Term
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Definition
-used most frequently in clincal chemistry
-consists of absorbance or reflectance technology
-uses color and color variation to determine concentration |
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Term
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Definition
-light is a type of radiant energy
-travels in waves
-distance between waves is the wavelength of light |
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Term
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Definition
-human eye response to wavelengths between 380-750 nm
-technology can measure shorter (UV) and longer (IR)
-wavelength determines the color |
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Term
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Definition
-red
-orange
-yellow
-green
-blue
-violet |
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Term
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Definition
-infrared 900
-red 650
-orange 610
-yellow 600
-green 540
-blue 475
-violet 425
-ultra violet 350 |
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Term
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Definition
| -the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light |
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Term
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Definition
-the amount of light that passes through a colored substance (transmittance)
-will not plot a straight line on a graph |
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Term
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Definition
| -used to measure the light transmitted by a solution to determine the light absorbing substance in the solution |
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Term
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Definition
| light source -> entrance slit -> grating/monochromator -> exit slit -> cuvette -> photodetector |
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Term
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Definition
| -most common is incadescent tungsten or tungsten-iodide lamp |
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Term
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Definition
-isolated individual wavelengths
-uses the width of entrance and exit slits |
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Term
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Definition
-the range of wavelengths
-the smaller the better, based on slit width |
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Term
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Definition
-interference filter
-prism
-diffraction gratings |
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Term
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Definition
| -two pieces of glass, mirrored on one side that are separated by transparent spacer |
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Term
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Definition
-narrow bean of light is focused on prism and refracted as it enters the more dense glass
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Term
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Definition
-most commonly used monochromator
-many parallel grooves etched onto a polished surface (15,000 - 30,000/inch) |
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Term
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Definition
-Barrier-layer Cell or Photocell
-Phototube
-Photomultiplier Tube |
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Term
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Definition
-lease expensive
-durable, but temp sensitive
-light passes through selenium layer and excites electrons into the silver layer, which flow towards the iron forming barrier |
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Term
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Definition
-contain a negative charged cathode and a positive charged anode in a glass case
-cathode is made of rubidium or lithium, emits electrons when exposted to light
-electrons jump to the positive anode, collected and returned through a measurable circuit |
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Term
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Definition
-light hits a coated cathode emitting electrons
-electrons attracted to a series of anodes known as dynoes
-each then has a successively higher voltage |
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