Derivatization of Fatty Aldehydes and Ketones: Girard’s Reagent T (GRT)

Abstract

In lipid metabolism and during oxidative stress, a number of fatty aldehydes are generated. Detection and quantitation of these reactive aldehydes is optimally achieved by trapping them with a derivatization reagent. In this chapter, we present Girard’s Reagent T (GRT) that is a robust agent for derivatizing aldehydes and ketones and provides a derivative that is highly charged for accurate ESI quantitation. GRT is a quaternary amine with a reactive hydrazine group that derivatizes aldehydes and ketones to form hydrazones:

$$ \mathrm{R}\hbox{--} C HO+ N{H}_2\hbox{--} NH\hbox{--} C O\hbox{--} C{H}_2\hbox{--} \mathrm{N}{\left( C{H}_3\right)}_3\to \mathrm{R}\hbox{--} \mathrm{C}=\mathrm{N}\hbox{--} NH\hbox{--} C O\hbox{--} C{H}_2\hbox{--} \mathrm{N}{\left( C{H}_3\right)}_3 $$

The aldehydes or ketones are augmented in mass by 113.09528 after derivatization with GRT and the [M+H]⁺ ions of these derivatives are monitored in ESI. In this chapter, we describe the use of GRT for quantitating fatty aldehydes (Johnson, Rapid Commun Mass Spectrom 21:2926–2932, 2007) ketosterols (Johnson, Rapid Commun Mass Spectrom 21:2926–2932, 2007; Johnson, Rapid Commun Mass Spectrom 19:193–200, 2005; Crick et al., Biochem Biophys Res Commun 446:756–761, 2014), and lipid oxidation products like formyl lysophosphatidylcholine (Fuchs et al., Lipids 42:991–998, 2007).