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Afterimages are common and frequent perceptual phenomena of everyday life. A typical appearance is the negative УghostФ image of a bright light source when we turn away from it. In the case of significant colour contrast, the afterimage can be coloured. The perceived false imageТs strength decreases gradually and completely disappears in a (10-100) s timescale. The underlying processes have multiple components: a quick adaptation on the retinal level, and a slower adaptation on the neural level. Several studies discuss these mechanisms, but there are still important questions to be answered. In our research, we apply the toplevel, blackbox style approach: instead of focusing on the inner details, we ask human test subjects to test and measure the duration and Уstrength scoreФ of the same lighttransitions. Our goal is to find the main features that affect the duration and subjective strength of the colour afterimages. Specifically, we examine whether the age and gender of the test subjects or the colourimetry parameters affect these parameters. Two set of experiments were performed: colourcolour transitions with 41 and colourgrey transitions with 16 test subjects between 19 and 62. We found that gender has no measurable influence, but age makes a difference in high significance. Both experiment types confirmed that over 40 years the average duration of colour afterimages decreases.

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Liquid chromatography is a useful method for selective analysis of vitamin A and E. The native components can be easily tested due to their UV-absorbance and beneficial separation characteristics. To test the food sample, vitamin A and E have to be separated from the fatty part of food. This step is performed by saponification, which is the critical step of procedure due to the heat and light sensitivity of both vitamins. The corresponding standards (MSZ-EN 12822-1, MSZ EN 12823-1) recommend a wide range of saponification temperature and time, giving an opportunity to optimize the recovery of the analyte.Experimental tests were performed from vegetable oil and margarine sample to find the temperature and time settings for the best recovery. Both factors were examined with centered two-level factorial design. Data analysis showed an increasing recovery of analytes towards the corner points of highest possible temperature and shortest possible saponification time. Finally, confirmatory tests were made.