Separation and Detection of Ceramides by HPLC Followed by Evaporative Light-Scattering Detection and Thin Layer Chromatography

IntroductionCeramides,simple sphingolipids,exist ineukaryotic cells either as free molecules or as thebackbone of all sphingolipid molecules. Asstructural components they are mostly localized inthe plasma membrane,contributing to membraneproperties such as increased rigidity and thestability of the lipid bilayer[1] .Their hydrophobicnature provides a hydrophobic environment for theoptimal activity of membrane- related enzymes andproteins. These molecules are redistributed acrossthe membrane bi…     

Effects of starvation for 4-20 days on the amino acid content of Biomphalaria glabrata as determined by cellulose HPTLC-densitometry with confirmation of identity using silica gel and RP-18 W plates with two mobile phases causing inversion of the separation mechanism

The effects of starvation at 4, 7, 10, 14, and 20 days on the amino acid content of Biomphalaria glabrata was determined by high performance thin layer chromatography (HPTLC)-densitometry. Cultures of control and starved snails were prepared for each duration of time. Samples were extracted using ethanol-water (70:30), and supernatant was collected after multiple centrifugations. Samples and standards were applied as bands using a CAMAG Linomat 4 onto cellulose HPTLC plates and developed in a 2-butanol-pyridine-acetic acid-water (39:34:10:26) mobile phase before spraying with ninhydrin detection reagent and scanning with a CAMAG 3 scanner to quantify ornithine (Orn), glycine (Gly), alanine (Ala), valine (Val), and leucine (Leu). Amino acid identification was confirmed by HPTLC on silica gel plates and RP-18?W plates using two different mobile phases causing inversion of the separation mechanism. Starvation led to an overall decrease in amino acid content in comparison to the control snails, however, the amount of amino acids in the starved snails had no correlation with the duration of starvation.     

复方儿茶生肌油中大黄薄层色谱鉴别方法的研究

采用薄层色谱鉴别法（TLC）对复方儿茶生肌油中大黄成分进行鉴别,结果表明,在制备供试品溶液时,采用5％氢氧化钠溶液提取样品中的大黄,比用甲醇分离效果更好,重现性好,可作为该制剂拟定质量标准的鉴别方法。     

华蟾素注射液有效组份的分离和鉴别

分别用水、50%乙醇洗脱HP-20大孔树脂分离华蟾素注射液,得到0.125%非极性组份和0.3625%极性组份。薄层色谱检测发现,极性组份用Dragendoff显色剂喷洒有斑点呈桔红色,推断为生物碱类物质;非极性组份喷洒20%乙酸-硫酸溶液有紫色斑点出现,推断为甾体强心甙类物质。高效液相色谱检测发现,非极性组份在40min以后出现紫外吸收峰,尤以47、51和53min以后出现的吸收峰明显;极性组份在10min以前有明显的紫外吸收峰,且与华蟾素注射液相应位置出现的紫外吸收峰相似。     

Fast Chromatographic Separation of Plasticizers on Thin Layers of an Inorganic Ion-Exchanger: Quantitative Determination of Di(2-ethylhexyl)phthalate

Fast and selective separation of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di(2-ethylhexyl)phthalate (DEHP), benzyl butyl phthalate, diisodecyl phthalate, dimethyl adipate, diethyl adipate, di(2-ethylhexyl)adipate, triethyl citrate, tributyl citrate, tributyl acetyl citrate and n-butyl stearate have been developed on thin layers of inorganic ion-exchanger stannic silicate using a mixture of toluene + ethyl acetate (10:1, v/v) as mobile phase. The development distance and time were 12 cm and 25 min, respectively. Quantitative determination of DEHP was made at wavelength 280 nm by Camag TLC Scanner-3. Limit of quantitation for DEHP was 0.50 μg per zone while its limit of detection was 0.05 μg per zone.     

Stability‐indicating chromatographic methods for determination of flecainide acetate in the presence of its degradation products; isolation and identification of two of its impurities

In this work, two stability‐indicating chromatographic methods have been developed and validated for determination of flecainide acetate (an antiarrhythmic drug) in the presence of its degradation products (flecainide impurities; B and D). Flecainide acetate was subjected to a stress stability study including acid, alkali, oxidative, photolytic and thermal degradation. The suggested chromatographic methods included the use of thin layer chromatography (TLC‐densitometry) and high‐performance liquid chromatography (HPLC). The TLC method employed aluminum TLC plates precoated with silica gel G.F₂₅₄ as the stationary phase and methanol–ethyl acetate–33% ammonia (3:7:0.3, by volume) as the mobile phase. The chromatograms were scanned at 290 nm and visualized in daylight by the aid of iodine vapor. The developed HPLC method used a RP‐C₁₈ column with isocratic elution. Separation was achieved using a mobile phase composed of phosphate buffer pH 3.3–acetonitrile–triethylamine (53:47:0.03, by volume) at a flow rate of 1.0 mL/min and UV detection at 292 nm. Factors affecting the efficiency of HPLC method have been studied carefully to reach the optimum conditions for separation. The developed methods were validated according to the International Conference on Harmonization guidelines and were applied for bulk powder and dosage form. Copyright © 2016 John Wiley & Sons, Ltd.     

