With the enhancement of environmental awareness,VOC-free coalescent agents attract more attentions.However,some concerns have been raised that high boiling point of VOC-free coalescent may lead to high level of coalescent residue in paint films,consequently affecting some paint film properties.To clarify the issue,it is important to quantify coalescent level in paint films and understand a correlation between the coalescent level and film performances.In this study,a new quantitative method based on pyrolysis GC-MS was developed.The results indicated that the developed method is applicable to monitoring coalescent change during drying process,and determining coalescent concentration level in dry paint films.The quantitative limit of the method is about 30 ppm,and relative standard deviation(RSD)for four parallel experiments is about 10%.