Search results for "Fluorometer"
showing 10 items of 12 documents
Cholera Toxin Subunit B for Sensitive and Rapid Determination of Exosomes by Gel Filtration.
2020
We developed a sensitive fluorescence-based assay for determination of exosome concentration. In our assay, Cholera toxin subunit B (CTB) conjugated to a fluorescence probe and a gel filtration technique (size-exclusion chromatography) are used. Exosomal membranes are particularly enriched in raft-forming lipids (cholesterol, sphingolipids, and saturated phospholipids) and in GM1 ganglioside. CTB binds specifically and with high affinity to exosomal GM1 ganglioside residing in rafts only, and it has long been the probe of choice for membrane rafts. The CTB-gel filtration assay allows for detection of as little as 3 × 108 isolated exosomes/mL in a standard fluorometer, which has a sensitivit…
Automated Photo-Induced Fluorescence Determination of Flumetsulam
2009
The present article deals with a new procedure for determination of the herbicide flumetsulam. The fluorimetric procedure is performed on the basis of photo-increased fluorimetric emission of the pesticide solution and by means of a multicommutation continuous-flow assembly. The alkaline solution containing the analyte is irradiated online and then directly forced through the fluorimeter flow cell. The analysis of different samples is completely automated, as the analyte separation was performed online by including a separation cartridge in the manifold. When dealing with solid samples (such as soil samples), the automation was completed by adding to the manifold the corresponding device fo…
Theoretical prediction of the native fluorescence of pharmaceuticals
2009
At present, to search fluorescent compounds or to increase the native fluorescence is an active research line specially and not only with analytical purposes. On some analytical areas and from the early times of applications of fluorescence (mid-fifties) the fluorimeter was defined as the suitable detector for determination of pharmaceuticals and subsequently, this detection mode has been widely applied. Therefore, it is mandatory to develop new strategies to discover or to enhance in a simple way the native fluorescence of organic compounds to increase the number of analytes to be determined by direct fluorescence. In the present paper are studied further applications of a new tool suitabl…
FIA-fluorimetric determination of adrenaline in pharmaceutical formulations by oxidation with molecular oxygen
1998
The fluorimetric determination of adrenaline is carried out in a continuous-flow assembly and by means of the molecular dissolved oxygen. The sample solution merges with an NaOH stream, then the resulting mixture is heated at 73 °C and led to the flow-cell of the fluorimeter. The flow-assembly is very simple and the procedure is quick (107 samples h−1) reproducible (R.S.D. 0.6%), selective and suitable to be applied to determination of adrenaline in formulations. Calibrations graph are linear over the ranges 0.05–15 and 20–40 mgl−1.
Changes in yield ofin-vivo fluorescence of chlorophyll a as a tool for selective herbicide monitoring
1993
Triazines and derivatives of phenylurea, which are often found in outdoor water samples, induce specific changes in the yield of thein-vivo chlorophyll α-fluorescence of PSII. These changes are correlated quantitatively with the concentration of the herbicides and can therefore be used to set-up a low-price monitor system. In order to detect selectively the herbicide-sensitive part of the fluorescence emission a pulse amplitude modulated fluorimeter was used. The bioassay system was optimised with respect to test organism, growing and measuring conditions. The relationship between fluorescence yield and herbicide concentrations were experimentally determined for the triazines atrazine and s…
A gated material as immunosensor for in-tissue detection of IDH1-R132H mutation in gliomas
2021
[EN] A nanodevice consisted on nanoporous anodic alumina (NAA) supports functionalized with specific and selective antibody-based gatekeepers for the detection of IDH1-R132H mutant enzyme is here reported. Molecular profile and tissue mutations of the tumours (such as IDH1/IDH2 mutations in gliomas) are a great source of information that already make a difference in terms of prognosis and prediction of response to combined therapy. However, standardized methodologies to determine this mutation are time-consuming and cannot provide information before or during surgical intervention, which significantly limits their utility in terms of intraoperative decisionmaking. To solve this limitation, …
Calibration of in situ chlorophyll fluorometers for organic matter
2019
AbstractOrganic matter (OM) other than living phytoplankton is known to affect fluorometric in situ assessments of chlorophyll in lakes. For this reason, calibrating fluorometric measurements for OM error is important. In this study, chlorophyll (Chl) fluorescence was measured in situ in multiple Finnish lakes using two sondes equipped with Chl fluorometers (ex.470/em.650–700 nm). OM absorbance (A420) was measured from water samples, and one of the two sondes was also equipped with in situ fluorometer for OM (ex.350/em.430 nm). The sonde with Chl and OM fluorometers was also deployed continuously on an automated water quality monitoring station on Lake Konnevesi. For data from multiple lake…
Elektrooptische Emissionsmessungen, II. Eine Apparatur zur spektralen Untersuchung feldinduzierter Änderungen der Fluoreszenzintensität von Molekülen…
1977
Es wird ein Spektralfluorometer beschrieben und diskutiert, das es gestattet, die Abhangigkeit der Fluoreszenzintensitat von einem auseren elektrischen Feld zu messen. Die experimentellen Variablen sind dabei die Anregungs- und Emissionswellenzahl sowie die Polarisationsrichtung des Anregungs- und Emissionslichts. A spectrofluorometer is described and discussed, which provides the possibility of measuring the dependence of the fluorescence on an external electric field. The experimentally variable parameters are the wavenumber and the direction of the polarization of the exciting and emitted light.
Is Your Moss Alive during Active Biomonitoring Study?
2021
Biomonitoring was proposed to assess the condition of living organisms or entire ecosystems with the use of bioindicators—species sensitive to specific pollutants. It is important that the bioindicator species remains alive for as long as possible while retaining the ability to react to the negative effects of pollution (elimination/neutralization of hazardous contaminants). The purpose of the study was to assess the survival of Pleurozium schreberi moss during exposure (moss-bag technique) based on the measurement of the concentration of elements (Ni, Cu, Zn, Cd, and Pb), chlorophyll content, and its fluorescence. The study was carried out using a CCM-300 portable chlorophyll content meter…
Study of the diurnal cycle of stressed vegetation for the improvement of fluorescence remote sensing
2006
Chlorophyll fluorescence (Chf) emission allows estimating the photosynthetic activity of vegetation - a key parameter for the carbon cycle models - in a quite direct way. However, measuring Chf is difficult because it represents a small fraction of the radiance to be measured by the sensor. This paper analyzes the relationship between the solar induced Chf emission and the photosynthetically active radiation (PAR) in plants under water stress condition. The solar induced fluorescence emission is measured at leaf level by means of three different methodologies. Firstly, an active modulated light fluorometer gives the relative fluorescence yield. Secondly, a quantitative measurement of the Ch…