Probot is designed for on-line collection of microliter and nanoliter fractions eluting from nano and capillary LC systems with highest reproducibility. Collection is possible on many different types of substrates (i.e., MALDI targets, PVDF membranes, 96, 384, or 1536 well plates or microchip structures). Additionally, the instrument can pipette or dispense samples and reagents. Probot is a versatile instrument, allowing the use of almost any MALDI target from different vendors.

Small nanoliter volumes can be collected onto MALDI targets with zero chromatographic dispersion to maintain the high resolution of the separation system. For high throughput, up to six high-density targets (576 spots each) can be placed on the table deck, allowing for the collection of 3456 spots in a fully automated run.

Probot can add matrix or makeup solutions with the microdosage pump while spotting nano LC fractions onto MALDI targets. For larger collection volumes, the matrix addition can be done coaxially at the needle tip. For smaller collection volumes, the addition is made prior to the spotting needle.

Probot moves its collection table and not the needle, which remains in a fixed position, allowing precise spotting of nanoliter volumes. All axes are controlled by reference switches with a reproducibility of ±1 motor step (2.5 µm), resulting in a table positioning precision of better than 20 µm. Due to this excellent precision, high-density MALDI targets with several hundreds spots or microchip structures can be used routinely for fraction collection.

The use of a fixed needle allows for the collection and spotting of small nanoliter volumes, impossible with a moving needle due to capillary forces.

In dual-collection mode, a fraction can be split over two different sample carriers (i.e., MALDI targets and well plates or PVDF membranes). The split ratio is programmable.