UV/visible spectrophotometer

Photolytic reactions were studied using Shimadzu UV-Visible spectrophotometer with Spectrum and Quantitative Mode. The pH measurements were performed by TOA Electronics pH meter at 20 °C. 

UV visible spectrophotometer. A1 (N03)3.9H20 monomer was prepared in same manner. In case of synthesis of dimer complex, 2 equivalent of the Co(salen) was taken with respect to AlX3.nH20. 

Ninhydrin Assays. Ninhydrin tests were performed using a modified procedme of Taylor et al. " APS Silica (10-75 mg) of various loadings (0.857, 0.571, and 0.343 mmol NH2/g Silica) was added to phosphate buffer (5 mL, 100 mM, pH 6.5), and 1 mL of a 5% w/v solution of ninhydrin in ethanol was added to the sluny. After stirring for an hour in a boiling water bath, the mixture was allowed to cool slowly to room temperature. The silica was then filtered and washed three times with 70°C distilled water. The filtrate was collected, added to a volumetric flask, diluted to 100 mL, and the absorbance of this solution at 565 mu was measured using a UV-visible spectrophotometer. The reference solution was prepared as above with unmodified amine-free silica. Calibration standards were prepared with aliquots of a 1 mg/mL solution of APS in ethanol. 

The UV spectrum of valproic acid (0.1% solution) in methanol is shown in Fig. 3, was recorded using a Shimadzu UV Visible Spectrophotometer 160 PC. The acid form of the drug has one maximum at 212 nm. In contrast, the sodium salt of the compound has no UV maximum between 800 and 205 nm, this in agreement with previous results reported by Chang [5]. 

A Cary 500 Scan UV-visible spectrophotometer was used to evaluate the amount of ibuprofen adsorbed and released by the MCM-41-IBU. 

Pigments from cells or thylakoid membranes were extracted in 80 % acetone and debris was removed by centrifugation at 10,000 g for 5 min. The absorbance of the supernatant at 652 nm was measured by a Shimadzu UV-visible spectrophotometer. The chlorophyll (a and b) concentration of the samples was determined according to Amon [1949], with equations corrected as in Melis et al. [2000],... 

The initial mixture and each time point are then assayed for doxorubicin and lipid. Lipid concentrations can be quantified by the phosphate assay (see above) or by liquid scintillation counting of an appropriate radiolabel. Doxorubicin is quantified by an absorbance assay (see below). The percent uptake at any time point (e.g., t = 30 minutes) is determined by %-uptake = [(D/L), =30minutes] x 100/[(D/L) inuiai]. Doxorubicin can be assayed by both a fluorescence assay and an absorbance assay, but we find the latter to be more accurate. The standard curve consists of four to five cuvettes containing 0 to 150 nmol doxorubicin in a volume of 0.1 mL samples to be assayed are of the same volume. To each tube is added 0.9 mL of 1% (v/v) Triton X-100 (in water) solution. For saturated lipid systems such as DSPC/Chol, the tubes should be heated in a boiling water bath for 10 to 15 seconds, until the detergent turns cloudy. Samples are allowed to cool, and absorbance is read at 480 nm on a UV/Visible spectrophotometer. 

Figure 5 Temperature-dependent turbidimetry profiles for solutions of poly(Lys-25) at pH 7.0 and 11.0. These measurements were performed on a Pharmacia Biotechnology Ultrospec 3000 UV/visible spectrophotometer equipped with a programmable Peltier cell and temperature control unit.

Experimental methods for determining 0 are well documented (2). These experiments are conveniently carried out and require only a method of producing reasonably narrow-bandwidth radiation, a method of measuring the flux of that radiation per unit area, and a UV-visible spectrophotometer. The quantum efficiency of typical diazonaphthoquinone sensitizers of the type that are used in the formulation of positive photoresists ranges from 0.2 to 0.3, whereas the quantum efficiency of the bis-arylazide sensitizers used in the formulation of two-component negative photoresists, ranges from 0.5 to 1.0. 

Then, k equals the observed reaction rate divided by the initial reactant concentration i.e., k = Vinitiai/[Ainitiai])-This method is most useful when one has an assay method that is sufficiently sensitive to ensure that only a small fraction, say 3-5%, of the reactant is depleted during the rate measurements. Typically, this is satisfactorily achieved with a UV-visible spectrophotometer, a fluorescence spectrometer, or a radioactively labeled reactant. The initial rate method is extremely convenient, and the preponderance of enzyme rate data has been obtained by initial rate measurements. Finally, one should note that the initial rate method can yield erroneous results if the initial reactant concentration is in doubt. This is not true for the plots of ln ([Ao] - [At]/([Ao] -[Aoo]) versus reaction time because one is considering the fraction of reactant A remaining. 

