Perfluorotributylamine, PFTBA

Before beginning ary analysis, an instrument must be checked for its performance. Every factory-built GC/MS instrument is equipped with a tuning substance, such as perfluorotributylamine (PFTBA). The characteristic mass ions of this compound (or any other tuning compound) and the relative area response corresponding... 

Mass Spectrometer. The mass spectrometer was a Hewlett-Packard 5988A quadrupole mass spectrometer with a dual EI/CI source and positive and negative ion detection. The system was controlled by a Hewlett-Packard 1000 computer. The mass spectrometer was periodically tuned manually using perfluorotributylamine (PFTBA) on ions m/z 69, m/z 214, and m/z 502 in El and PCI modes, and on ions m/z 245, m/z 414, and m/z 633 in NCI mode. 

Accurate mass scales (or calibration curves) are generally established by measuring the mass spectrum of a reference compound simultaneously with the spectrum of the sample. The precise mass of every ion in the spectrum of the reference compound is known, so a precise mass correlation is thereby provided. Common reference materials are perfluorokerosene (PFK) and perfluorotributylamine (PFTBA), the mass spectra of which are shown in Figures 3.1 and 3.2, respectively. Since all the ions formed from these compounds contain several fluorine atoms (18.9984) and no hydrogen atoms (1.0078), they have negative mass defects and are well separated from organic ions that normally have positive mass defects. Of course, other chemicals may be used to provide reference masses, as long as the exact masses in its spectrum are known. 

Before the mass spectrometer can be used to collect mass spectra, the instrument must be tuned and calibrated. The tuning procedure involves setting voltages associated with the ion source, lenses, and detector (to optimize sensitivity), and selecting values for potentials applied to the quadrupole (to set the instrument resolution). These tasks are accomplished while a calibration standard is continuously added to the instrument. A common calibration standard is perfluorotributylamine (PFTBA), (CF3CF2Cp2CF2)3N. Usually ions at miz 69,219, and 502 are monitored (Fig. 8.50). 

Figure 8.50 Electron ionization mass spectrum of perfluorotributylamine (PFTBA). inserts show the peak profiles for m/z 69, 219, and 502.

The study of droplet rupture and coalescence by direct visual observation has been utilized in numerous essential studies [39-43]. Of principal importance are the experimental studies by Amelina et al. on the analysis of colloid stability in artificial blood substitutes [40-43]. These studies involved the use of various nonpolar phases, including perfluo-rinated systems, such as perfluorodecalin (PFD), perfluorotributylamine (PFTBA), per-fluoromethylcyclohexylpiperidine (PFMCHP), and conventional hydrocarbons, such as heptane. Stabilizing agents included Pluronic surfactants (ethylene oxide (EO)/propylene oxide (PO) block copolymers), as well-fluorinated surfactants, such as perfluorodiisononyl-ene with 20 mol of EO (( )-PEG). Tables 4.1 and 4.2 show some very characteristic results. 

Perfluorotributylamine (PFTBA, FC43) Reference Table, 0000 Thermo Fisher Scientific Data Sheet PS30040 E. 

Perfluorotributylamine (PFTBA), a widely used reference substance for caUbration of the mass scale, M 671. 

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