|
|
|
|
|
|
|
|
|
|
||||||
          |
 |
||||||||
|
Spectrophotometers |
|||||||||
|
|
|
This instrument exemplifies 'ease of use'. 190nm to 800 nm range with instantaneous measurement of all wavelengths. Built in multi wavelength reading capability, kinetics, spectral scanning. The basic system provides final answers for applications such as fixed wavelength analysis, wavelength scanning, spectral manipulation, and time-based kinetic/rate determinations. Each system comes with a three-button mouse for function and parameter selection and to input numeric and alphanumeric data via the on-screen keypad (the external keyboard is optional). The systems comes with a 14-inch VGA color monitor. Programs for fixed wavelength, wavelength scanning, scatter correction, net A, time-based kinetic/rate determination, subtraction/addition, and manipulation of spectra are provided with each instrument. Non-volatile memory is standard for storage of methods and data. Results in seconds without the need for an external computer. This unit has the DNA package and micro cuvettes! New Price was over $ 12,000.00 $ Ordering Information
Ready to buy or learn more
Beckman DU640 is the
full featured scanning UV/Vis spectrophotometer
with a stable beam optical design with an extended
wavelength range from 190 to 1100 nm and bandpass of 1.8
nm. |
|||||||
|
|
|||||||||
|
|
Beckman DU 64 uv vis
scanning spectrophotometer This DU64 UV-visible scanning spectrophotometer is in perfect working order, excellent proven optics, bandpass of appx. 1.8 nm.
|
||||||||
|
|
|||||||||
|
|
HP 8452A Diode Array Spectrophotometer The HP 8452A Diode-Array Spectrophotometer is a single-beam, microprocessor-controlled spectrophotometer. Visible/UV - range of 190 to 820 nm with 2 nm resolution. It is used when speed of measurement is essential. It is faster, more sensitive and some believe it has more precision than a conventional spectrometer due to the photo diode-array detection system. With its diode array technology, the spectrophotometer is much faster then conventional instruments; with more precision, more sensitivity and more reproducible results. The spectrophotometer can be controlled from a computer equipped with HP UV-Vis software. It can also be equipped with accessories which include special cell holders, peristaltic pumps, auto sampler, a multicell transport, a Peltier temperature control accessory, and valve unit and valve – pump controller. All accessories are extra and they are not included with system. Our basic system ships with computer, software, and a singel cell holder. We have UV-Visible Software Rev. A running on Windows 95
|
||||||||
|
|
|||||||||
|
Don't see it? Call, we always have spectrophotometers, IRs and FTIRs from you favorite manufacturers |
|||||||||
|
|
|||||||||
|
Spectrophotometry
is a technique most scientists have used at some point in their careers.
Whether for confirmation of a compound's identity or for quantitation of a
protein, spectrophotometry in the ultraviolet and visible spectrum has
rapidly found increasing applications in numerous fields within the last few
years. To help meet this demand, manufacturers of instrumentation for UV/Vis
spectrophotometry now provide machines with a wide spectrum of features and
specifications. LabConsumer contacted 16 companies and received information
on over 50 UV/Vis spectrophotometers to choose from. As you will see,
spectrophotometry has come a long way since Dr. Arnold Beckman constructed
the original device in the 1940's.
What magic happens inside that UV/Vis spectrophotometer on the bench? Several things have to happen in order for you to jot down numbers in your notebook. First, a light source generates light at a specific wavelength or wavelengths. Commonly, UV/Vis spectrophotometers utilize two light sources: a deuterium arc lamp for consistent intensity in the UV range (190 to 380 nm) and a tungsten-halogen lamp for consistent intensity in the visible spectrum (380 to about 800 nm). Some spectrophotometers use xenon flash lamps, which offer decent intensity over the UV and visible regions. The source light is then directed to a dispersion device that causes different wavelengths of light to be dispersed at different angles. Two common dispersion devices used in UV/Vis spectrophotometers are prisms and holographic gratings. The angle of dispersion with a prism, however, can be nonlinear and sensitive to changes in temperature. Holographic gratings are glass blanks with narrow ruled grooves. The grating itself is usually coated with aluminum to create a reflecting source. Holographic gratings eliminate nonlinear dispersion and are not temperature sensitive. They do require filters, though, since light is reflected in different orders with overlapping wavelengths. Once the light has been passed through the dispersion device and the sample of interest it reaches a detector. Detectors in UV/Vis spectrophotometers come in a variety of shapes and sizes. Photomultiplier tubes are common; they provide good sensitivity throughout the UV/Visible spectral range and are highly sensitive at low light levels. Photodiodes have seen increasing use as detectors in spectrophotometers, bringing to the table a wider dynamic range. A photodiode is generally made up of a semiconductor and a capacitor to charge the semiconductor. As light hits the semiconductor, electrons flow through it, thereby lowering the charge on the capacitor. The intensity of light of the sample is proportional to the amount of charge needed to recharge the capacitor at predetermined intervals. As opposed to having single photodiodes, some spectrophotometers are composed of a photodiode array. Here, several photodiode detectors are arranged on a silicon crystal. The advantage of an array is the ability to do side-by-side readings, thus increasing speed. The entrance slit, dispersion device, and exit slit are referred to as the monochromator. Light passing through the monochromator exits as a band. The width of this band of light at half the maximum intensity is the spectral bandwidth. Bandwidth comes in to play with regard to accuracy, since the accuracy of any absorbance measurement is dependent on the ratio of the spectral bandwidth to the natural bandwidth of the substance being measured. The natural bandwidth is the width of the absorption band of the sample at half the absorption maximum. As a rule, a ratio between spectral bandwidth and natural bandwidth of 0.1 or less will generate absorbance measurements 99.5 percent accurate or better. Above this, accuracy deteriorates. In a conventional spectrophotometer, polychromatic light from the monochromator is transmitted through the sample, and the sample absorbance is determined by comparing the intensity of the light hitting the detector with just a sample blank with the intensity of light hitting the detector with the sample in place. With a diode array spectrophotometer, polychromatic light passes through the sample and is focused on the entrance slit of the polychromator (the entrance slit and dispersion device). The light is then dispersed onto the diode array with each diode measuring a portion of the spectrum.
All said
and done, which spectrophotometer will eventually end up on your lab bench?
The specifications of the spectrophotometer you purchase should fit your
applications. Specifications such as wavelength range, wavelength accuracy,
and bandwidth should be considered. Perhaps you want to read your samples in
a 96-well microplate as opposed to a normal cell or a sipper. Many
spectrophotometers are PC-based, and if this is what you desire, there are
plenty machines to choose from. Many of the simpler models have on-board
software, while many of the PC-based models require-and some manufacturers
include with the instrument-application-specific software. Machines range
widely in specifications, capabilities, and features. |
|||||||||
 |
|
|
|
|
|
|
|
|
|
|
|||||||||
