in the front of the chiller plate 50 then the bottom of the tubing 58 goes into an entry tube to the pump head 80 because of the negative 10 degrees c nominal temperature of chiller plate 50 co 2 rapidly liquefies prior to reaching the outlet 60 of the tubing 58 when it enters the pump head 80 thus co 2 is a gas when it enters the heat exchanger peltier tubing 58 and exits as a liquid ready for compression within the chiller plate 50 there is a limited volume of the tubing 58 for example about 40 to 45 cm of tubing so it can provide a few hundred microliters of total volume in the tubing 58 an alternative embodiment for a chiller plate 50 tubing 58 arrangement is to use a high surface area plate and expose the plate to a cavity or volume a larger volume with a high surface area plate such as with fins placed against a peltier unit creates a larger volume of gas in the liquid which can be siphoned out of the bottom of the unit another alternative embodiment is to coil the tubing continuously instead of a serpentine arrangement a further alternative uses two peltier units instead of just one for a chiller arrangement to extend the volume that can be liquefied after compression at the pump head 80 the flowstream of compressed co.