基于分子式数据库策略的FM-searcher软件在危害物非目标筛查分子式预测中的应用

利用高分辨质谱数据进行非目标筛查时,为提高分子式预测的前位命中率,为化合物的进一步筛查提供可靠的参考信息,本研究开发了基于分子式数据库策略的分子式计算器FM-searcher。该软件基于"存在即合理,大量存在即稳定"的核心思想,根据分子式在已有化合物数据库中出现的频率对分子式进行计算和排序,并依据排序对获得分子式的合理性进行判断,以提高分子式计算的合理性和前位命中率。以测定及搜集文献所得兽残、生物毒素等多类危害物共计219个精确分子质量作为测试数据,将该计算器计算的分子式前位命中率与普通算法(Xcalibur内嵌计算器)的计算结果进行比较。结果表明,FM-searcher在无任何元素限制时,仍可获得较高的前位命中率,前5、前3及首位命中率分别为91.8%、82.6%和50.7%;而普通算法在模糊限制元素时,其命中率分别为21.0%、15.1%、6.4%。在分小类精确限制元素组成时,得到的结果分别为82.2%、69.9%、48.9%。对实际样品基质中测定得到精确质量数的分子式进行计算,FM-searcher能够获得比普通计算器更高的正确分子式前位命中排位。该方法与普通算法相比,能够在更宽...

Application of FM-Searcher Software to Prediction of Molecular Formula in the Non-target Screening of Hazard Components Based on Molecular Formula Database Strategy

High resolution mass spectrometry is a powerful tool for non-target screening of a wide range of compounds, and the accurate mass measured by high resolution mass spectrometry could facilitate prediction of molecular formula of the compound, thus laying the foundation for further compound screening. A molecular formula calculator FM-searcher based on molecular formula database strategy was developed to improve top hits ratio of molecular formula prediction with high-resolution mass spectrometric data in non-target screening, and providing more reliable reference information for further screening of a compound. Based on the core idea of “Existence is reasonable, and a large number of existences are stable”, the software could calculate and sort the molecular formula according to the frequency of the molecular formula in the existing compound database, so as to judge the rationality of the molecular formula calculation and the top hits ratio. Based on a total of 219 accurate molecular weights of veterinary drugs, biological toxins and other hazardous substances obtained from the determination and collected from literatures, the top hits ratio of the formula calculated by FM-searcher was compared with that obtained by ordinary algorithm (the calculator in Xcalibur). The results showed that FM-searcher could achieve a higher top hit ratio without any element limitation; the top 5, top 3 and top 1 hit ratio are 91.8%, 82.6% and 50.7%, respectively. While for ordinary algorithm, the top 5, top 3 and top 1 hit ratio are 21.0%, 15.1% and 6.4% in the case of broad elements limitation; and in the case of precise elements limitation according to subcategories, the corresponding data results are 82.2%, 69.9% and 48.9%, respectively. Compared with the conventional method, this method could improve the hits ratio under broader element limitation, simplify the formula prediction process and improve efficiency with simple operation and practicability. The molecular formula of accurate mass measured in the actual sample matrix was also calculated, FM-searcher could still achieve a higher top hits rank of correct formula than an ordinary molecular formula calculator.