Thermospray interface repeller

The HPLC/MS system has been described previously . A Finnigan MAT TSQ 45 was interfaced to a Spectra-Physics SP8700XR gradient pump and ISCO LC-5000 syringe pump for postcolumn flow via a Vestec Thermospray system. A wire-repeller was inserted into the ion source opposite the ion exit orifice(4). 

The two examples discussed show the bioanalytical applicability of LC/MS, both in qualitative analysis and in target compound analysis. Although the moving belt interface owing to its El capabilities is ideally suited for the identification of unknown compounds and is used often for that purpose, identification problems can sometimes also be solved with thermospray LC/MS, for instance by applying repeller-induced fragmentation, and LC/MS/MS. The PSS approach is an example that indicates that LC/MS still can be improved. A more elaborate discussion on the so-called multidimensional approaches in LC/MS is given elsewhere (14). 

Thernospray HPLC/MS. Urine extracts were analyzed by thermospray/HPLC/MS to Identify the metabolites present. A Finnigan 4500 series mass spectrometer Interfaced with a Vestec Thermospray unit was used to perform the analysis. The aerosol thermocouple of the Interface was replaced with a repeller which was connected to an external power supply. The samples were analyzed under thermospray/fllament chemical Ionization with pulsed +/- Ion detection. A mobile phase consisting of acetonitrlle/0.1 M ammonium acetate with a linear gradient of 9X to 65% over 30 minutes was used In the anlaysls. 

Detector MS, Finnigan MAT TSQ 700 tandem quadrupole, MAT TSP-2 interface, thermospray, selective reaction monitoring m/z 340-266, collision offset -6 V, repeller 100 V, vaporizer 130°, source 200°, filament on 200 jjuA, argon 2.5 mTerr, multiplier 1500 V, dynode 15 kV, scan time 1.20 s, MSMSC factor 10... 

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