Wavelength detection

In situ qnantitatioa Quantitation by reflectance had to be performed as soon as possible, since the color intensity of a zone decreased ca. 40% within a day. Detection wavelength A = 34S nm detection limit 2.S ng per chromatogram zone (Fig.l). 

The diameter of a telescope entrance pupil or the distance between two telescopes determine the baseline, which determines the resolution of the interferometer in combination with the detected wavelength. The table compares the resolution of single telescopes and interferometers at optical and radio wavelengths. Note that the resolution of optical interferometers is comparable to that of radio very long baseline interferometry (VLBI). 

Fig. 5.4 Chromatogram of atenolol for column validation CRS which is supplied with theCRS. Asimilarchromatogram must be obtained to assure the suitability ofthe chromatographic system. (Column 4.6 x 150 mm Nucleosil C-18 [5 pm] Mobile phase 1.0 g sodium octane-sulphonate, 0.4gtetrabutyl ammonium hydroxide, 2.72 g potassium dihydrogen phosphate in 800 ml water [pH 3.0], 20 ml tetrahydrofuran and 180ml methanol, flowrate l.Oml/min and detection wavelength 226 nm).

Fig. 5.5 Chromatogram ofchlor-prothixene hydrochloride CRS which contains 2.7 % ofthe f -isomer. (Column 4 x 120 mm hypersil BDS [3 pm]. Mobile phase 6.0 g potassium dihydrogen phosphate, 2.9 g sodium lauryl sulphate, 9.0 g tetrabutylammonium bromide 550 ml water, 50 ml methanol and400 ml acetonitrile, flow rate 1.5 ml/min and detection wavelength 254 nm.)...

Fluorescence detectors can be made much more sensitive than uv absorbance detectors for favourable solutes (such as anthracene) the noise equivalent concentration can be as low as 10 12 g cm-3. Because both the excitation wavelength and the detected wavelength can be varied, the detector can be made highly selective, which can be very useful in trace analysis. The response of the detector is linear provided that no more than about 10% of the incident radiation is absorbed by the sample. This results in a linear range of 103-104. 

The chromatographic procedure may be carried out using (a) a stainless steel column (10 cm x 4.6 mm) packed with stationary phase C (3 pm) (Hypersil ODS in suitable), (b) as the mobile phase with a flow rate of 2 mL/min a 0.6% (w/v) solution of ammonium acetate in a mixture of 300 volumes of acetonitrile, 320 volumes of methanol and 380 volumes of water, and (c) a detection wavelength of 235 nm. 

Parameters that should be tested in HPLC method development are flow rate, column temperature, batch and supplier of the column, injection volume, mobile phase composition and buffer pH, and detection wavelength [2], For GC/GLC methods, one should investigate the effects of column temperature, mobile phase flow rate, and column lots or suppliers [38], For capillary electrophoresis, changes in temperature, buffer pH, ionic strength, buffer concentrations, detector wavelength, rinse times, and capillaries lots and supplier should be studied [35, 36], Typical variation such as extraction time, and stability of the analytical solution should be also evaluated [37],... 

Sample Anthraquinones Extraction/ Eluents Detection wavelength/ Remarks Ref. 

Sample Colourants Extraction/hyd ro I ys is reagents Eluents Detection wavelength/ ionization mode Remarks Ref. 

We conclude that when log f(R3.) is plotted against the detection wavelength, the resulting diffuse reflectance spectrum will be identical to the transmission spectrum of the compound. The only difference will be a displacement in the ordinate by the magnitude of -log s. 

A further specific assay is the HPLC-determination of bromocriptine mesilate following extraction with methanol from the dosage form using RP-18 as the stationary and aceto-nitrile/0.01 M ammonium carbonate solution 65 35 as the mobile phase. Uv-detection wavelength is set at 300 nm (26). 

Theoretically, 8/lp in the resonant wavelength shift scheme is independent of resonance shape or resonant bandwidth, and should be determined merely by instrument resolution, typically less than 10 pm. However, in reality, noise can perturb resonance spectra such that accurate determination of resonant wavelength shift becomes difficult for a broad resonance curve. To enhance accuracy in detecting wavelength shift, narrower resonance is required. This is equivalent to obtaining higher-g resonance behavior. To take into account noise-included detectability of 8/lp, 8/lp can be simply described as a fraction (p) of the full width at half maximum (FWHM) bandwidth of resonance, A7.. WnM. In this fashion, optical detection limit becomes pA/.. WnMAS or p/-vl(QS). In practice, p can be chosen as a reasonable value of 0.1. In the intensity variation scheme, 87 is determined by noise from environment and photodetectors. It can reach as low as several nanowatts with care. 

Procedure The chromatographic procedure may be performed using i Bondapack C18 column as the stationary phase and the above mentioned mobile-phase with a flow rate of 1.0 ml per minute and a detection wavelength of 280 nm. Carry out the HPLC analysis using solutions in the mobile-phase containing (1) 0.05% w/v of dichlorphenamide RS and (2) 0.05% w/v of dichlorphenamide sample. 

Liquid chromatography was carried out utilizing a Hitachi model 63M adsorbent Hitachi gel 3010, developing solvent methanol, detecting wavelength 280nm). 

Fig. 2.10. Separation of the colour pigments of chilli powder on an octadecylsilica column. Detection wavelengths 340 (a) and 440 (b) nm. Reprinted with permission from T. Cserhati et al. [34].

Fig. 2.11. Separation of colour pigments of chilli powders, a origin Malaysia, detection wavelength 340 nm b origin Malaysia, detection wavelength 440 nm c origin Thailand, detection wavelength 340 nm d origin Thailand, detection wavelength 440 nm. Reprinted with permission from a. Kosa et al. [35].

Fig. 2.23. Reversed-phase gradient HPLC profiles of carotenoids in human plasma. A human volunteer was given an oral dose of 5,6-epoxy-/l-carotene (9.1 /imol). Plasma was analysed for carotenoids before (a) and 6h after (b) the oral dose. Peak identification 1, bilirubin 2, lutein 3, zeaxanthin 4, /1-cryptoxanthin 5, 5,6-epoxy-/l-carotene 6, lycopene 7, /1-carotene. The detection wavelength was 445 nm. AU, absorbance unit. Reprinted with permission from A. B. Barua [50],...

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