RESUMEN
The main goal of this paper is to demonstrate capability of pulse thermovision (thermal-wave) methodology for sensitive detection of photothermal non-uniformities within light scattering and semi-transparent planar stationary phases. Successful visualization of stationary phases defects required signal processing protocols based on wavelet filtration, correlation analysis and k-means 3D segmentation. Such post-processing data handling approach allows extremely sensitive detection of thickness and structural changes within commercially available planar chromatographic layers. Particularly, a number of TLC and HPTLC stationary phases including silica, cellulose, aluminum oxide, polyamide and octadecylsilane coated with adsorbent layer ranging from 100 to 250µm were investigated. Presented detection protocol can be used as an efficient tool for fast screening the overall heterogeneity of any layered materials. Moreover, described procedure is very fast (few seconds including acquisition and data processing) and may be applied for fabrication processes online controlling. In spite of planar chromatographic plates this protocol can be used for assessment of different planar separation tools like paper based analytical devices or micro total analysis systems, consisted of organic and non-organic layers.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Cromatografía en Capa Delgada/métodos , Temperatura , Celulosa/química , Dióxido de Silicio/química , Factores de TiempoRESUMEN
The goal of this paper is to demonstrate the separation and detection capability of eco-friendly micro-TLC technique for the classification of spirulina and selected herbs from pharmaceutical and food products. Target compounds were extracted using relatively low-parachor liquids. A number of the spirulina samples which originated from pharmaceutical formulations and food products, were isolated using a simple one step extraction with small volume of methanol, acetone or tetrahydrofuran. Herb samples rich in chlorophyll dyes were analyzed as reference materials. Quantitative data derived from micro-plates under visible light conditions and after iodine staining were explored using chemometrics tools including cluster analysis and principal components analysis. Using this method we could easily distinguish genuine spirulina and non-spirulina samples as well as fresh from expired commercial products and furthermore, we could identify some biodegradation peaks appearing on micro-TLC profiles. This methodology can be applied as a fast screening or fingerprinting tool for the classification of genuine spirulina and herb samples and in particular may be used commercially for the rapid quality control screening of products. Furthermore, this approach allows low-cost fractionation of target substances including cyanobacteria pigments in raw biological or environmental samples for preliminary chemotaxonomic investigations. Due to the low consumption of the mobile phase (usually less than 1 mL per run), this method can be considered as environmentally friendly analytical tool, which may be an alternative for fingerprinting protocols based on HPLC machines and simple separation systems involving planar micro-fluidic or micro-chip devices.
Asunto(s)
Fraccionamiento Químico/métodos , Cromatografía en Capa Delgada/métodos , Análisis de los Alimentos/métodos , Plantas Medicinales/química , Spirulina/química , Química Farmacéutica , Solventes , Spirulina/clasificaciónRESUMEN
This paper is a continuation of our previous research focusing on development of micro-TLC methodology under temperature-controlled conditions. The main goal of present paper is to demonstrate separation and detection capability of micro-TLC technique involving simple analytical protocols without multi-steps sample pre-purification. One of the advantages of planar chromatography over its column counterpart is that each TLC run can be performed using non-previously used stationary phase. Therefore, it is possible to fractionate or separate complex samples characterized by heavy biological matrix loading. In present studies components of interest, mainly steroids, were isolated from biological samples like fish bile using single pre-treatment steps involving direct organic liquid extraction and/or deproteinization by freeze-drying method. Low-molecular mass compounds with polarity ranging from estetrol to progesterone derived from the environmental samples (lake water, untreated and treated sewage waters) were concentrated using optimized solid-phase extraction (SPE). Specific bands patterns for samples derived from surface water of the Middle Pomerania in northern part of Poland can be easily observed on obtained micro-TLC chromatograms. This approach can be useful as simple and non-expensive complementary method for fast control and screening of treated sewage water discharged by the municipal wastewater treatment plants. Moreover, our experimental results show the potential of micro-TLC as an efficient tool for retention measurements of a wide range of steroids under reversed-phase (RP) chromatographic conditions. These data can be used for further optimalization of SPE or HPLC systems working under RP conditions. Furthermore, we also demonstrated that micro-TLC based analytical approach can be applied as an effective method for the internal standard (IS) substance search. Generally, described methodology can be applied for fast fractionation or screening of the whole range of target substances as well as chemo-taxonomic studies and fingerprinting of complex mixtures, which are present in biological or environmental samples. Due to low consumption of eluent (usually 0.3-1mL/run) mainly composed of water-alcohol binary mixtures, this method can be considered as environmentally friendly and green chemistry focused analytical tool, supplementary to analytical protocols involving column chromatography or planar micro-fluidic devices.