PS118, PS160, PS340, PS463, PS537, and PS732) were obtained from Petrarch Systems, Inc. For the IR spectra a Nicolet MX-10 FT-IR spectrometer was used at a resolution of 1 cm". The UV spectra were measured on a Model DMS 90 Varian Associates UV-Visible spectrophotometer which was connected to an Apple 11+ desktop computer, equipped with an in-house modified Varian Associates software package. Other experimental details are described elsewhere(3). 

The calibration of a method involves comparison of the value or values of a particular parameter measured by the system under strictly defined conditions with pre-set standard values. Examples include calibration of the wavelength and absorbance scales of a UV/visible spectrophotometer (Ch. 4), calibration of the wavelength scale of an IR spectrometer (Ch. 5) and construction of chromatographic calibration curves (Ch. 12). 

The wavelength scale of a UV/visible spectrophotometer is checked by determining the specified wavelength maxima of a 5% w/v solution of holmium perchlorate. Figure 4.6 shows the spectrum of holmium perchlorate, the tolerances for ealibration wavelengths specified by the BP are 241.15 1 nm, 287.15 1 nm and 361.5 1 nm. 

Six tablets were subjected to. dissolution using the USP dissolution apparatus (Vanderkamp 600, Van-Kel Ind., NJ, USA) in 500 ml buffer pH 1.2 (the first hour) and 650 ml buffer pH 6.8 (1-14 h), maintained at 37°C and rotated with paddles at 50 rev min-1 (first hour) and 130 rev min-1 (1-14 h). The dissolution apparatus was connected to a UV-visible spectrophotometer (Uvikon 810, Roxche Bioelectronique Kontron, Marseille) and a computer (VAX 780 Digital). The absorbance of the dissolution medium at 275 nm was recorded automatically at intervals (1, 2, 4, 5, 8, 10, 12 and 14 h). The percentage of the drug released was calculated and the corresponding release profiles were obtained. 

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). 

Mills and Hoffmann (1992) investigated ultrasonic degradation of parathion. Parathion (0,0-diethyl O-p-nitrophenyl triphosphate) is a major pesticide used in large quantities worldwide. Organophosphate esters such as parathion have been used as alternatives to DDT and other chlorinated hydrocarbon pesticides however, the organophosphate esters are not rapidly degraded in natural waters. At 20°C and pH 7.4, parathion has a hydrolytic half-life of 108 days and its toxic metabolite, paraoxon, has a similar half-life of 144 days. Ultrasonic irradiation of 25 mL of parathion-saturated, deionized water solution was conducted in a water-jacketed, stainless-steel cell with a Branson 200 sonifier operating at 20 kHz and 75 W/cm2. The temperature of the sonicated solution was kept constant at 30°C. All sonolytic reactions were carried out in air-saturated solution. The concentration of the parathion hydrolysis product p-nitrophenol (PNP) was determined in alkaline solution with a Shimadzu MPS-2000 UV /visible spectrophotometer. 

All of the infrared experiments were performed on a Digilab FTS-40 Fourier transform infrared (FT-IR) spectrometer equipped with a narrow-band liquid-nitrogen-cooled mercury-cadmium-telluride (MCT) detector. The spectrometer was operated at a nominal resolution of 4 cm-1 using a mirror velocity of 1.28 cm/s. The data collected using the gas chromatography (GC) IR software were measured at 8 cm-1 resolution. Protein assays for all the experiments were measured on a Beckman DU-70 UV-visible spectrophotometer. 

All ground state diffuse reflectance spectra were recorded using a Phillips PU8800 UV-Visible spectrophotometer equipped with an integrating sphere, interfaced to an Elonex PC-386SX computer. These ground state diffuse reflectance spectra were measured relative to a BaSC>4 white reflectance standard (Eastman Kodak Ltd.). 

A Beckman Model 25 UV-Visible Spectrophotometer was used to determine the ultraviolet spectra of the Cellophane samples. Sample and reference films were held in custom-made sample holders. Scans of the UV-Visible spectrum indicated an absorption peak at about 265 nm. Therefore, all further measurements were made, at the wavelength of maximum absorption in the 255 - 270 nm region. 

The UV spectrum of nimodipine (10 pg/fiL) in ethanol is shown in Figure 3, and was recorded using a Shimadzu UV-visible Spectrophotometer 1601 PC. Nimodipine exhibited two maxima at 355 and 236.6... 

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