Ultraviolet spectrophotometers and

The ultraviolet spectrum of pseudoephedrine hydrochloride in ethanol was obtained with a Beckman ACTA CIII ultraviolet spectrophotometer and is shown in Figure 3.4 Pseudoephedrine hydrochloride exhibits absorption maxima at 208, 251, 257, and 264 nm with extinction coefficients of 8300, 161, 201, and 161, respectively. 

Figure 3.24 A typical double-beam recording visible and near-ultraviolet spectrophotometer...

Xue et al. [30] prepared a vaginal suppository formulation containing miconazole nitrate and determined its content by P-matrix ultraviolet spectrophotometry. The production of the suppository was finished with melting by the excipient of glyceryl esters fatty acid of artificial synthesis. Quantitative assay was conducted with a P-matrix ultraviolet spectrophotometer. The suppository was smooth and met the clinical requirement of vaginal disease treatment. The method of assay was accurate. 

In a further modification, Nordin and Bretthauer (N4) assay the residual UDPG by incubation with TNDPN. The final optical density is read at 400 mp, making an ultraviolet spectrophotometer unnecessary. 

For visible region the lenses and prisms of ordinary glass can be used but since glass is opaque to radiation of shorter wave lengths in ultraviolet spectrophotometers they are made of quartz. In infra red spectrophotometers they are made of large crystals of NaCl, CsF or KBr. 

Figure 2.29 Optical diagram of a double-beam spectrophotometer. Interchangeable lamps are available for work in the visible and ultraviolet regions and monochrornation...

Ultraviolet spectra were recorded on a Perkin-Elmer 402 UV spectrophotometer or Hitachi 150-20 UV spectrophotometer and Infrared spectra on a Perkin-Ehner 710B or a Perkin-Elmer 1600 series FTIR spectrometer. 

On-line size exclusion chromatographic (SEC) analyses were performed with a Waters Model 401 differential refractometer (DR), a Waters Model 480 ultraviolet (UV) variable wavelength spectrophotometer and a Foxboro Miran lA infrared (IR) photometer, equipped with a zinc selenide ultramicro flowcell of 1.5 mm nominal pathlength and 4.5 /xl volume, purchased from the same supplier. A set of ten Mycrostyra-gel (Waters Associates) columns, regenerated by Analytical Sciences Inc. (ASI) and of nominal porosities 100, 500 (two) 10 (two), 10 (three), 10 and lO X, in the order given and a mobile phase flow rate of 1 ml/min was used. The column set had a specific resolution of 19.7 in 1,4-dioxane, as determined by the method of Yau(2). 

The ultraviolet absorption spectra of benzoic in 96 % ethanol (concentration = 8.3 ppm) and in 0.01 N HCl (concentration = 8.2 ppm) were recorded on a Shimadzu UV-265 spectrophotometer, and are shown in Figure 4. The spectra were not found to be greatly affected by the nature of the solvent used. An absorbance maximum of 227 nm was noted for the 96 % ethanolic solution, while a maximum at 229 nm was found in the 0.01 N HCl solvent. The absorbencies within these two solutions were found to be 0.815 and 0.768, respectively, so that the respective molar absorptivities are computed to be 12000 and 11400 liter/cm mole. 

The ultraviolet absorption spectrum of diloxanide furoate was recorded on a Shimadzu model 1601 PC LJV/VIS spectrophotometer, and is shown in Figure 3. In aqueous solution, the spectrum exhibited a single absorption maximum located at 260 nm. For this band, the A o/ .ic , value was 700, and the molar absorptivity equal to 22970. 

The ultraviolet absorption spectra of procaine hydrochloride were obtained in ethanol and water on a Shimadzu 1601 PC UV/VIS spectrophotometer, and are shown in Figure 3,... 

Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers, ASTM E 257-93, 1998. 

Spectra. The visible and ultraviolet spectra for various solutions were determined using a Cary 14 recording spectrophotometer and 1-cm. quartz cells. Infrared spectra were obtained using a Perkin-Elmer 13 infrared spectrophotometer with sodium chloride optics and cells. 

Capillary electrophoresis has been applied by Chen and Gu (281) for simultaneous determination of oxytetracycline, tetracycline, chlortetracycline, and doxycycline residues in bovine milk. Separation was performed on a noncoated capillary column, 57 cm total length with 50 cm effective length, 75 m internal diameter (i.d.) and 375 m outside diameter (o.d.), using a mobile phase containing 10 mM sodium dodecyl sulfate, 50 mM borate, and 50 mM phosphate, pH 8.5. Under these conditions, concentrations below 10 ppb could be determined in milk using an ultraviolet spectrophotometer set at 370 nm. 

FigurB 25-26 Application of the method development triangle to the separation of seven aromatic compounds by HPLC. Column 0.46 x 25 cm Hypersil ODS (C)e on 5-(j.m silica) at ambient temperature ( 22°C). Elution rate was 1.0 mL/min with the following solvents (A) 30 vol% acetonitrile/70 vol% buffer (B) 40% methanol/60% buffer (C) 32% tetrahydrofuran/68% buffer. The aqueous buffer contained 25 mM KH2P04 plus 0.1 g/L NaN3 adjusted to pH 3.5 with HCI. Points D, E, and F are midway between the vertices (D) 15% acetonitrile/20% methanol/65% buffer (E) 15% acetonitrile/16% tetrahydrofuran/69% buffer (F) 20% methanol/16% tetrahydrofuran/64% buffer. Point G at the center of the triangle is an equal blend of A, B, and C with the composition 10% acetonitrile/13% methanol/11% tetrahydro-furan/66% buffer. The negative dip in C between peaks 3 and 1 is associated with the solvent front. Peak identities were tracked with a photodiode array ultraviolet spectrophotometer (1) benzyl alcohol (2) phenol (3) 3, 4 -dimethoxyacetophenone (4) m-dinitrobenzene (5) p-dinitrobenzene ...

The melting temperature (Tm) of DNA is affected by the base composition, with the G-C-rich DNA having a higher Tm than the A-T-rich DNA. The DNA samples could be heated in a spectrophotometer and the increase in absorbance of ultraviolet light (hy-perchromism) could be plotted against temperature. The A-T-rich DNA would have a lower Tm than the G-C-rich DNA. 

The mass spectra were determined on a LKB 900U Model GC/MS instrument. The elemental analysis was obtained by a VG-model ZAB double focusing high resolution mass spectrometer. The infrared spectra were measured on a Perkin-Elmer 567 spectrophotometer and with a chromatographic infrared analyzer (CIRA 101). The ultraviolet spectra were determined by a UV-visible spectrophotometer (Hitachi Perkin Elmer Model 139). 

New techniques and instruments, such as partition chromatography on paper strips and the photoelectric ultraviolet spectrophotometer, stimulate the development of biochemistry after World War II. New... 

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