Novel application for ion mobility spectrometry: diagnosing vaginal infections through measurement of biogenic amines

A method for diagnosis of bacterial vaginosis (BV) and other vaginal infections, based on measurement of biogenic amines present in a sample of vaginal fluid by ion mobility spectrometry (IMS) was developed. Sample introduction is through a two step procedure: addition of alkaline solution to release the volatile amines followed by heating and acid addition for emanation of the semi-volatile amines. Addition of n-nonylamine vapors to the carrier gas stream helps control the ionization processes and enhances the selective response to amines, even in the complex environment of biological matrices. A software package was developed for acquisition, storage and processing of the mobility spectra and for providing a diagnosis based on a table of rules. We report the results from testing of 210 samples of vaginal discharge fluid that were diagnosed by a gynecologist according to the widely used reference method (Amsel test) and by the new IMS method. The new method is rapid (less than 2 min per sample), has a high sensitivity (few False Negatives) and specificity (few False Positives) with an accuracy of >95% for BV. The use of this method can reduce the incidence of misdiagnosis, particularly when trichomoniasis is confused with bacterial vaginosis.