High sensitivity detection cell

Fig. 7 Electropherograms illustrating the marking with NBDPE for binary and ternary micellar systems (BS/PC/FA). (a) Detection by LIF, a comparison between simple and binary micelles (b) detection by UV using a high-sensitivity detection cell buffers contained a mM DPPC, y mM FA and 20 mM phosphate, pH = 7.4. (Modified from Ref. 36. With permission.)...

A high-sensitivity detection cell that can be fully decoupled from the separation capillary, either open or packed has been introduced by Agilent [25]. The cell is constructed from silica parts fused together and is flanked by flat, clear windows in order to minimize stray light. The optical path length is 1.2 mm and a 20-fold increase in detection sensitivity is reported, however, resolution is lost when the interpeak volume is lower than the cell volume (1.2 nL). 

Figure 3 High-sensitivity detection cells for LlV-Vis absorbance CE detectors (A) Z-cell (B) bubble cell and (C) multireflection cell.

The detection of the migrating sample boundary in CE can be accomplished by UV, fluorescent, electrochemical, radiochemical, conductivity, and mass spectrometry (MS) means. The use of high-sensitivity detection systems is always a key issue in CE applications. The sensitivity of HPCE detectors may be at least 2 to 3 orders of magnitude better than that of HPLC detectors. Since the detection cell volume is very small, the concentration sensitivity... 

When cells are suspended in a biological fluid or culture medium, both serum proteins and cells interact with the surface substrate. Serum protein adsorption behavior on SAMs has been examined with various analytical methods, including SPR [58-61], ellipsometry [13, 62, 63], and quartz QCM [64—66]. These methods allow in situ, highly sensitive detection of protein adsorption without any fluorescence or radioisotope labeling. SPR and QCM are compatible with SAMs that comprise alkanethiols. In our laboratory, we employed SPR to monitor protein adsorption on SAMs. 

Colloidal gold-labeled (strept)avidin can be used as highly sensitive detection reagents for microscopy techniques (Cubie and Norval, 1989) (Chapter 24). Finally, cytotoxic substances coupled to (strept)avidin can be used to direct cell-killing activity toward a tumor-cell-bound, biotinylated monoclonal antibody (or other targeting molecule) for cancer therapy (Hashimoto et al, 1984) (Chapter 21). 

Suehiro, J., Shutou, M., Hatano, T., and Hara, M. (2003). High sensitive detection of biological cells using dielectrophoretic impedance measurement method combined with electro-permeabilization. Sens. Actuators B Chem. 96,144-151. 

Dittrich, P.S., Schwille, P., An integrated microfluidic system for reaction, high-sensitivity detection, and sorting of fluorescent cells and particles. Anal. Chem. 2003, 75, 5767-5774. 

These assays resemble a hybrid of an immunohistochemistry assay and ELISA. Whole cells are fixed, for example with 3.7% formaldehyde, to MTPs permeabilized by repetitive washing with 0.1% Triton X-100, blocked with a protein solution, probed with primary antibodies (phospho-spe-cific, and non-phospho-specific), washed, and subsequently the secondary antibodies labeled with infrared fluorescent tags are added. After washing, these assays are read in a reader (such as the Odyssey or Aerius) designed for high sensitivity detection of two colors. The two colors are useful because one color can be used to accommodate a stain assigned as a total protein or cell number control or as an antibody to total protein, which allows for normalization. These assays may only require a single antibody versus the dual antibody sandwich required for ELISA. 

J. Stahl-Zeng, V. Lange, R. Ossola, K. Eckhardt, W. Krek, R. Aebersold, and B. Domon, High sensitivity detection of plasma proteins by multiple reaction monitoring of /V-glycosiles, Mol. Cell. Proteomics, 6 (2007) 1809-1817. 

There are three main types of mass analyzers in ESTMS-MS instruments triple quadrupole, ion traps, and quadrupole-time-of-flight (Q-TOF). There are several differences between the mass analyzers in MALDI-TOF and in ESI-MS-MS. Unlike in MALDI-TOF-MS, in ESTMS-MS two mass analyzers are used in tandem to increase the sensitivity of the technique. The peptide ions produced by the ESI sources are carried to the first mass analyzer and only peptides of a set miz ratio are selected. The selected ions are then carried to a collision cell where they are subjected to additional fragmentation to produce smaller amino acid ions using a process called as collision induced dissociation (CID). The CID process employs inert gases such as argon for the dissociation of peptides. These smaller amino acid ions are then resolved in the second mass analyzer before sending to the detector. This process essentially enables highly sensitive detection of actual amino acid sequence of the peptides based on the mIz ratios of individual amino acids. 

FIGURE 25.17 Electropherogram of 0.8 fjLglX Knowles Marsh water spike. CE conditions 161 nl injection 240 nm UV detection mobile phase 50 mmol/1 ammonium acetate at pH 4.75, with 12% acetonitrile added to inlet buffer vial 30 kV, 30 iiK, 30°C. Capillary length 122 cm (100 cm effective length) X 75 i.d. bare fused silica high-sensitivity optical cell. (From Krynitsky, A., J. Assoc. Off. Anal. Chem., 80, 108, 1997. With permission.)... 

A standard curve can be constructed from dilutions of purified superoxide dismutase. The detection Umit is 0.1 ng enzyme. The method is practicable in crude homogenates, like extracts of the red blood cell. The work with radioactive tracers, however, has some disadvantages. If the highly sensitive detection limit is not required, the classical electroimmunoassay can be used. 

Graphite furnace AAS generally offers highly sensitive detection for small sample amounts, however the sequential nature of the drying, ashing, and atomisation steps make it difficult to interface it to a continuous separation technique like HPLC. As a simple solution, the autosampler of a commercial GF-AAS instrament may be modified in such a way that the effluent is passed through a PTFE flowthrough cell from which the autosampler periodically injects a small aliquot (10—50 pL) into the furnace. Of course, this does not provide a continuous on-... 

Kitamura, N., Nakai, R., Kohda, H., Furuta-Okamoto, K., Iwata, H. Labeling of islet cells with iron oxide nanoparticles through DNA hybridization for highly sensitive detection by MRI. Bioorganic Medicinal Chemistry 21, 7175-7181 (2013)... 

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