Detection techniques for the

Electrospray ionization (ESI) is ideally suited as a detection technique for the online interfacing of liquid-phase separations (HPLC and CE) to MS, because it facilitates the transfer of analytes from the liquid phase of the HPLC or CE column to the gas phase of the MS. Also, it allows the detection of high molecular weight species, such as peptides. Three interface designs have been developed in the past 18 years for coupling CE with MS. The first CE-MS interface, coaxial sheath flow, was introduced by Smith and his group in 1987 (Olivares et al., 1987) and was improved upon in later work (Smith et al., 1988). Coaxial sheath flow is formed using two concentric metal capillaries, whereby the CE terminus and the makeup flow line are inserted into the... 

Berset JD, Ejem M, Holzer R, Lischer P (1999) Comparison of different drying, extraction and detection techniques for the determination of priority polycyclic aromatic hydrocarbons in background contaminated soil samples. Anal Chim Acta 383(3) 263-275... 

Caddy and Meek [34] combined gas chromatography with a fluorcence detection technique for the determination down to lOmg L 1 of PAHs in non saline water. The water sample was adjusted to pH2.5 then stirred with Celite. The Celite was then removed and extracted with cyclohexane. The cyclohexane was evaporated to a small bulk and this injected on to the gas chromatographic column (5% OV-1 or 5% Dexsil on 80-100 mesh DCMS Chromosorb W) and temperature programmed from 70 to 350°C. 

High-pressure liquid chromatography (HPLC) with fluorescence detection, ion-trap mass spectrometry (ITMS), and capillary electrophoresis (CE) with ultraviolet detection, three novel detection techniques for the analysis of cocaine in hair, have been evaluated by Tagliaro et aU°- and Traldi et al. The HPLC technique was highly sensitive, capable of detecting 0.015 ng/mg of cocaine in hair. The CE method was sensitive and highly selective. ITMS analysis of hair readily demonstrated the presence of cocaine in hair, but cocaine metabolites were more difficult to identify. 

Analyses of tropane alkaloids are mainly carried out by GC and HPLC and to a lesser extent by CE. This review describes recent applications developed for the analysis of this class of compounds in plant materials and biological matrices. Of course, mass spectrometry is generally used as the detection technique because of its high sensitivity and selectivity, but other techniques such as UV, fluorescence, flame ionization detection, nuclear magnetic resonance, among others have also been investigated. Finally, desorption electrospray ionization mass spectrometry is reported as a new interesting detection technique for the rapid analysis of samples without any sample preparation. 

Ultrasound detection as applied to solid samples can provide a variety of information depending on the particular technique and measured parameter(s). In addition to traditional US-based detection techniques for the analysis of solids (e.g. RUS [1]), a number of new teohniques, modes and methods have been reported over the last five years which have opened up new avenues for the examination of solids. 

A significant amount of literature regarding the antioxidant properties of flavonoids and other plant polyphenols is available. As the essence of redox chemistry involves electron transfer, it seems natural that electrochemical detection rivals spectrophotometric detection techniques for the compounds that are supposed to be antioxidants. With the improvements in electrochemical detector geometries and electronics over the last decade, coupled with a requirement for increased sensitivity, the use of electrochemical detectors offers significant additional advantages when combined with the traditional UV-VIS detection in the analysis of flavonoids and other plant polyphenols. ... 

Saleh, M.H. and Tan, B. 1988. HPLC-diode array detection technique for the identification and quantification of carotene formulations. Anal. Biochem. 33 247-252. 

Dudley, N. D., Ross, L. E., Noshkin, V. E., Application of Activation Analysis and Ge(Li) Detection Techniques for the Determination of Stable Elements in Marine Aerosols, 1968, p. 55, Proceedings of the International Conference on Modern Trends in Actication Analysis, National Bureau of Standards, Gaithersburg, Md. 

Malcik, N., Ferrance, J. P, Landers, J. P, and Caglar, P, The performance of a microchip-based fiber optic detection technique for the determination of Ca ions in urine. Sens. Act. B-Chem., 107, 24, 2005. 

There are, firstly, the improvement of frequency-doubling techniques in external cavities, the realization of more reliable cw-parametric oscillators with large output power, and the development of tunable narrow-band UV sources, which have expanded the possible applications of coherent light sources in molecular spectroscopy. Furthermore, new sensitive detection techniques for the analysis of small molecular concentrations or for the measurement of weak transitions, such as overtone transitions in molecules, could be realized. Examples are Cavity Ringdown Spectroscopy, which allows the measurement of absolute absorption coefficients with great sensitivity or specific modulation techniques that push the minimum detectable absorption coefficient down to 10 " cm ... 

CEC-ESI-MS is a new integrated separation and detection technique for the analysis of biomolecules. It is stiU in the development stage. The following topics are considered as future research directions including ... 

The most powerful detection technique for the trace analysis in complex matrices seems to be MS, separately or with inductively coupled plasma source or an electrospray source. 

The approach described can be used for the understanding of ds-DNA interactions with various complex agents and individual chemicals of environmental, food and medical interest. The use of voltammetric inexpensive and fast detection techniques for the in situ generation of reactive intermediates is, in a successful way, a complementary tool for the study of biomolecular interaction mechanisms. 

Electron Capture Detection Technique for the Determination of Paracetamol... 

In spite of the variety of CSPs available for HPLC, it has not been used very frequently for the analysis of chiral environmental pollutants. This is due to the fact that some organochlorine pollutants are transparent to UV radiation and, hence, the very popular UV detector cannot be used in HPLC for the purpose of detecting such xenobiotics. However, HPLC can be coupled with MS, polarimetry and other optical detection techniques for the chiral resolution of such types of pollutant. Apart from these points, some reports are available on the chiral resolution of some UV-absorbing chiral environmental pollutants by HPLC. 

The topic of detection techniques for the determination of acetic acid and acetate salts has been approached from various perspectives. 

During recent years some competition has developed between electric and photographic detection techniques for the determination of exact masses of gas chromatographic eluents. Habfast and Maurer... 

Chromatographic separation and detection takes place separately, which enables carrying out the analysis at a different time and making full use of the detection techniques for the analysis of constituents. 

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