Usefulness of NCI Mass Spectral Library

Introduction

In recent years, the effects of environmental pollutants on human beings is becoming a serious problem. In particular, endocrine disruptors affect human beings even in extremely small quantities. Therefore they need to be analyzed in extremely low concentrations. The negative chemical ionization (NCI) is one of the ionization methods for GC/MS and is characterized by superior selectivity and sensitivity. For compounds with high electron affinity, NCI can increase sensitivity by 10 - 100 times compared to the commonly used the electron ionization method. In addition, target substances can be selectively ionized, reducing the effects of interfering components. Thanks to these advantages, NCI is increasingly adopted in various fields for the quantitation of trace substances. NCI mass spectra are comparatively simple with smaller numbers of fragment ions, and had been thought to vary depending on the analytical conditions. Thus, its identification capability had not been highly evaluated. Accordingly there has been no mass spectral database for the NCI method. However, we have proved that NCI mass spectral database (library) can be used for qualification as a result of examining the dependency of NCI mass spectra on analytical conditions. This Application News presents the details of the investigation.

March 29, 2004 GMT