TY - JOUR A1 - Hennig, Andreas A1 - Hoffmann, Angelika A1 - Borcherding, H. A1 - Thiele, T. A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Simple colorimetric method for quantification of surface carboxy groups on polymer particles T2 - Analytical chemistry N2 - We present a novel, simple, and fast colorimetric method to quantify the total number of carboxy groups on polymer microparticle and nanoparticle surfaces. This method exploits that small divalent transition metal cations (M2+ = Ni2+, Co2+, Cd2+) are efficiently bound to these surface functional groups, which allows their extraction by a single centrifugation step. Remaining M2+ in the supernatant is subsequently quantified spectrophotometrically after addition of the metal ion indicator pyrocatechol violet, for which Ni2+ was identified to be the most suitable transition metal cation. We demonstrate that the difference between added and detected M2+ is nicely correlated to the number of surface carboxy groups as determined by conductometry, thereby affording a validated measure for the trueness of this procedure. The variation coefficient of ~5% found in reproducibility studies underlines the potential of this novel method that can find conceivable applications for the characterization of different types of poly(carboxylic acid)-functionalized materials, e.g., for quality control by manufacturers of such materials. PB - American Chemical Society CY - Washington, DC KW - Polymer surface KW - Complexometry KW - Quantification KW - Pyrocatechol violet PY - 2011 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/23892 AN - OPUS4-23892 SN - 0003-2700 SN - 1520-6882 VL - 83 IS - 12 SP - 4970 EP - 4974 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany