Base detection

Carroll, M. K. Tyson, J. F. An Experiment Using Time-Based Detection in Flow Injection Analysis, /. Chem. Educ. 1993, 70, A210-A216. 

Explosives. Explosives can be detected usiag either radiation- or vapor-based detection. The aim of both methods is to respond specifically to the properties of the energetic material that distinguish it from harmless material of similar composition. A summary of techniques used is given ia Table 7. These techniques are useful for detecting organic as well as inorganic explosives (see Explosives and propellants). 

It is appropriate at this juncture to illustrate the power of chemiluminescence in an analytical assay by comparing the limits of sensitivity of the fluorescence-based and the chemllumlnescence-based detection for analytes in a biological matrix. The quantitation of norepinephrine and dopamine in urine samples will serve as an illustrative example. Dopamine, norepinephrine, and 3,4-dihydroxybenzy-lamine (an internal standard) were derivatized with NDA/CN, and chemiluminescence was used to monitor the chromatography and determine a calibration curve (Figure 15). The limits of detection were determined to be less than 1 fmol injected. A typical chromatogram is shown in Figure 16. 

Van Den Beld, C. M. B. and Lingeman, H., Laser-based detection in liquid chromatography with emphasis on laser-induced fluorescence detection, Pract. Spectrosc., 12, 237, 1991. 

Lipinski et al. [12] and Pan et al. [463] compared several commonly used methods of solubility measurement in early discovery, where samples are often introduced as 10 mM DMSO solutions. Turbidity-based and UV plate scanner-based detections systems were found to be useful. The methods most often used in discovery and in preformulation will be briefly summarized below. 

In the first LDMS-based detection of malaria in human subjects (unpublished), lOOpl P. falciparum or P. v/vax-infected blood samples, grouped into three different parasitemia ranges—low (10-150 parasites/pl), mid (2 x 103 parasites/pl), and high (25 x 103-60 x 103 parasites/pl)—have been examined using both sample preparation protocols. Parasitemia levels in these samples were previously determined independently for each sample by optical microscopy examination of blood smears. The LDMS data clearly indicate that... 

A reverse cross-coupling reactions mediated by palladium was used to develop a colorimetric sensitive chemodosimeter for the detection of trace palladium (II) salts [93]. The decolorization of 4 is produced by a nucleophilic attack of ethanethiol in basic DMSO solutions. Palladium detection is done via thiol scavenging from the 4-ethanethiol complex leading to a color turn-on of the parent squaraine. Naked-eye detection of Pd(NC>3)2 is as sensitive as 0.5 ppm in solution, and the instrument-based detection can go as low as 0.1 ppm. 

Smith, P. W. (2002). Fluorescence emission-based detection and diagnosis of malignancy. J. Cell. Biochem. Suppl. 39, 54-9. 

A laser-based detection system for NO2 gas (which is an industrial hazard and common environmental pollutant) was developed by Koybayashi et al.4. This was achieved by splitting light, from an Ar-ion multi-line laser, into two paths, one passing through a measurement gas, and the other being transmitted directly to the measurement unit as a reference signal. The detection unit contained two filters to separate the two chosen laser lines, and these were then detected on separate optical receivers. One of these chosen laser lines coincided with a strong absorption line in the NO2... 

Bayer, E.A., Ben-Hur, H., and Wilchek, M. (1987a) Enzyme-based detection of glycoproteins on blot transfers using avidin-biotin technology. Anal. Biochem. 161, 123-131. 

D.G. Georganopoulou, L. Chang, J.M. Nam, C.S. Thaxton, E.J. Mufson, W.L. Klein, and C.A. Mirkin, Nanoparticle-based detection in cerebral spinal fluid of a soluble pathogenic biomarker for Alzheimer s disease. Proc. Natl. Acad. Sci. U.S.A. 102, 2273-2276 (2005). 

J. Wang, G. Liu, and A. Merkoci, Particle-based detection of DNA hybridization using electrochemical stripping measurements of an iron tracer. Anal. Chim. Acta 482, 149-155 (2003). 

Chip-Based Detection of Bar-Code DNA for Protein Identification... 

Applying different CL systems, continuous-flow CL-based detection of several analytes has been widely applied for determination of several biological compounds and drugs. This technique has already become a highly sensitive method of detection in FIA, in liquid and gas chromatography, and in immunoassays [6-12],... 

In the present chapter an overview is presented about CL-based detection in CE, reviewing advances in the development of new detectors, the various CL-based reactions employed, and the applicability and usefulness of analysis to a wide range of samples. 

Antibody-based detection methods include immuno-cytochemistry, which gives qualitative data but has very good spatial resolution. Radioimmunoassays provide a quantitative measure of release or content. One of the major limitations of all antibody-based methods is the potential for cross-reactivity among the many peptides. For example, some of the most sensitive gastrin antisera also detect CCK, since the peptides share a common COOH-terminal tetrapeptide sequence. Methods for detection of the mRNAs encoding neuropeptides include Northern blots, which provide quantitative data and information on splice variants, but lack fine anatomical resolution. The more commonly used polymerase chain reaction, which can be quantitative but often is used in a more qualitative manner, provides great sensitivity. Alternatively, in situ hybridization preserves anatomical relationships and can be used to obtain both qualitative and quantitative data. 

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