Use of a liquid chromatograph‐ion trap mass spectrometer for end‐group characterization of various polyethoxylate materials

The separation and detection properties of various ethoxylated polymers were investigated with atmospheric pressure ionization liquid chromatography/mass spectrometry (LC/MS). Interesting chromatographic elution behavior based on functionality was noted. LC/MS using in‐source CID (collision‐induced dissociation) and tandem mass spectrometry (MS/MS) detection was compared for end‐group identification. Excellent end‐group identification was achieved when the end‐group molecular weight (MW) was greater than 100 Da and the average MW of the polymer was less than 400 Da by both MS/MS and in‐source CID. In cases where the end‐group MW was less than 100 Da, because of the low mass cut‐off in a quadrapole ion trap analyzer, in‐source CID produced the only characteristic end‐group ions. The use of a dual scan function allowed investigation of the oligomeric distribution followed by a narrow low‐mass scan using in‐source CID to generate end‐group information. This approach is applicable on instruments without MS/MS capability.