Question

Name m or c m e loss of an o Consider this Only the highest as accuracy on. Therefore, to most applications aume n provides the molecular mass of the analye and all the peak the moder To date, most of the mass spectra that you have seen were collected on a low resolution, low as curacy GCMS. An excmple is shown below in Figure 3. ASSET m/z - 122 % abundance Figure 3. Mass spectrum of benzoic acid obtained on a low mass accuracy instrument with an e source. 11. Circle the molecular ion of benzoic acid in Figure 3. Use Table 2 to classity the observed mass as the average mass, the isotopic mass or the nominal mass 12. Explain how nominal mass is determined. 13. When interpreting mass spectra, when is it appropriate to use the average mass, the isotopic mass of the nominal mass?

Answer 1

M. - Hall culer ion peak of ben Zoic aud (nez) = 122.] The obserred mano here as nominal mass maa. M amo nom maro 12 ) Nominal maar dituemination of the nominal mass for an element in the mass number of itro most abundent naturally occuring stable isotope fore an ion ore molecule. The nominal mass in the sum of the nomainal massers of the constituent atoms. erga For example benzoic aid = (1246) + (5x1) + (12+] 6) + (16+1) 2x6 Hxár IL CO-H - 122 (13). when interpreeting mass spectra it in appreo priate to use nominal masses of a compound. During nominal mass ditee mination most abundent natureally occurring statale isotopes are taken. so it in easy to calculate the ion - peak of a compound during the study of marro espectra