Detection and Quantification of Polyquaterniums via Polyion-Sensitive Ion-Selective Optodes Inkjet Printed on...

A universal method for the detection, quantification, and characterization of polyquaterniums (PQs) in a simple background electrolyte solution and in more complex recreational swimming pool water samples is presented. This method involves the application of polycation-sensitive ion-selective optodes (ISOs) prepared by inkjet printing dinonylnaphthalenesulfonic acid (H⁺DNNS^-) and chromoionophore I directly onto Whatman^TM qualitative filter paper. No plasticizer or added polymer matrix is required for the fabrication of the sensing layer which is coated on the cellulose fibers of the filter paper. PQ-6, PQ-2, PQ-10, and poly(2-methacryloxyethyltrimethylammonium) chloride (PMETAC) are used as model PQ species for direct optical detection at ppm levels. We further demonstrate that PQ-6 can be detected in recreational swimming pool water samples using this new type of sensor, and that detection of polyanions is also possible using an indirect detection method. Lastly, to circumvent the challenge of polyion-sensitive ISOs exhibiting a pH dependence, the sensors were soaked in buffer and dried to provide local buffering for applied liquid samples and an optical signal independent of sample pH.