Thin-Layer Chromatographic Detection of Selected Pyrethroids with p-Benzoquinone Reagent

JPC – Journal of Planar Chromatography – Modern TLC - Cypermethrin is frequently encountered in poisoning cases in India. In TLC, the compound can be detected by spraying the plate with...     

Thin Layer Chromatographic Technique for Detection and Identification of Endosulfan Insecticide with m-Dinitrobenzene Reagent

JPC – Journal of Planar Chromatography – Modern TLC - Endosulfan is commonly encountered in poisoning cases in India. In TLC the compound can be detected by spraying the plate with...     

Physico-chemical phenomena of double-layer spray and effect on enhancement and stabilization of fluorescence

Summary It was surprisingly found in TLC that double spraying of plates could enhance fluorescence of dansyl derivatives 200–360 fold after spraying with 20% triethanolamine in propane-2-of followed by 30% paraffin oil in hexane on a developed plate containing dansyl chloride derivatives. Visual detection limits as low as 1–6 pmole per spot even a month after spraying with a reproducibility of about 5–6% rsd were obtained. Spraying calibration graphs showed a dose-dependency of at least 1 pmole up to 1.5 nmole per spot. The stability of fluorescence of derivatives to light was increased and spectra of compounds acquired a hypochromic shift in which the color changed from yellow to blue. The graphical method employing the “organic concept” is introduced to explain this kind of synergistic effect of double spraying using different solvents.     

Metallofluorescent indicators as spray reagents for the in situ determination of organophosphorus pesticides on thin-layer chromatograms

Fluorescence-quenched solutions of palladium(II)-calcein and palladium(II)-calcein blue are shown to be sensitive spray reagents for the detection and in situ determination of organothiophosphorus insecticides on thin-layer chromatograms. The palladium is displaced from its non-fluorescent indicator complex by the pesticide producing fluorescent spots on the plate. Visual detection limits for 16 insecticides are given. As little as 10–50 ng of phosphorodithioate pesticides can be detected within l h after spraying and drying the plate, while the detection limits for phosphorothioates are somewhat higher (ca. 50–100 ng). Quantitative measurements may be conveniently made 18–24 h after spraying and drying the plate. Plots of fluorescence (as peak area) versus quantity of pesticide are linear over a 10–15 fold range. The relative standard deviation of replicate spots of Guthion (50–400 ng) and Cygon (50–100 ng) is 4–9 % and less than 15 % for 10 ng of Cygon or 20 ng of Guthion. The method was applied to the analysis of lake water spiked with Cygon. The recovery of 2–20 μg l^-1 of the pesticide was 87–113% with no clean-up other than t.l.c. required.     

Rapid and sensitive determination of tryptophan, serotonin and psychoactive tryptamines by thin-layer chromatography/fluorescence detection

A rapid, sensitive and selective method for the determination of tryptophan (Trp), serotonin (5-HT) and psychoactive tryptamines (PATs) by thin-layer chromatography (TLC) with fluorescence detection is proposed. These compounds form fluorophores on the developing plate by heating after spraying with sodium hypochlorite, hydrogen peroxide or potassium hexacyanoferrate(III)-sodium hydroxide reagent. Fluorescent spots (vivid blue) were observed by irradiation with ultraviolet light (365 nm). The detection limits of Trp, 5-HT and PATs were in the range from 0.01 microg to 0.06 microg. This method was effectively applied to the detection of confiscated PAT powder and PAT in abusers' urine samples.     

薄层色谱分离库仑滴定法测定杀虫单

本文提出了用薄层色谱库仑滴定法测定杀虫单（ＳＣＤ）［ＣＨ３）２ＮＨＣ Ｈ（ＣＨ２Ｓ２Ｏ３）２Ｎａ．Ｈ２Ｏ］的方法。试样中的各成分用上行展开法的硅胶Ｇ板上分离，用碘蒸气或喷洒ＰｄＣｌ２溶液确定ＳＣＤ的位置，该试剂与杀虫单反应生成橙黄色产物。     

Screening for inhibitors of histone deacetylase by incorporating a spraying method to micro-arrayed compound screening

