Determination of Heavy Metals in Tea Through Coprecipitation Separation and Enrichment Combined with Partial Least Square-Spectrophotometry

Using the copper reagent as the coprecipitator under the alkaline condition of pH 10.0, the rapid coprecipitation enrichment of trace metal ions Ni²⁺, Pb²⁺ and Cd²⁺ and Cu²⁺ in tea had been carried out, and the optimal conditions for the formation of complexes of copper reagent with metal ions were analyzed. 4-(2-pyridylazo) resorcinol (PAR) was used as the color developing agent for the four heavy metals, in the spectrophotometric analysis. Partial least square-UV-visible spectrophotometry was used to determine the simulate mixed sample of the four components of the metal ions at the same time, with those in tea. This method is simple, the result is reliable, and is of certain practical value to the determination of heavy metals in tea.