Basic Knowledge CH 5 System of measurement Flashcards
Deci
D, 10^-1
Centi
c, 10^-2
Mili
m, 10^-3
Micro
u, 10^-6
Nano
N, 10^-9
Pico
p, 10^-12
Femto
10^-15
What is the formula for converting temperatures from degrees Celsius to degrees Fahrenheit ?
F= 9/5 (C+32)
What is the formula for converting temperature from degrees Fahrenheit to degrees Celsius?
C=5/9(F-32)
What type of labware is not calibrated to hold a particular or exact volume but is available in various volumes depending on the desired use?
Containers and receivers
Which type of labware must go through a rigorous process of volume calibration to ensure the accuracy of the measurement required for lab testing ?
Volumetric glassware
Deliver the amount of liquid contained between two calibrated mars on a cylinder or pipette
- Great accuracy is less critical
- Primarily in measuring reagents, but are not calibrated with sufficient tolerance to use in measuring standard or control solutions, unknown specimens or filtrates.
- Requires draining between two marks; they introduce one or more error compared with volumetric pipettes, which will have only one calibration mark.
- Use for speed more than precision
Graduated Pipette (TD to deliver pipette)
The ofrices, or tip opening, is larger. The rate of the fall of liquid is much too fast for great accuracy or precision. Used in which relative values are sought.
Serologic Pipette
One of the most precise pipette. This type of pipette is calibrated to contain a specific amount of liquid. It must be rinsed out with diluent.
- Used when small amounts of blood or specimen is needed
- Are mostly calibrated to contain the stated volume rather than to deliver it.
Micropipette (to-contain pipette)
Calibrated to deliver a fixed volume of liquid by drainage. Are suitable for all accuracy measurements of volumes of 1 mL or more and are calibrated to deliver the amount inscribed on them.
-Used to measure standard solutions, unknown blood and plasma filtrates, serum, plasma, urine, cerebrospinal fluid, and some reagents.
Volumetric pipette
The cups holding the tubes of material to be centrifuge occupy a vertical position when the centrifuge is at rest but assume a horizontal position when the centrifuge revolves. The particles being centrifuged constantly move along the tube, and any sediment is distributed evenly against the bottom of the tube.
Horizontal-head centrifuge (swinging buckets)
The cups are held in a rigid position at a fixed angle. This position makes the process of centrifuging more rapid than with the horizontal head centrifuge. During the centrifugation, particles travel along the side of the tube to form a sediment that packs against the bottom and side of the tube.
Fixed-angle head centrifuge
What is the equation used to calculate relative centrifugal force of a centrifuge ?
RCF= 1.12x10^-5 X r X (rpm)^2
Electronic pipette used to prepare multiple sample for analysis. Typically part of an automated analyzer
Automated (Specialized pipettes)
Handheld devices using disposable tips. Can contain or deliver small volumes of liquid ranging from 1 to 1000 ul
Semi-Automated (Specialized pipette)
Glass pipette using a bulb in the middle of the pipette with a tapered delivery tip
Transfer/Volumetric (Manual pipette)
Glass or plastic pipette uniform in diameter with a tapered delivery tip
Measuring/Graduated (Manual pipette)
Must be rinsed with the appropriate solvent after the first liquid has drained from these pipettes
To contain (TC)/ Rinse-out
Filled and allowed to drain by gravity. Held vertically and tip placed against side of receiving vessel.
To deliver(TD) Self draining
Filled and allowed to drain after which the remaining fluid in the tip is blown out. Identified by two frosted bands near the mouthpiece.
To deliver (TD) Blow-Out
Relies on a piston for creating suction to draw the sample into a disposable tip
-Tip Changed after each use
Air displacement (Automated pipette)
Operates by moving the piston in the pipette tip or barrel much like a hypodermic syringe
- Commonly used as a dispenser
- Does not require a different tip
Positive displacement (Automated pipette)
Verifies the accuracy of the amount of water that is dispensed by the pipette
Gravimetric Calibration
Verifies the accuracy of the amount of dye-pipette into a specific volume of water and read spectrophotometrically
Volumetric calibration
It is a solid sedimentation
Precipitate
Liquid or top portion
Supernatant
Used to separate cells from serum/plasma
ex: Horizontal-head (swinging bucket)
Fixed-angled(angled head)
Table Top Centrifuge
Separates small liquid samples of <2mL in plastic conical shaped containers
Microcentrifuge
High speed (up to 150,000 rpm) used to separate chylomicrons from serum
Ultracentrifuge
Speed and time should be checked every what ??
6 month
Centrifugal Force (RCF) depends on ???
-Mass
- Speed (rpm)
- Radius (r) in cm
Clinical laboratory standards institute recommends blood samples be centrifuge at what RCF ?
1,000-1,200 x g (or 3,500 rpm) for 10-15 minutes
The force acting on samples during centrifugation
Relative centrifugal force or g force
At what temp. for Heat block and water baths?
36-38 C
At what temp for Room temperature ?
20-24 C
At what temp for Freezer in laboratory ?
<-20 C
At what temp for freezer in blood bank ?
<-65 C
At what temp for refrigerator in laboratory ?
2-8C
At what temp for refrigerator in blood bank?
1-6 C
What types are thermometers are used ?
- Mercury-in-glass
- Digital
- Electronic
Maintains national standards for temperature
NIST (National institute of Standards and technology )
Reading of a thermometer compared to a known temperature standard through process of ________.
Calibration
True/False : NIST-certified thermometers- come with a certificate of calibration.
TRUE
A calibrated thermometer can be used to measure the temperature of other thermometers as long as the final thermometer is then compared to NIST standard through a process called what ?
Traceability
How close a laboratory test result is to a true value
Accuracy
How close test results for the same specimen tested several times are to each other
Precision
Reflects the innate reproducibility of the signal generated by the test solution and the stability of the analyzer used to measure that signal.
Precision
Calculated using the mean value (average) of all test values and the the deviation of each measurements from the mean
Standard deviation
When precision is expressed as percent of the mean
Coefficient of Variation
When the standard deviation of repeated measures of a control sample is calculated and set up on a curve
Confidence internal
The measurement is wrong by the same amount every time
Systematic error
The results vary a little bit due to unpredictable difference caused by things like human error measuring
Random Error
What is better for screening test?
Sensitivity
What is better for confirmatory test?
Specificity
Average of a set of values
Mean
Midpoint value
Median
Sample value that appears with greatest frequency
Mode
Is the purest for water purity
Type 1
