sample preparation) is an extraction technique that allows the CTC autosampler used on most brands of chromatographs to function as a solid-phase extraction (SPE) or sample filtration robot. ITSP incorporates a septum-sealed needle guide above the sorbent bed that not only creates a sealed system but also allows the SPE device to be carried about the work area.

ITSP uses the liquid handling syringe to deliver reagents and sample directly to the sorbent with constant flowrate and precise volume control. The result is very good reproducibility of extraction for even the smallest volume samples. Elution of the analytes using top-down elution ensures higher recovery into a small elution volume than other microscaled techniques.

The gripping action of the septum also allows for the ITSP device to be transported to any location on the autosampler. By defining waste and elution locations, the device can be prepared in one location and moved to elute the collected compounds in another. Once the extracted analytes are eluted into a clean receptacle, the instrument can discard the cartridge and inject the eluate onto the analytical instrument. ITSP cartridges are available in a wide range of stationary phases, including reverse phase, normal phase, ion exchange and mixed bed phases. The filtration cartridges (0.45 µm) are available with different filtration membranes, including PTFE, nylon and PVDF.

ITSP methods are identical to other SPE methods in all respects other than scale. They enable the extraction of small volume samples without compromise and for a significant reduction in reagent consumption and waste disposal. Because ITSP methods use the same sorbents as conventional SPE, the user’s existing methods may be easily adapted, conferring advantages in automation, speed and sensitivity, and savings in materials costs.