Migration Test principles

The test principle is such that the extraction of migratable substances from a sample of the plastics is determined as the mass of non-volatile residue after evaporation of the solvent following immersion. Test specimens of at least 1 dm2 (single side considered) are immersed in the extraction solvent at the specified test conditions and then... 

An important conclusion from these findings was that even though this analytical method works in principle with olive oil as a food simulant, the migration test using olive oil or another fat simulant can provide false-negative results. Therefore, the method should only be applied in the case of short exposure periods with olive oil. If the method is carried out with olive oil, a recovery check with spiked olive oil applying the same time/temperature migration test conditions is necessary. In the case that such a recovery check indicates loss" of HMDA and/or EDA, then alternatively 95 % ethanol or iso-octane should be used as substitute fatty food simulants. 

For borderline cases where recoveries are outside of the analytical tolerance, at say 50-70%, it is arguable whether correction of the concentrations found in the migration test for the recovery is justified. But it can be viewed to be a worst case and so in principle it is recommended. Losses may also occur due to insolubility of the substance in the food simulant or adsorption onto glass/metal surfaces and this should be investigated by rinsing the cell with a suitable solvent. 

A moisture-absorbing pad may be tested with this protocol. In principle such a pad will absorb the meat drip into its fibres or in a cross-linked polymer. Due to the absorption capacity the migration of the absorber s constituents is not likely. However, in case the absorber starts to become saturated, migration is more likely. To simulate this, an absorber should first be saturated with water to approximately 80% of its capacity before migration testing. 

The advantage of the use of CE for identification screening is based on the high peak capacity of the system and the separation ability to identify substance mixtures. Due to variations in the electroosmotic flow, the migration times in CE are less stable as in a HPLC system. Therefore, the identification tests in CE are based on the principle of calculating the... 

By applying the procedures mentioned above, monomers and additives can be adequately tested. However, other components, the NlASs, can be present in the food contact material and potentially migrate to food. Such unlisted components are gaining renewed attention. In principle, they are already regulated in Article 3 of Framework Directive EC 1935/2004, i.e., food contact materials should not endanger human health. Unlisted substances that could be found in food contact materials may include ... 

ABSTRACT Using the overburden rock fissure 0 -ring theory, and based on the three-dimensional stope Merry flow continuity equation, differential equations and gas migration momentum dispersion equation, combined with the similarity theory, the similarity criteria relationship of experimental model is established. Such design contains a variety of ways to build a three-dimensiond ventilation stope experimental model. Make use of this model as the basis for the test-bed U-shaped ventilation flow field experiment, then input obtained experimental data into MATLAB software for numerical analysis. Finally get the discipline of air leakage field under the U-type ventilation and gas field distribution, then take it as the basis to determine the principles of Spontaneous Combustion Prevention and gas control. 

Figure 33 Principle of AuNP-based dip-stick assay. AuNP-labeled antibodies form a sandwich structure with a sample containing the hCG antigen and capture the antibody, then the complex migrates to form a red line (C = control, T = test).

The actuation principle of EAPap actuators was investigated in terms of ion migration and piezoelectric effects. To physically investigate the actuation mechanism, several tests were performed. TSC measurement showed a linear relationship of depolarized current with the applied electric field, indicating dipolar orientation. By comparing XRD spectra before and after electrical activation, the possibility of recrystallization in the cellulose material was observed. Dielectric property measurement indicated a dependence of the dielectric constant on fiber direction. Thus, we conclude that the combination of piezoelectric effect and ionic migration effect might be the actuation principle. 

Spot test analysis makes frequent use of electrochemical separation methods. Especially in paper chromatography use is made of differential diffusion in which an electrical field serves to accomplish the desired separation. Of particular interest in spot test analysis is the employment of electrographic methods for examining metals, alloys and ores. The basic principle employed is the anodic solution of the metals. In practice, the specimen is made the anode and a piece of aluminum foil serves as cathode. Filter paper is moistened with the appropriate reagent solution and then placed between these two electrodes. The proper voltage is then applied. The movement of the metals then leads to an imprint on the paper and so reveals the exact position of the metals that have migrated from the surface of the test specimen. Hermance and Wadlow have published a comprehensive review of this procedure. 

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