Stationary fluorescence techniques

The investigation of children with thyroglossal cysts shows a definite useful clinical application of the fluorescent technique using either a scanner or a stationary system. These cysts may be confused with ectopic thyroids and misdiagnosis may lead to excision of the patient s only thyroid tissue and result in hypothyroidism. It is thus essential to establish that a normal thyroid is present before excising a suspected thyroglossal cyst. A radionuclide scan is usually advised but a fluorescent study either with a scanner or more simply with a... 

Studies of Photoinduced NH Tautomerism by Stationary and Time-Resolved Fluorescence Techniques... 

If the mixture components are not colored, any of a number of techniques designed to make the spots visible may be employed. These include iodine staining, in which iodine vapor is allowed to contact the plate. Iodine will absorb on most spots, rendering them visible. Alternatively, a fluorescent substance may be added to the stationary phase prior to the separation (available with commercially prepared plates), such that the spots, viewed under an ultraviolet light, will be visible because they do not fluoresce while the stationary phase surrounding the spots does. 

The mixed mode of sorption of the dye l,l -dioctadecyl-3,3,3, 3 -tetramethylindocar-bocyanine pechlorate (Dil) at the interface of an ODS stationary phase and ACN-water mobile phase was studied by single-molecule resolution and fluorescence imaging techniques. The measurements indicated that minimally four types of adsorption sites are present on the surface of the ODS stationary phase. The desorption times of the dye are different at the different adsorption sites resulting in a deformed peak shape [152],... 

Ion chromatography (1C) is a separation technique related to HPLC. However, because it has so many aspects such as the principle of separation and detection methods, it requires special attention. The mobile phase is usually composed of an aqueous ionic medium and the stationary phase is a solid used to conduct ion exchange. Besides the detection modes based on absorbance and fluorescence, which are identical to those used in HPLC, ion chromatography also uses electrochemical methods based on the presence of ions in a solution. The applications of ion chromatography extend beyond the measurement of cations and anions that initially contributed to the success of the technique. One can measure organic or inorganic species as long as they are polar. 

Involves a sample being vaporized and injected into the head space of the chromatographic column. The sample is transported through the column by the flow of an inert gas (mobile phase). The column itself contains a liquid stationary phase which is adsorbed onto the surface of an inert solid. Retention time with detection techniques (spectrophotometer, mass spectrometry, fluorescence) identifies the compound. 

HPLC, when compared to other instrumental methods, presents significant advantages for the simultaneous analysis of creatinine and purine derivatives. The variety of instrumental and experimental conditions (columns, buffers, organic modifiers, detectors, etc.) of these methods reported in the literature offers versatility and flexibility. Chromatographic conditions for these analytes are not complicated when reversed-phase columns are employed. New stationary phases with high separation power provide short analysis times. The mobile phases used are also very simple ones (organic-water mixmres with controlled pH) both isocratic elution and gradient elution are recommended. Different sensitivity detectors (UV, electrochemical, fluorescence, and combined techniques such as HPLC-MS) are very valuable for the... 

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