Authors:Anna Gałan, Wioleta Jesionek, Barbara Majer-Dziedzic, Łukasz Lubicki, and Irena Choma
Coffee, due to its common consumption, is one of the main sources of polyphenols in human diet. Coffee species and coffee-related products differ in composition and content of main components, such as chlorogenic acid and caffeine. Chemical and biological fingerprints of various Coffea arabica L. extracts were obtained in order to check and compare their antibacterial and antioxidant properties. The antibacterial activity of green and roasted coffee seeds and pomace was evaluated against Bacillus subtilis using thin-layer chromatography (TLC)-direct bioautography. TLC-2,2-diphenyl-1-picrylhydrazyl (DPPH) test was used to determine antioxidant properties of the afore-mentioned extracts. Furthermore, different solvents and several extraction methods such as simple maceration, maceration under stirring, and ultrasonic accelerated extraction were tested. The most efficient method of extraction of caffeine and chlorogenic acid was chosen based on quantitative TLC analysis. Additionally, these two main components of coffee were quantitatively determined in commercial products of green coffee.
Micelle/water partition coefficients were obtained for procaine hydrochloride using micellar liquid chromatography (MLC) to
illustrate the potential application of this technique to compounds of pharmaceutical interest. Experiments were conducted
over a temperature range which led to calculation of a Gibbs free energy, enthalpy and entropy of transfer for procaine hydrochloride.
Successful application of this technique was confirmed using a second compound over a range of temperatures, namely caffeine.
Overall, this work confirms that MLC can be used to determine precise and accurate partition coefficients that possibly more
closely mimic biological membranes than traditional in vitro systems, namely octanol/water.
Authors:Ádám Dávid, Emil Mincsovics, István Antal, Éva Furdyga, Zsolt Zsigmond, and Imre Klebovich
We report a new combination of overpressured-layer chromatography (OPLC) with near-infrared (NIR) spectroscopy for pharmaceutical analysis. Different pharmaceutical preparations containing caffeine, paracetamol, and acetylsalicylic acid as model compounds were separated by OPLC. The band density in the solid phase after OPLC was suitable for study of the separated components directly on the layer by NIR spectroscopy.We have demonstrated the applicability of rapid OPLC separation combined with UV densitometry and NIR spectroscopy for both qualitative and quantitative analysis. This OPLC-UV-NIR technique is thus suitable for rapid, nondestructive investigation of multicomponent pharmaceutical preparations and enables a different type of pharmaceutical analysis, e.g. starting-material tests, in-process control, end-product control, stability testing, etc. Another benefit of this newly developed combination of rapid off-line techniques is the possibility of simultaneous collection of qualitative and quantitative chromatographic and spectral information.
Authors:M. Szeitz-Szabó, L. Bíró, Gy. Bíró, and J. Sali
In 2009 Hungarian Food Safety Office (HFSO) performed a countrywide representative dietary survey to obtain food consumption data for quantitative food safety risk assessment utilizable in the field of public health nutrition as well. The consumption of foodstuffs, daily energy- and nutrient intakes, nutritional habits and dietary supplement usage of Hungarian population was assessed. The complex system has included three-day dietary record and a food consumption frequency questionnaire. Some anthropometric parameters were also self-recorded. According to the body mass index, a considerable proportion of both the 31–60 years old males (69%) and females (46%) were overweight or obese. The energy intake of the Hungarian adult population is slightly exceeds the recommendation. The intake of proteins is satisfactory in general. The average intake of total fats is very high (36.1–38.9 energy percent), and the fatty acid composition — mostly the ratio of n-6/n-3 fatty acids — is unfavourable, but the fatty acid pattern regarding saturated- (SFA), mono- (MUFA) and polyunsaturated (PUFA) fatty acid ratio shows favourable tendency. The proportion of complex carbohydrates within the intake of energy providing macronutrients is far lower than the optimal level, but it is a positive finding that added sugar intake is below the outmost recommendation. The average daily cholesterol intake is high (males: 469 mg, females: 335 mg), whilst the dietary fibre intake is lower than the recommended. The article provides data on alcohol, caffeine and fibre consumption, too.
