Effects of Aoueous Phase Composition on the Leach Behavior of Nuclear Waste Glasses

1986 ◽  
Vol 84 ◽  
Author(s):  
Xiangdong Feng ◽  
Aaron Barkatt
Keyword(s):  
Ph Value ◽  
Glass Composition ◽  
High Surface ◽  
Volume Ratio ◽  
Ph Effects ◽  
High Dilution ◽  
Composition Effects ◽  
Neutral Media ◽  
Leach Behavior

AbstractA systematic matrix of leach tests on a Rest Valley waste glass composition is described. These tests are intended to provide quantitative systematic information on leachant composition effects. and accordingly elucidate the controlling orocesses in hiuh-solute media. e.g. silicate ground water. brine. etc. In order to separate the effects of the nature and concentration of solutes from pH effects. leach tests were first carried out on the glass in de-ionized water under highly interactive conditions (high surface to volume ratio) in a configuration which pre- vented lowering the pH due to the intrusion of CO:. After determination of the resulting pH. the leach behavior of the glass was characterized in a series of high-dilution tests in various leachants buffered at this pH value in order to quantify the effects of leachant composition and concen- trations on the leaching orocess. The high-dilution conditions were used at this stage to ensure that the leachant composition mould not be signifi- cantly affected by accumulation of leached glass components. It was concluded that increased ionic strength appears to depress the leach rates in near-neutral media but enhances the leach rates under moderately basic conditions.

scholarly journals Dipsticks with Reflectometric Readout of an NIR Dye for Determination of Biogenic Amines

Chemosensors ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 99
Author(s):  
Sarah N. Mobarez ◽  
Nongnoot Wongkaew ◽  
Marcel Simsek ◽  
Antje J. Baeumner ◽  
Axel Duerkop
Keyword(s):  
Biogenic Amines ◽  
Indium Tin Oxide ◽  
Near Infrared ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Sample Pretreatment ◽  
Primary Amines ◽  
Nir Dye

Electrospun nanofibers (ENFs) are remarkable analytical tools for quantitative analysis since they are inexpensive, easily produced in uniform homogenous mats, and provide a high surface area-to-volume ratio. Taking advantage of these characteristics, a near-infrared (NIR)-dye was doped as chemosensor into ENFs of about 500 nm in diameter electrospun into 50 µm thick mats on indium tin oxide (ITO) supports. The mats were made of cellulose acetate (CA) and used as a sensor layer on optical dipsticks for the determination of biogenic amines (BAs) in food. The ENFs contained the chromogenic amine-reactive chameleon dye S0378 which is green and turns blue upon formation of a dye-BA conjugate. This SN1-reaction of the S0378 dye with various BAs was monitored by reflectance measurements at 635 nm where the intrinsic absorption of biological material is low. The difference of the reflectance before and after the reaction is proportional to BA levels from 0.04–1 mM. The LODs are in the range from 0.03–0.09 mM, concentrations that can induce food poisoning but are not recognized by the human nose. The calibration plots of histamine, putrescine, spermidine, and tyramine are very similar and suggesting the use of the dipsticks to monitor the total sample BA content. Furthermore, the dipsticks are selective to primary amines (both mono- and diamines) and show low interference towards most nucleophiles. A minute interference of proteins in real samples can be overcome by appropriate sample pretreatment. Hence, the ageing of seafood samples could be monitored via their total BA content which rose up to 21.7 ± 3.2 µmol/g over six days of storage. This demonstrates that optically doped NFs represent viable sensor and transducer materials for food analysis with dipsticks.

A Method for the Quantitative Determination of the Antithrombin III (AT III) a Citivity in Plasma and Serum Using the Complex Formation with Heparin

1975 ◽  
Author(s):  
H. E. Karges ◽  
N. Heimburger ◽  
C. Loechelt
Keyword(s):  
Plasma Concentration ◽  
Antithrombin Iii ◽  
Ph Value ◽  
Immunological Methods ◽  
Good Reproducibility ◽  
High Dilution ◽  
At Iii ◽  
The Mean ◽  
Native Plasma

