Migration study of organotin compounds from food packaging by surface-enhanced Raman scattering

Overview

Mandrile and colleagues evaluated surface-enhanced Raman scattering (SERS) for detecting dibutyltin maleate (DTM) and tributyltin chloride (TBT) migrating from intentionally spiked PVC cling film into 3% acetic-acid food simulant. The study is useful food-contact leachate context, but it is not a market-occurrence survey because the PVC films were experimentally additivated. Organotin values are reported as compound-specific DTM/TBT or as tin equivalents and should not be collapsed into total tin or inorganic tin.

Key numbers

• Source identity: Talanta 220 (2020) article 121408; DOI 10.1016/j.talanta.2020.121408; local readable PDF has 20 pages.
• Food-contact matrix: an industrial food-grade PVC cling film described as 10 mm thickness in the extracted text was dissolved and re-cast after spiking with TBT, DTM, or both compounds.
• Regulatory context stated by the authors: for organotin compounds, the specific migration limit was 0.05 mg of tin per kg of food; the paper gives corresponding legal limits of 0.15 mg/l for DTM and 0.14 mg/l for TBT.
• Migration test setup: 5 cm2 film portions, 8.33 ml of 3% acetic-acid food simulant, proportional relationship 1 dm3 simulant per 6 dm2 packaging, 10 days at 40 ºC.
• SERS calibration: DTM dynamic range 0-1 mg/l with reduced χ2 = 0.8; TBT dynamic range 0.5-5 mg/l with reduced χ2 =0.2.
• SERS detection limits as described in different parts of the paper: abstract says DTM and TBT were detected down to 0.01 mg/l and 0.08 mg/l; the Results section reports TBT LOD 0.10 mg/l and LOQ 1.53 mg/l; the conclusion says TBT down to 0.1 mg/l.
• ICP-MS calibration in 3% acetic acid: DTM R2 0.99, LOD 0.005 mg/l, LOQ 0.007 mg/l; TBT R2 = 0.99, LOD 0.027 mg/l, LOQ 0.092 mg/l.
• UV-Vis DTM calibration: linear dynamic range 0.1 to 2.0 mg/l, reduced χ2 = 1.4, LOD 0.08 mg/l, and LOQ 0.13 mg/l.
• Authors’ overall comparison: the organotin migration limit was exceeded for all tested spiked-PVC cases except PVC spiked with low-concentration DTM.

Spiked PVC-film loadings

Table 1 reports the following added organotin and corresponding tin loadings; the paper states uncertainty for all values is 0.1 mg/g.

Migration results as compound concentrations

The Results prose reports SERS and UV-Vis compound concentrations in mg/l food simulant:

Table 2 migration results as tin equivalents

Table 2 reports mg(Sn)/kg (simulant) by method:

Methods (brief)

The authors prepared spiked PVC films from dissolved PVC cling film and TBT/DTM stock solutions, then performed migration tests into 3% acetic acid under EU food-contact-material simulant conditions. Simulants were analyzed by direct-in-liquid SERS using 30 nm silver nanoparticles, by ICP-MS for tin, and by UV-Vis for DTM. ICP-MS used five tin isotopes (116Sn, 117Sn, 118Sn, 119Sn, 120Sn) with gallium isotopes as internal standards; high-concentration migration samples were diluted at 1:40.

Related evidence

• Flexible pouches/films
• Tin
• Organotins

Update history

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