Authors:Lenka Findoráková, Katarína Győryová, Eva Večerníková, and Vladimír Balek
Thermal behaviours of three zinc(II) benzoate complex compounds (two new with caffeine and urea), namely Zn(C6H5COO)2, Zn(C6H5COO)2·caf2, Zn(C6H5COO)2·u2, were characterized by using thermogravimetry (TG/DTG), differential thermal analysis (DTA), evolved gas analysis (EGA) with
mass spectrometry (MS) detection and emanation thermal analysis (ETA). Temperature intervals of the stability of the compounds
as well as the mechanisms of their thermal degradation were determined. From TG and DTA results it followed that the oxidative
degradation of urea with CO2 or caffeine with CO2 from the investigated Zn(II) benzoate complex compounds takes place as the first step of their thermal degradation. In the
second step of thermal degradation diphenylketone was release. The evolved gas analysis has been used to determine intermediate
products of thermal degradation and temperature ranges of their evolution from the samples. From the emanation thermal analysis
results it followed that changes in the surface area and microstructure accompanied the thermal degradation of the compounds
studied and that no microstructure changes can be supposed in the resulting zinc oxide on heating from 650 up to 850 °C.
Authors:I. Boros, G. Horváth, S. Lehel, T. Márián, Z. Kovács, J. Szentmiklósi, G. Tóth, and L. Trón
[11C]-labeled form of ten A2a adenosine receptor specific 8-styryl-7-methyl-xanthine derivatives ([11C]-caffeines) were synthesised by N-methylation of the corresponding 8-styryl-xanthine derivatives using [11C]-methyl iodide in optimized reaction conditions. The results show that the [11C]-methylations take place with excellent radiochemical yields (35–93%), and can be utilised easily in online preparations.
These labeled ligands may facilitate the positron emission tomographic (PET) investigation of adenosine A2a receptors.
A simple, rapid, cost-effective, and eco-friendly method is proposed for the simultaneous determination of some common over-the-counter drugs (aspirin, paracetamol, and caffeine [APC]) in saliva and pharmaceutical formulations based on the coupling of ultrasound-assisted emulsification microextraction (USEME) with thin-layer chromatography (TLC)‒image-processing analysis. The process involves the rapid injection of 65 μL of chloroform in diluted saliva samples (2 mL) followed by ultrasonication, which results in the formation of an emulsion. This solution is centrifuged, and 20 μL was spotted on TLC plate which was allowed to develop in mobile phase of ethyl acetate and acetic acid (95:5, v/v). The developed TLC plate was photographed, and the spots of APC were quantified by using the freely available ImageJ software (National Institute of Health [NIH], Bethesda, MD, USA). Factors which can influence the yield of USEME were screened using 27‒4 Placket–Burman design (PBD), and significant factors were optimized using central composite design (CCD). The recoveries and detection limits for all the analytes were found to be in the range of 89.2–94.1% and 0.007–0.012 mg spot−1, respectively. The assay was found to be linear in the range of 0.04–0.2 mg spot−1 with correlation of coefficient of 0.990–0.994. Intra- and inter-day precision for the assay were found to be in the range of 3.12–4.93% and 5.66–8.61%, respectively. The developed method does not require any special instrument and handling skill for the quantitative analysis of APC in saliva and pharmaceutical formulations.
In thin-layer chromatography the development step distributes the sample throughout the layer, a process which strongly affects the reflection signals. The essential requirement for quantitative thinlayer chromatography is not a constant sample concentration but constant sample distribution in each sample spot. This makes evaporation of the mobile phase extremely important, because all tracks of a TLC plate must be dried uniformly. This paper shows that quantitative TLC is possible even if the concentration of the sample is not constant throughout the layer or if the distribution of the sample is not known. With uniform sample distribution, classical
theory is valid for isotropic scattering only. In the absence of this constraint classical
theory must be extended to situations where scattering is asymmetric. This can be achieved by modification of the original
equation. Extended theory is presented which is not only capable of describing asymmetrical scattering in TLC layers but also includes a formula for absorption and fluorescence in diode-array TLC. With this new theory all different formulas for diode-array thin-layer chromatographic evaluation are combined in one expression.