Traditional polymer-separation methods, such as size-exclusion chromatography and (gradient) liquid adsorption chromatography, cannot provide separations exclusively based on the number of deprotonated carboxylic-acid groups along the backbone chain of polymers. A novel separation method, based on non-aqueous ion-exchange chromatography (NAIEX), was developed, which allows such a separation of acid-functional polymers that are soluble in organic solvents. The polar, aprotic N-methyl-2-pyrrolidone was found to be a suitable solvent. It features a high relative permittivity (favouring dissociation of ion pairs into free ions) and it is a good solvent for polymers and organic salts, such as triethyl-ammonium formate. A negative charge is established on these polymers by deprotonation of the carboxylic-acid groups in the presence of an organic superbase (tetramethyl guanidine). Traditional potent organic bases, such as triethylamine, do not possess the base strength to compensate for the increase in pK_a of polymeric carboxylic acid groups in non-aqueous conditions. Triethyl-ammonium formate is proposed as an alternative to traditional salts used for elution in aqueous ion-exchange chromatography. Separation was performed on an industry-standard strong-anion-exchange column and (near-)universal detection of the polymers was performed by high-temperature evaporative-light-scattering detection. The NAIEX method yielded a separation based on the acid-functionality distribution of the polymer. NAIEX was compared with traditional normal- and reversed-phase liquid-chromatography approaches for the separation of acid-functional copolymers.

传统的聚合物分离方法（例如尺寸排阻色谱法和（梯度）液体吸附色谱法）不能仅基于沿聚合物主链的去质子化羧酸基团的数量提供分离。开发了一种基于非水离子交换色谱法（NAIEX）的新型分离方法，该方法可分离可溶于有机溶剂的酸官能聚合物。发现极性非质子的N-甲基-2-吡咯烷酮是合适的溶剂。它具有较高的相对介电常数（有利于离子对解离成游离离子），并且是聚合物和有机盐（例如甲酸三乙铵）的良好溶剂。通过在有机超碱（四​​甲基胍）存在下使羧酸基团去质子化，可在这些聚合物上建立负电荷。传统的强效有机碱（例如三乙胺）不具备碱强度来补偿p的增加在非水条件下的聚合羧酸基的K _a。提出了甲酸三乙基铵作为在水离子交换色谱中用于洗脱的传统盐的替代品。在工业标准的强阴离子交换柱上进行分离，并通过高温蒸发光散射检测对聚合物进行（几乎）通用检测。NAIEX方法根据聚合物的酸官能度分布进行分离。将NAIEX与传统的正相和反相液相色谱方法进行了酸官能共聚物的分离。