AKTS Software Technical Comments



SML 6 Software - General Presentation

B. Roduit1, R. Brandsch2, V. Dudler3

1AKTS AG Advanced Kinetics and Technology Solutions, TECHNOArk 1, Siders, Switzerland
2MDCTec Systems GmbH, Provinostr. 52, 86153 Augsburg, Germany
3Federal Food Safety and Veterinary Office FSVO, Schwarzenburgstrasse 155, CH-3003 Bern, Switzerland


Employing advanced numerical algorithms, migration modelling with the SML software [1] allows prediction of the amount of organic migrant (like residual monomers, additives, contaminants, reaction products, non-intentionally added substances from plastic multi-layer or multi-material multi-layer materials) which migrate into the packed food or other contact media like pharmaceuticals, cosmetics, drinking water or environment. The application of the software insures the compliance of plastic food contact materials and articles with specific migration limits according to EU Regulations [2, 3] and Swiss Legislation [4]. The technique allows the specific migration assessment for complex materials, with different geometries and any multi-layer structure. Simulation of the migration process is based on Ficks 2-nd law of diffusion under consideration of partitioning between adjacent layers or contact media in closed systems [1-4]. Temperature dependence of the diffusion process is considered by the Arrhenius equation. Diffusion coefficients of migrants in polymers are estimated by generally recognized estimation procedures (Piringer model) based on polymer specific constants (AP-values) [2] which are available for certain polymers. Extension of the AP value model by Brandsch for estimation of diffusion coefficients based on the glass transition temperature of polymers opens modelling opportunities for any polymer or polymer mixture by applying a glass transition temperature. Estimation of partition coefficients between contact layer and contact medium (e.g. polymer and food simulant or water) is based on the migrants polarity expressed by the octanol/water partition coefficient of the migrants [5]. Time dependent migration curves and the concentration profile inside all layers of multi-layer structures can be computed for both, migrant from the material and from the contact medium. The software allows the simulation of release of migrants from multi-layer materials in extended temperature ranges and/or under changing temperature conditions. Complex surrounding temperature profiles can be considered such as stepwise, modulated, temperature shock and additionally for temperature profiles reflecting real atmospheric temperature changes (yearly temperature profiles of different climates with daily minimal and maximal fluctuations).

AKTS-SML Version 6 - General Presentation
Version 6 | *.pdf | 2.75 MB



Probabilistic migration modelling focused on functional barrier efficiency and low migration concepts in support of risk assessment

R. Brandsch1

1MDCTec Systems GmbH, Augsburg, Germany


Migration modelling provides reliable migration estimates from food-contact materials (FCM) to food or food simulants based on mass-transfer parameters like diffusion and partition coefficients related to individual materials. In most cases, mass-transfer parameters are not readily available from the literature and for this reason are estimated with a given uncertainty. Historically, uncertainty was accounted for by introducing upper limit concepts first, turning out to be of limited applicability due to highly overestimated migration results. Probabilistic migration modelling gives the possibility to consider uncertainty of the mass-transfer parameters as well as other model inputs. With respect to a functional barrier, the most important parameters among others are the diffusion properties of the functional barrier and its thickness. A software tool that accepts distribution as inputs and is capable of applying Monte Carlo methods, i.e., random sampling from the input distributions of the relevant parameters (i.e., diffusion coefficient and layer thickness), predicts migration results with related uncertainty and confidence intervals. The capabilities of probabilistic migration modelling are presented in the view of three case studies (1) sensitivity analysis, (2) functional barrier efficiency and (3) validation by experimental testing. Based on the predicted migration by probabilistic migration modelling and related exposure estimates, safety evaluation of new materials in the context of existing or new packaging concepts is possible. Identifying associated migration risk and potential safety concerns in the early stage of packaging development is possible. Furthermore, dedicated material selection exhibiting required functional barrier efficiency under application conditions becomes feasible. Validation of the migration risk assessment by probabilistic migration modelling through a minimum of dedicated experimental testing is strongly recommended.