A prerequisite of most AT III assays is the defibrination of the samples. Defibrination of plasma, however, is generally associated with a loss of AT III. This especially true of heat defibrination. Furthermore, according to our experience, most of the functional determinations don’t correlate well with the immunological ones, and don’t provide reproducible results. Therefore, it was the aim of our investigations to establish a method which omits the defibrination and yields reproducible results.The method reported is based on the identity of AT III and heparin cofactor antithrombin II (AT II) respectively. AT III is converted by heparin from a progressive into an immediate inhibitor, allowing a plasma dilution of 1:50. Due to this high dilution, the defibrination step can be omitted and AT III determined in native plasma. To transform AT III completely into its heparin complex, 5 USP units heparin are used. α2-macro-globulin up to 400% of normal plasma concentration does not influence the assay. When determinations are performed at a certain pH value, good reproducibility is obtained. The mean error of determinations of the same sample does not exeed 4%. Maximal deviations were in the range of 5 to 10%. The results of functional determinations are compared with those obtained by two immunological methods. Deviations scarcely exeed the limits of methodical errors.

A Novel Formaldehyde Gas Sensor Based on Ag-LaFeO3 Using Molecular Imprinting Technique

2016 ◽  
Vol 847 ◽  
pp. 287-293
Author(s):  
Yu Min Zhang ◽  
Chang Yi Hu ◽  
Jin Zhang ◽  
Qing Ju Liu ◽  
Qin Zhu ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Molecular Imprinting ◽  
High Selectivity ◽  
High Surface ◽  
Volume Ratio ◽  
Substrate Material ◽  
Small Dimension ◽  
Molecular Imprinting Technique ◽  
First Time

A novel gas sensor for the determination of formaldehyde was developed based on molecular imprinting technique (MIT). MIT was for the first time used to recognize small organic molecule by our group. The molecular imprinting nanoparticles (MINs) with a small dimension which possess extremely high surface-to-volume ratio were synthesized using imprinting polymerization with formaldehyde as template and Ag-LaFeO3 as substrate material. The structure of the MINs is orthogonal perovskite. And then the MINs were printed onto an alumina tube. Subsequently, a high selectivity molecular imprinting gas sensor for detection of formaldehyde was achieved. At 86°C, the response to 0.5 ppm formaldehyde based on the sensor is 16, and the response is lower than 2 for the other test gases. The response time and recovery time are 55 s and 40 s, respectively.

Preconcentration and determination of ranitidine hydrochloride in real samples by using modified magnetic iron oxide nanoparticles

2016 ◽  
Vol 94 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Elaheh Konoz ◽  
Amir H.M. Sarrafi ◽  
Hamed Sahebi
Keyword(s):  
Human Plasma ◽  
Ph Value ◽  
Limit Of Detection ◽  
Solid Phase ◽  
High Surface ◽  
Sodium Dodecyl ◽  
Magnetic Iron Oxide Nanoparticles ◽  
Ranitidine Hydrochloride ◽  
Relative Standard

This method shows a novel, fast, and simple magnetic solid-phase extraction (SPE) and spectrophotometric procedure for preconcentration and determination of ranitidine hydrochloride in human plasma and aquatic samples by using Fe3O4 nanoparticles (NPs) modified by sodium dodecyl sulfate (SDS) as an extractor. The unique properties of Fe3O4 NPs including high surface area and strong magnetism were utilized effectively in the magnetic SPE process. The determination method is based on the SDS-coated Fe3O4 NPs with extracted ranitidine-HCl, which was subsequently monitored spectrophotometrically at λmax = 320 nm. Effects of different parameters influencing the extraction efficiency of ranitidine-HCl including the pH value, amount of SDS, and Fe3O4 NPs, extraction time, desorption solvent, desorption time, and sample volume were optimized. Under optimized conditions, the method was successfully applied to the extraction of ranitidine-HCl from human plasma and aquatic samples. The extraction recovery in human plasma and different matrixes of waters were investigated and values of 89.0%–103.4% were obtained. The calibration graph for the determination of ranitidine-HCl was linear in the range of 0.025–1.50 μg mL−1 with R2 = 0.9946. The limit of detection of the proposed method was 7.5 × 10−3 μg mL−1. The repeatability and reproducibility (relative standard deviation) of the mentioned method were 0.83% and 1.22%, respectively. The experimental results showed that the proposed method was feasible for the analysis of ranitidine-HCl in environmental and biological samples.

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