Gold chloride (0.017g) was dissolved in deionised water (0.001M, 50ml) and heated under reflux. A solution of sodium citrate tribasic in deionised water (0.039M, 5mL) was prepared and added to the reaction mixture with continuous stirring for a further 20 minutes under reflux. The mixture was cooled to room temperature and later stored under refrigeration (2-8 °C).