Bomin Kim (Department of Chemistry, Kyungpook National University, Daegu, 41566, Republic of Korea)

Sunghwan Kim (Department of Chemistry, Kyungpook National University, Daegu, 41566, Republic of Korea)

Bomin Kim (Department of Chemistry, Kyungpook National University, Daegu, 41566, Republic of Korea)

Sunghwan Kim (Department of Chemistry, Kyungpook National University, Daegu, 41566, Republic of Korea)

In marine environments, microplastics can undergo surface oxidation and photodegradation under sunlight, releasing dissolved organic products. However, previous studies have mainly focused on the distribution, physical behavior, and ecotoxicity of microplastics, while quantitative assessment of photodegradation products remains challenging due to limited availability of standards and sample preparation constraints. This study aimed to develop a quantitative method for PET photodegradation products based on a standard material–TOC relationship. PET was photodegraded under artificial seawater conditions to prepare samples, followed by TOC analysis and LC-MS/MS-based quantitative analysis. First, SPE pretreatment and concentration were performed, and nine standard compounds were selected through qualitative analysis from PET-derived and plasticizer-derived photodegradation-related compounds. The same samples were then analyzed for TOC, and LC-MS/MS conditions suitable for quantification were applied. Correlations between calibration curves of the selected standards and TOC values were evaluated, and a quantification factor for PET photodegradation products was derived from these relationships. This study proposes a practical approach for indirectly estimating the abundance of PET-derived photodegradation products in complex seawater samples using TOC values. It also provides a basis for the quantitative evaluation of microplastic photodegradation products.