Dipartimento Di Scienza E Tecnologia del Farmaco, Università Degli Studi Di Torino, Via Pietro Giuria 9, 10125, Turin, Italy.
Food Chemistry, Technische Universität Dresden, Dresden, Germany.
Anal Bioanal Chem. 2023 May;415(13):2493-2509. doi: 10.1007/s00216-023-04516-x. Epub 2023 Jan 12.
Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOFMS) is one the most powerful analytical platforms for chemical investigations of complex biological samples. It produces large datasets that are rich in information, but highly complex, and its consistency may be affected by random systemic fluctuations and/or changes in the experimental parameters. This study details the optimization of a data processing strategy that compensates for severe 2D pattern misalignments and detector response fluctuations for saliva samples analyzed across 2 years. The strategy was trained on two batches: one with samples from healthy subjects who had undergone dietary intervention with high/low-Maillard reaction products (dataset A), and the second from healthy/unhealthy obese individuals (dataset B). The combined untargeted and targeted pattern recognition algorithm (i.e., UT fingerprinting) was tuned for key process parameters, the signal-to-noise ratio (S/N), and MS spectrum similarity thresholds, and then tested for the best transform function (global or local, affine or low-degree polynomial) for pattern realignment in the temporal domain. Reliable peak detection achieved its best performance, computed as % of false negative/positive matches, with a S/N threshold of 50 and spectral similarity direct match factor (DMF) of 700. Cross-alignment of bi-dimensional (2D) peaks in the temporal domain was fully effective with a supervised operation including multiple centroids (reference peaks) and a match-and-transform strategy using affine functions. Regarding the performance-derived response fluctuations, the most promising strategy for cross-comparative analysis and data fusion included the mass spectral total useful signal (MSTUS) approach followed by Z-score normalization on the resulting matrix.
全二维气相色谱飞行时间质谱联用技术(GC×GC-TOFMS)是用于复杂生物样品化学分析的最强大的分析平台之一。它产生的数据集信息量丰富,但高度复杂,其一致性可能会受到随机系统波动和/或实验参数变化的影响。本研究详细介绍了一种数据处理策略的优化,该策略可补偿 2 年分析的唾液样本中严重的二维图谱错位和检测器响应波动。该策略是在两个批次上进行训练的:一个批次来自接受高/低美拉德反应产物饮食干预的健康受试者(数据集 A),另一个批次来自健康/不健康肥胖个体(数据集 B)。联合非靶向和靶向模式识别算法(即 UT 指纹图谱)针对关键过程参数(即信噪比(S/N)和 MS 谱相似度阈值)进行了调整,然后针对时间域中模式重新对准的最佳变换函数(全局或局部、仿射或低阶多项式)进行了测试。在获得最佳性能的情况下,可靠的峰检测表现最佳,其计算方法为假阴性/阳性匹配的百分比,信噪比阈值为 50,光谱相似度直接匹配因子(DMF)为 700。通过包括多个质心(参考峰)的监督操作以及使用仿射函数的匹配和变换策略,在时间域中对二维(2D)峰进行交叉对准可完全有效。关于基于性能的响应波动,用于交叉比较分析和数据融合的最有前途的策略包括总有用信号(MSTUS)方法,然后对所得矩阵进行 Z 分数标准化。