Quantitative analysis of polypropylene glycol polymers by liquid chromatography tandem mass spectrometry based on collision induced dissociation technique.

Polypropylene glycol (PPG) is a commonly used synthetic polymer in many fields. Investigating the toxicity and pharmacokinetic behavior of PPG polymers is necessary and important for evaluating their safety in medicine and daily cosmetics. In this study, PPG425, PPG1K and PPG2K were selected as the target polymers for cytotoxicity and cellular pharmacokinetics study of PPG polymers. Structural diversity and polydisperse molecular weights (MWs) are significant challenges for quantification of PPG polymers by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Collision induced dissociation in source or collision cell generated a series of PPG-related product ions at m/z 59.0, 117.1, 175.1, 233.2, 291.2, 349.3, 407.2, 465.3 and 523.5 corresponding to fragments containing 1, 2, 3, 4, 5, 6, 7, 8, 9 repeating propylene oxide subunits. PPG425 was determined by the sum of the MRM acquisitions used the transitions [M+H] precursor ions → product ions. PPG1K and PPG2K were determined by the MRM acquisitions used the transitions [M+H] precursor ions → product ions at m/z 233.2(four subunits)→59.0(one subunit). Based on the collision induced disassociation technique and structural specific product ions, pharmacokinetic studies of PEG425, PPG1K and PPG2K were successfully conducted in McF-7 cells. The experimental results revealed that PPG polymers are not biologically inert and they can enter into McF-7 cells. The safety of PPG polymers should be considered when they are used as pharmaceutical or cosmetic excipients.