| (19) |
 |
|
(11) |
EP 0 217 644 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
16.03.1988 Bulletin 1988/11 |
| (43) |
Date of publication A2: |
|
08.04.1987 Bulletin 1987/15 |
| (22) |
Date of filing: 25.09.1986 |
|
|
| (84) |
Designated Contracting States: |
|
CH DE FR GB IT LI NL SE |
| (30) |
Priority: |
01.10.1985 US 782512
|
| (71) |
Applicant: FINNIGAN CORPORATION |
|
() |
|
| (72) |
Inventors: |
|
- Fies, William J.
()
- Story, Michael S.
()
|
|
| |
|
| (54) |
Quadrupole mass filter |
(57) An unbalanced radio frequency voltage is supplied between two pairs of conductive
rods (10a, 10c; 10b, 10d) of a quadrupole mass filter of a mass spectrometer system.
Means (S2) are provided for d.c. voltage polarity reversal for monitoring positive
and negative ions. The d.c. voltage is derived by rectification of the radio frequency
voltage.