We have developed a method of spraying assay reagents onto a target gel in the Micro-Arrayed Compound Screening ( micro ARCS) format. After application of target gels to compound sheets, subsequent reagents can be applied by spraying onto the target gel. The spraying method conserves on assay reagents by up to 10-fold, eliminates the need for casting additional agarose gels, and increases the throughput of a screen by 3-fold. To demonstrate the efficacy of applying the spraying method to micro ARCS, we screened over 600,000 compounds for inhibitors of histone deacetylase (HDAC). Commercially available HDAC substrate and reaction developer were sprayed directly onto the gel to initiate the reaction and to amplify the signal, respectively. Picks in the primary screen were retested at a density of 384 compounds per sheet in the micro ARCS format. IC(50) values for active compounds were confirmed in a 96-well plate assay. The screen identified several small molecule inhibitors of the enzyme, including members of several classes of known HDAC inhibitors. The combination of the high-density format of micro ARCS, the efficiency of the spraying method, and a timed sequence of adding assay reagents permitted a screening throughput of 200,000 tests an hour. We present the details of the screening format and the analysis of the hits from the screen.     

High-throughput microwave-assisted organic synthesis: moving from automated sequential to parallel library-generation formats in silicon carbide microtiter plates

A 48 deep-well microtiter plate system for sealed vessel parallel microwave synthesis is described. The plate consists of a standard 6 x 8 matrix of 48 wells with a maximum working volume of 300 microL and is made out of strongly microwave-absorbing sintered silicon carbide. In combination with an alumina sealing plate equipped with adequate conical bore holes for sample withdrawal, the setup can be used for microwave processing at temperatures up to approximately 200 degrees C and 20 bar of pressure. The microtiter plate setup displays excellent temperature and reaction homogeneity and was used for the generation of a 30-member library of 2-aminopyrimidines.     

Thin-layer chromatographic screening procedure for some drugs in horse plasma

A thin-layer chromatographic screening procedure for some basic, neutral and acidic drugs was developed using 3 ml of horse plasma. Chloroform-2-propanol (95:5, v/v) was used as the extraction solvent. The drugs were identified by a high-performance thin-layer chromatographic plate and spraying successively with some detection reagents. In this study, the extraction recovery rates and the detection limits were determined at the same time.     

喷涂轨迹对铝合金表面等离子喷涂Mo/8YSZ功能梯度热障涂层温度场的影响规律研究

为了突破传统Mo/8YSZ双层热障涂层高温易剥离的技术瓶颈,研究喷涂轨迹对等离子喷涂功能梯度热障涂层温度场的影响规律,利用ANSYS有限元仿真模拟软件,基于"生死单元"的方法,建立了等离子喷涂功能梯度热障涂层的有限元模型,模型中考虑了材料的相变潜热及不同温度下的热物性参数,分析了不同喷涂轨迹下喷涂构件温度及温度梯度的分布情况。结果表明:当喷涂粘结层和过渡层材料时,采用同向的喷涂轨迹时,喷涂构件的温度最高;采用同种材料同向喷涂,异种材料喷涂方向相反的喷涂轨迹时,喷涂构件的温度次之;采用"S"型的喷涂轨迹时,喷涂构件温度最低。当喷涂陶瓷层材料时,采用"S"型的喷涂轨迹时,喷涂构件的温度最高;采用同向的喷涂轨迹时,喷涂构件的温度次之;而采用同种材料同向喷涂,异种材料喷涂方向相反的喷涂轨迹时,喷涂构件的温度最低。采用"S"型喷涂轨迹进行喷涂作业时,喷涂构件左右两端面温度分布的均匀性优于另外两种喷涂方式;采用同向的喷涂轨迹进行喷涂作业时,基体温度的波动幅度较另外两种喷涂方式小。通过设计梯度结构,并调控喷涂轨迹,可减小构件厚度方向的温度梯度,从而提升基体与涂层的结合强度。     

Post TLC developing technique for tyrosinase inhibitor detection

Post TLC developing technique was developed to detect substances which can inhibit tyrosinase activity. The method involved spraying the TLC plate or chromatographic paper containing sample spot(s) with tyrosinase and l-tyrosine solutions successively. A positive result could be visualized directly as white spot(s) against a brownish-purple background. The method can either be used as a quick screening method for tyrosinase inhibitor detection or a guiding procedure for an isolation of tyrosinase inhibitors from mixtures or natural product extracts. The technique is sensitive enough to give a clear result in the presence of only 6 ng glabridin.     