Asunto(s)
Cromatografía en Capa Delgada/métodos , Esteroides/análisis , Animales , Cromatografía Líquida de Alta Presión , Peces , Hidrólisis , Peso Molecular , Extracción en Fase Sólida , Espectrofotometría Ultravioleta , TemperaturaRESUMEN
The main goal of present paper is to demonstrate the separation and detection capability of micro-TLC technique involving simple one step liquid extraction protocols of complex materials without multi-steps sample pre-purification. In the present studies target components (cyanobacteria pigments, lipids and fullerenes) were isolated from heavy loading complex matrices including spirulina dried cells, birds' feathers and fatty oils as well as soot samples derived from biomass fuel and fossils-fired home heating systems. In each case isocratic separation protocol involving less that 1 mL of one component or binary mixture mobile phases can be completed within time of 5-8 min. Sensitive detection of components of interest was performed via fluorescence or staining techniques using iodine or phosphomolybdic acid. Described methodology can be applied for fast fractionation or screening of whole range of target substances as well as chemo-taxonomic studies and fingerprinting of complex mixtures, which are present in raw biological or environmental samples.
Asunto(s)
Fraccionamiento Químico/métodos , Cromatografía en Capa Delgada/instrumentación , Cromatografía en Capa Delgada/métodos , Mezclas Complejas/análisis , Monitoreo del Ambiente , Fulerenos/análisis , Yodo/química , Lípidos/análisis , Microquímica/instrumentación , Molibdeno/química , Ácidos Fosfóricos/química , Hollín/análisis , Spirulina/química , TemperaturaRESUMEN
In this paper a simple protocol is described for estimating of solid-phase extraction (SPE) elution volumes of steroids based on retention data generated from micro-planar chromatography. Particularly, the retention of selected steroids, including estrogens and progestagens, was studied on wettable with water octadecylsilica HPTLC plates and mobile phases composed of methanol:water mixtures ranging from 20 to 100% (v/v). It was found that TLC retention data can be linearized by plotting R(M) values of steroids against a reciprocal form of the organic modifier molar fraction (1/X(s)). Using such a mathematical approach, the retention parameter of steroids investigated could be easily back-calculated for a wide range of mobile-phase compositions, using few initial experimental data points. The hold-up time of SPE cartridges filled with 0.5 g of C-18 adsorbent was determined experimentally, and appropriate retention factor values (k(SPE)) for components of interest studied were calculated. Using an appropriate slope and intercept coefficients of the linear-regression equation formed as log k(SPE) = aR(M) + b, the steroids SPE elution volumes were predicted beyond the experimental data range that was available for a solid-phase extraction experiment, particularly for mobile phases that contained a high level of water.
Asunto(s)
Extracción en Fase Sólida/métodos , Esteroides/aislamiento & purificación , Métodos Analíticos de la Preparación de la Muestra , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Metanol/química , Análisis de Regresión , Esteroides/química , Factores de Tiempo , Agua/químicaRESUMEN
Thermostated micro thin-layer chromatography was applied for separation and quantification studies of Spirulina maxima dyes isolated from pharmaceutical formulation by a simple one-step liquid extraction. The isolation process was performed using a number of liquids, including water; 10 mM water solutions of native alpha-, beta-, and gamma-cyclodextrin and their hydroxypropyl derivatives; and a number of common organic liquids characterized by different polarity, namely, methanol, ethanol, 1-propanol, 2-propanol, acetonitrile, acetone, tetrahydrofuran, dichloromethane, toluene, and n-hexane. Chromatographic studies were performed on RP18W plates working inside a small thermostated horizontal chamber allowing a development distance of 45 mm. Using a mobile phase consisting of acetone-n-hexane (30 + 70, v/v) and 40 degrees C separation temperature, plate peak capacity of at least 15 spots/lane and developing time <5 min were obtained. Validation data indicated that under such conditions, with an office scanner used for chromatogram digitalization, spot quantification could be accurately performed within an analyte mass range of 2 factors. The raw quantitative data obtained from microchromatograms acquired under visible light conditions were explored using cluster analysis and principal components analysis. Chemometric investigations revealed that the best extraction liquids for isolation of dye mixtures from Spirulina samples were methanol, ethanol, tetrahydrofuran, and dichloromethane. Moreover, it was found that the liquids' parachor values could be used for estimation of the dye extraction efficiency from complex samples.
Asunto(s)
Colorantes/química , Spirulina/química , Química Física , Cromatografía en Capa Delgada , Análisis por Conglomerados , Ciclodextrinas/química , Indicadores y Reactivos , Análisis de Componente Principal , Estándares de Referencia , Solventes , AguaRESUMEN
Temperature-controlled micro thin-layer chromatography (TLC) was applied for separation and quantification studies of testosterone and its derivatives including methyltestosterone, testosterone propionate, isobutyrate, phenylpropionate, isocaproate, enanthate and caprate. Chromatographic studies were performed on silica-, octadecylsilica- and aluminum-coated plates working inside a small thermostated horizontal chamber unit allowing one-dimensional and two-dimensional developing modes with an elution distance of 45 mm. Retention properties of steroids were investigated across a whole range of binary mixtures such as methanol/water, acetonitrile/water, methanol/dichloromethane and acetone/hexane (0-100% v/v). Moreover, the effect of temperature ranging from -20 to +60 degrees C under saturated and unsaturated chamber conditions was also investigated. Our results revealed that depending on the mobile phase polarity the separation system based on the low carbon load wettable with water RP18W plates may work as a normal-phase (NP) or reversed-phase (RP) chromatographic system. It has been also demonstrated that micro TLC equipment can be applied as a fast retention screening device as well as simple and robust quantitative tool for determination of testosterone residue containing testosterone derivatives in complex samples.