Application of factorial designs for optimisation of on-line determination of cadmium, lead and nickel in welding fumes by atomic absorption spectrometry

A flow-injection flame atomic absorption spectrometric method using diluted nitric acid and ultrasound energy to assist metals acid leaching from welding fumes was optimised. Several variables were simultaneously studied by applying a Plackett-Burman design. Results showed that the statistically significant variables (95%) were concentration of nitric acid solution for cadmium, lead and nickel, ultrasonic water-bath temperature for lead and nickel, and sonication time for nickel. Factors such as ultrasonic water-bath temperature and sonication time were finally optimised by using a central composite design. Detection limits were 0.1, 1.0 and 3.4 µg m-3, and repeatability (n = 11) were 3.2, 1.9 and 1.6%, for cadmium, lead and nickel, respectively. The proposed method was applied to the determination of cadmium, lead and nickel in welders' workplace environments.