Rapid preparation of smooth nanocellulose films using spray coating

Spraying of nanocellulose (NC) on a solid surface to prepare films is an alternative technique to vacuum filtration, which requires a long drainage time and produces films which can sometimes be difficult to separate from the filter. This letter reports a rapid preparation technique for nano-cellulose films using a bench scale system spray coating nanocellulose suspension onto stainless steel plates. After spraying NC suspension onto a smooth steel plate travelling on a constant velocity conveyor, the films can be dried directly on the plates using standard laboratory procedures, saving processing time and effort. By adjusting the suspension consistency, we were able to reproducibly make films with a basis weight ranging from 52.8 ± 7.4 to 193.1 ± 3.4 g/m² when spraying on to a plate moving at a velocity of 0.32 cm/s. The operator preparation time for the nanocellulose film was 1 min, independent of the sample basis weight, which compares to production times reported in the literature of 10 min using filtration techniques. The films made by spray coating showed higher thickness, but comparable uniformity, to those made by vacuum filtration. Optical profilometry measurements showed that over a 1 cm × 1 cm inspection area that the surface roughness (RMS) of the NC film is only 389 nm on the spray coated side in contact with the steel plates, compared to 2087 nm on the outside surface. Thus, the reduction in preparation time for producing the nanocellulose film recommends this spray coating technique as a rapid and flexible method to produce NC films at the laboratory scale.     

Microstructure and surface residual stress of plasma sprayed nanostructured and conventional ZrO2‐8wt%Y2O3 thermal barrier coatings

The nanostructured agglomerate feedstock which can be used for plasma spraying was obtained successfully by the reconstituting nanoparticle technique. Nanostructured and conventional ZrO₂‐8wt%Y₂O₃ (8YSZ) thermal barrier coatings (TBCs) have been prepared by atmospheric plasma spraying (APS) on NiCoCrAlY coated 45# steel substrates. The microstructure and phase composition of feedstock and corresponding coating were characterized by SEM and XRD. The elastic modulus was tested by the nanoindenter instrument. The surface residual stresses were examined by XRD stress test equipment. The numerical value probability statistics of surface residual stress by the Weibull distribution theory was implemented under different thermal spray parameters. The value of residual stresses increased with increasing the thickness of the ceramic coating. The surface residual stress of nanostructured 8YSZ coating is lower than that of the conventional 8YSZ coating. A physical mechanical model is put forward to explain the causation of the variation of residual stresses. At the same time, the variation characteristic of surface residual stress is discussed by introducing the closed form solution of residual stress of laminar layer plate. Copyright © 2010 John Wiley & Sons, Ltd.     

Derivatisation of sympathomimetics with primary amino groups on thin-layer plates by spotting the sample spots with fluorescamine

Summary A method has been developed for the quantitative determination of sympathomimetics containing a primary amino group on thin-layer plates with fluorescamine. The reaction is carried out by spotting fluorescamine solution in acetone on top of the sample spots. The fluorescamine derivatives are subsequently separated using appropriate solvent systems. Spotting a buffer before reaction and spraying with triethanolamine after development is unnecessary. The consumption of reagent is extremely low. For ten thin-layer plates with ten sample spots per plate only 0.2 cm³ reagent solution are needed. The method has been applied to the quantitative determination of some compounds with primary amino groups in pharmaceutical preparations.Dedicated to Prof. Dr. G. Zigeuner on his 60^th birthday.     

Thin-layer chromatographic separation and in situ fluorimetric determination of ofloxacin in plasma and pleural fluid

A thin-layer chromatographic assay for the determination of ofloxacin in human plasma and pleural fluid is described. After extraction of ofloxacin from samples with dichloromethane, chromatography was performed on thin-layer plates (silica gel) with a mobile phase consisting of ethanol and water; the tank atmosphere was equilibrated with concentrated ammonia. The precision of the assay could be considerably increased along with the measured fluorescence intensity of ofloxacin by spraying the plate with a citric acid solution and dipping it into paraffin or using a mixture of both components. Peaks were quantified by densitometric evaluation of the chromatograms. The method shows a very low limit of detection (1 ng/ml) as well as good precision and linearity in the range 0.001-2.0 micrograms/ml for both plasma and pleural fluid.     

