Abstract A study of the dark-blue insoluble precipitate that makes up gall ink using bamboo nib-spray mass spectrometry (PS-MS) is described. A ferrous tannate complex is formed, i.e. an insoluble organic metal complex - iron gallate ink (IGI) is produced when tannin is mixed with iron sulfate. Since it is not possible to detect this IGI precipitate by conventional electrospray ionization (ESI) mass spectrometry, we report on an attempt to resolve this problem by a new method in this study in an. The method involved “two steps” using bamboo nib-spray/MS. A gallic acid solution was initially used as a model sample and the ESI mode was operated under a negative voltage. This approach permitted the optimized position between the spray-tip and the mass inlet (either distance or angle) to be determined. Following this, the ESI applied voltage was changed to positive and, at this moment, a ferrous sulfate solution was added to the spray-tip, both reactants are sprayed out immediately and are simultaneously ionized while a complex binding reaction occurs. This permits the IGI dark-blue insoluble precipitate to be ionized and detected. As a result, several specific peaks could be observed. The resulting m/z = 153, 225, 243, 431 peaks are assigned to [C7H5O4]+, [C7H5O5Fe]+, [C7H5O5Fe‧H2O]+, and [(C6H3O3) (C6H4O3)Fe2‧4H2O]+, respectively.

中文翻译：

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基于“两步法”竹笔尖喷雾/质谱分析铁胆墨水的化学和结构

摘要 描述了使用竹笔尖喷雾质谱 (PS-MS) 对构成胆汁的深蓝色不溶性沉淀物的研究。形成鞣酸亚铁络合物，即当鞣酸与硫酸铁混合时产生不溶性有机金属络合物-没食子酸铁油墨(IGI)。由于无法通过传统的电喷雾电离 (ESI) 质谱法检测到这种 IGI 沉淀物，因此我们报告了在本研究中尝试通过一种新方法解决此问题的方法。该方法涉及使用竹笔尖喷雾/MS 的“两步法”。最初使用没食子酸溶液作为模型样品，ESI 模式在负电压下运行。这种方法允许确定喷嘴和质量入口之间的优化位置（距离或角度）。按照此，将 ESI 施加的电压改为正电压，此时，将硫酸亚铁溶液添加到喷嘴中，两种反应物立即喷出并同时电离，同时发生复杂的结合反应。这允许 IGI 深蓝色不溶性沉淀物被电离和检测。结果，可以观察到几个特定的​​峰。得到的 m/z = 153、225、243、431 个峰分别归属于 [C7H5O4]+、[C7H5O5Fe]+、[C7H5O5Fe‧H2O]+ 和 [(C6H3O3) (C6H4O3)Fe2‧4H2O]+。可以观察到几个特定的​​峰。得到的 m/z = 153、225、243、431 个峰分别归属于 [C7H5O4]+、[C7H5O5Fe]+、[C7H5O5Fe‧H2O]+ 和 [(C6H3O3) (C6H4O3)Fe2‧4H2O]+。可以观察到几个特定的​​峰。得到的 m/z = 153、225、243、431 个峰分别归属于 [C7H5O4]+、[C7H5O5Fe]+、[C7H5O5Fe‧H2O]+ 和 [(C6H3O3) (C6H4O3)Fe2‧4H2O]+。