Provincial Key Laboratory of Agricultural Environmental Engineering, College of Resources and Environment, Sichuan Agricultural University, Ya'an 625014, Sichuan Province, China.
Rapid Commun Mass Spectrom. 2010 Jun 15;24(11):1625-8. doi: 10.1002/rcm.4540.
Isoprene is one of the most important non-methane hydrocarbons (NMHCs) in the troposphere: it is a significant precursor of O(3) and it affects the oxidative state of the atmosphere. The diastereoisomeric 2-methyltetrols, 2-methylthreitol and 2-methylerythritol, are marker compounds of the photooxidation products of atmospheric isoprene. In order to obtain valuable information on the delta(13)C value of isoprene in the atmosphere, the stable carbon isotopic compositions of the 2-methyltetrols in ambient aerosols were investigated. The 2-methyltetrols were extracted from filter samples and derivatized with methylboronic acid, and the delta(13)C values of the methylboronate derivatives were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The delta(13)C values of the 2-methyltetrols were then calculated through a simple mass balance equation between the 2-methyltetrols, methylboronic acid and the methylboronates. The delta(13)C values of the 2-methyltetrols in aerosol samples collected at the Changbai Mountain Nature Reserves in eastern China were found to be -24.66 +/- 0.90 per thousand and -24.53 +/- 1.08 per thousand for 2-methylerythritol and 2-methylthreitol, respectively. Based on the measured isotopic composition of the 2-methyltetrols, the average delta(13)C value of atmospheric isoprene is inferred to be close to or slightly heavier than -24.66 per thousand at the collection site during the sampling period.
异戊二烯是对流层中最重要的非甲烷碳氢化合物（NMHCs）之一：它是臭氧的重要前体，影响大气的氧化状态。差向立体异构的 2-甲基四醇、2-甲基苏糖醇和 2-甲基赤藓糖醇是大气异戊二烯光氧化产物的标记化合物。为了获得有关大气中异戊二烯的稳定碳同位素组成值的有价值信息，研究了环境气溶胶中 2-甲基四醇的稳定碳同位素组成。通过甲基硼酸衍生化，从滤膜样品中提取 2-甲基四醇，并用气相色谱/燃烧/同位素比质谱（GC/C/IRMS）测定甲基硼酸酯衍生物的 δ13C 值。然后，通过 2-甲基四醇、甲基硼酸和甲基硼酸酯之间的简单质量平衡方程计算 2-甲基四醇的 δ13C 值。在中国东部长白山自然保护区采集的气溶胶样品中，2-甲基赤藓糖醇和 2-甲基苏糖醇的 δ13C 值分别为-24.66±0.90‰和-24.53±1.08‰。根据 2-甲基四醇的测量同位素组成，推断在采样期间采集地点大气中异戊二烯的平均 δ13C 值接近或略重于-24.66‰。
