Oliver Kappenstein

Development of a manual method for the determination of mineral oil in foods and paperboard.

So far the majority of the measurements of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) were obtained from on-line high performance liquid chromatography-gas chromatography-flame ionization detection (on-line HPLC-GC-FID). Since this technique is not available in many laboratories, an alternative method with more easily available tools has been developed. Preseparation on a small conventional liquid chromatographic column was optimized to achieve robust separation between the MOSH and the MOAH, but also to keep out the wax esters from the MOAH fraction. This was achieved by mixing a small portion of silica gel with silver nitrate into highly activated silica gel and by adding toluene into the eluent for the MOAH. Toluene was also added to the MOSH fraction to facilitate reconcentration and to serve as a keeper preventing loss of volatiles during solvent evaporation. A 50 μl volume was injected on-column into GC-FID to achieve a detection limit for MOSH and MOAH below 1 mg/kg in most foods.

Toxicologically relevant phthalates in food.

Various phthalates have been detected in a wide range of food products such as milk, dietary products, fat-enriched food, meat, fish, sea food, beverages, grains, and vegetables as well as in breast milk. Here we present an overview on toxicologically considerable phthalate levels in food reported in the literature. The most common phthalates detected are di-(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DnBP), and di-isobutyl phthalate (DiBP). Milk analyses demonstrate that background levels in unprocessed milk are usually low. However, during processing the phthalate contents may significantly increase due to migration from plastic materials in contact with food. Among dietary products fat-enriched food such as cheese and cream were identified with highest levels of DEHP. Plasticized PVC from tubes, conveyor belts, or disposable gloves used in food processing is an important source for contamination of food, especially of fatty food. Paper and cardboard packaging made from recycled fibers are another important source of contamination. In addition, gaskets used in metal lids for glass jars have been identified as possible source for the contamination of foodstuffs with phthalates. The highest concentrations of DEHP reported (>900 mg kg(-1)) were detected in food of high fat content stored in such glass jars. Beyond classical food, DEHP and DnBP were identified in human breast milk samples as the main phthalate contaminants. Phthalate monoesters and some oxidative metabolites were also quantified in breast milk.

Inter-laboratory comparison study on the determination of primary aromatic amines in cold water extracts of coloured paper napkins

To evaluate the competence in the analysis of primary aromatic amines (PAAs) in cold water extracts from napkins, an inter-laboratory comparison study was conducted with 19 participating laboratories. Two cold water extracts spiked at two different PAA concentration levels, each containing four different PAAs (aniline, o-toluidine, 2,4-dimethylaniline and o-anisidine) and, additionally, four different napkins containing one of the PAAs each were distributed between the laboratories. In this exercise, the influence of different parameters in the preparation of cold water extracts from napkins according to the European Norm (EN) 645 was also investigated. For the already spiked cold water extracts and the napkins, 88% and 77% of the results were satisfactory with zU-scores of ≤ |2|. The Horwitz ratio (HorRat) values for the spiked cold water extracts were in the range of 0.48–1.25. For the napkins, HorRat values were in the range of 1.261.91, whereas the lowest assigned value was 0.97 µg l−1 (o-toluidine). Thus, the results show that preparation and instrumental analysis of PAAs in cold water extracts from napkins according to EN 645 has been well established. Graphical Abstract

