A highly efficient sample introduction system for interfacing micro. uidic chips with ICP-MS

A sample introduction system specifically designed for interfacing laboratory on a chip devices with ICP-MS is presented. The development and optimisation of this highly efficient interface is described. This system uses an extremely low. ow micro-cross-flow nebuliser (MCFN) sited directly at the liquid exit of the chip. An evaporation chamber has been incorporated into the interface in order to prevent the losses associated with traditional spray chambers, allowing the entire sample aerosol to enter the plasma. The optimised system achieved a sensitivity of 13 500 cps for 10 mu g L-1 indium at 5 mu l min(-1). The stability of the sample introduction over 10 min was 2.6% RSD (n = 453) and no sample recondensation was ever observed in the evaporation chamber at. ow rates up to 20 mu l min(-1). Hydrodynamic sample injection was performed via a manual switching valve, with a reproducibility of 5.10% RSD (n = 6). Sample volumes of 440 nl can be analysed. The advantages and potential applications, in particular for elemental speciation, are discussed.