Charged particle activation analysis at RIKEN: Past,present and future

To study the effect of rhizosphere pH condition on the cadmium uptake movement, ¹⁰⁹Cd, was applied as a radioisotope tracer to a soybean plant grown in a water culture at pH 4.5 or pH 6.5. The distribution of ¹⁰⁹Cd in the soybean plant was observed radiographically with an imaging plate (IP). The amount of Cd transported from the root to the upper part of the plant at pH 4.5 was approximately two times higher than that at pH 6.5. However, the movement of Cd in the upper part of the plant was similar under both pH conditions. The distribution of Cd inside the internodes at pH 4.5 also showed similar pattern to that at pH 6.5, suggesting that once Cd reached to the vessel of the root, the movement of Cd was not dependent on rhizosphere pH conditions.     

叶面喷施硅硼锰肥对四季桂生长的影响

研究了在叶面喷施的条件下，硅硼锰以及硅硼锰配合对盆栽四季桂生长的影响。结果表明，在基肥较足的基础上，硼肥可以增加四季桂新梢长度以及新梢粗度，对于开花也有促进作用；施用硅肥可明显提高叶片功能；单独喷施猛肥效果不明显。混合使用，效果较好。     

Simultaneous spray coating of interacting species: general rules governing the poly(styrene sulfonate)/poly(allylamine) system

Simultaneous spraying of two solutions of interacting species onto a substrate held vertically leads to the formation of nanometer-sized coatings. Here we investigate the simultaneous spraying of poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) solutions leading to the formation of a film composed of PSS/PAH complexes. The thickness of this film increases linearly with the cumulative spraying time. For a given spraying rate of PAH (respectively PSS), the growth rate of the film depends strongly upon the PSS/PAH ratio and passes through a maximum for a PSS/PAH ratio lying between 0.55 and 0.8. For a PSS/PAH ratio that is maintained constant, the growth speed of the film increases linearly with the spraying rate of polyelectrolyte of both solutions. Using X-ray photoelectron spectroscopy, we find that the film composition is almost independent of the PSS/PAH (spayed) ratio, with composition very close to 1:1 in PSS:PAH film. The 1:1 PSS:PAH composition is explained by the fact that the simultaneous spraying experiments are carried out with salt-free solutions; thus, electroneutrality in the film requires exact matching of the charges carried by the polyanions and the polycations. Zeta potential measurements reveal that, depending on whether the PSS/PAH spraying rate ratio lies below or above the optimal spraying rate ratio, the film acquires a positive or a negative excess charge. We also find that the overall film morphology, investigated by AFM, is independent of the spraying rate ratio and appears to be composed of nanometer-sized grains which are typically in the 100 nm range.     

Routine Hptlc in Industrial Analysis: Process Control of Fermentations

Abstract

Quantitative HPTLC is a cost saving and reliable chromatographic routine method for the control of many fermentation processes, as for example the fermentation of penicillin V. The following substances are analyzed: lactose or sucrose, soya oil (against foaming), phenoxyacetic acid (precursor), penicillin V and p-hydroxypenicillin V, as final products. The derivatization after chromatography is performed with an automated spraying device, the measurement—perpendicularly to the direction of chromatography—and evaluation are computerized. The time requirements per sample range from 6 to 15 minutes, the pure analysis time per sample from 5 to 12 minutes. The break-down time of the complete HPTLC apparatus system is about 0,6% of the working time, all substances to be determined can be measured with one scanner, in every interval and sequence desired. The accuracy, expressed by the coefficients of variation (N = 8 – 9, on one plate), ranges from 1,6 to 3,0 %, for very low concentrations up to 6, 6%.     

Low Cost,Efficient TLC Sprayer

JPC – Journal of Planar Chromatography – Modern TLC - The construction of simple, inexpensive, compressed air-operated spraying device which can handle small and large volumes...