Schirmer paper tear sampling of human eye diseases for paper spray mass spectrometry analysis

Paper spray mass spectrometry (PSMS) is a powerful analytical technique for direct analysis of human body fluids. Schirmer paper is commonly used to collect human tears in clinical examination. In this work, Schirmer paper was used for noninvasive sampling and storing of healthy and disease-infected human tears, and was then performed PSMS for direct tear analysis under both positive and negative detection modes. 24 healthy tear samples, 34 tear samples of meibomain gland dysfunction, 44 tear samples of senile cataract, and 32 tear samples of allergic conjunctivitis were investigated in this work. Screening potential biomarkers of different eye diseases were carried out by combining multivariate analysis methods. 41 positive ions and 53 negative ions were proposed to be potential biomarkers in this work. The capacity of Schirmer paper for storing tear sample at different temperatures was investigated. The present study shows that direct coupling Schirmer PSMS with multivariate analysis could be a simple, rapid, and in vivo method for screening the biomarkers from human tears that involved different eye diseases.