Preconcentration of Lead in Digested Protein Powders for Analysis by FAAS

Baghaie, Neena, Jessica LaBond, Sabrina Baghaie, Katherine Lanigan, and Elizabeth Roberts-Kirchhoff

Protein powders are easily acquired in today’s market. According to an article in Consumer Reports1, some highly-marketed protein powders contain traces of heavy metals including lead. A method for cloud point extraction was developed and subsequently used to extract lead using Triton X-114 and 1-phenylthiosemicarbazide (1-PTSC). The conditions for formation and isolation of the lead-containing micelles included adjusting the pH to 9.0 prior to addition of the detergent and 1-PTSC and heating the samples. The metal-rich phase was isolated by centrifugation and then cooling. The phase containing the concentrated metals was suspended in nitric acid/methanol mixture prior to analysis. This method was used first with a series of lead standards, and then later with digested protein powder samples. All samples were analyzed on a Perkin-Elmer 400 AAnalyst flame atomic absorption spectrometer.