Page 117 - Pharmaceutical Organic Chemmistry-3 (Theoritical book) 24-25

Clinical Pharmacy PharmD - 2024/2025 Level 2 Pharmaceutical Organic Chemistry-3 (PC 305)
❖ The halogens isotopes have certain pattern that is reproducible and could be used to

confirm the structure of the analyzed sample.

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1. Cl: chlorinated compounds show 2 peaks separated by 2 (m/z) on X-axis; M
37
35
molecular ion peak for ( Cl isotope-normal abundant isotope) & M +2 peak for ( Cl
37
35
isotope) with (3:1 - Cl : Cl) relative peak abundance (%).
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2. Br: brominated compounds show 2 peaks separated by 2 (m/z) on X-axis; M
79
81
molecular ion peak for ( Br isotope-normal abundant isotope) & M +2 peak for ( Br
81
79
isotope) with (1:1 - Br : Br) relative peak abundance (%).

12
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M peak: at 60 (m/z) for ( C-normal isotope), notice that here, molecular ion peak is the base
13
peak (with 100% abundance) / M peak: at 61 (m/z) for ( C- isotope).
+1

13
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+2
+1
M peak (also base peak): at 78 (m/z) / M peak: at 79 (m/z) for ( C- isotope) / M peak: at 80
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(m/z) for ( Cl- isotope).