Grafting of cyclodextrins onto filter paper

Grafting of cyclodextrins and cyclodextrins derivatives on cellulosic surface, such as paper or filter paper, provides hosting cavities that can include a large variety of chemicals for specific cellulose finishing. In this study grafting of monocholorotriazinyl-β-cyclodextrin (MCT-β-CD) and β-cyclodextrin (β-CD) to filter paper has been performed. β-cyclodextrin has been bonded to filter paper using 1,4-butanediol diglycidyl ether as the crosslinking agent. The untreated and treated filter papers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), demonstrating the covalent binding of cyclodextrins to filter paper. The quantification of β-CD and MCT-β-CD grafted to filter paper was determined by the dye extinction method with the inclusion of phenolphthalein. The final β-CD content amounted to 15.9 μmol per gram of support (1.8% by weight), and 72.8 μmol per gram of support (11.3% by weight) for MCT-β-CD.     

Precise electroosmotic flow measurements on paper substrates

A novel method for electroosmotic flow (EOF) measurement on paper substrates is presented; it is based on dynamic mass measurements by simply using an analytical balance. This technique provides a more reliable alternative to other EOF measurement methods on porous media. The proposed method is used to increase the amount and quality of the available information about physical parameters that characterize fluid flow on microfluidic paper–based analytical devices (μPADs). Measurements were performed on some of the most frequently used materials for μPADs, i.e., Whatman #1 , S&S, and Muntktell 00A filter paper. Obtained experimental results are consistent with the few previously reported data, either experimental or numerical, characterizing EOF in paper substrates. Moreover, a thorough analysis is presented for the quantification of the different effects that affect the measurements such as Joule effect and evaporation. Experimental results enabled, for the first time, to establish well-defined electroosmotic characteristics for the three substrates in terms of the magnitude of EOF as funtion of pH, enabling researchers to make a rational choice of the substrate depending on the electrophoretic technique to be implemented. The measurement method can be described as robust, reliable, and affordable enough for being adopted by researchers and companies devoted to electrophoretic μPADs and related technologies.     

Surface-enhanced Raman spectrometry on a silver-coated filter paper substrate

The production, morphology, and optical properties of silver-coated filter paper as a new active substrate for surface-enhanced Raman spectrometry (SERS) are reported. The procedure involves a simple, one-stage reduction of filter-paper-supported silver nitrate with sodium tetrahydroborate. Intense and reproducible spectra of a variety of ionic and molecular adsorbates including p-aminobenzoic acid, acridine, 9-aminoacridine, 2-aminoanthracene, 6-nitroquinoline and 5-aminoquinoline are obtained. Simplicity, low cost, speed and availability are salient features of the substrate, which extend the applicability of the SERS technique to more practical situations.     

Determination of mugram amounts of palladium in titanium alloys by x-ray fluorescence spectrometry after solvent extraction and collection on a filter paper

Palladium is separated from large amounts of titanium matrix and other elements by solvent extraction with diethyldithiocarbamate, and is collected into the small central area on a filter paper for subsequent x-ray fluorescence measurement. The palladium diethyldithiocarbamate chelate is extracted quantitatively into chloroform at pH 9.5 in the presence of large amounts of tartrate and EDTA. Palladium in the range 30–100 μg can be determined with coefficients of variation of 0-6–1.4%. The detection limit is 0.3 μg of palladium; up to 500 μg of copper does not interfere.     

X-Ray fluorescence analysis using the filter paper method for the determination of La,Pr and Nd in solution

The use of radioisotope-induced energy dispersive X-ray fluorescence technique for elemental analysis in solutions by the filter paper method has been investigated. The calibration has been found to be linear over the range studied. Non-uniformity of specimen, the precision and accuracy of the method have been examined. The minimum detectable amounts have also been determined.     

Microanalysis on controlled spot test paper by X-ray fluorescence

Summary X-ray instrumentation combined with a confined spot test technique has proven very useful for the determination of major constituents and trace constituents in microsamples, i.e., less than 3 mg of material. When the concentration of the major constituent is about 50%, the sample size needed is approximately 250g. Samples containing as little as 0.1% of the element of interest require approximately 1 mg of sample. This technique is simple and rapid with respect to operator time and is quite versatile, being applicable to the determination of elements above atomic number 12.

---

Zusammenfassung Tüpfeln auf begrenzten Flecken, verbunden mit Röntgenfluoreszenzspektrometrie, hat sich für die Bestimmung von Haupt- und Spurenbestandteilen von Mikroproben unterhalb 3 mg sehr bewährt. Ungefähr 250g Probe werden benötigt, wenn die Hauptbestandteile etwa 50% der Probe ausmachen; etwa 1 mg Probe wird benötigt, wenn das zu bestimmende Element in der Größenordnung von 0,1% vorliegt. Das Verfahren, das sich für die Bestimmung von Elementen mit einer Atomnummer über 12 eignet, ist einfach, vielseitig anwendbar und benötigt wenig Zeit.

---

Résumé L'utilisation mixte d'un appareillage de rayons X et d'une technique rigoureuse d'analyse à la touche s'est montrée très utile pour le dosage des constituants principaux et des traces sur des échantillons à l'échelle micro, c'est-à-dire de poids inférieur à 3 mg. Pour une concentration du constituant principal d'environ 50%, le poids de la prise d'essai doit être approximativement de 250g. Les échantillons qui ne contiennent que 0,1% environ de l'élément qui intéresse, exigent approximativement 1 mg de prise d'essai. Cette technique est simple et rapide par rapport au temps dont dispose l'opérateur; elle présente une grande souplesse puisqu'elle est applicable au dosage des éléments dont le nombre atomique est supérieur à 12.

