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ABSTRACT Ion chromatography is the anion analysis benchmark. A miniature form, Open Tubular Ion Chromatography (OTIC), has attractive attributes for efficient ion separations. Here, we fabricate and characterize high‐density polyethylene (HDPE) open tubular anion exchange columns (OTCs). We attach positively charged latex particles onto negatively charged capillary surfaces. For efficient OTIC, column diameters need to be < ∼20 µm; functionalizing the bore is challenging. Methods to introduce acid groups to an HDPE capillary bore, e.g., sulfonation using chlorosulfonic or sulfuric acid solutions, with or without grafting of an aromatic ring through photo‐ or chemical grafting first, are explored. Following quaternary ammonium latex attachment, the ion exchange capacity and separating abilities of each OTC were measured as an index of OTC performance. Gradual loss of capacity was observed for many of these; high‐resolution mass spectrometry confirmed the leaching of detached oxidized/sulfonated oligomeric fragments and consequent poisoning of the latex sites. Ways to ameliorate this and/or to rejuvenate the columns are also described. 

Poly‐ and perfluoroalkyl substances (PFAS) are a class of persistent organic pollutants whose high stability and appreciable water solubility have led to near‐global contamination. PFAS are bioaccumulative toxins that have been linked to a myriad of disorders and have been detected nearly universally in human blood. Liquid chromatography‐tandem mass spectrometry is the most frequent method used for quantitation, though this typically only measures a few dozen of the >14 000 known PFAS and has been shown to account for a small portion of the total organic fluorine present. Sum parameter methods such as total, extractable, and adsorbable organic fluorine have emerged as alternative measurements for PFAS determination. Combustion ion chromatography has become the preferred method for organofluorine measurement where the sorbent or extract containing PFAS is combusted and the emitted hydrofluoric acid (HF) is a measure of the cumulative organofluorine present. Herein we critically review the types of organofluorine measurement, their separation from the sample matrix, and key parameters of the analytical instrument that affect sensitivity, reproducibility, and recovery with regards to PFAS analysis.