Thermospray HPLC

Abian, J. and G.D. Barceld (1993). Analysis of chloro-triazines and their degradation products in environmental samples by selecting various operating modes in thermospray HPLC/MS/MS. J. Agri. Food Chem., 41 1264-1273. 

Sulphonated Azo dyes - Optimisation of nH ion sonrco Thermospray HPLC-MS - [16]... 

These compounds 52, 53, 54 and 55 have been deuterium-labelled37 in 33%, 80%, 81% and 70% yield, respectively, starting from the corresponding unlabelled compounds by direct transesterification with perdeuteriated methanol containing 0.1 M NaOH (equation 15). The 2H-labelled methyl esters 52-55 have been used as internal standards for thermospray HPLC mass spectrometric determination of alkaloids produced by Catharanthus roseus, many of which are medicinally important38. 

Thermosprav HPLC/MS. Thermospray HPLC/MS was performed on a Finnigan MAT 4500 quadrupole mass spectrometer (San Jose, CA). 

Tandem MS. The thermospray HPLC/MS/MS was performed on a Finnigan MAT TSQ-46C triple quadrupole mass spectrometer interfaced to an INCOS Data System (Finnigan MAT, San Jose, CA). The triple quadrupole was operated with the first and second quadrupoles in the RF mode during HPLC/MS operation. For HPLC/MS/MS analysis, the first quadrupole selected the [M+H] ion of the compound, while the third quadrupole was scanned over the mass range of 12-300 daltons. The second quadrupole serves as a collision chamber. Argon collision gas was added to the enclosed chamber of this quadrupole to give a pressure of 2 mtorr for collisional activation of the sample ions. 

The diversity of compounds that can be analyzed by HPLC currently preclude the use of any one HPLC/MS technique to specifically detect trace quantities. Thermospray is one of the most popular HPLC/MS techniques due to its ability to ionize nonvolatile and thermally labile compounds with minimal compromises on a HPLC separation or MS operation. Ion evaporation ionization (no filament or discharge) is suitable for numerous compounds, but often results in spectra with insufficient structural information (i.e. one ion spectra), with sensitivities varying drastically between compound classes. In cases where thermospray specificity or sensitivity is not sufficient, complementary HPLC/MS approaches need to be employed. The use of thermospray HPLC/MS and complementary techniques (i.e. immobilized enzyme bioreactors, chemical degradation and particle beam HPLC/MS) have been evaluated for the specific analysis of three major classes of compounds--peptides, pharmaceuticals, and pesticides. 

Compounds that have PA significantly lower than ammonia (i.e. carboxylic acids) do not undergo proton transfer reactions, partially accounting for the diversity of sensitivities observed in thermospray HS. Derivatization to increase the PA of a sample is one way to Increase Cl sensitivity. Diethylamlnoethyl (DEAE) derivatives (reaction shown below) can change the PA of carboxylic acids, greatly enhancing the signal level obtained by thermospray HPLC/MS [15]. 

Voyksner, R. D. Thermospray HPLC/MS for Monitoring the Environment A Chemical Analysis Series on Application of New Mass Spectrometry Techniques in Pesticide Chemistry Rosen, J. J. Wiley and Sons, NV, 1987 Vol. 91, Chapter 11, p 146. 

A method that uses high performance liquid chromatography/ mass spectrometry (HPLC/MS) for the analysis of chlorinated phenoxyacid herbicides is described. During method development different techniques were used to increase both the sensitivity and the specificity of thermospray HPLC/MS for chlorinated acid herbicides. These included the operation of the instrument in the negative chemical ionization (NCI) mode initiated by discharge and the use of a wire-repeller in the ion source for efficient extraction of positive ions. Single quadrupole repeller-induced and multiple quadrupole collision activated dissociation (CAD) experiments were also performed to increase the structural information of the mass spectra. 

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. 

Peak 1 (RRT 0.64) This is an early eluting peak and none of the thermospray/HPLC/MS spectra corresponded to its RRT. No further work was pursued since this peak represented 2.45 - 5.59% of all the metabolites. 

TABLE IV. COMPARISON OF HPLC AND THERMOSPRAY/HPLC/MS RETENTION TIMES OF THE URINE EXTRACT... 

Almost always GC-MS has been the chosen tool for identification of alkanes from geological or living sources, and such methods in general are outlined in preceding chapters. More recently, the tandem mass-spectrometric (MS-MS) technique has been applied to the effluent from GC columns and adaptions of the standard GC-MS methods have been applied for the analysis of triterpanes and steranes (C30 compounds and the like) that often occur in petroleum and are valuable geological markers . Supercritical fluid chromatography linked to MS will undoubtedly also become a widely used technique for separation and analysis of petroleum and natural waxes, as will thermospray HPLC-MS methods. 

Carbamate, methyl -urea and oxime pesticides and herbicides AgO.IM NH,0 CCH, Large dynamic range of 10 Thermospray HPLC-MS Ippb [25]... 

---