Luminescence cell detection concentration

It is important to model a correlation spectroscopy system, firstly to predict performance, and also to aid the very important choice of optical filter (or choose the best LED or super-luminescent optical fibre source to give the optimal spectral output), in order to achieve the best detection performance or best selectivity possible. The length of the cells and the pressure of gas (or gas concentration) are also important parameters (although all simulated results described below are based on use of lm long cells). 

Alcohol oxidase was used to generate H202 followed by its reaction with luminol in the presence of K3[Fe(CN)6] as a catalyst [53], The luminescence was transmitted from the flow cell to the detector via optical fibers. Ethanol can be determined in the 3-750-pmol/L concentration range, with a detection limit of 3 pmol/L. Also, using an immobilized alcohol dehydrogenase reactor in glass beads, a FIA sensor for a reduced form of NADH was constructed by the ECL using the above-mentioned ruthenium tris(2,2 -biryridine) complex. The sensor was satisfactorily applied to the determination of ethanol concentration [54],... 

The luminescent ATP assay is the most sensitive HTS method available for measuring the viability of cell populations in microwell plates. The limits of detection determined in samples of eukaryotic cells serially diluted from a known concentration may fall below 10 cells per well (Figure 6.7). This enables miniaturization to a 1536-well format. 

A green fluorescent protein-based Pseudomonas fluorescens strain biosensor was constructed and characterized for its potential to measure benzene, toluene, ethylbenzene, and related compounds in aqueous solutions. The biosensor is based on a plasmid carrying the toluene-benzene transcriptional activator (Stiner and Halverson, 2002). Another microbial whole-cell biosensor, using Escherichia coli with the promoter luciferase luxAB gene, was developed for the determination of water-dissolved linear alkanes by luminescence (Sticher et al., 1997). The biosensor has been used to detect the bioavailable concentration of alkanes in heating oil-contaminated ground-water samples. 

Instrumentation. The flow system employed in this work is shown in Fig. 1. A peristaltic pump was used to deliver all flow streams at a flow rate of 3.0 mL/min (per tube). 120 p.L of mixture solution of sample and luminol was injected by a sixway injection valve into the carrier stream. The CL signal produced in the flow cell was detected and recorded with a computerized ultraweak luminescence analyzer (type BPCL, manufactured at the Institute of Biophysics, Academia Sinica, Beijing, China). The concentration of sample was quantified by the peak height of the CL intensity. 

Fig. 2.7 Lipophilic IsoK/LG scavengers protect against cytotoxicity induced by oxidative stress. HepG2 cells were incubated with vehicle, pyridoxamine, pentyl-pyridoxamine, or salicylamine for 30 min prior to treatment with various concentrations of hydrogen peroxide (Davies et al., 2006). Viability was determined by detection of ATP using ATPlite luminescence assay and percent viability calculated relative to untreated cells (Mean SEM n = 8)...

Chemiluminescence.—It has been suggested that problems which occur in the determination of yields of bio- and chemi-luminescence may be due to the sample cell. Errors of 25% may be caused by reflection and refraction from interfaces, and, consequently, frosted containers and point-source geometries were recommended. Several authors have concentrated on the use of sensitizers for the enhancement of chemiluminescence. The heavy-atom effect was found to operate in the energy transfer from enzyme-generated acetone to xanthene dyes. 9,10-Diphenylanthracene (9,10-DP A) has been suggested to be a poor singlet counter for chemiluminescence as some triplet states were also counted. In another report, 9,10-dibromoanthracene was found to be a more effective enhancer, when compared with 9,10-DPA, for chemiluminescence from a cyclic peroxide. Luminol chemiluminescence was employed in the analysis of Cr" ions in sea-water. Enhancement with bromide ions enabled detection limits of 3.3 X 10 m to be achieved. 

Table 1 shows the results from testing test-kits 1,2 and 4 with the promyelocytic leukemia rat cell line lPC-81, the rat glioma cell line C6, and the luminescent bacteria V. jischeri. Details of the experimental procedure and the biometrical evaluation have been described previously [13]. For a first comparison. Table 2 shows data for selected conventional organic solvents (V. Jischeri data from [15]). The solvents were chosen because of their widespread use. The comparison shows that, in the case of V. Jischeri, ILs are more toxic than the conventional solvents tested, with the exception of MTBE, which has effect concentrations similar to the least toxic IL. In the case of the IPC-81 WST-1 assay, all ILs with detectable EC50 values are more toxic than the conventional solvents under investigation, while for the less toxic ILs no conclusion is possible on whether they are more toxic than conventional solvents or not. 

A chemiluminescence method has been described for the determination of PG in edible oils using the enhancing effect of this antioxidant on the luminescent signal of 2-phenyl-4,5-di(2-furyl)-lH-imidazole (PDFI) and potassium ferricyanide system in an alkaline medium [57]. The method involves the use of solid-phase extraction with a Cjg cartridge as the stationary phase for sample treatment. The interferents were retained on the cartridge while PG was eluted. A flow system was used to introduce the reagents (PDFI, sodium hydroxide, and potassium ferricyanide) and the sample into the sample cell of the instrument and to measure the enhanced chemiluminescence signal, which was linearly related to the PG concentration. A detection limit of 36 ng/mL PG was obtained. 

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