Beckman spectrophotometer

The data from the Beckman spectrophotometer measiired at three different wavelengths, 280 and 350 nm are shown in Figures 5... 

The final optically clear solution is evaluated as to intensity of color at 555 m/x, and with slit width at 0.02 to 0.04 mm., on a Beckman spectrophotometer adjusted to 100% transmittance with an untreated sample freshly processed in parallel with the unknown sample. From a standard calibration curve (see Figure 3), the concentration of parathion may readily be ascertained, and an appropriate factor converts this value to micrograms of parathion present in the original field sample. 

Absorption curves of the colored solutions were run on a Beckman spectrophotometer using 1.00-cm. quartz cells. A typical curve, shown in Figure 1, has an absorption maximum at about 515 millimicrons. The Coleman Junior spectrophotometer was used for routine determinations of Compound 118 throughout this study. 

The authors would like to thank Dr. Dennis Nagy (Air Products and Chemicals, Inc.) for his assistance with PCS measurements, Dr. F. M. Fowkes for his helpful discussions, and Air Products Chemicals, Inc., for providing the PVA samples and the Beckman spectrophotometer facilities. 

The values agree well in position with those of Woldbye (17) (which were for solutions M in sodium nitrate), but our extinction coefficients are consistently about 10% higher than his. In addition, we note a weak maximum for T at 330 m/i and report some information on the spectra in the doublet region. These last measurements were made on filtered 0.04M solutions, using 5 cm. cells. The general absorption curves were obtained by a Cary Model 14 spectrophotometer, but for most of the kinetic studies and analytical measurements, optical densities at selected wave lengths were determined by a DU Beckman spectrophotometer. 

Prod shall have lumps of 1/2 inch max size easily broken by light finger press -By using a Brice-Keane sugar photometer or a Beckman spectrophotometer at 590 nanometers... 

Kinsey, V. E. Assembly for Positioning Cuvettes Used for Microanalysis with Beckman Spectrophotometer. Anal. Chem. 22, 362 (1950). 

Of the various methods available for the determination of ozone in gaseous mixtures (4), the spectrophotometric methods, particularly the ultraviolet, appeared to be most suited for the purpose. These methods are all based on the strong absorption maximum for ozone in the ultraviolet at 254 mjm,. Thus, one can determine ozone concentration with a Beckman spectrophotometer by the usual procedure. Several other instruments (I, 3, 6) have been specifically designed to measure ozone concentrations by this photometric method. The meters constructed by the authors also operate on this principle. The total ozone stream, or an aliquot of known proportion, is passed through the meter and the per cent transmittance at 253.7 mju, is read from the dial. The ozone concentration at this temperature and pressure is then either determined from a calibration curve (Figure 1), constructed from titration data (the dial could bo calibrated directly in concentration units), or calculated (3) using Beer s law ... 

L7. Lowry, O. H., and Bessey, O. H., The adaptation of the Beckman spectrophotometer to measurements on minute quantities of biological materials, J. BioL Chem. 163, 633-639 (1946). 

Green glistening crystals or dark green powder. Soluble in water (blue soln) sparingly so) in ale. Absorption max 620-634 nm (3 ml of a soln of 50 mg in 250 ml H20 diluted io 200 ml read in a Beckman spectrophotometer 1 cm cell). USE Biological stain. 

The Conway microdiffusion method (2) was employed to determine the amounts of ammonia and amines resulting from irradiation of duplicate samples and subsequent dissolution in 0.006N H2S04. The Russell procedure (15) for a quantitative colorimetric determination was employed with the readings made at 628 mfi on a Beckman Spectrophotometer. 

By using a Brice-Keane sugar photometer or a Beckman spectrophotometer at 590 nanometers... 

The separated nucleosides were quantitatively determined by elution from spots with 0.5 ml water and then analyzed with a Beckman spectrophotometer (25 Model) at pH = 6, 1, and 13. ... 

Caster, W. O. 1951. Variability in the Beckman spectrophotometer. Anal. Chem. 23,1229. 

In our assay for TPNH-cytochrome c reductase, we used glucose 6-phosphate and Zwischenferment (yeast glucose 6-phosphate dehydrogenase) to generate reduced TPN, and thus began my interest in the oxidative pathway. This also introduced me to the powerful tool of absorption spectrophotometry, 3 years before the Beckman spectrophotometer. Warburg, who was probably the first to build an instrument for enzyme studies, had discovered the absorption bands of the reduced coenzymes, but he was devoted to his manometric techniques, and it remained for Haas and myself to apply the new technique to the routine assay of an enzyme-catalyzed reaction, which we measured by following the rate of appearance of the reduced band of cytochrome c. 

Beckman Spectrophotometer. This is fitted with a special adapter and cuvettes to permit the use of 0.05 ml. fluid volumes (obtainable from Pyrocell Mfg. Co., 207 East 84 Street, New York). 

Of the enzymic methods, the use of hexokinase alone (4) or in combination with the zwischenferment is of intermediate ease and rapidity. If the enzymes have been prepared and a colorimeter or Beckman spectrophotometer is at hand, this is a convenient and rapid assay method for ATP. If desiccated fireflies and a suitable light detection apparatus are available, the firefly luminescence assay has all the advantages of specificity, extreme sensitivity, and rapidity. 

U.V. absorption spectrum was followed in 0.02 g% water solution with Beckman spectrophotometer. 

This experiment is easily performed by observing from above the fluorescence of a dilute solution iluminated with the required wavelength in the Beckman spectrophotometer in a darkened room. As the wavelength is changed the fluorescence passes through maxima and minima of brightness. In compounds with appreciable fluorescence the maxima and minima of absorption may be located in this way with fair accuracy. 

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