Breath selection methods for compact mass spectrometry breath analysis

摘要

Compactmass spectrometry (CMS) is a versatile and transportable analytical instrument that has the potential to be used in clinical settings to quickly and non-invasively detect a wide range of relevant conditions frombreath samples.The purpose of this study is to optimise data preprocessing protocols by three proposedmethods of breath sampling, using theCMS. It also lays out a general framework for which data processingmethods can be evaluated. Methods. This paper considers data fromthree previous studies, each using a different breath samplingmethod.These include a peppermintwashout study using continuous breath sampling with a purified air source, an exercise study using continuous breath sampling with anambient air source, and a single breath sampling study with an ambient air source. For each dataset, different breath selection (data preprocessing)methodswere compared and benchmarked according to predictive performance on a validation set and quantitative reliability ofm/z bin intensitymeasurements. Results. For both continuousmethods, the best breath selectionmethod improved the predictivemodel compared to no preselection, asmeasured by the 95%CI range for Youden’s index, from 0.68-0.86 to 0.86-0.97 for the exercise study and 0.69-0.82 to 1.00-1.00 for the peppermint study.The reliability of intensitymeasurements for both datasets (asmeasured bymedian relative standard deviation (RSD)),was improved slightly by the best selectionmethod compared to no preselection, from18%to 14%for the exercise study and 7%-5%for the peppermint study. For the single breath samples, all themodels resulted in perfect prediction, with a 95%CI range forYouden’s index of 1.00-1.00.The reliability of the proposedmethod was 38%. Conclusion. Themethod of selecting exhaled breath from CMS data can affect the reliability of themeasurement and the ability to distinguish between breath samples taken under different conditions. The application of appropriate data processingmethods can impr