Determination of Residual Amounts of 3,3'-Dichloro-4,4'-diaminodiphenylmethane in Plastic Track by High Performance Liquid Chromatography

The plastic track sample was made to small particles with sizes ranging between 0.85 mm and 1.40 mm by any of those ready methods. A portion (0.500 0 g) of the crushed sample was taken and extracted ultrasonically with 10 mL of acetone for 60 min. The extract was collected and evaporated to near dryness and then to dryness by N₂-blowing. The residue was taken up with 1.0 mL of methanol, and the solution was filtered through 0.22 μm filtering membrane. The filtrate was used for HPLC determination of the content of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA). In HPLC separation, C₁₈ reverse phase chromatographic column was used as stationary phase, and mixtures of water (A) and methanol (B) in various ratios were used as mobile phases in the gradient elution. MOCA in the eluate was detected by diode array detector at the wavelength of 245 nm. Linear relationship between values of peak areas and the respective mass concentrations of MOCA was found in the range from 1.0 to 50.0 mg·L^-1, with detection limit (3S/N) of 1.0 mg·kg^-1. Test for recovery was made by standard addition method at 3 concentration levels of 2.50, 10.0 and 100 mg·kg^-1, giving results of recovery in the range of 86.4%-92.3%, and RSDs (n=6) ranged from 3.2% to 4.2%.