PHA repeat unit composition was determined by gas chromatography/mass spectrometry (GC/MS) of the 3-hydroxymethyl
esters. Prior to analysis, PHA polymers were re-precipitated three
times into cold methanol in order to remove all the residual free
glycerol. For methanolysis, a 15% solution (v/v) of sulphuric acid
in methanol (5 mL) was added to a mixture of PHA (15.0 mg) in
chloroform (5.0 mL).