Ozbek et al. 2016 — Trace metal determination in Turkish vinegars by MIP OES

This study validated a microwave-induced plasma optical emission spectrometry (MIP OES) method for simultaneous determination of ten elements (Al, B, Co, Cr, Cu, Fe, Mg, Mn, Pb, Zn) in 35 vinegar samples produced in Turkey, requiring only simple dilution into 2% acetic acid without acid digestion. All measured concentrations fell well below the Turkish Food Codex maximum allowable values (Pb ≤1 mg/L; Cu + Zn ≤10 mg/L; Fe ≤10 mg/L); the highest observed Pb value across the sample set was 0.15 mg/L (one grape vinegar). The method is suitable for routine quality-control analysis of acidic food matrices.

Key numbers

Method LODs (µg/L, Table 1): Al = 0.62, B = 7.67, Co = 4.55, Cr = 0.52, Cu = 1.22, Fe = 5.72, Mg = 1.32, Mn = 0.35, Pb = 2.42, Zn = 26.0.

Recovery tests on grape, apple, and balsamic matrices (Table 2, n=3 per matrix; per-analyte spike levels were Pb 0.01, Cu 0.05, Co 0.10, Mn 0.50, and Al/B/Cr/Fe/Mg/Zn 1.00 mg/L): all analytes between 92.1% (Cr in apple vinegar) and 104.2% (Mn in grape vinegar). Certified reference material wastewater CWW-TM-E (High Purity Standards, Charleston, USA; certified value 0.025 µg/mL ± 0.5% for each analyte) returned found values 0.021–0.029 µg/mL across analytes; Zn <LOQ; Mg not certified. The t-test reported no significant difference from certified values at 95% confidence.

Vinegar concentrations (mg/L, Table 4, n=35 samples):

• Pb: 0.01 to 0.15 mg/L (10 to 150 µg/L). Highest single value 0.15 mg/L (Grape 10). Most samples 0.01–0.05 mg/L. All samples far below the 1 mg/L Turkish Food Codex limit.
• Al: 0.02 (homemade) to 5.19 (one apple vinegar); most grape and apple values 0.4–2.3; the three balsamic vinegars measured 1.63, 0.56, and 2.29 mg/L.
• Cr: 1.95 to 3.95 mg/L across all vinegar types; most samples cluster at 1.95–2.10 mg/L. The authors note these Cr values are notably higher than prior literature on other regional vinegars and attribute the difference to the geographic origin of Turkish samples.
• Cu: 0.001 to 0.13 mg/L; max 0.13 mg/L (Grape 10), 0.11 mg/L (Grape 11); the great majority of samples 0.01–0.05 mg/L.
• Fe: 0.06 (homemade) to 7.01 (one balsamic) mg/L; balsamic and fig vinegars highest (6.59, 6.84, 7.01 mg/L). Turkish Codex limit 10 mg/L.
• Zn: 0.16 to 2.42 mg/L; fig vinegar highest at 2.42 mg/L. All samples below the combined Cu+Zn Codex limit of 10 mg/L.
• Mn: 0.003 (homemade) to 2.49 (Grape 10) mg/L; most samples 0.05–1.0 mg/L.
• Mg: 15.86 (one apple) to 169.03 (fig) mg/L; balsamic and fig vinegars elevated (80–170 mg/L) versus grape and apple (typically 15–100 mg/L).
• Co: below LOD in 31 of 35 samples; detected only in Grape 1 (0.34), Grape 2 (0.62), Balsamic 1 (0.26), and Balsamic 2 (0.09) mg/L.
• B: not detected in several apple, grape, and one balsamic sample; highest in balsamic (8.76 and 7.80 mg/L) and fig (3.19 mg/L).

Cd, As, Hg, Ni, and Sn were not measured in this study.

Methods

Instrument: Agilent 4200 MIP OES (Agilent Technologies, Melbourne, Australia) equipped with an Inert One Neb nebulizer and a double-pass glass cyclonic spray chamber. Nitrogen plasma sustained at 2.45 GHz; N₂ extracted from air with a dual-flow nitrogen generator (F-DGSi Thyster 8/1 LV). Samples diluted (typically 1:1) with 2% acetic acid to bring total dissolved solids to 2–4% (manufacturer torch tolerance is 4%). Diluted samples directly aspirated; no acid digestion. Atomic emission lines used: Al 396.152, B 249.772, Co 340.512, Cr 425.433, Cu 324.754, Fe 371.993, Mg 285.213, Mn 403.076, Pb 405.781, Zn 481.053 nm. Read time 5 s, three replicates per measurement. Calibration: aqueous standards (1000 mg/L mixed standard from Carlo Erba, diluted daily); linear regression for nine analytes (r² ≥ 0.996), rational (non-linear) curve for Mg. LOD = 3σ/slope; LOQ = 10σ/slope (n=10 blank aspirations). Method validated by spike recovery on three vinegar matrices and by analysis of the CWW-TM-E certified wastewater reference material. Concentrations reported as mg/L of the as-purchased vinegar (the native basis of the product placed on market).

