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what are 4 types of light measurement other than spectrophotometric?
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1. Nephelometry2. Refractometer3. Reflectance photometer4. Fiber optics
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What is a transmittance curve, and what does it show?
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Curve that shows the specificity and sensitivity of a particular wavelength for a sample.
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what are the components in a spectrophotometer?
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1. Power supply2. Light source3. Monochromator4. Cuvette5. Photodetector - Input Trans6. Amplifier/Signal modifier7. Readout device - output transducer
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what is the refractive index?
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a number related to the quantity, charge, and mass of vibrating particles in a solution.
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How does a diffraction grating act as a monochromator?
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it bends light as it passes through a tiny slit.
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What can be used as a readout device?
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-Galvanometer-Meter-Null balance (wheatstone)
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What is nephelometry?
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the measurement of light scattered by particles in a solution.
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What are 3 types of light sources?
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1. Visible - Tungsten2. UV - Gas3. IR - Scanning laser diode
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What is the principle of absorptivity?
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Incident light passes through a sample; the light NOT absorbed gets TRANSMITTED.
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What is an output transducer?
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the component that recieves the signal from the input transducer and displays the measurement.
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What are 3 applications of refractometry?
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-Grams protein-Specific gravity-Electrophoreis - need to know total protein in serum. -Dipsticks for urine.
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how do you figure out concentration of sample from reflectance photometry?
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Light reflected = 1/conc.
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what are 3 types of prisms, what are they for?
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Glass - visible lightQuartz - UVFused silica - UV
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What is a refractometer?
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an instrument that measures the refractive index of a solution
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what are the components in an instrument system?
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-Input transducer-Signal modifier-Output transducer
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what wavelength does IR spectroscopy measure at?
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690-1000 nm
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What can be used as the input transducer in a spec?
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-Photovoltaic cell-Phototube-PMT-Phototransistor
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What is the bandpass?
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the range of wavelengths at which %T is one half its max.
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what is a transducer?
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device to convert energy or info from one form to another.
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what are 2 examples of output transducers?
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1. Meter2. Recorder3. Chart4. Galvanometer
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How do you use a %T curve?
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by scanning the wavelengths, then selecting the highest %T because that gives the optimal sensitivity and specificity.
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What are the variables in beer's law?
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A=abcA = absorptiona = absorptivity constantb = sample path - cuvette widthc = analyte concentration
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What types of cuvettes are used for -Visible spectrum-UV light
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Vis = glassUV = Quartz or plastic
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what is zero control for?
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getting rid of dark current.
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what are 3 types of monochromators?
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1. prism2. Diffraction grating3. Filter
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what are some clinical applications of IR spec?
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-Msr through thick tissue - blood glucose for diabetics-Pulse oximeter-Blood CO2 cultures
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what are 2 types of filters?What are filters used for?
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1. Absorption - it absorbs unwanted wavelengths. 2. Interference - it uses CONSTRUCTIVE interference to produce the desired wavlngth. Typically used for colorimeters
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what are 2 types of diffraction gratings?
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1. Reflectance2. Transmission
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what are 3 applications of nephelometry?
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Amylase Lipase analysisImmunoglobulin determinationHematology counters
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What two types of light sources are used in nephelometry?
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1. Tungsten2. Laser
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what is a monochromator?
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it isolates light of a single color from an impure source.
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what is an agricultural use of IR spec?
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Measuring maturty of apples
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what are longer waves, Red or Violet?
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Violet = short waves, hi energyRed = long waves, low energy
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What are some requirements for the light source?
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-Intense light source-Steady, cool, easily colimated-Directs at sample w/ lens
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what are 4 ways to measure light with photometry?
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1. Absorption2. Emission3. Reflectance4. Nephelometry
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What does bandpass tell?
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the quality of diffraction grating - the quality of light passing through the sample.
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What is a signal modifier?
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Device that recieves input transducer data and changes it to a form suitable for the output transducer.
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what's different about the construction of the nephelometer?
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the light detector (input transducor) is at an angle that is NOT 180 degrees from the sample.
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what is light?
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segment in the spectrum of electromagnetic radiation that may or may not be visible to us.
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what is the principle of reflectance photometry?
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Sample gets adsorbed to a reflective surface, amount of liht reflected is 1/Conc of the sample.
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What are the types of spectrophotometers?
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1. Single beam2. Double beam -in time -in space
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what is IR spectroscp?
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IR light makes molecules vibrate, transmitting very characteristic light.
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what are 5 examples of signal modifiers?
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1. amplifier2. log to linear convertor3. Analog to digital converter4. Integrator5. Waveshaping
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What is color?
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the wavelength of light NOT absorbed bysomething, but transmitted
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what's the name of that reflectance photometer?
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the VITROS
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What is photometry?
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the measurement of light
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what is the range..Visible
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IR = 700-2000 nmVis = 400-700 nmUV = 180-400 nm
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What is reflectance photometry?
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dry slide technology that measures light reflected from a reflective surface w/ sample adsorbed onto it.
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What is a clinical application of reflectance photometry?
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the dipstick reader to eliminate variation between techs.
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What are some requirements for the power supply?
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-voltage has to be DC, not AC-Has to be divided. -Constant and well regulated.
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what type of measurement is spectrophotometry and atomic absorption?
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absorption
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What are 3 examples of input transducers?
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1. Photovoltaic cell (light energy to electrical)2. Electrode (chem to electrical energy3. Thermistor (thermal energy to electrical)
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what are the two things used to calibrate an instrument system?
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1. Zero control2. Amplifier gain
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what are 3 types of emission photometry?
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luminescenceflame photometryfluorescence
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What does an Input transducer do?
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detects the magnitude of the quantity being measured.
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