Overview
Roncevic et al. measured tin concentrations in 25 canned fruit and vegetable samples from Slovak retail markets using hydride generation ICP-OES (HG-ICP-OES), comparing results against the established flame AAS reference method (CEN/TS 15506:2007). The study found a wide range of tin concentrations depending on can lining type: fully lacquered cans had concentrations from below the AAS detection limit (5 mg/kg) up to 77.2 mg/kg, while unlacquered tinplate cans had concentrations from 23.3 mg/kg up to 199.2 mg/kg (one pineapple compote sample). Only one sample approached the EU maximum level of 200 mg/kg; all others were compliant. The HG-ICP-OES method achieved a sample LOQ of 6.4 µg/kg, substantially lower than the AAS method (5 mg/kg), enabling quantification in fully lacquered cans where AAS returned only below-LOD results.
Key numbers
All concentrations in mg/kg wet weight. Values are mean plus or minus one standard deviation from replicate analysis (n = 2 replicates per sample as HG-ICP-OES vs. AAS comparison).
| Sample | Can type | Sn (mg/kg, HG-ICP-OES) |
|---|---|---|
| Peach compote | Lacquered | 69.6 plus or minus 1.1 |
| Tomato puree, double concentrated | Lacquered | 2.5 plus or minus 0.1 |
| White beans, sterilized | Lacquered | 5.8 plus or minus 0.1 |
| Red beans, sterilized | Lacquered | 3.5 plus or minus 0.1 |
| Champignons (sample A) | Lacquered | 0.44 plus or minus 0.02 |
| Champignons, sterilized (sample B) | Lacquered | 77.2 plus or minus 0.7 |
| Peeled plum tomatoes, sterilized | White lacquer | 10.9 plus or minus 0.2 |
| Fruit salad | Yellow lacquer | 1.21 plus or minus 0.04 |
| Pineapple compote (8 samples, range) | Tinplate | 23.3 to 199.2 |
| Pineapple compote, highest sample | Tinplate | 199.2 plus or minus 3.2 |
| Peach halves | Tinplate | 29.6 plus or minus 0.4 |
| Peach halves in syrup | Tinplate | 104.9 plus or minus 1.8 |
| Compote of mixed fruits | Tinplate | 54.82 plus or minus 0.8 |
| Apricot compote (less sweet) | Tinplate | 115.6 plus or minus 1.3 |
| Apricot compote | Tinplate | 76.7 plus or minus 1.4 |
| Fruit cocktail in light syrup (sample A) | Tinplate | 115.8 plus or minus 1.4 |
| Fruit cocktail in light syrup (sample B) | Tinplate | 107.3 plus or minus 1.3 |
| Mandarin orange segments | Tinplate | 104.8 plus or minus 1.2 |
The pineapple compote at 199.2 mg/kg was the only sample approaching the EU maximum level of 200 mg/kg. All 25 samples were compliant with the WHO limit of 250 mg/kg. All lacquered-can samples were below the AAS detection threshold of 5 mg/kg (reported as below LOD by the AAS method), confirming that the HG-ICP-OES sensitivity gain over AAS is meaningful in the lacquered-can context.
Analytical performance:
| Parameter | HG-ICP-OES (189.991 nm line) | AAS |
|---|---|---|
| LOD (solution) | 1.9 µg/L | n/a |
| LOQ (sample) | 6.4 µg/kg | 5 mg/kg (5,000 µg/kg) |
| Recovery (spike) | 98 to 102% | 99 to 102% |
Evidence Fitness
Reconstructable dataset for tin occurrence in canned fruit and vegetable products from a Slovak retail market. Direct measurements with well-characterized method performance. The dataset confirms the large effect of can lining type (lacquered vs. unlacquered tinplate) on tin concentrations. The small sample size (n=25) limits representativeness. The AAS comparison validates the HG-ICP-OES values.
Methods
25 samples purchased from Slovak retail; can lining type (lacquered vs. tinplate) determined from can manufacturer markings and visual inspection. Sample preparation: homogenization of the full can contents, microwave-assisted digestion at 80 degrees C for 2 hours in hot block CS 54, transfer through filter paper to 50 mL volumetric flask. HG-ICP-OES used a Prodigy high-dispersive ICP instrument; hydride generation with sodium tetrahydroborate; primary emission line Sn(II) at 189.991 nm with backup lines at 224.605 and 283.999 nm. AAS comparison by CEN/TS 15506:2007. LOQ of 6.4 µg/kg (HG-ICP-OES) versus 5 mg/kg (AAS). Recovery verified at 98-102% by spike recovery on fully intact cans.
Limitation: tin speciation (inorganic vs. organotin) was not performed; total tin values in canned food matrices are treated as inorganic tin per standard practice.
Implications
- Certification: demonstrates that unlacquered tinplate cans for acidic fruit products (pineapple, apricot, peach, fruit cocktail, mandarin orange) can carry tin concentrations in the 20-200 mg/kg range, while lacquered cans remain well below 10 mg/kg for most products (exception: peach compote in lacquered can at 69.6 mg/kg and champignons at 77.2 mg/kg, possibly related to damage to the lacquer or partial lacquering). The 199.2 mg/kg pineapple sample is the highest value in this dataset and approaches the EU limit.
- Courses: clean illustration of the lacquer effect on tin release; the range from 0.44 mg/kg (fully lacquered champignons) to 199.2 mg/kg (unlacquered tinplate pineapple) in the same product category makes the food-contact mechanism concrete.
- App: canned acidic fruits (pineapple, peach, apricot, mixed fruit cocktail, mandarin) in tinplate cans are the highest-tin products in this dataset; canned tomato products in lacquered cans are low.
- Microbiome: not addressed.
Provenance notes
Open access under CC BY license. Retrieved from PMC as PMC3328928. The paper was published in the International Journal of Analytical Chemistry (Hindawi), volume 2012.
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