Problem seem unsolvable? Try Ferkin-Elmer's new kind of UV/VIS Spectrophotometer: the Model 356. Combine conventional doublebeam performance with highly versatile double-wavelength capa bilities and you have the Model 356. Problems usually considered too difficult to solve by UV analy sis are done easily and reliably by the Model 356. This different kind of instrument will solve your analytical problems better than any other instrument if y o u ' r e : a biochemist or biophysicist and your samples are highly turbid; or a plant physiologist and your samples are plant leaves; or a physiologist whose samples are m i c r o t o m e d tissue sections; or a textile or paper chemist who must measure dyes or inks on pa per or textiles; or an a n a l y t i c a l c h e m i s t w h o must make measurements on over lapped absorption bands; or Cytochrome in Yeast
c o n c e r n e d with environmental pollution problems requiring meas urement of pesticides, herbicides, polynuclear aromatics and other types of organic and inorganic pol lutants; or required to measure the rate of change of fwo components in a reaction cell simultaneously; or measuring the rates of reac tions that produce absorbance changes as small as 0.006A/hr. The Model 356 solves such problems when other s p e c t r o p h o tometers can't for a number of reasons. Analyses of turbid samples are done with the large photomultiplier of the Model 356 only 3mm from the sample—light scattering losses are minimized. Band overlap problems are minimized by direct recording of the first derivative curve of the ab sorption spectrum. Trace analyses are done by using the 100X scale expansion to achieve lower detection limits.
Simultaneous measurement of concentration changes of two c o m ponents in a single reaction cell can be done by using the DoubleWavelength mode. Kinetics of slow reactions or reactions at high dilution are made using the low noise 100X scale ex pansion and the Do/Jb/e-Wavelength mode. For full details, write for our Model 356 brochure t o : Instrument Division, Perkin-Elmer C o r p o r a t i o n , 702 Main Avenue, Norwalk, C o n necticut 06852.
PERKIN-ELMER Bovine Albumin
Derivative curve
--Λ Absorption curve 450
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WAVELENGTH IN nm CYTOCHROMES IN YEAST - This absorption spectrum of a yeast cell suspension clearly shows the absorption bands of the various cyto chromes. To compensate for high turbidity, 8 sheets of filter paper were required in the ref erence beam. The sampling geometry and the sensitivity of the Model 356 are such that the transmitted light has been measured through fifteen sheets of Whatman® No. 2 filter paper at 600 m/ί with 1 π\μ bandpass.
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LEAVES — This is the absorption spectrum of a lettuce leaf at liquid nitrogen temperature. Note the shoulder at approximately 700 π\μ. This may arise from a component referred to as P700 and is quite difficult to detect in vivo.
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300 WAVELENGTH IN nm
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MILK — These curves illustrate the relationship between the absorption spectrum of a milk sam ple containing added bovine albumin, and its first derivative curve. The presence of bands hidden in the absorption spectrum is clearly shown in the first derivative curve.
Circle No. 190 on Readers' Service Card
ANALYTICAL CHEMISTRY, VOL. 42, NO. 2, FEBRUARY 1970
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