- 學位論文
氣相層析電噴灑游離質譜於酚類分析之方法開發與應用
Development and Application of a Method for the Analysis of Phenols by GC-ESI/MS
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摘要
以液相層析質譜分析酚類時，分析物容易受到共析基質之干擾，因而影響分析方法之靈敏度。氣相層析質譜雖可因較佳之分離效果而較少基質效應，但電子撞擊游離法容易將分析物擊碎成碎片離子，造成分析方法靈敏度下降。因此，本研究開發一氣相層析電噴灑游離質譜分析方法，希望結合氣相層析之良好分離效果與電灑法質譜之高靈敏度。分析策略是先以矽烷化的方式將酚類衍生上非極性的三甲基矽烷基團，使其在氣相層析中達到良好之分離效果；接著，利用矽烷化酚類易水解之特性，使其在電灑液滴帶往質譜端的過程中，水解成較極性之未衍生酚類型式，以電灑法質譜偵測其分子離子訊號，達到提升靈敏度之訴求。 本研究之第一部分探討氣相層析電噴灑游離質譜分析酚類。藉由矽烷化的方式，使酚類於氣相層析中達到良好之分離效果。並藉由增加電噴灑溶液中水相的比例，以提高矽烷化酚類之水解效率。其中，以矽烷化氯酚之水解效率最佳。矽烷化硝基酚因不完全水解，使其可同時被偵測到水解後未衍生硝基酚與未水解矽烷化硝基酚之訊號，可作為一定性之依據。本研究之第二部分則著重於使用氣相層析電噴灑游離質譜分析19種氯酚化合物。電灑法質譜軟游離的特性可有效地將訊號集中在分子離子，提升分析方法之靈敏度。使用SIM和MRM模式偵測氯酚標準溶液，其偵測極限介於1 ppb至1 ppt之間，證實本分析方法具有良好之矽烷化效率及衍生物水解效率。本研究之第三部分為氣相層析電噴灑游離質譜應用於土壤中氯酚之分析。氣相層析之良好分離能力可改善共析基質干擾的問題，得以簡化繁瑣的土壤淨化步驟。此方法分析土壤中氯酚之偵測極限介於1 ppb至1 ppt之間。
並列摘要
Phenols are predominantly analyzed by liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS). The main problems encountered in LC/MS arise from coeluting matrix, which would affect the sensitivity of the analyte. On the other hand, better separation resolution could be achieved by GC/MS, but with low sensitivity due to heavy fragmentation under electron impact ionization (EI). In this work, we combined gas chromatography with electrospray ionization/mass spectrometry (GC-ESI/MS) in the analysis of phenols. In order to overcome peak tailing and obtain better resolution in GC, silylation of phenols was introduced. Because trimethylsilyl (TMS) derivatives of phenols hydrolyzed easily, electrospray droplets would chemically transform them into underivatized states. Sensitivity enhancement is expected, because phenolic groups are easily deprotonated under negative ion ESI. The first part of this work was the analysis of phenols by GC-ESI/MS. Better separation resolution was achieved by silylation. Most TMS derivatives can be hydrolyzed by increasing the ratio of water in spray solvents. Among TMS derivatives of phenols, chlorophenols (CPs) showed the best hydrolysis efficiency. Due to partial hydrolysis, TMS derivatives of nitrophenols (NPs) could be detected in the forms of both underivatized NPs and TMS derivatives of NPs, providing evidence for qualitative analysis. The second part of this work was the optimization of the analysis of 19 CPs by GC-ESI/MS. The sensitivity of this method could be enhanced due to the characteristics of soft ionization of ESI/MS. For CPs standard solutions, the limits of detection (LODs) were in the range of 1 ppb to 1 ppt using selected ion monitoring (SIM) and/or multiple reaction monitoring (MRM) mode. The third part of this work was the analysis of CPs in soil by GC-ESI/MS. The problem caused by coeluting matrix could be overcome by the high separation resolution of GC. The complicated purification procedure of soil samples could be simplified. The LODs of this method were in the range of 1 ppb to 1 ppt for CPs in soil samples.
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