     

Iodine and creatinine testing in urine dried on filter paper

Iodine deficiency is a world-wide health problem. A simple, convenient, and inexpensive method to monitor urine iodine levels would have enormous benefit in determining an individual's recent iodine intake or in identifying populations at risk for iodine deficiency or excess. Current methods used to monitor iodine levels require collection of a large volume of urine and its transport to a testing laboratory, both of which are inconvenient and impractical in parts of the world lacking refrigerated storage and transportation. To circumvent these limitations we developed and validated methods to collect and measure iodine and creatinine in urine dried on filter paper strips. We tested liquid urine and liquid-extracted dried urine for iodine and creatinine in a 96-well format using Sandell–Kolthoff and Jaffe reactions, respectively. Our modified dried urine iodine and creatinine assays correlated well with established liquid urine methods (iodine: R² = 0.9483; creatinine: R² = 0.9782). Results demonstrate that the dried urine iodine and creatinine assays are ideal for testing the iodine status of individuals and for wide scale application in iodine screening programs.     

Quantitative estimation of substances spotted on filter paper by photoacoustic spectroscopy

Quantitative estimation of coloured as well as colourless substances spotted on filter paper has been carried out by means of photoacoustic spectroscopy. The technique should be specially useful in the estimation of biological substances. Contribution No. 378 from the Solid State and Structural Chemistry Unit     

Automated filter paper assay for determination of cellulase activity

Recent developments in molecular breeding and directed evolution have promised great developments in industrial enzymes as demonstrated by exponential improvements in β-lactamase and green fluorescent protein (GFP). Detection of and screening for improved enzymes are relatively easy if the target enzyme is expressible in a suitable high-throughput screening host and a clearly defined and usable screen or selection is available, as with GFP and β-lactamase. Fungal cellulases, however, are difficult to measure and have limited expressibility in heterologous hosts. Furthermore, traditional cellulase assays are tedious and time-consuming. Multiple enzyme components, an insoluble substrate, and generally slow reaction rates have plagued cellulase researchers interested in creating cellulase mixtures with increased activities and/or enhanced biochemical properties. Although the International Union of Pure and Applied Chemists standard measure of cellulase activity, the filter paper assay (FPA), can be reproduced in most laboratories with some effort, this method has long been recognized for its complexity and susceptibility to operator error. Our current automated FPA method is based on a Cyberlabs C400 robotics deck equipped with customized incubation, reagent storage, and plate-reading capabilities that allow rapid evaluation of cellulases acting on cellulose and has a maximum throughput of 84 enzyme samples per day when performing the automated FPA.     

Use of inorganic fiber filter paper in gravimetric microanalysis

Summary Filter mats for filtersticks, filter tubes, andGooch crucibles are easily prepared with the use of filter papers made of glass fibers or fibers of vitreous silica. The reliability of such filter mats for the purpose of quantitative micro analysis has been tested with silica fiber paper which is somewhat more difficult to use, but permits high ignition temperatures.

---

Zusammenfassung Filterstäbchen, Filterröhrchen undGooch-Tiegel können in einfacher Weise mit beständigen Filterschichten aus anorganischem Filtrierpapier, das aus feinen Glasoder Quarzfäden hergestellt ist, versehen werden. Die Eignung solcher Filterschichten für Zwecke der quantitativen Mikroanalyse erscheint durch Versuche mit Quarzfaserpapier erwiesen, das schwieriger zu handhaben ist als Glasfaserpapiere, dafür aber hohe Glühtemperaturen zuläßt.

---

Résumé On prépare aisément avec de la soie de verre ou de la silice vitreuse des plaquettes filtrantes pour baguettes, tubes et creusets de Gooch. De telles plaquettes ont été soumises à l'épreuve pour la micro-analyse quantitative avec de la laine de silice qui est un peu plus difficile à employer mais permet des températures d'ignition plus élevées.

     

Metal nanoparticle-enhanced room temperature phosphorescence of diiodofluorescein on the filter paper substrate

<正>Metal-enhanced room temperature phosphorescence of diiodofluorescein was first observed on filter paper surface.The phosphorescence intensity is 2.5-fold brighter from diiodofluorescein on silver nanoparticles-deposited filter paper as compared with an identical control sample without silver nanoparticles.Furthermore,enhanced absorption was also observed for the same system.Our findings suggest that both singlet and triplet states can couple to surface plasmons and enhance phosphorescence quantum yields at room temperature,as well as to increase the excitation rate of lumophores at room temperature.     

Temperature effects on the solid-matrix luminescence properties of 4-phenylphenol adsorbed on filter paper

Experimental values of fluorescence quantum yield, phosphorescence quantum yield, and phosphorescence lifetime were obtained at temperatures from 23 degrees to -180 degrees for 4-phenylphenol adsorbed on filter paper. From the experimental values, rate constants for phosphorescence and radiationless transition from the triplet state were calculated along with the triplet formation efficiency. The data revealed several important aspects that are responsible for the room-temperature fluorescence and phosphorescence of 4-phenylphenol adsorbed on filter paper.     

SERS of C60/C70 on gold-coated filter paper or filter film influenced by the gold thickness

SERS of C(60)/C(70) adsorbed on gold nanoparticles coated on filter paper or filter film was studied. As a new SERS substrate, dried gold-coated filter paper or filter film has a high SERS activity, whose enhancement factor can be up to about 10(5), because it avoided the influence of solvents in C(60)/C(70) solution and water in gold hydrosols. The influence of the gold thickness coated on filter paper or filter film to SERS of C(60)/C(70) adsorbed on gold nanoparticles was mainly discussed. It is indicated that the SERS effect of C(60)/C(70) was very sensitive to the distribution and aggregated characteristics of gold nanoparticles, and the SERS intensity of each mode increased at its own proportion, but it integrally tended to saturation when the thickness of colloidal gold coatings increased.