The invention provides incorporating techniques, detector techniques and extraction techniques. A method for producing a system adapted to interact with a dissolved species, the method comprising providing a first component incorporating a complexing functionality, X, and a polymerisable functionality, R, the complexing functionality being capable of forming a complex with the dissolved species, and providing a second component polymerisable with the first component, the method involving contacting the first component with a species with which it complexes and subsequently contacting the complexed first component with the second component and polymerising the two to produce a polymer incorporating the complexing functionality X, the method further comprising the removal of the complexed species from the functionality X, wherein the complexable functionality is selective from functionalities of the formula: = CTCOOH, where T is hydrogen or any halogen, (most preferably chlorine) methyl and halogen substituted forms thereof; or CCOOH; ou PhCOOH.