Andrew's git - notes.git/blob - chem/organic-analysis.tex

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  12\fancyhead[LO,LE]{Organic Analysis}
  13\fancyhead[CO,CE]{Andrew Lorimer}
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  17\begin{document}
  18
  19  \title{Organic Analysis}
  20  \author{Andrew Lorimer}
  21  \date{}
  22  \maketitle
  23
  24  \section{Mass Spectrometry}
  25
  26    \textbf{Separation of particles by mass}
  27
  28    Identifies molecules by searching for:
  29    \begin{enumerate}
  30      \item The molecular ion \ce{M+}
  31      \item Fragments of the molecule (as ions)
  32    \end{enumerate}
  33
  34    Complicated by noise from different isoptopes of elements (related to relative abundance of isotopes). Every molecule has a \textit{unique} mass spectrum which can be used to identify a substance.
  35
  36    \subsection*{Process}
  37
  38    \begin{enumerate}
  39      \item Sample species are bombarded with electrons
  40      \item Positive ions are formed by detaching electrons
  41      \item Ions are accelerated by an electric field
  42      \item Accelerated ions are deflected by a magnetic field in a circular radius
  43    \end{enumerate}
  44
  45    \[ \text{deflection radius} \propto \dfrac{m}{z} \]
  46
  47    \begin{align*}
  48      \therefore \qquad \uparrow \text{mass} & \implies \downarrow \text{deflection} \implies \uparrow \text{radius} \\
  49      \uparrow \text{charge} & \implies \uparrow \text{deflection} \implies \downarrow \text{radius}
  50    \end{align*}
  51
  52    \subsection*{Reading a mass spectrum}
  53
  54    \(x\) axis: mass-charge ratio \(\frac{m}{z}\) of fragments \\
  55    \(y\) axis: relative abundance of fragments (molecular MS) or isotopes (isotopic MS) with that \(\frac{m}{z}\)
  56    
  57    \begin{itemize}
  58      \item Most ions have a single +ve charge, \therefore \(\frac{m}{z} = m\)
  59      \item Ions with double or triple +ve charges can show up in lower abundance as \(\frac{m}{2}\) or \(\frac{m}{3}\)
  60      \item \textbf{Base peak}: most abundant ion, assigned 100
  61      \item \textbf{Molecular ion}: molecule as singly charged ion \ce{M+}
  62      \item \textbf{Molecular fragments}: can show functional groups and other characteristic combinations of elements
  63    \end{itemize}
  64
  65    \subsubsection*{Combined techniques}
  66
  67  \section{IR Spectroscopy}
  68
  69  \section{Magnetic resonance imaging}
  70
  71
  72\end{document}