以極致液相層析/串聯式質譜術定量尿液中雙酚類及鄰苯二甲酸酯之代謝物

Abstract

雙酚類與鄰苯二甲酸酯屬於人工合成之化合物，雙酚類用於製造聚碳酸酯塑膠材料及環氧樹脂；鄰苯二甲酸酯則主要做為塑化劑，可使塑膠更具有延展性與耐用性，廣泛應用於日常用品中。人體可能經由吸入、飲食途徑暴露到這些化合物，對人體產生生殖與發育健康影響。生物監測方法透過提供人體檢體中化學物質的資訊呈現暴露量，有利於進一步檢視相關健康風險。本研究以尿液做為生物基質，並測定6種雙酚類與12種鄰苯二甲酸酯的代謝物，評估人體內在暴露劑量。 本研究樣本來自於2019年國民營養變遷調查，共150個尿液樣本，年齡範圍介於14-91歲。本研究先前實驗室的尿液前處理方法，在尿液中加入45 µL的β-glucuronidase /arylsulfatase之混合酵素，於37度C水解40分鐘後，再加入乙腈沉澱蛋白質，經Sirocco 96孔萃取盤過濾，加入20 µL的二甲基亞碸，最後再經濃縮、甲醇回溶。 本研究利用極致液相層析(ultra-performance liquid chromatography)，搭配串聯式質譜儀，以同位素稀釋技術進行定量。所有待測物以Atlantis Premier BEH C18 AX (50 × 2.1 mm, 1.7 µm)管柱進行層析，使用梯度流析，水相為5 mM醋酸銨水溶液，有機相為5 mM醋酸銨之甲醇，管柱溫度為30度，流速為0.5 mL/min，總層析時間為10分鐘。上機標準品檢量線線性範圍大多介於0.5-500 ng/mL。 本研究為了使待測物達到最佳的層析結果優化了移動相條件；共測試四種移動相組合，包含:(1) 5 mM醋酸銨水溶液(A)/甲醇(B)；(2) 5 mM醋酸銨水溶液(A)/乙腈(B)；(3) 5 mM醋酸銨水溶液 + 0.1 %乙酸水溶液(A)/甲醇(B)；(4) 5 mM醋酸銨水溶液(A)/5 mM醋酸銨之甲醇(B)。以5 mM醋酸銨水溶液為水相與5 mM醋酸銨之甲醇為有機相時，大部分待測物有良好滯留與對稱峰型，峰寬介於3-6秒間。方法確效結果顯示，檢量線線性關係良好，判定係數皆大於0.99；待測物基質效應介於42-94%，萃取效率則介於80-129%；同日與異日間定量偏差、相對標準偏差大多小於20%，顯示方法具有良好的定量能力。 尿液樣本定量結果顯示，雙酚A與常見塑化劑 Diethyl phthalate、Di(2-ethylhexyl) phthalate、Dibutyl phthalate、Diisobutyl phthalate代謝物檢出率高於75%，其幾何平均濃度介於3.83-12.5 μg/g-cr，約高於其他待測物1.4倍以上；而替代物如雙酚S以及Bis(2-propylheptyl) phthalate和Bis(2-ethylhexyl) terephthalate代謝物幾何平均濃度分別為0.46、1.21、4.16 μg/g-cr ，並且檢出率99%以上。比較不同性別、年齡與地區暴露差異，發現年齡具有顯著暴露差異(p-value < 0.05)，大部分雙酚類與鄰苯二甲酸酯代謝物之長者(65歲以上)暴露幾何平均濃度(0.06-16.4 μg/g-cr)高於低年齡組(小於65歲，0.03-9.53 μg/g-cr)。綜述而言，本研究提供一個可有效地同時定量尿液中多種雙酚類與鄰苯二甲酸酯代謝物的分析方法，可供未來進行生物監測研究，以利於其評估人體暴露情況。

