Troncoso and Guzman 1988 — Metallic contaminants in Andalusian vinegars
This early study measured the content of Fe, Zn, Cu, Pb, and As in 16 white wine vinegar samples from Western Andalusia, Spain, using direct flame atomic absorption spectrophotometry (AAS) without prior digestion — a feasible approach because the authors determined that no interfering components would plug the flame. Results showed no important metallic contamination overall; only one sample exceeded the Spanish regulatory limit of 1 ppm for total (Pb + As). The study is notable as the first systematic characterization of metallic contamination in Andalusian vinegars and is frequently cited as a baseline reference for Spanish vinegar metals data.
Key numbers
All values in ppm (mg/kg). Units as reported; to convert to µg/kg (ppb), multiply by 1000.
Iron (n=16): range 1.95–19.7 ppm; mean 8.44 ± 0.07 ppm. Three samples exceeded the Fe limit associated with “hazy phenomena” (>10–15 ppm) though no cloudiness was observed.
Zinc (n=16): range 0.51–36.90 ppm; mean 7.86 ± 0.51 ppm. 25% of samples exceeded 10 ppm (Spanish regulatory limit for total Zn + Cu is 10 ppm). Highly variable.
Copper (n=16): range 0–6.14 ppm; mean 1.35 ppm. All samples below 10 ppm (Spanish/Codex limit for total Zn + Cu). 63% of samples had Zn + Cu total within Spanish limits.
Lead (n=16): range 0.20–1.21 ppm; mean 0.55 ± 0.05 ppm. Only sample #4 exceeded 1 ppm (1.21 ppm). Table 3 values by sample: 0.39, 0.44, 0.63, 1.21, 0.43, 0.39, 0.80, 0.59, 0.53, 0.65, 0.27, 0.76, 0.48, 0.78, 0.32, 0.20 ppm. Mean 0.55 ppm = 550 µg/kg.
Arsenic (n=16): range 0.039–0.242 ppm; mean 0.136 ppm. No sample exceeded 0.3 ppm (OIV limit for wine). Total As + Pb exceeded 1 ppm in only one sample (#4: 1.21 + 0.242 = 1.45 ppm).
Correlation: moderate correlation between Cu and Fe (r=0.685).
Regulatory context: Spanish regulations — total Zn + Cu ≤ 10 ppm; total Pb + As ≤ 1 ppm. Codex draft (1982): Pb 1 mg/kg, Cu 10 mg/kg, Zn 10 mg/kg, Fe 30 mg/kg. US Agriculture Dept: max admissible Pb in cider vinegar = 3.5 ppm.
Methods (brief)
Flame AAS (Perkin Elmer 2380): direct analysis of liquid samples without digestion. Elements determined directly (no interfering components that plug flame). Samples classified into 3 groups by acidity (3%, 7%, 8% acetic acid); calibration standards prepared in matching acetic acid concentrations to minimize matrix effects. Pb: 217.0 nm; Zn: 213.9 nm; Cu: 324.8 nm; Fe: 248.3 nm; all with air-acetylene flame. Arsenic: AAS with hydride generator (Perkin Elmer MSH 10), 193.7 nm, sodium borohydride/NaOH reduction, standard addition method. Evidence tier B reflects the 1988 publication, small n, and direct-injection AAS methodology without validated digestion (unlike the later Ndung’u 2004 work that established digestion requirements).
Implications
Certification: Provides a historical baseline for Andalusian (Sherry-region) wine vinegar. Lead mean 550 µg/kg, range 200–1210 µg/kg. Arsenic mean 136 µg/kg (total As), none exceeding the OIV wine limit of 300 µg/kg. The arsenic values are total arsenic without speciation; inorganic fraction unknown. Modern certification work requires iAs speciation; this dataset does not provide it.
Courses: Illustrative of how direct-injection AAS can be used for iron and zinc in vinegar, but the lead and arsenic values from 1988 should be considered with appropriate caution given the methodological context of the era (no digestion for Pb; hydride generation for As). Nonetheless widely cited as a reference point for Andalusian vinegar baseline.
App: Pb in wine vinegar approximately 200–1200 µg/kg range across both this and Acosta 1993 data; Andalusian Sherry-type wine vinegar may carry moderate Pb. Total As present but at low levels and without speciation.