多頻雷射於基質輔助雷射脫附/游離-飛行時間質譜法之開發與應用

Abstract

本論文提出在基質輔助雷射脫附/游離-飛行時間質譜法(MALDI-TOF MS)中結合多頻雷射配合各種種類基質的新技術。為了誘導出大量的Raman散射雷射，以一經過橢圓偏光的355 nm Nd:YAG雷射激發高壓的氫氣，可以得到其振動與轉動的Raman emissions，其能階分別是4155 cm-1及587 cm-1，而得到的多頻Raman雷射(multi-frequency Raman laser)其波長分佈在246.1~865.9 nm之間。使用此一多頻的雷射源作為離化的光源，並且配合可以吸收不同波長能量的基質，其中包含：4-methoxycinnamic acid (MCA)、-cyano-4-hydroxycinnamic acid (CHCA)、sinapinic acid (SA)、7-(diethylamino)coumarin-3-carboxylic acid (DCCA)、rhodamine 6G及activated carbon等等分別對大小生化分子peptide與protein的標準品做分析測試。上述的各種基質均可以對標準品分析物達到不同的離化效果，其中對於小分子peptide的分析則是發現當以DCCA作為基質時，會有較佳的解析度並且可以減低其質譜雜訊，其原因則是因為DCCA可視為一種 “cold”的能量吸收劑，當分析物被離化在飛行的過程中較不會有碎裂(fragmentation)的情形發生，並且當以多頻雷射代替單一355 nm的作法時其S/N比會有所改善，除此之外對於小分子cyclohexyl methylphosphonic acid及pinacolyl methylphosphonic acid 兩種化學戰劑降解產物的分析發現，本研究首次以DCCA配合多頻雷射進行分析可以達成在地下水中的檢測，但是傳統的CHCA並無法直接做到。故此多頻雷射系統離化光源可以運用於一般化合物的分析並可以研究不同種類的基質其離化效果與其過程會產生的效應。 此外在此亦提出一個以基質輔助雷射脫附游離飛行時間質譜法 作為快速對濫用藥物進行檢測與監控的新方法。本方法中，cetrimonium bromide (CTAB)乃是一種陽離子界面活性劑，被添加到常用的MALDI基質-cyano-4-hydroxycinnamic acid (CHCA)中，此一作法可以對安非他命、甲基安非他命、3,4-methylenedioxy- amphetamine (MDA)、3,4-methylenedioxymethamphetamine(MDMA)、咖啡因、K他命、tramadol作分析並得到十分簡潔的質譜圖，而尿液中的MDMA則是可以其同位素MDMA-D5作為內標物達到定量的分析效果。在分析此一添加內標物的尿液樣品時，其檢量線濃度範圍為0.1~100 ppm，而其線性關係R2可達0.9993，運用本方法可進行真實樣品尿液中DMDA的測定。藉由t-test方法其結果有超過95%的可信度，此一技術可以成功的對濫用的毒品做快速監控，並且可以對吸毒者的尿液做MDMA的定量分析。故此在刑事鑑定分析中與傳統的GC/MS 檢測方法相比，MALDI-TOF MS配合同位素內標的方法，確實可達到快速定性定量的檢測需求。

The method of various matrixes for multi-frequency laser for use in MALDI- TOF MS is reported here for the first time. An elliptically polarized beam of a Nd: YAG laser emitting at 355 nm is used for inducing numerous Raman lasers (including vibrational and rotational Raman emissions for hydrogen; 4155 cm-1 and 587 cm-1-shifts, respectively) generated from 246.1 to 865.9 nm. Using these multi-frequency emissions as ionization source with matrixes which can absorb different wavelength source, including: 4-methoxycinnamic acid (MCA), -cyano-4-hydroxycinnamic acid (CHCA), sinapinic acid (SA), 7-(diethylamino)coumarin-3-carboxylic acid (DCCA), rhodamine 6G and activated carbon, smaller peptide and protein standards were examined, respectively. With all of these matrixes, mass spectra of the analytes could clearly be detected. However, for the peptide standards analysis, it could get the better resolution than others and the noise of the mass spectra also reduced, while DCCA was the using matrix. According to the experimental results, it is proposed that DCCA is suggested a “cold” matrix of energy absorber; doesn’t induce the fragmentation of analytes during the drifting process. The S/N ratios are also improved while multi-frequency laser is used in the study. Furthermore, this method has been used to analyze small molecules, cyclohexyl methylphosphonic acid and pinacolyl methylphosphonic acid (chemical warfare agent degradation products) with DCCA, yet CHCA fails to achieve, for groundwater analysis. Thus the multi-frequency laser system using as an ionization source is practicable to make an analysis and a study of various matrixes ionization effects. Besides, a novel method for the rapid drug-screening of clandestine tablets by MALDI-TOF mass spectrometry is described. In this method, cetrimonium bromide (CTAB), a cation surfactant, is added to the conventional -cyano-4-hydroxycinnamic acid (CHCA) matrix solution used in preparing the MALDI samples. This procedure permits very clean mass spectra to be collected for amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy- methamphetamine (MDMA), caffeine, ketamine and tramadol. The quantification of MDMA was achieved using stable-isotope-labeled MDMA (MDMA-D5) as the internal standard. For the analysis of MDMA/MDMA-D5-spiked urine samples, the calibration curve was linear in the range of 0.1-100 ppm with a coefficient of determination, r2, of 0.9993. This assay was used to determine MDMA in actual urine samples. No significant bias is shown between the two methods by t-test at 95% confidence level. The method was used successfully in the rapid drug-screening of actual clandestine tablets, which had been seized from the illicit market, and the quantification of MDMA in suspect urine samples by using stable-isotope-labeled MDMA (MDMA-D5) as the internal standard. The study concludes that MALDI-TOF MS can serve as a reliable and complementary method to GC/MS for use in forensic analysis.