Overview
Lopez and colleagues tested two field methods, portable X-ray fluorescence and a simple colorimetric test for hexavalent chromium, against laboratory ICP-MS for detecting lead chromate adulteration in seven spice types. The spice set was chosen to cover a wide lead range, so it is a method-validation study, not a survey of market occurrence. It is filed as context for lead in spice-containing foods.
Key numbers
- Portable XRF and ICP-MS lead results agreed within 5% for spice powders and 24% for dried roots (Abstract).
- Portable XRF detection limit about 2 mg lead/kg for spice powders measured in their plastic bags (Abstract).
- The colorimetric test turned color above roughly 5 to 70 mg/kg lead in dried turmeric roots and 1000 mg/kg in powders, and failed for the spice-salt mixture (Abstract).
- Lead across all 69 samples by ICP-MS: median 137 mg/kg, maximum 11,531 mg/kg (Table 1, p. 16998), reflecting purposive selection.
Methods (brief)
Triplicate pXRF readings through the collection bags; ICP-MS after microwave nitric acid digestion with triplicate digestions and blanks; a diphenylcarbazide assay read by eye after 45 minutes. Lead to chromium molar ratios were used to flag lead chromate pigment.
Evidence Fitness
A methods paper. The samples were selected to test detection across a range, so their lead values are not representative of any market and are not recorded as occurrence findings. Per-sample data are in a supplement not filed. It is context for chili-con-carne-with-beans and cinnamon-roll (spice ingredients), not evidence on those foods, and those pages are not linked.