187 

 method, given the lack of chromatographic separation as well as the transmission 



losses through an additional mass-filtering quadrupole and the less-than-unit 



efficiency of CID. 



Compound Class Screening 



An example of the information obtained by GC/MS/MS neutral loss scans for 

 screening a complex sample (8 handled glass beads) is shown in figure 4-5. Depicted 

 are the reconstructed ion chromatograms for the neutral losses of 46 Da (top), 30 

 Da (middle), and 18 Da (bottom) from positive ions. The neutral loss of 46 is 

 indicative of carboxylic acid presence. The RIC traces for neutral losses of 30 Da 

 and 18 Da confirm that these peaks found in the top trace are acids. There are 

 some additional GC peaks found in the neutral loss of 30 Da and neutral loss of 18 

 Da chromatograms which do not match up to the peaks found in the top 

 chromatogram. These peaks, according to the table 4-3, are most likely due to 

 aldehydes and/or ketones for a neutral loss of 30 Da; the additional GC peaks in the 

 neutral loss of 18 Da chromatogram arise from the presence of ketones and/or 

 alcohols. A final note pertaining to these chromatograms is that the major peaks are 

 those of acids (confirmed in Chapter 5). The pattern of peaks is similar to that seen 

 in the GC/MS analyses conducted in Chapter 5 due to the abundance of carboxylic 

 fatty acids in the sample. 



The most abundant GC peak in figure 4-5 is centered approximately at scan 

 1675. The neutral loss mass spectrum for a neutral loss of 18 Da of this peak is 



