Fluorescence detection limit

After the dipped or sprayed chromatogram has been dried in a stream of cold air long-wave UV light (2 = 365 nm) reveals fluorescent yellow zones (flavonoids). Sterigmatocystine, which can be detected without derivatization on account of its red intrinsic fluorescence (detection limit 0.5 pg), also fluoresces pale yellow after being heated to 80°C [9] or 100°C [13] for 10 min on the other hand, citrinine, zearalenone and vomitoxin fluoresce blue. 

Pesticides, e.g. dursban, azinphos-methyl, menazon, imidan, phosalone, zinophos 200-225°C, 20-120 min Induced fluorescence or amplification of natural fluorescence detection limits 10-300 ng. [20]... 

Organophosphorus pesticides, e.g. coumaphos, menazon, maretin, dursban 200 °C, 45 min Induced fluorescence or amplification of natural fluorescence, detection limits 1-80 ng. [21]... 

Lipids, e.g. sitosterol, geraniol, dolichol, squalene, cholesterol 200 C, 15 min Induced fluorescence detection limits <1 pg cholesterol. [3]... 

Sugars, e.g. glucose, rham-nose, xylose etc. 160 °C, 3-4 min or infrared lamp Induction of brilliant stable fluorescence Xcxc = 365 nm and Xf, >400 nm, (cut off filter K 400), sugar alcohols do not fluoresce detection limits 5-10 ng. [2]... 

Induced fluorescence or amplification [20] of natural fluorescence detection limits 10-300 ng. 

Induced fluorescence or amplification of natural fluorescence, detection limits 1-80 ng. 

Bulk HPLC Add 0.5 ml to Bond Ultrasphere. C1LOH-ILO(I 1) Fluorescence Detection limit 1 pal pK ... 

Further attempts to produce a peak upon injection of j8-estradiol solutions were made using various concentrations of j6-estradiol dansylate in the mobile phase, but these were also unsuccessful. Thus, it appears that our designed reporter was not appreciably retained by the polymer and thus could not be displaced. Subsequently, we examined a variety of other non-specific reporters, varying their concentrations in the mobile phase from their fluorescence detection limit to levels at which they could easily be detected using UV spectroscopy ca. 1-100 nM). Unfortunately, no peaks were observed. 

Table 13.1 SERRS limits of detection for a range of dye-labeled oligonucleotides using citrate reduced silver nanoparticles. No value indicates the experiment was performed but the limit of detection is higher than the base concentration of each dye ( 1 x 10 M). The fluorescence detection limits were not measured (N.M.) for all of the dyes hence the not measured entries...

Cavalli P. and Rossi G. (1984) Laser excited atomic and ionic nonresonance fluorescence detection limits for several elements in an argon inductively coupled plasma, Spcctrochim Acta, Part B 39 115—117. 

Smith BW, Glick MR, Spears KN and Wine-FORDNER JD (1989) A comprehensive table of atomic fluorescence detection limits and experimental conditions. Appl Spectrosc 43 376-414. 

It is worth stating that, after a certain limit has been reached, further increase in lamp brightness is not useful for atomic absorption. Thus, when a lamp is bright enough to permit, say, lOOX scale expansion, a further brightness increase will not lead to better results. (However, in the new technique of atomic fluorescence, detection limits are directly proportional to lamp brightness.)... 

The use of atomic fluorescence for the determination of mercury was first reported by Thomson and Reynolds in 1971 [2]. Since then, several authors [3-6] have described enhancements to the technique that have reduced formal instrument detection limits (IDL) for the fluorescence technique to the 1-10 ng/1 range. Knox et al. [7] report on the use of atomic fluorescence detection limit for mercury to less than 1 ng/1. A European standard EN 13506 was published in 2001. This uses vapor generation coupled to direct atomic fluorescence measurement. The most recent version of the US EPA standard 1631 utilizes an additional gold amalgamation step. The amalgamation provides the potential for an additional order of sensitivity but also requires considerable attention to detail and cleanliness to avoid contamination. 

Sugars, e.g. lactose, glucose, fructose 120°C, IS min Induced fluorescence detection limits in nanogram range. [32]... 

Table 11-3 lists atomic fluorescence detection limits for 39 elements. All data are for water solutions however, the source units varied, as did flame conditions. The detection limits therefore may not be entirely consistent, nor can they be exactly applied to diflerentlnstrumental or analytical situations. They represent the type of result that can be expected if care is taken to optimize operating conditions. 

UV absorbance detection has been most widely used for vitamin A analysis. However, because retinol and retinyl esters are highly fluorescent, detection limits of one order of magnitude better than in assays with UV detection can be obtained using fluorescence detection. Also, electrochemical detection is a valuable alternative to UV and fluorescence detection provided the eluent contains water to incorporate essential electrolytes. Another detector for LC is the mass spectrometer. The LC-MS approach has also been applied to the analysis of vitamin A and its metabolites. 

When excited at 340 run, the isoindole derivatives of amine compounds fluoresce strongly at around 420 nm. The sensitivity is high, as only the products fluoresce and the mobile phase exhibits little or no native fluorescence at these wavelengths. Thus, with laser induced fluorescence, detection limits reach the lower femto- to attomolar range. Owing to the delicate nature of the optical equipment this technique is not suitable for shipboard use, but even with standard filter or spectrofluorimeters amino add concentrations in the lower pico-molar range can be determined (Evens et al., 1982). 

When the laser wavelength used to excite the Raman effect lies under an intense electronic absorption band of a chromophore, this condition will lead to a considerable resonance errhancement of the Raman signal by a factor of 10 to 10. With resonance Raman in the absence of fluorescence, detection limits for an individual component can be less than one femtogram [25]. 

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