膠囊錠狀食品中褪黑激素(melatonin)檢驗方法之探討

Determination of Melatonin in Foods in Capsule or Tablet form

褪黑激素為腦部松果腺所分泌的荷爾蒙，於人體之天然含量極低，卻具有藥理活性，本研究建立以高效液相層析法搭配光二極體陣列檢測器（HPLC/PDA），分析膠囊錠狀食品中褪黑激素（melatonin）含量之方法。膠囊錠狀食品經甲醇萃取過濾後，採用C18層析管柱，以乙腈及0.085%磷酸溶液為移動相溶液進行梯度沖提，於波長220nm進行高效液相層析分析。褪黑激素標準曲線之線性關係良好（濃度0.03 - 85.35 μg/mL），其判定係數（r^2）均於0.999以上。同日內與異日間試驗之相對標準偏差（RSD）分別為0.05 - 0.14%及0.40 - 0.50%。於檢體中添加褪黑激素8.35 - 167.48 ppm，其平均回收率介於79.5 - 92.4%，相對標準偏差（RSD）介於0.19 - 1.94%，而定量極限與偵測極限分別為15.0及3.0 ppm。應用本方法於市售成分組成均不同之27件標示含有褪黑激素檢體之分析，僅1件檢體之層析圖譜仍見些微干擾，針對該檢體進行個別層析條件調整後，亦可成功分離，其餘檢體之層析圖譜均無干擾之情形，顯示本研究建立之高效液相層析法對於市售含褪黑激素產品之分析結果良好，可供各界進行褪黑激素檢測之參考。

Melatonin is a natural hormone secreted by pineal gland in the mammalian brain. Although the content of melatonin is considerably low in human body, it still possesses pharmacological activity. A method for the analysis of melatonin in foods in capsule or tablet form by high performance liquid chromatography/photodiode array detector (HPLC/PDA) was developed. Methanol was applied for the extraction of melatonin from foods. The extracts were analyzed by a HPLC/PDA system consisted of a C18 column and gradient mobile phase of acetonitrile and 0.085% H3PO4. The detection wavelength was 220 nm. The method demonstrated good linearity at melatonin concentration range of 0.03 - 85.35 μg/ mL, with a determination coefficient (r^2) above 0.999. The recovery studies were conducted by spiking melatonin into blank samples at the concentration range of 8.35 - 167.48 ppm. The average recoveries, relative standard deviations (RSDs) of intraday and interday recovery studies, limit of detection (LOD) and limit of quantification (LOQ) were 79.5 - 92.4%, 0.05 - 0.50%, 3.0 ppm and 15.0 ppm respectively. The method selectivity was tested in 27 commercial products. The results showed only 1 sample revealed chromatographic interference which was resolved after manual adjustment. This report provides a reference method for administrative authorities and the public.