Pharmaceutical technology offers various dosage forms that can be applied interdisciplinary. One of them are spherical pellets which could be utilized as a carrier in emerging second-generation detection tubes. This detection system requires carriers with high specific surface area (SSA), which should allow better adsorption of toxic substances and detection reagents. In this study, a magnesium aluminometasilicate with high SSA was utilized along with various concentrations of volatile substances (menthol, camphor and ammonium bicarbonate) to increase further the carrier SSA after their sublimation. The samples were evaluated in terms of physicochemical parameters, their morphology was assessed by scanning electron microscopy, and the Brunauer-Emmett-Teller (BET) method was utilized to measure SSA. The samples were then impregnated with a detection reagent o-phenylenediamine-pyronine and tested with diphosgene. Only samples prepared using menthol or camphor were found to show red fluorescence under the UV light in addition to the eye-visible red-violet color. This allowed the detection of diphosgene/phosgene at a concentration of only 0.1 mg/m3 in the air for samples M20.0 and C20.0 with their SSA higher than 115 m2/g, thus exceeding the sensitivity of the first-generation DT-12 detection tube.
- Publikační typ
- časopisecké články MeSH
Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, prevent them and minimize the damages associated with them. One of the most important characteristics of corrosion processes is the corrosion rate. The measurement of corrosion rates is often very difficult or even impossible especially in less conductive, non-aqueous environments such as biofuels. Here, we present five different methods for the determination of corrosion rates and the efficiency of anti-corrosion protection in biofuels: (i) a static test, (ii) a dynamic test, (iii) a static test with a reflux cooler and electrochemical measurements (iv) in a two-electrode arrangement and (v) in a three-electrode arrangement. The static test is advantageous due to its low demands on material and instrumental equipment. The dynamic test allows for the testing of corrosion rates of metallic materials at more severe conditions. The static test with a reflux cooler allows for the testing in environments with higher viscosity (e.g., engine oils) at higher temperatures in the presence of oxidation or an inert atmosphere. The electrochemical measurements provide a more comprehensive view on corrosion processes. The presented cell geometries and arrangements (the two-electrode and three-electrode systems) make it possible to perform measurements in biofuel environments without base electrolytes that could have a negative impact on the results and load them with measurement errors. The presented methods make it possible to study the corrosion aggressiveness of an environment, the corrosion resistance of metallic materials, and the efficiency of corrosion inhibitors with representative and reproducible results. The results obtained using these methods can help to understand corrosion processes in more detail to minimize the damages caused by corrosion.
- MeSH
- elektrická vodivost terapeutické užití MeSH
- koroze * MeSH
- kovy chemie MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- audiovizuální média MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
Colorimetric biosensors of cholinesterase inhibitors are ideal for fast, reliable, and very simple detection of agents in air, in water, and on surfaces. This paper describes an innovation of the Czech Detehit biosensor, which is based on a biochemical enzymatic reaction visualized by using Ellman's reagent as a chromogenic indicator. The modification basically consists of a much more distinct color response of the biosensor, attained through optimization of the reaction system by using Guinea Green B as the indicator. The performance of the modified biosensor was verified on the chemical warfare agents (sarin, soman, cyclosarin, and VX) in water. The detection limits ascertained visually (with the naked eye) were about 0.001 µg/mL in water (exposure time 60 s, inhibition efficiency 25%).
Cholinesterase inhibitors are widely used as pesticides in agriculture, but also form a group of organophosphates known as nerve chemical warfare agents. This calls for close attention regarding their detection, including the use of various biosensors. One such biosensor made in the Czech Republic is the Detehit, which is based on a cholinesterase reaction that is assessed using a colour indicator-the Ellman's reagent-which is anchored on cellulose filter paper together with the substrate. With the use of this biosensor, detection is simple, quick, and sensitive. However, its disadvantage is that a less pronounced yellow discoloration occurs, especially under difficult light conditions. As a possible solution, a new indicator/substrate carrier has been designed. It is made of glass nanofibres, so the physical characteristics of the carrier positively influence reaction conditions, and as a result improve the colour response of the biosensor. The authors present and discuss some of the results of the study of this carrier under various experimental conditions. These findings have been used for the development of a modified Detehit biosensor.
