Electrospray ionization interface to high pressure mass spectrometry and related methods
摘要
說明書
Ions (shown as the spray triangle) produced during electrospray were conducted from atmospheric pressure (760 Torr) into the first chamber of the mass spectrometer (?1 Torr, ambient air) using a custom interface. First, ions traveled through a stainless steel capillary (2) (0.01 in. ID, Valco Instruments Co, Inc., Houston, Tex.), to which a voltage was applied, typically between +100 and +250 V. The capillary was held in place by a Swagelok UltraTorr fitting (Swagelok, Inc., Solon, Ohio). Ions were then accelerated by a copper electrode (28) and focused with a single “gate” electrode (38) into the trap (30). The end of the capillary and the accelerating electrode were fixed approximately 3 mm from the gate electrode. Ions were typically accumulated for 5 ms before analysis. They were then scanned out of the trap and detected with an electron multiplier (Detech 2300, Detector Technology, Inc., Sturbridge, Mass.). A typical mass spectrum was an average of 30 to 1000 individual mass scans.
Differential pumping held the mass analyzer and detector at independent pressures. The electron multiplier used for detection operated at lower pressures (<20 mTorr). Differential pressure was provided by two sets of pumps. A dry scroll pump (SH-110, Agilent Technologies, Inc., Santa Clara, Calif.) was used on the mass analyzer-chamber (?1 Torr) and an Agilent TPS Bench turbomolecular pump (Model TV81M) backed by a dry scroll pump (SH-110) was used on the detector chamber (?10 mTorr).
