Mass spectrometer and method and improved ion transmission
US4963736A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1989 |
| Grant date | Oct 16, 1990 |
| Priority date | — |
| Expiry date | Nov 15, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J49/063
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a mass spectrometer system, ions travel through an orifice in an inlet plate into a first vacuum chamber containing AC-only rods, and then through an orifice into a second vacuum chamber containing a standard quadrupole. The second vacuum chamber is held at low pressure, e.g. 0.02 millitorr or less, but the product of the pressure in the first chamber times the length of the AC-only rods is held above 2.25.times.10.sup.-2 torr cm, preferably between 6.times.10.sup.-2 and 15.times.10.sup.-2 torr cm, and the DC voltage between the inlet plate and the AC-only rods is kept low, e.g. between 1 and 30 volts, preferably between 1 and 10 volts. This produces a large enhancement in ion signal, with less focussing aberration and better sensitivity at high masses, and also allows the use of smaller, cheaper pumps so the system can be more easily transportable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.