FID or MS for mineral oil analysis

Recently, Spack et al. (2017) published an article with the title ‘‘Understanding the Contamination of Food with Mineral Oil: The Need for a Confirmatory Analytical and Procedural Approach’’. The main message was that ‘‘LC/GC–FID is a useful screening method but in cases of positive samples it must be complemented by a confirmatory method such as for example GC– MS’’. In their text the authors claim that interferences are causing false positive results that can be filtered out by using GC–MS. However, there are also conflictive sentences like ‘‘The ions used to ‘filter’ the MOSH humps are not very selective, which is why a review of the chromatographic profile is of importance’’, and GC/MS chromatograms showing that synthetic hydrocarbons could not be filtered out. Certainly, nobody would question that MOSH and MOAH analysis needs careful interpretation of the chromatograms to avoid the inclusion of hydrocarbons of natural or synthetic origin, like terpenes, natural waxes or oligomeric polyolefins. Faulty data have caused serious problems and must be avoided. However, the question is whether or not MS is the tool that solves the problem and whether its use should be mandatory in standardized methods for confirmation of samples considered ‘‘positive’’. The authors used MS in total ion current (TIC) mode for quantitative determination and the ions m/ z 43, 57, 71, and 85 for the verification of the presence of MOSH. In addition, the ions m/z 91, 105, 119 and 133 were used for verification of MOAH. Finally they came up with the following statement: ‘‘If the profiles [of the ‘‘qualifier ions’’ mentioned] can be overlaid, then there is certainty of the presence of saturated hydrocarbons of petrogenic origin.’’ The authors tried to support their conclusion by providing data from an interlaboratory comparison study and by some examples of their own analyses. However, in both cases no epoxidation step was applied to eliminate olefins mainly from the MOAH fraction. There is also no indication about what types of substances have been removed by the seemingly little selective fragments used. For their own analyses, two different methods of sample preparation were used, namely online HPLC with silica gel for FID and SPE cleanup on silica gel containing silver nitrate for GC–MS. As silver nitrate may have removed some polyunsaturated natural hydrocarbons from the MOAH fraction (Zoccali et al. 2016), it cannot be ruled out that this upstream cleanup step rather than the MS itself caused the difference. Further, saponification was only used for GC–MS analysis. The comparison between FID and MS for MOSH and MOAH analyses was repeatedly discussed in the Opinion articles are not peer-reviewed, but concise commentary articles with a reference to a recent occasions and/or developments in the fields of food, feed and commodities as well as crop protection products, veterinary drugs, genetic engineering and consumer protection. Please email us your comments, criticisms, or differing points of view to: jvl@bvl.bund.de. The editorial office reserves the right to reject and to edit and/or condense articles for publication.

Metal release from coffee machines and electric kettles

The release of elemental ions from 8 coffee machines and 11 electric kettles into food simulants was investigated. Three different types of coffee machines were tested: portafilter espresso machines, pod machines and capsule machines. All machines were tested subsequently on 3 days before and on 3 days after decalcification. Decalcification of the machines was performed with agents according to procedures as specified in the respective manufacturer’s manuals. The electric kettles showed only a low release of the elements analysed. For the coffee machines decreasing concentrations of elements were found from the first to the last sample taken in the course of 1 day. Metal release on consecutive days showed a decreasing trend as well. After decalcification a large increase in the amounts of elements released was encountered. In addition, the different machine types investigated clearly differed in their extent of element release. By far the highest leaching, both quantitatively and qualitatively, was found for the portafilter machines. With these products releases of Pb, Ni, Mn, Cr and Zn were in the range and beyond the release limits as proposed by the Council of Europe. Therefore, a careful rinsing routine, especially after decalcification, is recommended for these machines. The comparably lower extent of release of one particular portafilter machine demonstrates that metal release at levels above the threshold that triggers health concerns are technically avoidable.

Release of aluminium and thallium ions from uncoated food contact materials made of aluminium alloys into food and food simulant

In order to investigate the release of aluminium ions from food contact materials, three different types of uncoated aluminium menu trays for single use were tested with the foodstuffs sauerkraut juice, apple sauce and tomato puree, as well as with the food simulants 5 g/L citric acid solution and artificial tap water. To mimic a consumer relevant exposure scenario, the aluminium trays were studied using time and temperature gradients according to the Cook & Chill method, also taking into account storage time at elevated temperatures during the delivery period. The release of aluminium was found to exceed the specific release limit (SRL) of 5 mg aluminium per kilogram of food specified by the Council of Europe by up to six times. Furthermore, a release of thallium was also detected unexpectedly. Kinetic studies showed a comparable behaviour in the release of aluminium, manganese and vanadium as components of the aluminium alloy itself. In contrast, thallium could be identified as a surface contaminant or impurity because of an entirely different kinetic curve. Kinetic studies also allowed activation energy calculations. Additional camping saucepans were tested as an article for repeated use. In three subsequent release experiments with citric acid (5 g/L), artificial tap water and tomato puree as benchmark foodstuffs, the results were comparable to those of the uncoated wrought alloy aluminium trays.

