Source material, acquiring

The Fourier transform mid-infrared (FTIR) spectra of the talc materials from the various vendors were measured by the neat, diffuse reflectance technique. Spectra of the three materials, acquired at a spectral resolution of 1 cm1, are presented in Figure 5. Identical spectra, including peak frequencies, peak width at half height, and peak shape, were measured for the three sources of talc. The major absorption bands and assignments are detailed in Table II [23]. 

The resins are substances derived mostly from vegetable sources some have been used as binders in the preparation of paints and varnishes, others as incense burned in ritual ceremonies, and a few, such as amber, have been used on their own, as semiprecious stones. It should be noted, however, that since the midtwentieth century the term resin has acquired a new meaning that of a synthetic pliable "plastic" material that can be shaped, mostly when hot. Synthetic resins are used mainly for packaging and for making textile fibers and automobile parts. In the discussion that follows the term resin is used to refer only to resins of natural origin (Serpico and White 2000a Parry 1918). 

Figure 31 shows the NMR spectrum recorded from the polyamide filter, and it is a high-quality match with polyamide 6,6, the structure of which is shown on the figure. Figure 32 compares the NMR spectrum for the filter along with that of the contaminant. Although the contaminant spectrum has more noise due to the low level of material available, it is evident that the spectrum acquired from the contaminant has peaks identical to those of the filter. Therefore, it can be concluded that the contaminant is polyamide 6,6, and the likely source was the fuel delivery system module filter. 

There may also be a need for standards that can be used to calibrate instruments, check for progressive shifts in their measurement responses, and ensure that data acquired from different sources are comparable. In most other analytical fields we have standard materials, and these should not be hard to establish. Amongst those that we use is a homogeneous pyrophyllite from the Manuels deposit near St. John s. 

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