Karavoltsos et al. 2020 — Copper complexation and 16 trace metals in Greek vinegars
This study applied differential pulse anodic stripping voltammetry (DPASV) to characterize copper complexing capacity in 43 Greek retail vinegars, and used ICP-MS to quantify 16 trace elements (Al, As, Ba, Cd, Co, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Rb, Sr, V, Zn). Balsamic vinegars consistently showed higher concentrations of Al, Cr, Fe, Mn, Rb, Co, and Sr compared to common vinegars, reflecting their production from cooked concentrated grape must. Of the toxicologically significant metals, Pb concentrations ranged up to 86 µg/L (ppb) in one balsamic red vinegar with honey, and two samples (5% of total) exceeded California’s Proposition 65 threshold for balsamic vinegar of 34 µg/L; As and Cd were lower but detectable.
Key numbers
All concentrations reported as µg/L (= ppb for liquid matrices). ICP-MS, Thermo Scientific ICAP Qc.
As (arsenic, total):
- Range across all vinegars: <0.05 to 26 µg/L
- Median common vinegars: 2.6 µg/L; median balsamic: 4.2 µg/L (difference not significant, p = 0.095)
- Maximum daily intake at 15 mL serving = 0.40 µg, far below BMDL0.5 of 3 µg/day (for 60 kg person)
- Note: paper reports total As (tAs), not speciated iAs; speciation unknown
Pb (lead):
- Range: <0.05 to 86 µg/L
- Median common vinegars: 6.0 µg/L; median balsamic: 9.8 µg/L (not significantly different, p = 0.654)
- Second highest: 63 µg/L in a red balsamic
- Two samples (5%) exceeded California Prop 65 threshold of 34 µg/L for balsamic vinegar (at 0.5 µg/day allowance and 15 mL serving)
- Main Pb sources identified as anthropogenic: chemicals used during production and storage materials
Cd (cadmium):
- Range: 0.03 to 2.3 µg/L
- Highest in aged balsamic from red grapes (2.3 µg/L)
- Median common vinegars: 0.30 µg/L; median balsamic: 0.10 µg/L (p = 0.046, common higher)
- All well below PTDI of 3.3 mg/L for 60 kg person
Al (aluminum):
- Median balsamic: 4,657 µg/L (4.66 mg/L); median common: 768 µg/L (0.77 mg/L); p < 0.001
Cr (total chromium):
- Median balsamic: 44 µg/L; median common: 17 µg/L; p < 0.001
Ni (nickel):
- Reported among 16 elements (Figure 2; Table S2); median concentrations between 10 and 100 µg/L category
Cu:
- LT (complexing capacity) ranged 0.05–52 µM; highest in balsamic red (median 16 µM vs. 0.86 µM common)
- 21% of samples showed total Cu exceeding LT, indicating free labile Cu; almost all were common vinegars
Enrichment factors (IEF relative to upper continental crust) were highest for Rb (~100), Zn (~100), Cd (~100), As (~50), reflecting fertilizer inputs and crop uptake in viniculture.
Methods
ICP-MS (Thermo Scientific ICAP Qc, single-collision cell mode, KED with He gas) for 16 trace elements after HNO3/H2O2 digestion. Internal standards: 45Sc, 103Rh. LODs (µg/L): Co 0.02, Cs 0.02, Cd 0.03, As 0.05, Pb 0.05, V 0.05, Ba/Cr/Rb/Sr 0.10, Mn 0.20, Cu/Ni 0.40, Zn 1.0, Al 2.0, Fe 3.0. CRM validation: ERM-CD281 (rye grass) and BCR 279 (sea lettuce), recoveries within ±20%. DPASV for Cu complexation using µAutolab III with static mercury drop electrode.
Limitation: Total arsenic only; iAs/organic As speciation not performed. Publication provides total Cr, not hexavalent Cr.
Implications
Certification: This is a key A-tier source for vinegar Pb, As (total), Cd, and Al. Balsamic vinegars are the highest-risk vinegar subcategory for Pb (up to 86 ppb), with 5% exceeding California Prop 65. Ordinary wine and fruit vinegars are substantially lower risk. The paper’s Pb data directly informs any HMT&C condiment threshold for balsamic vs non-balsamic vinegars.
Courses: Illustrates the role of copper complexation by polyphenols in balsamic vinegars; demonstrates how production concentration increases Al, Fe, Mn, Cr, and Pb in balsamic relative to wine vinegar.
App: Pb typical range for common Greek vinegars: <1–30 µg/L (ppb); balsamic: 1–86 ppb. Cd typical: 0.03–2.3 ppb. Total As: <0.05–26 ppb, median ~3–4 ppb. All values are for as-sold liquid matrices.
Microbiome: Not applicable.