Instant Notes: Analytical Chemistry

Section E – Spectrometric techniques E14 MASS SPECTROMETRY Principles Mass spectrometry(MS) is an analytical technique in which ...

E14 – Mass spectrometry 271 The principal components are ● a sample inlet,which facilitates the controlled introduction of gaseo ...

272 Section E – Spectrometric techniques There are several types of mass analyzer. (i) A single focusing magnetic mass analyzer( ...

E14 – Mass spectrometry 273 opposite pairs of rods. This results in ions of one particular m/zvalue passing straight through the ...

Single magnetic analyzers have resolving powers of up to about 5000, but much higher resolution instruments are required to dist ...

E14 – Mass spectrometry 275 Fragmentation The production of a molecular ion is often followed by its dissociation, or frag- ment ...

276 Section E – Spectrometric techniques CNH 2 C 6 H 5 –C 2 H 2 NH 2 C 6 H 5 C m/z 105 m/z 51 m/z 77 m/z 44 M•+ m/z 121 + +e– –2 ...

E14 – Mass spectrometry 277 tables for all possible combinations of these elements up to an RMM of several hundred. Theoretical ...

278 Section E – Spectrometric techniques ● the identification of unknowns and of structural features from fragmentation patterns ...

E14 – Mass spectrometry 279 The spectrum of methylbenzene(Fig. 9) typifies alkyl-substituted aromatic compounds, with a base pea ...

280 Section E – Spectrometric techniques 100 80 60 40 20 0 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 Relative abunda ...

E14 – Mass spectrometry 281 of about one-third the intensity atm/z51, the expected ratio for a species with only one chlorine at ...

282 Section E – Spectrometric techniques 100 80 60 40 20 0 20 (^182857) 77 105 121 51 0 40 60 80 100 120 Relative abundance m/z ...

Section F – Combined techniques F1 ADVANTAGES OF COMBINED TECHNIQUES Other sections of this text describe some of the many techn ...

from a gas chromatograph at atmospheric pressure into the vacuum inlet of a mass spectrometer. There are two alternative strateg ...

Section F – Combined techniques F2 SAMPLE IDENTIFICATION USING MULTIPLE SPECTROMETRIC TECHNIQUES In order to study and identify ...

compounds or whose spectra are not present in the database. For example, the presence of a strong peak in an IR spectrum near 17 ...

presence of aliphatic groups, or unsaturated or aromatic structures may be inferred from the position of the −C-H stretching ban ...

Applications Example 1 The spectra shown in Figure 1 (a)−(d)were obtained for a compound of composi- tion C 67.0%, H 7.3%, N 7.8 ...

F2 – Sample identification using multiple spectrometric techniques 289 4000 3000 2000 1500 1000 500 %T cm–1 100 50 0 40 27 43 52 ...