Abstract
This work was undertaken to develop an improved gas chromatography (GC) analysis of poly (3‐hydroxyalkanoate) (PHA) quantification method based on acidic methanolysis. This is achieved by investigating the kinetics of acidic hydrolysis of PHAs with sulfuric acid in the chloroform/aqueous solution to identify suitable hydrolytic pretreatment conditions for quantitative analysis of PHAs. The target parameters included sulfuric acid concentration, salt (NaCl) addition, kind of PHAs (commercial products of poly‐3‐hydroxybutyrate (PHB), poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV‐8%) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx‐3.8% and‐10.5%), as well as the type of PHA‐producing microorganisms (Cupriavidus taiwanensis 184 and Burkholderia sp. PTU9). These results show that esters would preferentially accumulate in the organic phase when NaCl was added in the two‐phase system, thereby enhancing the accuracy of GC analysis. Decomposition efficiency of different types of PHAs was found to be dependent on sulfuric acid concentration, such as 1% H~2~SO~4~ was favorable for PHB decomposition, while 5 and 7% H~2~SO~4~ should be used to decompose PHBV and PHBHHx. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.