Considering the sampling volume of spectrophotometer, the subsequent dilution could not avoid, which would affect the ratio of volumes between water phase and organic phase thus led to
poor enhancement factors. To weaken the negative effect, four par-allel samples were simultaneously operated in the process. The experimental assembly as well as the extraction procedure was schematically illustrated inFig. 1. For each sample, 5mL analyt-ical solution containing Cd and 0.010mmol L−1 dithizone were mixed in the solution and then kept on a magnetic stirring instru-ment at 240rpm for 10min. The trace analyteswere extracted into
the solvent drop from the sample solution. After extraction, the
droplet was carefully retracted into the micro syringe and then
collected in a tube. After that, proper type and volume of dilution
solvent was adapted to properly dilute the concentrated samples,
considering the sampling volume of spectrophotometer. Then, the
resultant sample solution was transported to spectrophotometer
for the determination.