Lab Modules 1-6 Flashcards
Principle of kohler illumination
Align components to provide even illumination
Match the numerical aperture of the condenser to that of the objective lens - provides best resolution
Calibration curve title includes:
Analyte Method Instrument name and number Wavelength Date Technologist
What does Beer’s Law state
Absorbance is directly proportional to concentration
Purpose of a reagent blank
Accounts for A due to original colour of reagents
Principle of flame photometry
Certain elements emit characteristic wavelengths when heated in a flame that allows for quantitation in clinical samples
Most common elements measured in flame photometry
Sodium, potassium, lithium
In flame photometry, Na is measured at what wavelength?
589 nm
In flame photometry, K is measured at what wavelength?
766 nm
In flame photometry, Li is measured at what wavelength?
670 nm
Major components of the flame photometer
Atomizer/burner, wavelength selector, photodetector, processor, display
What is the internal standard used in the flame photometer?
Cesium
What is the fuel-oxidant combination used in the flame photometer?
Propane and compressed air
What is the purpose of internal standard?
Account for variations in the system
What is osmolality
Number of osmoles/kg solvent
What are osmoles
osmoles = moles x # of particles into which the molecule dissociates
example: NaCl -> Na + Cl (2 particles)
1 mole NaCl x 2 = 2 osmoles
How does an osmometer determine the concentration of solutions?
Measures the freezing point depression and converts it to mOsm/kg H2O
Measured osmolality
Determined by analytical means, usually by freezing point depression
Calculated osmolality
Indirect
Determined by using concentrations of the main osmotically active substances (sodium, glucose, urea)
Calculated osmolality formula
= 1.86 [Na] + [Glucose] + [Urea] + 9
Osmolal gap
The difference between the measured and calculated osmolality
Can reflect the presence of other osmotically active substances such as volatiles
Osm gap = measured - calculated
Unaccounted osmolal gap
The difference between the measured and calculated osmolality plus the concentration of ethanol
Can reflect the presence of volatiles other than ethanol
Unaccounted = measured - (calculated + ethanol)
Basic principles of vitros instrument operation
Slide identification Slide spotting Incubation Read reflectance of coloured end product Calculate and print results
What type of photometer is the Vitros DT 60?
Refectance
The layer of the Vitros slide which distributes serum evenly, traps interfering proteins, and reflects light is:
Spreading layer
What is used to measure potential in a Vitros photometer?
Electrometer (voltmeter)
4 electrolytes that can be determined in the DTE:
Na, K, Cl, CO2
On the Ektachem slide, the ion selective membrane functions to:
Select the electrolyte to pass through to the reference layer
On the Ektachem slide, the reference electrode:
Has a constant potential
On the Ektachem slide, the measuring electrode:
Has a variable potential proportional to the electrolyte
