AbstractWe report the minimum amounts of polysaccharides (6.5 ng) that can be studied using capillary electrophoresis‐laser‐induced flurescence (CE‐LIF) and describe the separation of the various monosaccharides susceptible to occur in Sinorhizobium cell wall. On‐gel hydrolysis of the polysaccharides is described. It allowed the easy and rapid determination of the monosaccharide composition of the excised lipopolysaccharides. The composition obtained fits with gas chromatography‐mass spectrometry (GC‐MS) results. This study underlines the simplicity of using CE‐LIF, which remains an entirely “water medium” method, unlike GC‐MS which is, in addition, less sensitive (at least 100‐fold) than CE‐LIF.