John M. McGuire

New approaches to on-line ion-pair extraction and derivatization for high-performance liquid chromatography-mass spectrometry

Abstract In a continuation of earlier work, the use of ion-pairing reagents to increase the compatibility of high-performance liquid chromatography (LC) coupled with mass spectrometry (MS) is demonstrated. Counter-ions were selected for examination on the basis of the structural requirements for mass spectrometric fragmentation and the on-line extractability of their ion pairs with different solutes into organic solvents. The use of aromatic ( e.g. , naphthalenesulfonate, picrate) instead of aliphatic ( e.g. , n -decylsulfate) counter-ions shows a significant simplification of the resulting electron impact mass spectra of the solutes. Thus, structural information on the solutes can be easily obtained, especially when relevant peaks occur at lower m /= values. A second example of on-line chemical transformation for LC-MS is shown in the use of trimethylanilinium hydroxide for selective methylation. These results along with previous work, demonstrate practical approaches to enhance the on-line LC-MS method using the moving-belt interface.

Band broadening phenomena with the moving belt LC-MS interface

Abstract The effects of solvent deposition and belt speed on the chromatographic performance of a moving belt LC-MS interface were studied. Spray deposition was utilized for transfer of the chromatographic effluent to the belt surface and a continuously variable drive was used to study the effect of belt speed. Quantitation of these variables was done by calculating the central moments of the generated total ion chromatograms. Close correlation between HPLC-MS and HPLCUV chromatography was obtained under optimized conditions of sample deposition, belt speed and flow rate.

Multispectral identification of alkyl and chloroalkyl phosphates from an industrial effluent

Multispectral techniques (gas chromatography combined with low and high resolution electron-impact mass spectrometry, low and high resolution chemical ionization mass spectrometry, and Fourier transform infrared spectroscopy) were used to identify 13 alkyl and chloroalkyl phosphates in a water sample taken from the effluent of a plant that manufactures fire-retardant chemicals. Of the 13 phosphates identified, only 4 were located in hbrary mass spectral data bases; thus, techniques other than conventional low resolution electron-impact mass spectrometry with data base matching were required. Several of the Identified phosphates are commonly used ftre retardants; however, three exhibited chemical structures different from those of the commercially manufactured fire retardants and the reactants used in their synthesis.