Determination of elemental compositions by gas chromatography/time-of-flight mass spectrometry using chemical and electron ionization.
Determination of elemental compositions by gas chromatography/time-of-flight mass spectrometry using chemical and electron ionization.
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DOI：
10.1002/rcm.4482
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发表时间：
2010-04-30
期刊：
影响因子：
--
通讯作者：
Fiehn O
中科院分区：
文献类型：
--
作者：
Abate S;Ahn YG;Kind T;Cataldi TR;Fiehn O
许多代谢组学应用在标准70 eV电子电离（EI）参数下使用气相色谱/质谱（GC/MS）。然而，分子离子的丰度通常非常低，阻碍了用于鉴定未知化合物的元素组成的计算。在改变离子源的束转向电压时，对于烷烃、脂肪酸甲酯和三甲基甲硅烷基化代谢物，在70 eV EI处分子离子的相对丰度增加了10倍，伴随着离子强度的2倍绝对增加。在高质量调谐条件下，比较了EI和化学电离（CI）中分子种类的丰度、质量精度和同位素比精度。一式三份分析了不同三甲基甲硅烷基化代谢物组的33个峰，得到342种离子种类（[MRH]R、[M-CH 3]R用于CI，[M]+●、[M-CH 3]+●用于EI）。平均而言，CI产生比EI高8倍的分子种类。采用内标法，获得了平均质量误差为1.81.6mm/z单位，平均同位素比值误差为2.3±2.0%（A+1/A比值）和1.71.8%（A±2/A比值）。当使用七条黄金法则算法和PubChem查询通过化学和启发式规则约束计算的元素组成的列表时，在60%的情况下，正确的公式被检索为最高命中，并且在80%的情况下在前3个命中内。
Many metabolomic applications use gas chromatography/mass spectrometry (GC/MS) under standard 70eV electron ionization (EI) parameters. However, the abundance of molecular ions is often extremely low, impeding the calculation of elemental compositions for the identification of unknown compounds. On changing the beam-steering voltage of the ion source, the relative abundances of molecular ions at 70eV EI were increased up to ten-fold for alkanes, fatty acid methyl esters and trimethylsilylated metabolites, concomitant with 2-fold absolute increases in ion intensities. We have compared the abundance, mass accuracy and isotope ratio accuracy of molecular species in EI with those in chemical ionization (CI) with methane as reagent gas under high-mass tuning. Thirty-three peaks of a diverse set of trimethylsilylated metabolites were analyzed in triplicate, resulting in 342 ion species ([MRH]R, [M–CH3]R for CI and [M]+●, [M–CH3]+● for EI). On average, CI yielded 8-fold more intense molecular species than EI. Using internal recalibration, average mass errors of 1.81.6mm/z units and isotope ratio errors of 2.3±2.0% (A+1/A ratio) and 1.71.8% (A±2/A ratio) were obtained. When constraining lists of calculated elemental compositions by chemical and heuristic rules using the Seven Golden Rules algorithm and PubChem queries, the correct formula was retrieved as top hit in 60% of the cases and within the top-3 hits in 80% of the cases.
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影响因子：
7.4
作者：
Kind, Tobias;Wohlgemuth, Gert;Lee, Do Yup;Lu, Yun;Palazoglu, Mine;Shahbaz, Sevini;Fiehn, Oliver
通讯作者：
Fiehn, Oliver
影响因子：
7.4
作者：
Fiehn, O;Kopka, J;Willmitzer, L
通讯作者：
Willmitzer, L
影响因子：
3
作者：
Kind T;Fiehn O
通讯作者：
Fiehn O
DOI：
10.1016/1044-0305(92)80006-7
发表时间：
1992-11-01
影响因子：
3.2
作者：
BONIN, MA;ASHLEY, DL;PATTERSON, DG
通讯作者：
PATTERSON, DG
DOI：
10.1016/0020-7381(83)85063-3
发表时间：
1983-01-01
期刊：
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES
影响因子：
--
作者：
SCHEPPELE, SE;GRINDSTAFF, QG;HWANG, CS
通讯作者：
HWANG, CS