Renaud Justin B, Hoogstra Shawn, Quilliam Michael A, Sumarah Mark W
London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
Biotoxin Metrology, National Research Council Canada, Halifax, Nova Scotia, B3H 3Z1, Canada.
J Chromatogr A. 2021 Feb 22;1639:461901. doi: 10.1016/j.chroma.2021.461901. Epub 2021 Jan 13.
A major challenge for LC-MS analysis is the ability to compare data between laboratories and across instrument platforms. Currently, mycotoxin determination relies on dereplication strategies based on physicochemical properties such as the m/z of the precursor and product ions. Unlike these intrinsic properties, retention time (t) is an extrinsic property impacted by LC conditions, including mobile phases and column chemistry, making exchange of data between groups difficult. To address this, we are introducing the concept of incorporating an electrospray compatible, retention index (RI) system based on a series of N-alkylpyridinium-3-sulfonates (NAPS) into routine mycotoxin determination. These standards of differing alkyl chain length span RI units from 100 to 2000, are UV active and have fixed positive and negative charges for electrospray ionization in either mode. Using high resolution LC-MS/MS, the RIs of 96 mycotoxins and fungal secondary metabolites were normalized as a proof of concept with the NAPS RI system under multiple pH, column and gradient chromatographic conditions. This method was then applied to the analysis of a crude extract of Penicillium roqueforti, where we were able to decrease the number of false positives by implementing an RI filter as well as a secondary correction factor. Additionally, we developed software that allows users to convert published RIs to a predicted t values. Integration of the NAPS RI system into routine LC-MS analysis will improve compound identifications and help facilitate ease of data sharing.
液相色谱-质谱联用（LC-MS）分析面临的一个主要挑战是能否在不同实验室和不同仪器平台之间比较数据。目前，霉菌毒素的测定依赖于基于物理化学性质（如前体离子和产物离子的质荷比）的去重复策略。与这些固有性质不同，保留时间（t）是一种受液相色谱条件（包括流动相和柱化学性质）影响的外在性质，这使得不同组之间的数据交换变得困难。为了解决这个问题，我们引入了一个概念，即将基于一系列N-烷基吡啶-3-磺酸盐（NAPS）的电喷雾兼容保留指数（RI）系统纳入常规霉菌毒素测定中。这些不同烷基链长度的标准品的RI单位范围从100到2000，具有紫外活性，并且在两种模式下的电喷雾电离中都带有固定的正电荷和负电荷。使用高分辨率液相色谱-串联质谱（LC-MS/MS），在多种pH值、色谱柱和梯度色谱条件下，用NAPS RI系统对96种霉菌毒素和真菌次生代谢产物的RI进行了归一化，作为概念验证。然后将该方法应用于罗克福特青霉粗提物的分析，在该分析中，我们通过实施RI过滤器以及二级校正因子，能够减少假阳性的数量。此外，我们开发了一款软件，允许用户将已公布的RI转换为预测的t值。将NAPS RI系统整合到常规LC-MS分析中将改善化合物的鉴定，并有助于促进数据共享。