Limitations relevant to HMT&C analyte coverage: the method covers ten analytes by atomic emission only. It does not speciate arsenic (the paper does not measure As at all), does not speciate chromium (reported Cr is total Cr, not Cr-VI), does not measure mercury (no cold-vapor or atomic fluorescence accessory described), and does not measure Cd, Ni, or Sn. The paper’s contribution to HMT&C-relevant analytes is therefore Al, Pb, and total Cr in Turkish vinegars.

Implications

Certification: Pb concentrations in Turkish vinegars sampled here are uniformly low (max 150 µg/L; 32 of 35 samples at or below 50 µg/L), well below the 1 mg/L Turkish Food Codex limit. Balsamic and fig vinegars in this sample set carry meaningfully higher Al, Fe, and Mg than grape or apple vinegars; the paper reports these values but does not attribute mechanism. The Cr values reported here (1.95–3.95 mg/L total Cr, with the modal value near 2 mg/L) are notably higher than other published vinegar literature; the authors attribute this to sample origin rather than methodological artifact, and this source should not be used in isolation to set a Cr literature baseline for the vinegar row.

Courses: Useful illustration of dilute-and-shoot MIP OES as a practical alternative to ICP-MS for routine vinegar monitoring. Demonstrates that matrix effects are manageable in diluted acetic acid matrices without the need for matrix-matched standards or acid digestion.

App: Pb in Turkish grape and apple vinegars in this sample set: typical 10–80 µg/L, maximum observed 150 µg/L. These figures are from a single regional sample and likely do not generalize to other production regions, particularly for balsamic-style vinegars.

Verification notes

Page was originally drafted under the legacy manual-fetch-kimi handle and last updated 2026-05-14. Merge-enhanced on 2026-05-26 against the source PDF to:

• Replace legacy raw_handle: manual-fetch-kimi with the canonical MFK handle.
• Correct raw_path to the actual filename (the prior path was truncated).
• Correct sample_n from 32 to 35 (Table 4 contains 17 grape + 12 apple + 3 balsamic + 1 pomegranate + 1 fig + 1 homemade = 35).
• Expand metals from the five HMTc-adjacent analytes to all ten analytes the paper actually measures (routing layer only generates rows for HMTc-mapped abbreviations Al, Pb, Cr; the additional analytes are recorded for documentary fidelity).
• Add wine-vinegar to ingredients (the 17 “grape” vinegars are wine vinegars in the wine-vinegar commodity).
• Remove the prior products/fresh-fruit entry from the products array — this is a vinegar paper, not a fresh-fruit paper; the original routing assignment was a false-positive scope.
• Replace the legacy ## Wiki pages updated on ingest heading with the implications and verification-notes structure used by current source pages.
• Correct Cu and Mn ranges in Key numbers: Cu max is 0.13 mg/L (Grape 10), not 0.05 mg/L as previously stated; Mn max is 2.49 mg/L (Grape 10), not 1.51 mg/L as previously stated.
• Correct recovery range from 91–104% to the table-derived 92.1–104.2% (the abstract gives the rounded 93–104%; the table is authoritative).
• Explicitly note which HMTc-panel analytes are NOT measured (Cd, As, Hg, Ni, Sn).

Auto-audit subagent (2026-05-26) verdict REVISE; 2 findings applied: (i) corrected spike-level wording in Key numbers to show analyte-specific spike concentrations rather than a continuous 0.01–1.00 mg/L range (Table 2 spike levels are Pb 0.01, Cu 0.05, Co 0.10, Mn 0.50, others 1.00 mg/L); (ii) removed the “consistent with concentration effects during balsamic production” mechanism claim from Implications — the paper reports balsamic/fig values are higher but does not attribute mechanism, so the claim was unsupported synthesis. 1 finding documented but not applied: the audit noted that mapping the paper’s “grape vinegar” samples to the wine-vinegar ingredient slug is an inference (the paper does not explicitly state these are wine-fermentation-derived; Turkish üzüm sirkesi can be produced from grape must as well as from wine). The mapping is retained because (a) the paper itself states all vinegars are produced “by alcoholic and subsequent acetic fermentation” from wines, sugary, or starchy foods, and (b) other vinegar source pages in the corpus (acosta1993, ndungu2004) follow the same convention of routing “grape vinegar” to the wine-vinegar commodity slug.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.