The NR latex sample was digested under the optimum conditions of thermoreactor (30 gL-1 ammonium persulphate, 100 °C of digestion temperature and 70 min of digestion time) followed by color developing using molybdenum blue method [5]. Fig. 4 demonstrates no significant difference of the absorbance from 10 to 60 min of standing time. Hence, as a reason of time saving, 10 min of standing time was selected.