UV spectrometer

Similar reflection plates are used for recording ultraviolet-visible and Raman spectra of matrix isolated molecules, although the traditional beam path passing through transparent quartz windows is more frequently used in UV spectrometers. Sapphire rods, which are placed in the spectrometer cavity, are applied as targets in matrix esr studies. 

Hunt et al.150 proposed the incorporation of LC-MS techniques to eliminate other identity assays required in the QC lab. A LCQ ion trap mass spectrometer was added downstream of the UV spectrometer. In addition to a UV trace, a total ion current chromatogram was generated. Comparison to a reference chromatogram was performed to define identity without extensive interpretation of the mass spectral data. This LC-MS method eliminated the need for other identity assays such as N-terminal sequencing and was validated as a release assay for three proteins.150... 

Start the UV-spectrometer at least 15 min before taking the reading, so that the instrument is stabilised. 

The term "UV spectroscopy" generally refers to electronic transitions oeeurring in the region of the electromagnetic spectrum (A, in the range 200-380 nm) aeeessible to standard UV spectrometers. 

The basic layout of a simple dispersive IR spectrometer is the same as for an UV spectrometer (Figure 2.1), except that all components must now match the different energy range of electromagnetic radiation. The more sophisticated Fourier Transform Infrared (FTIR) instruments record an infrared interference pattern generated by a moving mirror and this is transformed by a computer into an infrared spectrum. 

We are indebted to George L. Clink for the NMR analyses and to W.T. Quinlin and R. S. Skelton for help in adapting the UV spectrometer software. The work was performed under auspices of the Department of Energy, Contract No. DE-AC04-76DP-00487. 

Ideally, the degrees of sensitivity of the two detectors should also be comparable. Because of this last reason, it is not attractive to combine a hot wire detector with a flame ionization detector in GC (a combination that also conflicts with the third limitation above) or a differential refractometer with a UV spectrometer in LC. 

The absorption of a 171-nm photon excites an electron from the 1r bonding MO of ethylene to the 1r antibonding MO. This absorption requires light of greater energy (shorter wavelength) than the range covered by a typical UV spectrometer. 

For each study, at least three pellets of the same type were used so an average value could be achieved. Each pellet was placed in 100 mL of PBS-B solution and placed on a stirrer at 37°C to simulate a natural body state. Aliquots of 200 pL were taken from each jar to measure absorbance by the UV Spectrometer. These data are compared to the calibration curve, wherein, concentrations can ultimately be deciphered. For each set of conditions that was examined, corresponding positive and negative controls were present. The positive controls were the drug load of the pellet dissolved in PBS-B solution. The negative controls were pellets only containing the polymer and no drug. Further details of the experimental set up can be found in (5,15,16). 

In this work, the efTect of anodic oxidation treatments on activated carbon fibets (ACFs) was studied in the context of Cr(Vl), Cu( II), and Ni( II) ion adsorption behaviors. Ten wt% phosphoric acid and sodium hydroxide were used for acidic and basic electrolytes, respectively. Surf properties of the ACFs were determined by XPS. The specific surface area and the pore stnicture were evaluated from nitrogen adsorption data at 77 K. The heavy metal adsorption rates of ACFs were measured by using a UV spectrometer and 1C P. As a result, the anodic treatments led to an increase in the amount of total acidity by an increase of acidic functional groups such as carboxyl, lactone, and phenol, in spite of a decrease in specific surface area, due to the pore blocking by increased acidic functional groups. 

Meinard, C. Bruneau, P. Perronett, J. High-Performance hquid chromatograph coupled with two detectors a UV spectrometer and a polarimeter. J. Chromatogr. 1985, 349, 109-116. 

Figure 44. Schematic of the Continuously Operating Multicomponent Industrial UV Spectrometer manufactured by BERNATH ATOMIC GMBH of Wennigsen/Germany.

Figure 45, Absorption Cell of the Continuously Operating Multicomponent Industrial UV Spectrometer of BERNATH ATOMIC GMBH. (1) Inlet. (2) Outlet. (3) End Cap. (4) Window. (5) Tubular Cell. (6) Electric Heating. (7) Casing,...

Modern UV spectrometers may offer the option of first and second-derivative UV spectroscopy and measurements in the 240-320 nm range using these techniques can be interpreted to determine the ratios of the various a romatic residues in peptides. Thus, tyrosine can be differentiated from tryptophan through first-derivative spectroscopy and phenylalanine can be differentiated from tyrosine and tryptophan through second-derivative spectroscopy (Miclo et al., 1995). 

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