Bisphenols are utilized in the production of polycarbonate plastics and epoxy resins. Phthalates are a class of chemicals that are incorporated into plastics to enhance their flexibility and durability. They are also used in other products, such as food packaging, personal care products, and medical devices. Bisphenols and Phthalates can leach out of these products and into the environment and enter the food chain；humans may get exposed from ingestion, inhalation, or direct use of related products. However, studies have revealed that these compounds cause various health problems, including reproductive and developmental effects. Human biological monitoring is a valuable tool for assessing human exposure to chemicals and can provide crucial information for examining related health risks. This study used urine as the biological matrix, and measured six bisphenols and twelve phthalate metabolites. One hundred and fifty urine samples in this study were obtained from the 2019 National Nutrition and Health Survey；the age of the subjects ranged from 14 and 91 years old. This study employed the urine pretreatment method optimized previously in our laboratory. We added a 45 µL mixture of β-glucuronidase/arylsulfatase enzymes to the urine for enzyme hydrolysis for 40 minutes at 37°C. Thereafter, 405 µL acetonitrile was added to precipitate proteins. The samples were then filtered through 96-well Sirocco plates, and 20 µL of dimethyl sulfoxide were added to the filtrates. Finally, the samples were concentrated and reconstituted with 80 µL methanol. This study quantified analytes with ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) and isotope-dilution techniques. All analytes were separated on an Atlantis Premier BEH C18 AX column (50 × 2.1 mm, 1.7 µm) with gradient elution. The mobile phase consisted of (A) 5-mM ammonium acetate aqueous solution (pH 6.45) and (B) 5-mM ammonium acetate in methanol (pH 7.55). The chromatographic temperature was 30°C, and the flow rate was 0.5 mL/min with a total chromatographic time of 10 minutes. The linear range of the calibration curves using chemical standards was mainly between 0.5-500 ng/mL. This study optimized the mobile phase conditions to achieve the best chromatographic results for analytes. Four mobile phase combinations were tested, including: (1) 5-mM ammonium acetate aqueous solution (A)/methanol (B); (2) 5-mM ammonium acetate aqueous solution (A)/acetonitrile (B); (3) 5-mM ammonium acetate aqueous solution + 0.1% acetic acid aqueous solution (A)/methanol (B); (4) 5-mM ammonium acetate aqueous solution (A)/ 5-mM ammonium acetate solution in methanol (B). Most analytes were well retained and separated when using 5-mM ammonium acetate aqueous solution as the aqueous mobile phase and 5-mM ammonium acetate in methanol as the organic mobile phase. The method validation results showed that the coefficients of determination of the calibration curves were greater than 0.99. The matrix effect factors of analytes ranged from 42% to 94%, and the extraction efficiency ranged from 80% to 129%. The quantitative biases and relative standard deviations of the intra-day and inter-day analyses were mainly lower than 20%, which indicated good quantitative accuracy and precision. The quantitative results of the urine sample showed that the positive rates of bisphenol A and common plasticizers of Diethyl phthalate, Di(2-ethylhexyl) phthalate, Dibutyl phthalate, and Diisobutyl phthalate metabolites were higher than 75%. Their geometric mean concentrations ranged from 3.83 to 12.5 μg/g-cr, about 1.4 times higher than other analytes. The geometric mean concentrations of alternative substances, such as Bisphenol S, and the metabolites of Bis(2-propylheptyl) phthalate and Bis(2-ethylhexyl) terephthalate were 0.46, 1.21, and 4.16 μg/g-cr, respectively, with positive rates of over 99%. We compared exposure levels by gender, age, and region; significant differences in age were observed on most bisphenols and phthalate metabolites (p-value < 0.05), with higher geometric mean concentrations observed in the elderly (over 65 years old, 0.06-16.4 μg/g-cr) than in the younger group (below 65 years old, 0.03-9.53 μg/g-cr ). In summary, this study provides an effective method for simultaneously quantifying various bisphenols and phthalate metabolites in urine, facilitating future biomonitoring studies for evaluating human exposure.