Analysis of gardenia blue in foods by thin-layer chromatography

In the present study, a thin-layer chromatography (TLC) method for the analysis of gardenia blue was described. Gardenia blue is obtained from the fruits of Gardenia augusta Merrill or Gardenia jasminoides Ellis. Recently, gardenia blue has frequently been used in Japan as a natural coloring in various foods. However, the structural characterization of gardenia blue components has not been yet clarified and even chromatographic separation of the components has not been reported. Synthetic colors in foods are generally analyzed by TLC; so, we therefore investigated the analysis of gardenia blue in foods with TLC. We established two TLC conditions; reversed phase C-18 TLC using a solvent system of aqueous 0.2% TFA–acetonitrile–ethanol (1:2:3) and TLC on cellulose plate using a solvent system consisting of acetone–3-methyl-1-butanol–water (6:5:5). Both conditions yielded three well-delineated spots with good separation. We applied these separations to the analyses of gardenia blue in coloring matter preparations from different manufacturers and in foods on the market. After the gardenia blue was extracted from the samples with water, the extract was evaporated and the residue was dissolved in water–methanol (1:1). Aliquots of the dissolved solutions were then applied to TLC and their chromatographic behaviors were observed. Each preparation showed characteristic spot patterns depending on the manufacturers. The R_f values of the separated spots when extracted from foods are slightly different from the R_f values of the spots observed for standards, and we were thus able to identify the manufacturers using the spot pattern of gardenia blue. The present study is considered to be useful for the establishment of a method of analysis for gardenia blue in coloring preparations and foods.     

The effect of pomegranate seed powder addition on radical scavenging activity determined by TLC–DPPH test and selected properties of gluten-free pasta

The aim of the present work was to study the effect of pomegranate seeds powder (PSP) supplementation to gluten-free (GF) sheeted pasta on cooking properties, sensory characteristics and antioxidants properties using TLC-DPPH test. Five levels of pomegranate seed powder were used (2.5, 5.0, 7.5, 10.0 and 12.5%) on formula replacement basis. Antioxidant potential of GF pasta increased with the addition of pomegranate seeds powder. The GF pasta without additives and with 2.5% concentration of PSP did not reveal ability to scavenge free radicals. The highest aforementioned activity was observed for crude pomegranate seed extract followed by GF pasta with 12.5, 10.0, 7.5 and 5.0% addition of PSP. The total dietary fibers content of pasta increased from 5.68 to 14.80?g/100?g with the increase in the incorporation of PSP from 0 to 12.5%. The results revealed that cooking loss of gluten-free pasta increased from 9.09 to 10.18%, whereas pasta firmness decreased from 381.43 to 366.30?N, upon incorporation of PSP. Pomegranate seeds powder decreased the lightness of the pasta from 82.26 to 57.27. Sensory analysis suggested that control pasta (without PSP) and pasta supplemented with low levels of PSP have the most acceptable quality. In conclusion, incorporating PSP at low levels enhanced the nutritional quality of pasta without a significant adverse effect on its cooking, textural and sensory properties.     

Separation and characterization of antioxidants from Spirulina platensis microalga combining pressurized liquid extraction, TLC, and HPLC-DAD

A new procedure has been developed to separate and characterize antioxidant compounds from Spirulina platensis microalga based on the combination of pressurized liquid extraction (PLE) and different chromatographic procedures, such as TLC, at preparative scale, and HPLC with a diode array detector (DAD). Different solvents were tested for PLE extraction of antioxidants from S. platensis microalga. An optimized PLE process using ethanol (generally recognized as safe, GRAS) as extraction solvent has been obtained that provides natural extracts with high yields and good antioxidant properties. TLC analysis of this ethanolic extract obtained at 115 degrees C for 15 min was carried out and the silica layer was stained with a DPPH (diphenyl-pycril-hydrazyl) radical solution to determine the antioxidant activity of different chromatographic bands. Next, these colored bands were collected for their subsequent analysis by HPLC-DAD, revealing that the compounds with the most important antioxidant activity present in Spirulina extracts were carotenoids, as well as phenolic compounds and degradation products of chlorophylls.     

薄层色谱法测定调味品中苯甲酸的研究

提出了聚酰胺薄膜上分析调味品中苯甲酸的样品处理方法及标准样品加标法。样品在展开剂上行展开10cm,该方法不需要大型仪器和特殊试剂,适用于多个样品的快速检测,也适用于山梨酸的检测。