大容量注入インライン濃縮HPLC/MS分析による大気中ニトロフェノール類日内変動の解析  [in Japanese] Investigation of Daily Variation of Atmospheric Nitrophenols by Means of Inline Preconcentration-HPLC/MS Analysis with Large Volume Injection  [in Japanese]

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Abstract

ニトロフェノール類(NPs)は健康リスクのある化合物として知られており,また,大気中で様々な経路により生成するが,その実態はあまり知られていない.本研究では,シリカゲル充填チューブに2時間ごとに捕集したNPsを高速液体クロマトグラフィー/質量分析法(HPLC/MS)にて分析を行い,日内変動の解析を試みた.捕集法の検討やHPLCへの大容量注入濃縮の自動化をはかり,各種NPの分析が可能になった.検出には大気圧イオン化質量分析を用いた.2時間捕集による大気中各種NPの定量下限は0.08~0.67 ng m<sup>-3</sup>の範囲であった.本法により日内変動を調べたところ,夏は日中に濃度が高くなり,また冬は夜半前に高濃度になり,季節で異なった日内変動パターンが得られた.これは,季節により,支配的となる二次的生成機構が異なったためと考えられる.すなわち,夏季はOHラジカル,冬季はNO<sub>3</sub>ラジカルに起因する反応に依存していると考えられる.また,冬季のNP総濃度は夏より高濃度となり,特に2-nitorophenolが約半分を占めた.逆に夏はモノニトロフェノールのジニトロ化の進行が示唆された.雨水に含まれるNPsやフィルターに捕集されたNPsについても分析を行ったところ,大気中NO<sub>2</sub>の増減と同じような季節変動を示した.一連の分析結果から,各種NPの存在状態は極性や反応性によってそれぞれ異なっており,また大気中で二次的な生成や消失を繰り返しながら大きく濃度変動していることが示された.

Nitrophenols (NPs), having effects on human health, are produced in the atmosphere via several pathways. However, the behavior details of atmospheric NPs are not well understood. In this work, daily variations of NPs were investigated by repeating 2-h collection using silica-gel columns followed by HPLC/MS analysis. The collection method was optimized and large-volume injection and in-line preconcentration was automated for the HPLC analysis. The quantification limits by atmospheric-pressure chemical ionization mass analysis for each atmospheric NP ranged between 0.08 and 0.67 ng m<sup>−3</sup> with a time resolution of 2 h. Clear daily variations were obtained by this method. Whereas NP concentrations were high around noon in the summer, they were maxima before midnight in the winter. This was likely due to a difference in the main mechanism for NP formations: mainly the OH radical and the NO<sub>3</sub> radical initiated the formation reaction in the summer and winter, respectively. In the winter, the total NP concentration was higher than that in the summer especially 2-nitrophenol which accounted for half of all NPs measured. On the contrary, formation of dinitrophenol from mononitrophenol seemed to proceed abundantly in the summer. Also, a seasonal variation was detected from rain water analysis and filter sampling. The concentrations and partition of NPs were different, alowing differences in the polarity and reactivity. It was considered that the NP concentrations changed dynamically in the atmosphere via secondary production, and reactions to disappear.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 62(9), 775-783, 2013-09-05

    The Japan Society for Analytical Chemistry

References:  33

Codes

  • NII Article ID (NAID)
    10031186092
  • NII NACSIS-CAT ID (NCID)
    AN00222633
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    05251931
  • NDL Article ID
    024880341
  • NDL Call No.
    Z17-9
  • Data Source
    CJP  NDL  IR  J-STAGE 
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