We want to quantify immobilized sulfonic acid (e.g. taurine). For taurine there are assays, but would they also work with immobilized taurine (attached over the amino group)? And I suppose these tests would not work e.g. with sulfanilic acid?

Would that work with a total sulfite assay? Or has someone another idea?

EDX would not be an option, as this is not available. A chromogenic approach would be good.

Thanks a lot!