A novel asymmetrical arc-shaped electrode ion trap for improving the performance of a miniature mass spectrometer.

RATIONALE: The pivotal challenge associated with miniature mass analyzers is their proper design and construction without sacrificing performance. In order to analyze and improve the performance of a miniature linear ion trap with odd and even multipole fields, we designed a novel asymmetrical arc-shaped electrode ion trap (AAEIT), and tested the properties of AAEITs with different dimensions. METHODS: A series of asymmetrical ion traps using arc-shaped electrodes were designed to optimize the properties (resolutions and intensity) of the coupling effects between odd and even multipole fields. Using arginine and reserpine, we evaluated the performance of mass resolution, ion intensity ratio and deduced the collision-induced dissociation (CID) efficiency using a self-constructed electrospray ionization mass spectrometry (ESI-MS) platform. RESULTS: An AAEIT with field radius dimensions of 5 mm × 5.75 mm exhibits a good performance: its maximum resolution of 833 (FWHM) at m/z 175 was achieved for the side of small electrode. With this AAEIT, a tandem mass (MS/MS) capability with 91.0% CID efficiency was obtained with reserpine (m/z 609). CONCLUSIONS: The results indicated that the AAEIT, comprising both odd and even multipole fields, could act as a qualified linear ion trap mass analyzer with compact structure, high resolution, and high tandem mass analysis efficiency. It has a great potential in miniature mass spectrometry.

Determining the age at death of females in the Chinese Han population: using quantitative variables and statistical analysis from pubic bones.

Determining the age at death of females by skeletal features is extremely difficult and important, both in forensics and in physical anthropology. Our previous study of male pubic symphysis suggests that the indicators of morphological changes provide the best results for personal age identification. The indicators that help deduce of the age of females was approximately the same as males except for two specific indicators, which are bone density of the symphysial surface and viz. Viz are ridges and furrows on the symphysial surface, ossific nodules, lower extremities, ventral and ridge of the rampart, dorsal margin, ventral beveling and general macroscopic changes on the symphysial surface. Samples were drawn from 338 female individuals. The study procedures are as follows: Firstly, we examined the morphological features of pubic symphysis using the criteria similar to Hanihara's, Gilbert-McKern and Suchey-Brooks's methods. Secondly, we evaluated each stage with an appropriate score. Thirdly, we deduced four equations to assess the morphological features of the ages of females by statistic analysis. The results were discussed by comparing with Hanihara's, Gilbert-McKern and Suchey-Brooks's methods. The results were consistent and the developing methods for determining the age of death of females were produced.