Department of Chemistry, Federal University of Minas Gerais, Av. Presidente Antônio Carlos, 31270-901, Belo Horizonte, Minas Gerais, Brazil.
Anal Bioanal Chem. 2013 Sep;405(24):7643-51. doi: 10.1007/s00216-013-6986-y. Epub 2013 Jul 20.
The different chemical forms of arsenic compounds, including inorganic and organic species, present distinct environmental impacts and toxicities. Desorption electrospray ionization mass spectrometry (DESI-MS) is an excellent technique for in situ analysis, as it operates under atmospheric pressure and room temperature and is conducted with no/minimal sample pretreatment. Aimed at expanding its scope, DESI-MS is applied herein for the quick and reliable detection of inorganic (arsenate--As(V): AsO4(3-) and arsenite--As(III): AsO2(-)) and organic (dimethylarsinic acid--DMA: (CH3)2AsO(OH) and disodium methyl arsonate hexahydrate: CH3AsO3·2Na·6H2O) arsenic compounds in fern leaves. Operational conditions of DESI-MS were optimized with DMA standard deposited on paper surfaces to improve ionization efficiency and detection limits. Mass spectra data for all arsenic species were acquired in both the positive and negative ion modes. The positive ion mode was shown to be useful in detecting both the organic and inorganic arsenic compounds. The negative ion mode was shown only to be useful in detecting As(V) species. Moreover, MS/MS spectra were recorded to confirm the identity of each arsenic compound by the characteristic fragmentation profiles. Optimized conditions of DESI-MS were applied to the analysis of fern leaves. LC-ICP-MS was employed to confirm the results obtained by DESI-MS and to quantify the arsenic species in fern leaves. The results confirmed the applicability of DESI-MS in detecting arsenic compounds in complex matrices.
砷化合物的不同化学形式，包括无机和有机物种，具有不同的环境影响和毒性。解吸电喷雾电离质谱（DESI-MS）是一种出色的原位分析技术，因为它在大气压和室温下运行，并且不需要/只需进行最小限度的样品预处理。本研究旨在扩展其应用范围，将 DESI-MS 应用于快速可靠地检测蕨类植物叶片中的无机（砷酸盐-As(V)：AsO4(3-)和亚砷酸盐-As(III)：AsO2(-)）和有机（二甲砷酸-DMA：(CH3)2AsO(OH)和二水合亚砷酸钠六水合物：CH3AsO3·2Na·6H2O）砷化合物。通过在纸张表面沉积 DMA 标准品来优化 DESI-MS 的操作条件，以提高离子化效率和检测限。在正离子和负离子模式下都获得了所有砷物种的质谱数据。正离子模式可用于检测有机和无机砷化合物。负离子模式仅可用于检测 As(V)物种。此外，还记录了 MS/MS 谱图，通过特征碎片谱图确认每个砷化合物的身份。优化后的 DESI-MS 条件用于分析蕨类植物叶片。LC-ICP-MS 用于确认 DESI-MS 获得的结果，并定量蕨类植物叶片中的砷物种。结果证实了 DESI-MS 在检测复杂基质中砷化合物的适用性。