View Study: Taylor & Francis Group



Mathematical Modeling of the Extractables Release from Multi-Layered Plastic Films used in Drug Product Containers

D. Jenke, V. J. Barge1

1Baxter Healthcare Corporation, 25212 West Illinois Route 120, 60073 Round Lake, Illinois, United STates


The release of extractables from multi-layered plastic films such as those used in containers for liquid drug products has been investigated. Targeted extractables were chosen from the films extractable profile, as elucidated by a controlled extraction study. The total available pool of targeted extractables was ascertained via exhaustive sequential extraction of the film and the film layer responsible for the target extractables was established. This information, along with the films structure, was used to produce a mathematical migration model for each of these targets. The film was fashioned into pouches, filled with a simulating solvent and the release of the targeted extractables to the pouches contents was measured. The measured and modeled concentrations were found to be very similar, establishing the models ability to effectively mimic the experimental system. This result suggests that mathematical modeling, which is widely used in the food industry to assess the safety of food packaging, may be applicable to packaged pharmaceutical products.

View Study: Wiley Online Library



Migration of antimony from PET trays into food simulant and food: determination of Arrhenius parameters and comparison of predicted and measured migration data

M. Haldimann, A. Alt, A. Blanc, K. Brunner, F. Sager and V. Dudler1

1Federal Food Safety and Veterinary Office FSVO, Schwarzenburgstrasse 155, CH-3003 Bern, Switzerland


Migration experiments with small sheets cut out from ovenable PET trays were performed in two-sided contact with 3% acetic acid as food simulant at various temperatures. The fraction of diffusible antimony (Sb) was estimated to be 62% in the PET sample under study. Apparent diffusion coefficients of Sb in PET trays were determined experimentally. Measurement of migration between 20 and 150C yielded a linear Arrhenius plot over a wide temperature range from which the activation energy (Ea) of 188 ± 36 kJ mol-1 and the pre-exponential factor (D0) of 3.6 x 1014 cm2s-1 were determined for diffusing Sb species. Ea was similar to previously reported values for PET bottles obtained with a different experimental approach. Ea and D0 were applied as model parameters in migration modelling software for predicting the Sb transfer in real food. Ready meals intended for preparation in a baking oven were heated in the PET trays under study and the actual Sb migration into the food phase was measured by isotope dilution ICP-MS. It was shown that the predictive modelling reproduces correctly experimental data.

View Study: Food Additives & Contaminents: Part A, Vol. 30 (2013) 3, 587-598



Guideline for the Mathematical Estimate of the Migration of Individual Substances from Organic Material in Drinking Water

Umweltbundesamt für Mensch und Umwelt (Federal Environment Agency)


The mathematical estimate of migration can be used in place of experimental proof to verify the requirements of KTW, Coating or Lubricant Guidelines for the migration of individual substances.
Organic material, such as plastics, which comes into contact with drinking water, can release substances into the water (mass transfer or migration). This lowers the concentration of substances in the organic material and increases it in water (mass transport). The stage that determines the speed of the mass transfer is the diffusion of the substance in organic material. The transfer of substances from organic material in drinking water can be measured in a laboratory (performance of the migration test and analysis of the test water on formulation-specific individual substances with a migration restriction) under standard conditions (surface-volume ratio, number of change cycles, time, temperature) or can be calculated by simulation using diffusion models (modelling). Annex 1 illustrates the involvement of simulation in assessing organic material in contact with drinking water.

Download: Guideline for the Mathematical Estimate of the Migration of Individual Substances from Organic Material in Drinking Water (pdf, 313 KB)



Leitlinie zur mathematischen Abschätzung der Migration von Einzelstoffen aus organischen Materialien in das Trinkwasser

Bundesgesundheitsbl 2009 · 52:1105-1112


Die mathematische Abschätzung der Migration kann verwendet werden, um die Anforderungen der KTW-Leitlinie, Beschichtungsleitlinie oder der Schmierstoffleitlinie an die Migration von Einzelstoffen anstelle eines experimentellen Nachweises zu überprüfen.
Organische Materialien – zum Beispiel Kunststoffe –, die Kontakt mit Trinkwasser haben, können Stoffe an das Wasser abgeben (Stoffübergang oder Migration). Dabei sinkt die Konzentration der Stoffe in dem organischen Material und nimmt im Wasser zu (Stofftransport). Der geschwindigkeitsbestimmende Schritt des Stoffübergangs ist die Diffusion der Stoffe im organischen Material. Der Übergang von Stoffen aus organischen Materialien ins Trinkwasser kann einerseits unter standardisierten Bedingungen (Oberflächen-Volumen-Verhältnis, Anzahl Wechselzyklen, Zeit, Temperatur) im Labor gemessen (Durchführung des Migrationstests und Analyse des Prüfwassers auf rezepturspezifische Einzelstoffe mit einer Migrationsbeschränkung) oder andererseits durch Simulation auf der Basis von Diffusionsmodellen (Modellierung) berechnet werden. In der Anlage 1 ist die Einbindung der Simulation bei der Beurteilung von organischen Materialien im Kontakt mit Trinkwasser dargestellt.

