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Contact shots to the head often provoke a transfer of biological traces into firearm barrels, which are not visible at endoscopic inspection. STR-PCR can amplify these latent traces and assign them to the victim. Via RNA-DNA-co-extraction also miRNA can be detected, which allow a conclusion to be drawn about the body fluid or tissue. Molecular genetic analysis of experimental stains in firearm barrels requires the guarantee that the barrel is initially free of any nucleic acid. Twelve shots were fired to so-called "reference cubes" (10 % gelatine, 12 cm edge length, embedded paint-blood-pad) using three current handguns: from 20 and 30 cm distance, four at close range (1-2.5 cm) and six contact shots. After endoscopic examination and swabbing of the barrels, a previously described mechanical and chemical cleaning using DNAExitusPlus™ was performed. The inner surface of the barrel was thoroughly wiped off using moistened forensic swabs, which were submitted to RNA-DNA-co-extraction. The combined thorough mechanical cleaning with Ballistol® and the application of DNAExitusPlus™ eliminated any profilable DNA in all samples. However, in 10 of 12 samples RNA concentrations between 0.11 - 0.79 ng/μl were measured. Furthermore, in 9 of 12 samples blood-specific miRNA (miR-451a) was detected. Summarizing, none of the experimentally contaminated barrels was RNA-free despite the performed cleaning procedure. Further investigation showed, that even "professional" cleaning by a gunsmith did not remove RNA.

Experimental design is introduced as a novel procedure to optimise solid-phase microextraction for the determination of orange juice flavour using gas chromatography and mass spectrometry. A central composite design was chosen to study the effects of variation in levels of extraction time (3-15 min), extraction temperature (30-80°C) and pH value (3-11). The models fitted for the prediction of the extraction of terpene flavour compounds (limonene, myrcene, pinene, copaene, caryophyllene), as indicated by r 2 values of more than 0.97. Various surface plots were generated to describe the relationship between operating variables and predicted extraction yields. Optimum conditions with the highest desirability (minimal extraction time, highest yield for all components) were 9 min, 40°C and pH 11.

Aloe vera beverages have to be produced exclusively using material of the plant species Aloe barbadensis MILLER. Commercial material was reported to be frequently adulterated by artificial preservatives or to lack significant amounts of Aloe ingredients. HPTLC and HS-SPME/GC/MS methods to assess the authenticity of Aloe vera beverages were developed in this study, allowing to differentiate between authentic and adulterated products. In one case a commercially available Aloe vera juice could be proven to be exceedingly watered down. Parallel to the authenticity control, the HS-SPME method employed in this work allowed to detect the preservatives benzoic acid, sorbic acid and pHB-esters. In 17 of 24 (71%) currently available Aloe-food products an illegal addition of preservatives of up to 1000 mg/l could be ascertained. The presented analyses of Aloe vera beverages lead to the conclusion, that this product line does not give any cause for hygienic but rather legal concerns: controls have to be intensified to ensure sufficient product quality with regard to preservatives.