Spectrophotometric Determination of Cadmium in Edible Fungi with Separation by Dispersive Liquid-Liquid Microextraction

0.500 0 g of the cleaned, crushed and dried sample was digested with HNO₃ (5 mL) and H₂O₂ (3 mL) in microwave oven under the mode of programmed temperature elevation. After digestion, the sample solution was evaporated to about 1 mL in boiling water bath, and then water was added to make up its volume to 50 mL. 5.00 mL of the solution was taken and the following solutions were added in succession:1 0.2 g·L^-1 5-Br-PADAP:2.0 mL; 2 ammoniacal buffer (pH 9.0):3.0 mL; and 3 100 g·L^-1 Triton X-114:3.0 mL。Then the volume was made up to 25 mL with water and mixed thorough to have the colored complex of Cd²⁺ formed. After 10 min, 1.0 mL of octyl alcohol was added and swirled for 1 min. After centrifugation for 5 min and phase separation, the lower phase was removed and the red colored upper phase was taken and made up its volume to 3 mL with ethyl alcohol. The absorbance of the red solution was measured at 540 nm. Linearity for Cd²⁺ was kept in the range within 10.00 mg·L^-1, and the detection limit (3s) found was 0.05 mg·L^-1. Values of recovery obtained by standard addition method were in the range of 93.3% to 103%. Values of RSDs (n=6) found were less than 5.0%.