View Study: Leitlinie zur mathematischen Abschätzung der Migration von Einzelstoffen aus organischen Materialien in das Trinkwasser



Application of Finite Element Analysis (FEA) for the simulation of release of additives from multilayer polymeric packaging structures

B. Roduit, Ch. Borgeat1, S. Cavin2, C. Fragnière2, & V. Dudler2

1AKTS AG Advanced Kinetics and Technology Solutions, TECHNOArk 1, Siders, Switzerland, and
2Federal Food Safety and Veterinary Office FSVO, Schwarzenburgstrasse 155, CH-3003 Bern, Switzerland


Computer programmes are available to predict, for consumer protection purposes, the migration of additives from a polymeric package during its contact with food. However most of these programs were developed to estimate migration only from single layer polymeric packaging under isothermal conditions. In this work a diffusion model was developed to simulate the migration from multilayer packaging and under non-isothermal temperature conditions, too. Finite Element Analysis (FEA) is used as a numerical approximation method to solve the diffusion equations describing such processes. The possibilities and limitations of the FEA method are presented and the correlation between experimental and computed results is discussed.

View Study: Food Additives & Contaminants Vol. 22, Issue 10, (2005)



Simulation of Deterrent Diffusion in Double Base Propellant Under Different Temperature Profiles

Bertrand Roduit1, Rainer Brandsch2, Patrick Folly3, Alexandre Sarbach3, Beat Berger3, Beat Vogelsanger4, Bruno Ossola4, Laurence Jeunieau5, Pierre Guillaume6

1AKTS AG, http://www.akts.com, TECHNOArk 1, 3960 Siders, Switzerland, b.roduit@akts.com
2MDCTec Systems GmbH, Provinostr. 52, 86153 Augsburg, Germany
3armasuisse, Science and Technology Centre, 3602 Thun, Switzerland
4Nitrochemie Wimmis AG, 3752 Wimmis, Switzerland
5Royal Military Academy, Avenue de la Renaissance 30, 1000 Bruxelles, Belgium
6PB Clermont s.a., Rue de Clermont 176, 4480 Engis, Belgium


Propellants can burn so rapidly that the initial rise of pressure in weapons may be faster than desired. To avoid this unwanted effect, burning rate of the propellants is moderated by applying a surface coating. Coating agents are usually deterrents (moderants), substances that gelatinize or plasticise the nitrocellulose matrix of the propellants decreasing its initial burning rate, therefore, in turn, the rate of gaseous phase formation. The knowledge of the diffusion rate of deterrents helps therefore in developing propellants with superior ballistic performance. Another parameter, namely the rate of the migration of deterrent into the propellant matrix during ageing / storing is also important as it influences the ballistic shelf-life i.e. the period of time during which the ballistic requirements are fulfilled. As migration measurements are often difficult, expensive and timeconsuming the development of the simulation tools of above processes seems to be of a great importance. The present paper describes the simulation method for deterrent and blasting oil diffusion in double base propellant applying the temperature dependence of the diffusion coefficients D determined in isothermal experiments and taking into account the influence of the swelling effect of the propellant matrix. The simulations were done using the AKTS-SML software [1], which allowed considering the migration of both, deterrent and nitroglycerine through the swollen matrix of the propellant. Furthermore, after determination of the temperature dependence of the diffusion coefficient D, it was possible to predict the deterrent migration under any, arbitrarily chosen temperature profile such as oscillatory temperature mode, real atmospheric temperature profiles or under temperature mode corresponding to atmospheric changes according to STANAG 2895 [2].

View Study (pdf, 239 KB)



Diffusion Coefficients of Antimony Catalyst in Polyethylene Therephthalate (PET) materials :

Download: Diffusion Coefficients of Antimony Catalyst in Polyethylene Therephthalate (PET) materials (pdf, 75 KB)



Food Contact Materials Compliance Database :

Risk assessment and management tool
Download: Compliance Base (pdf, 1.07 MB)