Patent ID: 7693573

Claim:
A Iontophoretic sampling device for non-invasively monitoring the relative levels of two substances present in a biological system, said device comprising: an electrical power supply, a collection assembly comprising a first collection chamber containing a first electroconductive medium in contact with a first electrode and a second collection chamber containing a second electroconductive medium in contact with a second electrode, said electrodes being reversible electrodes and being each in contact with the electrical power supply when the collection assembly is inserted in the iontophoretic device; a means for analysing two or more selected charged and/or uncharged substances in either one or both of the collection chambers in order to determine their extracted amounts, a means for converting the extracted amounts of a first substance and a second substance to the extraction ratio of the first substance to the second substance, wherein said first and second substances are selected in such a way that the transport and/or transference number of the first substance is independent of the transport and/or transference number of the second substance.