light - Answers an energy source that can be characterized in terms of wavelength, amplitude
and frequency
-the visible spectrum
wavelength - Answers the distance between waves
amplitude - Answers the height of a wave
frequency - Answers how many waves pass in one second (related to speed)
high energy waves - Answers high frequency, very short and compact wavelengths
-e.g. violet
low energy waves - Answers low frequency, long wavelengths
-e.g. red
visible spectrum - Answers the portion of the electromagnetic spectrum from red (lowest
energy) to violet (highest energy)
transmitted light - Answers light that is able to pass through a solution
absorbed light - Answers light that enters but does not leave a solution
inverse (fill in the blank) - Answers light Transmittance (T) and absorbance have a
_____________________ relationship
-the more light that is absorbed, the less light there is left over to transmit
beer's law - Answers A=abc
-A= absorbance (calculated, no units)
-a= molar absorptivity: constant for a compound (L/mol*cm)
-b= light path through the solution: constant because same cuvette is used (cm)
-c= concentration of substance: value that is responsible for changes in absorbance because its
the only non-constant (mol/L)
directly (fill in the blank) - Answers absorbance and concentration have a _______________
proportional relationship
-the higher the absorbance in a sample, the higher the concentration of absorbing substance
was
,spectrophotometer - Answers -light source
-entrance slit: ensures no excess light is able to enter
-monochromator: isolates the particular wavelengths you want to measure
-exit slit
-sample contained (cuvette): determines the constant b (path of light through solution) in beers
law
-photodetector: converts light energy photons into electrical energy
-readout device: generates a voltage signal that measures how much light was detected
glass filter (monochromator) - Answers colored glass that absorbs and transmits particular
wavelengths of light
-broad bandpass (50 nm)
-cheap
interference filter (monochromator) - Answers a set of mirrored surfaces that bounce light back
and forth to produce constructive interference to produce desired bandpass
-5-10 nm bandpass (pretty narrow)
glass prism (monochromator) - Answers a curved spectrum is produced and can be rotated to
allow desired wavelength through the entrance slit
diffraction grating (monochromator) - Answers parallel grooves that produce a linear straight
spectrum through bending of light
-best monochromator
-bandpass can be < 1 nm (VERY specific)
calibrator (standard) - Answers a solution that is used in laboratory instrument to establish a
relationship between the instrument's signal readout and the concentration of an analyte
-has a single known value (known concentration of analyte) to see if the instrument is
measuring properly
-used to calibrate machine
reference range calculation - Answers mean +/- 2 standard deviations
establishing reference range - Answers -evaluate 120 patient samples from a healthy population
, -population must represent the geographic area that is being served
-evaluate the mean and standard deviation
reference range - Answers a value that represents the mean + or - 2 standard deviations
-95% of readings should fall in this range
-represents the "normal" ranges for patients to fall in
precision - Answers how closely results agree with one another when the results are run in
duplicate
accuracy - Answers how close the measured results are to a "true"/ accepted value
therapeutic range - Answers the amount of a drug that is needed to achieve the desired
therapeutic effect without being too high (toxic) or too low (no effect)
-the actual dosage that is required to achieve this effect varies a lot depending on the patient
critical result - Answers a lab result that is so far out of the normal range that it is life-
threatening to the patient and requires immediate action by a licensed care provider to correct
the value
-needs to be corrected immediate to protect safety of the patient
analytical measurement range - Answers the range from the highest to lowest values that a lab
instrument/ method can accurately measure
-samples above this range will have to be diluted and then multiplied by dilution factor
-e.g. a blood glucometer can only measure from 50-500 mg/dL
clinically reportable range - Answers the range of lab result values that are considered clinically
significant
-anything below or above the range is not reported as a number it is just reported as "high" or
"low"
-anything outside of the range may be considered critical so the actual number does not matter
standard deviation - Answers a measure of precision that indicates how far away a value is from
the mean
-square root of variance
variance - Answers an measure of precision that indicates how close together a group of
numbers are