Zhu, Zhiguang Direct quantitative determination of adsorbed cellulase on lignocellulosic biomass with its application to study cellulase desorption for potential recycling / Zhiguang Zhu, Noppadon Sathitsuksanoh and Y.-H. Percival Zhang YA2010 M02 Ninhydrin assay Source: Analyst 134 (11) 2009 : 2267-2272 0003-2654