- MeSH
- biosenzitivní techniky metody MeSH
- cholinesterasové inhibitory chemie MeSH
- nanovlákna chemie MeSH
- sklo chemie MeSH
- Publikační typ
- časopisecké články MeSH
The aim of the presented research was the preparation of an innovative carrier with significantly improved properties for the fast and sensitive detection of cholinesterase inhibitors such as nerve agents. This innovative carrier was in the form of spherical pellets containing different amounts of Neusilin. Neusilin is a synthetic and amorphous form of magnesium aluminometasilicate with a high specific surface area, and the immobilized enzyme butyrylcholinesterase with an activity of 50nkat·g-1. Pellets were prepared by the extrusion-spheronization method and dried in a hot air oven under two conditions - at 30°C for 72h and at 60°C for 24h. Dried pellets were consequently impregnated with a solution containing butyrylcholinesterase. Impregnated pellets were evaluated for their quality parameters, enzymatic activity and inhibition. Activity and inhibition were tested according to the standard Ellman's method. It was observed that the addition of Neusilin significantly increased the hardness, intraparticular porosity, sphericity and activity of the carriers as well as intensity of the color transition. Therefore it is shown that these carriers have unquestionable advantages over common carriers of their kind. Drying temperatures have been shown to have no effect on properties of pellets except for a change in their size. Results were confirmed by statistical evaluation using ANOVA and PCA.
- MeSH
- butyrylcholinesterasa chemie MeSH
- celulosa chemie MeSH
- cholinesterasové inhibitory chemie MeSH
- enzymy imobilizované chemie MeSH
- fysostigmin chemie MeSH
- lékové formy MeSH
- nosiče léků chemie MeSH
- pomocné látky chemie MeSH
- poréznost MeSH
- povidon chemie MeSH
- sarin MeSH
- silikáty chemie MeSH
- sloučeniny hliníku chemie MeSH
- sloučeniny hořčíku chemie MeSH
- tvrdost MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: The aim of the study was to use methods of pharmaceutical technology, and prepare carriers in the form of pellets suitable as a filling of detection tubes for enzymatic detection of cholinesterase inhibitors. The enzymatic detection was based on enzymatic hydrolysis of acetylthiocholine iodide and the subsequent colour reaction of its hydrolysis product with Ellman's reagent. The suitable carriers should be in the form of white, regular and sufficiently mechanically resistant particles of about 1 mm allowing it to capture the enzyme during the impregnation process and ensuring its high activity for enzymatic detection. METHODS: Carriers consisting of microcrystalline cellulose, lactose, povidone, and sodium carboxymethyl cellulose were prepared using extrusion-spheronization method under three different drying conditions in either a hot air oven or a microwave oven. Subsequently, the carriers were impregnated with acetylcholinesterase and their size, shape, mechanical resistance, bulk, tapped and pycnometric density, Hausner ratio, intraparticular and total tapped porosity, and activity were measured and recorded. RESULTS: In this procedure, carriers with different physical parameters and different acetylcholinesterase activity were evaluated. It was found that higher acetylcholinesterase activity was associated not only with a higher intraparticular porosity but also with more regular particles characterized by high sphericity and low total tapped porosity. CONCLUSION: This unique finding is important for the preparation of detection tubes based on enzymatic detection which is still irreplaceable especially in the field of detection and analysis of super-toxic cholinesterase inhibitors.
- MeSH
- acetylthiocholin analogy a deriváty metabolismus MeSH
- celulosa analýza MeSH
- cholinesterasové inhibitory metabolismus MeSH
- kyselina dithionitrobenzoová MeSH
- laktosa analýza MeSH
- poréznost MeSH
- povidon analýza MeSH
- sodná sůl karboxymethylcelulosy analýza MeSH
- sulfhydrylová reagencia MeSH
- testování materiálů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A simple colorimetric tube detector for the detection of 2-(dialkylamino)ethanethiols and V-series nerve agents in water and in aqueous solutions is proposed. The detector is based on the reaction of the compounds with a chromogenic Folin-Ciocalteu reagent yielding a blue coloured reduction product. The detection limit of 2-(dialkylamino)ethanethiols is 2.5 mg/l, measurement range up to 250 mg/l. The detection limit of the V (VX) agent is 10 mg/l. The method allows V agents and their precursors and hydrolysis products to be easily distinguished from G-series nerve agents.
- MeSH
- chemické bojové látky * izolace a purifikace škodlivé účinky MeSH
- chemické znečištění vody * analýza škodlivé účinky MeSH
- indikátory a reagencie MeSH
- kolorimetrie metody přístrojové vybavení využití MeSH
- lidé MeSH
- organothiofosforové sloučeniny * izolace a purifikace MeSH
- statistika jako téma MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
