Development of a wet digestion method for paints for the determination of metals and metalloids using inductively coupled plasma optical emission spectrometry.

Paints, a complex matrix, have a variable composition that is dependent on the application. In this work, a new wet digestion procedure for the determination of Al, As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Sn, Sr, Ti and Zn in paint samples using inductively coupled plasma optical emission spectrometry (ICP OES) has been developed. An experimental design approach was employed to determine the optimal conditions for achieving complete solubilization and/or decomposition in the sample preparation method. An efficient sample preparation was developed that consisted of a pre-digestion step at 40°C for 20 min using 1 mL of HNO3 to eliminate organic solvents followed by digestion at 120°C for 3h using 5 mL of HCl and 1 mL of HF in a block digestion. The proposed procedure promotes the complete solubilization of different bases of paints at low temperature and atmospheric pressure. The accuracy was determined by addition/recovery tests and comparing the results with those obtained using the ASTM D335-85a standard sample preparation method. The limits of quantification were 1.78, 0.11, 0.006, 0.006, 0.01, 0.04, 0.006, 0.006, 0.02, 0.07, 0.30, 1.30 and 0.30 mg kg(-1) for Al, As, Ba, Cd, Cr, Cu,Mn, Ni, Pb, Sn, Sr, Ti and Zn, respectively. The proposed method was applied for the analysis of inorganics via the ICP OES of paints with different colors and bases used to cover wall surfaces.