Appropriate sample preparation is pivotally important to obtain high-quality mass spectrometry imaging (MSI) data. Unlike mammalian tissues, preparation of cryosections from plant tissues for MSI measurement is quite challenging due to its intrinsic complex texture and cellular structure. This is especially true for leaf samples which are generally thin, water-rich, and fragile. In this work, a systematic study was performed, aiming to evaluate three embedding materials and five mounting approaches for matrix-assisted laser desorption ionization (MALDI) MSI of secondary metabolites in cross sections of the ginkgo leaf. Delocalization of endogenous metabolites was chosen as a major indicator for evaluation of three embedding materials including ice, carboxymethyl cellulose (CMC), and gelatin and different mounting approaches. Image distortion and analyte delocalization were observed when ice was used as an embedding medium. CMC embedding provided better results compared to the ice by using modified mounting approach. Among three embedding materials, no delocalization was observed in specimens embedded with gelatin, and gelatin embedding is the least affected by different mounting approaches. An alternative approach to mitigate analyte delocalization is the removal of embedding media embraced the tissue sections before mounting, which is particularly suitable for ice-embedded samples. Additionally, the extent of analyte delocalization was closely related to their lipophilicity/hydrophilicity properties, and less analyte diffusion was observed for hydrophobic analytes than for the water-soluble compounds.

适当的样品制备对于获得高质量质谱成像（MSI）数据至关重要。与哺乳动物组织不同，由于其固有的复杂质地和细胞结构，从植物组织制备冷冻切片以进行MSI测量非常具有挑战性。对于通常稀薄，富水且易碎的叶子样品，尤其如此。在这项工作中，进行了系统的研究，旨在评估银杏叶横截面中次生代谢物的基质辅助激光解吸电离（MALDI）MSI的三种包埋材料和五种安装方法。选择内源性代谢物的离域作为评估三种包埋材料（包括冰，羧甲基纤维素（CMC）和明胶）和不同安装方法的主要指标。当使用冰作为包埋介质时，观察到图像失真和分析物离域。通过使用改进的安装方法，与冰相比，CMC嵌入提供了更好的结果。在三种包埋材料中，在明胶包埋的标本中未观察到离域，并且明胶包埋受不同安装方法的影响最小。减轻分析物离域的另一种方法是在安装前去除包埋在组织切片中的包埋介质，这特别适用于冰包埋的样品。另外，分析物离域的程度与它们的亲脂性/亲水性密切相关，并且与水溶性化合物相比，疏水性分析物观察到的分析物扩散较少。