Alandra Lopez

All Publications

• Assessing Analytical Methods for the Rapid Detection of Lead Adulteration in the Global Spice Market. Environmental science & technology Lopez, A. M., Nicolini, C. M., Aeppli, M., Luby, S. P., Fendorf, S., Forsyth, J. E. 2022

  Abstract

  Lead adulteration of spices, primarily via Pb chromate compounds, has been documented globally as a growing public health concern. Currently, Pb detection in spices relies primarily on expensive and time-consuming laboratory analyses. Advancing rapid Pb detection methods, inclusive of their accuracy and precision, would improve field assessments by food safety inspectors, stakeholders, and the public in the hope of reducing Pb exposure risks at its source. Here, we present two field procedures for Pb detection: portable X-ray fluorescence analysis (pXRF) and a simple colorimetric test. We assess their efficacy to detect Pb and its chemical form in seven spice types, including powders, spice-salt mixtures, and dried roots, compared to the proven laboratory technique, inductively coupled plasma mass spectrometry (ICP-MS). Lead concentrations measured using pXRF and ICP-MS were within 5% of each other for spice powders and 24% for dried roots. By pXRF, spice samples were analyzed within collection plastic bags without preparation, resulting in a detection limit of 2 mg Pb/kg for spice powders, which is comparable to national food standards. The colorimetric test utilized here targets hexavalent chromium, making the method selective to Pb chromate adulteration assuming that this is its dominant source in spices. Color development, and thus detection, was observed when Pb concentrations exceeded approximately 5-70 mg/kg in dried turmeric roots and 1000 mg/kg in spice powders; however, it was ineffective for the spice-salt mixture. We show that pXRF analysis and a colorimetric assay provide information that may improve field decisions about Pb adulteration in a range of spice types, helping to minimize Pb exposure.

  View details for DOI 10.1021/acs.est.2c03241

  View details for PubMedID 36343212

• Perchlorate and Agriculture on Mars SOIL SYSTEMS Oze, C., Beisel, J., Dabsys, E., Dall, J., North, G., Scott, A., Lopez, A., Holmes, R., Fendorf, S. 2021; 5 (3)

  View details for DOI 10.3390/soilsystems5030037

  View details for Web of Science ID 000702098200001

• Soil and Aquifer Properties Combine as Predictors of Groundwater Uranium Concentrations within the Central Valley, California Environmental Science & Technology Lopez, A. M., Wells, A., Fendorf, S. 2020: 10

  View details for DOI 10.1021/acs.est.0c05591

• Protecting Groundwater Quality in California: Management Considerations for Avoiding Naturally Occurring and Emerging Contaminants Fakhreddine, S., Sherris, A., Lopez, A. M., Wells, A., Holmes, R., Nico, P., Bruton, T., Fendorf, S., Babbitt, C. Environmental Defense Fund. 2019 40