On-line suppressor

The method of analysis of sample ions in a liquid sample comprising:

• a) providing a device comprising an inlet opening and an outlet opening and an inner diameter, wherein there is an aperture through one side of the tube into a lumen of the tube, wherein at least a portion of the inner surface of the tube has a first charge
• wherein there is an ion exchange barrier covering the aperture on the outside of the tube,
• wherein the inner surface of the tube, from the inlet opening to the aperture, is coated with ion exchange particles, wherein the ion exchange particles have a second charge opposite the first charge,
• wherein the inner surface of the tube, from the outlet opening to the aperture, is not coated with ion exchange particles
• b) using an eluent comprising ions to flow a liquid sample comprising sample ions to be detected through the tube,
• c) exchanging eluent counterions of the eluent using the ion exchange barrier to remove eluent counterions from the lumen,
• d) detecting the ions of the liquid sample with a detector.

The method of making an ion chromatography device comprising the steps of:

• provide a tube with an inlet opening and outlet opening and an inner diameter of from about 40 microns to about 10 microns,
• functionalizing the lumen to provide charged functionality
• remove a portion of the tube to form an aperture into the lumen of the tube,
• simultaneously flow a suspension comprising ion exchange nanoparticles, oppositely charged to that of the tube lumen, into the inlet opening and a first fluid into the outlet opening so they both exit through the aperture,
• remove excess unbound nanoparticles by flowing a second fluid through the inlet opening while flowing the first fluid through the outlet opening so they both exit through the aperture,
• cover the aperture on the outside of the exposed lumen with an ion exchange barrier.