For the first time, matrix-assisted laser desorption/ionization (MALDI) method was successfully applied for identification of the concentration of individual polyethylene glycol (PEG) oligomer used in the complex mixture solutions used for evaluation of separation performance of nanofiltration membranes. As a result, it was possible to plot MWCO curve based on the filtration complex solution contained PEG oligomers with a molecular weight of up to 2000 g/mol. To eliminate the influence of porous support, the dense membranes made of two polymers of intrinsic microporosity, poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) and poly(4-methyl-1-pentene) (PMP), were selected in this study. It was found that the molecular weight cut-off (MWCO) parameter for PTMSP and PMP determined by using of linear PEG were as 1550 ± 30 and 910 ± 30 g/mol, respectively. Such noticeable difference in MWCO was explained by the fact that PMP has about 2 times lower fraction accessible volume comparing with PTMSP (FAV_PTMSP = 30%, FAV_PMP = 16%). It was shown that the branched PEGs, trimethylolpropane ethoxylates (TMPE), can overcome the problem of high flexbility of linear PEGs. For example, the corresponded MWCO values for PTMSP and PMP determined with TMPE were 910 ± 30 and 820 ± 30 g/mol, respectively.

首次将基质辅助激光解吸/电离（MALDI）方法成功用于鉴定用于评估纳滤膜分离性能的复杂混合物溶液中所用的单个聚乙二醇（PEG）低聚物的浓度。结果，有可能基于包含分子量高达2000 g / mol的PEG低聚物的过滤复合溶液绘制MWCO曲线。为了消除多孔载体的影响，我们选择了由两种具有固有微孔性的聚合物制成的致密膜，聚（1-三甲基甲硅烷基-1-丙炔）（PTMSP）和聚（4-甲基-1-戊烯）（PMP）这项研究。发现通过使用线性PEG测定的PTMSP和PMP的分子量截留（MWCO）参数分别为1550±30和910±30g / mol。FAV _PTMSP  = 30％，FAV _PMP  = 16％）。结果表明，支链PEG三羟甲基丙烷乙氧基化物（TMPE）可以克服线性PEG的高柔韧性问题。例如，用TMPE测定的PTMSP和PMP的相应MWCO值分别为910±30 g / mol和820±30 g / mol。