Kubachka et al. 2019 — FDA HPLC-ICPMS method for arsenic speciation in fruit juices (AOAC First Action 2016.04)
This FDA methods paper describes and validates a modified HPLC-ICPMS extraction procedure for quantitative arsenic speciation (iAs, DMA, MMA, AsB) in commercial fruit juices. The key methodological advance is the use of 0.28 M nitric acid (HNO3) extraction, which improves mass balance in low-recovery juices (particularly pomegranate and prune) relative to the original water-extraction procedure. The method became AOAC First Action Method 2016.04, making it the FDA reference method for arsenic speciation in fruit juices and relevant to the FDA action level of 10 µg/kg (ppb) iAs in apple juice.
Key numbers
- FDA action level for iAs in apple juice: 10 µg/kg (10 ppb), issued 2013
- Arsenic species measured: inorganic arsenic (iAs = arsenite + arsenate), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenobetaine (AsB)
- Extraction modification: 0.28 M HNO3 (versus water extraction in original method) significantly improves mass balance for pomegranate juice (from ~60% to >90% recovery) and prune juice
- Separation: HPLC with anion-exchange column; detection: ICPMS
- LOD and LOQ: method validation confirms LOQ below the 10 ppb FDA action level for iAs in apple juice matrices
- Fruit juices analyzed: apple (highest-volume commercial use), pear, grape, pomegranate, prune, cherry
- iAs concentrations in commercial samples: typically below 10 ppb in apple juice from US commercial sources; higher in some grape and apple juices depending on origin
- DMA predominates in some rice-derived or seafood-contaminated matrices; in fruit juices, iAs and DMA both relevant
Methods (brief)
HPLC-ICPMS (high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry) with anion-exchange chromatographic separation of arsenic species. 0.28 M HNO3 acidic extraction replaces water extraction for improved mass balance. Certified reference materials used for validation. Developed by FDA CFSAN (Center for Food Safety and Applied Nutrition) scientists; published as AOAC First Action Method 2016.04. US Government work = public domain. Published in Food Analytical Methods (Springer).
Implications
Certification: This is the FDA reference method for arsenic speciation in fruit juices; any HMT&C certification testing program that includes fruit juice categories should specify this method or its successor for iAs determination. The 10 ppb FDA action level for apple juice iAs is the regulatory anchor. Courses: Excellent for illustrating why speciation matters (total arsenic in fruit juice may exceed iAs by 3-5x when organic arsenicals are present, particularly AsB from seafood ingredients) and why method validation at the action level is important. App: iAs < 10 ppb should be the expected range for compliant US commercial apple juice; higher values signal non-compliance or unusual origin. Microbiome: Not addressed.