Use of a Portable X-Ray Fluorescence Analyzer for Rapid and Accurate Determination of Iron in Vitamins and Supplements

Authors

  • Cassandra Casillas San Francisco State University
  • Swee Chew San Francisco State University
  • Alex Lam San Francisco State University
  • Juan Castillo San Francisco State University
  • Pete Palmer Dept. of Chemistry & Biochemistry, San Francisco State University https://orcid.org/0000-0002-3173-5726

DOI:

https://doi.org/10.21423/JRS.REGSCI.102258

Keywords:

SRM, ICP-MS, LOD, ppm, XRF

Abstract

This study describes the development of an X-Ray Fluorescence (XRF) method to quantify iron in vitamins and supplements. Four different products and a NIST Standard Reference Material (SRM) were prepared by homogenizing 20 tablets in a mixer mill and diluting known masses of each sample into known masses of cellulose. Calibration standards were similarly prepared by diluting known masses of iron oxide into known masses of cellulose. Analyses were performed using a handheld XRF analyzer using one-minute analysis times. The method gave linear calibration curves with R2 values greater than 0.9995, and good accuracy as demonstrated by relative errors of 9% in the analysis of the NIST SRM. Experimentally determined concentrations of the samples were compared to the nominal concentration of the samples based on the mass of iron per tablet and the average tablet mass. XRF results gave relative differences of +4% and -4% for two iron supplements. XRF results gave a larger relative difference of -19% for the women’s vitamin product. Although the label on the men’s vitamin product stated it was iron-free, XRF and Microwave Plasma Atomic Emission Spectrometry (MP-AES) analyses showed it contained iron levels of 157 and 133 µg/g (ppm), respectively. This XRF method offers a simpler, faster, and less expensive alternative to conventional atomic spectrometry-based methods for this type of application.

Author Biographies

Cassandra Casillas, San Francisco State University

Undergraduate student

Swee Chew, San Francisco State University

undergrad student

Alex Lam, San Francisco State University

undergrad student - note he has graduated and I am unable to access his email address

Juan Castillo, San Francisco State University

undergrad student

Pete Palmer, Dept. of Chemistry & Biochemistry, San Francisco State University

Pete Palmer received a B.S. in Chemistry from Canisius Collegeand a Ph.D. in Analytical Chemistry from Michigan State University. After graduation, he worked in the Corporate Research Division of Proctor & Gamble designing and developing laboratory robotics systems, and at NASA Ames Research Center where he led efforts to apply Mass Spectrometry to life support, atmospheric, and ecosystems monitoring applications. Pete is currently a Professor in the Department of Chemistry and Biochemistry at San Francisco State University (SFSU), Co-Director of SFSU’s Mass Spectrometry Facility, and Science Advisor for the FDA. His research interests focus on the development, characterization, and application of highly automated instrumentation for trace chemical analysis. Some of his applications to date include the development of Direct Sampling Mass Spectrometry and Solid Phase Microextraction GC/MS methods for life support and air quality monitoring, development of the first Proton Transfer Reaction Ion Trap Mass Spectrometer for monitoring volatile organic compounds in air, numerous case studies on the determination of pesticide contamination on Native American artifacts, and pioneering the use of X-Ray Fluorescence Spectrometry for rapid screening of toxic elements in consumer products. Pete received the Jefferson Award in 2005 for community service in applying chemical analysis to serve the public interest.  

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Published

2023-02-21

Issue

Vol. 10 No. 2 (2022): Special Issue on Regulatory Applications of Portable Tools and Methods to Monitor Toxic Substances in Consumer Products

Section

Scientific Articles

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Copyright (c) 2023 Cassandra Casillas, Swee Chew, Alex Lam, Juan Castillo, Pete Palmer

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