Transfer of primary aromatic amines from coloured paper napkins into four different food matrices and into cold water extracts

ABSTRACT The aim of this study was to compare the transfer of primary aromatic amines (PAAs) from napkins into cold water extract (CWE) with transfer into four different food matrices. An HPLC-MS/MS multi-analyte method for quantification of 26 PAAs in CWE was validated and applied. In addition, the method was validated for seven different PAAs in four different food matrices (cucumber, rice, pickled gherkin and butter cookie) representing wet, dry, acidic and fatty food. The CWEs of 12 coloured napkin samples were analysed, and 3 napkins released more than 0.01 mg kg−1 PAAs into the CWE. These three napkins were chosen for transfer testing with food samples. In total, seven different PAAs were quantified in the food samples. Results show that the transfer of the tested PAAs into the CWE is in most cases comparable to the transfer into the tested food samples. In some cases, the CWE overestimates transfer into food, except for the transfer of aniline into pickled gherkin, where the CWE underestimates transfer. Therefore, the CWE serves as an adequate and certainly not overestimating simulation of reality for the tested transfer of PAAs into the food samples.

Validation and application of an LC-MS/MS method for the determination of cyclic oligomers originating from polyamide 6 and polyamide 66 in food simulant

ABSTRACT Polyamides (PAs) are used in the production of various food contact materials (FCMs) and articles such as kitchen utensils and packaging material. Cyclic oligomers have been identified as potential migrants from PA. This study describes the development, validation and application of a multi-oligomer analytical method based on LC-ESI-MS/MS for the identification and quantification of eight cyclic oligomers of PA 6 and four PA 66 migrating from FCMs into food simulant B (3% acetic acid) and beverages. It was proved that doubly charged precursor ions of the cyclic PA 6 and PA 66 oligomers above a mass of 500 Da are formed during the ionisation process of the electrospray technique used. Direct injection of a diluted food simulant into the LC-ESI-MS/MS system after migration makes the validated method a valuable tool for investigating migration of cyclic PA oligomers. The validation results demonstrate that the multi-oligomer method is applicable for the analysis of cyclic PA 6 and PA 66 oligomers in food simulant B. For all investigated cyclic PA oligomers, detection limits were in the range of 0.1–1.1 µg/l. Linearity (r2 ≥ 0.99), trueness values between 91% and 122%, and intra-day (RSDr < 10%) and inter-day precision (RSDR < 19%) were determined and satisfied validation criteria set out by the European Reference Laboratory for FCMs. The method was extended to tap water and tea. Finally, the multi-oligomer method was successfully applied to determine cyclic PA oligomers in migration solutions originating from different PA FCMs. In all migration solutions, concentrations of cyclic PA oligomers were determined above the LOQ. A preliminary risk assessment based on in silico tools was performed. The results demonstrate the urgent need for toxicological data that would facilitate the evaluation of the health risk of cyclic PA oligomers.

N-nitrosamines migrating from food contact materials into food simulants: analysis and quantification by means of HPLC-APCI-MS/MS.

ABSTRACT It was the aim of the work described here to develop a validated analytical method for the determination of N-nitrosamines in food simulants. Here, we present the validation of a liquid chromatography–atmospheric pressure chemical ionisation–tandem mass spectrometry method for the determination of 13 N-nitrosamines in the food simulants deionised water, 3% acetic acid and 10% ethanol. Method validation encompassed linearity, LOD, LOQ, recovery, precision and stability of the N-nitrosamines. The method was found to be sufficiently rugged and suitable for routine analysis. In addition, the developed method is on average 10 times more sensitive than the gas chromatography–thermal energy analyser (GC-TEA) method that is currently stipulated in Recommendation XXI for commodities based on natural and synthetic rubber issued by the German Federal Institute for Risk Assessment (BfR). The developed method was applied to determine the N-nitrosamine contents in migration solutions of 12 elastomer samples covering a range of different elastomer types. In 10 out of 12 samples, N-nitrosamines were determined. In most samples, the guidance value of 1 µg/dm2 specified in BfR Recommendation XXI was not exceeded. In conclusion, the analytical method presented here offers a useful alternative to the GC-TEA method currently stipulated in BfR Recommendation XXI. This is of wider relevance, since BfR recommendations are used for compliance assessment of Article 3, paragraph 1 a of the Regulation (EC) No. 1935/2004 with respect to their health safety.