Model No.: LCQ Classic Manufacturer: Thermo Electron Corp. Location: RRC-East, SES 109A

The Thermo Finnigan LCQ classic is a quadrupole ion trap LC mass spectrometer equipped with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) ion sources, interfaced to a Thermo Separation Products liquid chromatography (LC) system.

The LC system consists of a SpectraSYSTEMS SCM 1000 vacuum membrane degasser, AS 3000 autosampler, a P4000 gradient elution pump and a UV 2000 dual-wave length detector. The autosampler has a 120 random vial access capacity. The P4000 is a narrow-bore quaternary low-pressure pump with a 0.5-10 ml/min flow rate range. Conventional mobile phases are methanol/acetonitrile/water.

Arrangements for the use of other mobile phases must be made prior to sample submissions. Provision of LC columns is the responsibility of the investigator. Samples may be introduced to the MS either by direct infusion from the built-in syringe pump or subsequent to HPLC separation.

Positive and negative ion ESI and APCI mass spectra can be acquired over the mass to charge range m/z 50 to m/z 2000 at unit resolution and with a peak width of 0.25 daltons/z. Acquisition of such spectra is important for protein/peptide sequencing because it permits identification of ions possessing up to 4 charges. A specific ion may be selected, stored in the trap and collided with He gas in an attempt to have it undergo fragmentation reactions. The spectrum of the fragment ions resulting from such collisions can then be obtained. Also, one of these fragment ions can be selected, stored in the trap and induced to undergo collision-induced fragmentation. This process may be repeated up to 10 times. This MS/MS technique is important in structure determinations because ESI and APCI mass spectra are characterized by the presence of molecular and/or adduct ions (e.g., the molecular ion coordinated with one or more ubiquitous Na ions) and the absence of fragment ions that are often of diagnostic value in structure determination.

The operation of both the LC and the LCQ are controlled by a PC based data system. The BioExplore software allows for deconvoluting the spectrum of a multiply-charged protein or peptide m/z charge state envelope into the corresponding uncharged mass spectrum.

The LCQ Classic was installed in 1998 and was obtained on an NSF grant by Drs. Richard B. van Breemen, Stuart Scheppele and Charles E. Brown.

Acknowledgement Section of Manuscripts

If your publication includes data/results/mass spectra obtained with the LCQ mass spectrometer, the following statement, or similar, must be included in the Acknowledgements Section.