Cloud point extraction for assessment of lead and cadmium levels of somatic cells in raw milk using graphite furnace atomic absorption Spectrometry

Abstract

The main objective of present study is to assess the probable associations between somatic cell (SC) levels and concentration of lead and cadmium in raw milk. Milk samples were collected from individual quarters of 30 Holstein cows and divided into three groups based on somatic cell level, including: low somatic cell level (< 200,000), intermediate somatic cell level (200,000-800,000) and high somatic cell level (> 800,000 cell mL-1). A ligandless cloud point extraction (CPE) procedure has been developed for determination of Pb and Cd in microwave-assisted digested milk by using graphite furnace atomic absorption spectrometry (GFAAS). The analytes are quantitatively extracted to the phase rich in the non-ionic surfactant Triton X-100 after centrifugation. The surfactant rich-phase was dissolved with 0.5 mL 1.0 mol L-1 HNO3 in methanol to decrease the viscosity. The optimal extraction and reaction conditions (e.g., surfactant concentration, pH and effect of time) were obtained. The detection limits of proposed method were calculated 28 and 2.36 ng L-1 for Pb and Cd, respectively.