POCT Flashcards
(26 cards)
What integration is needed to provide a holistic view of pt care
Electronic health records transmitted from POCT results
how to avoid inaccuracies with the pt
education on test requirements
What are POCT
-Lateral flow immunoassay - preg test or rapid AG test
-electrochemical analyzer
-handheld analyzer - insertion of test strips
what can accuracy and reliability of these tests be dependent on
timing , patient conditions and execution of test
Lateral flow limitations
waiting too long to read the test = false pos or neg
Pre Analytical source of interference in POCT
patient prep
sample collection
sample handling
hemolysis
-glucose sample should not be contaminated with excess fluid or alcohol
Device related interference of POCT
calibration error
software error
do regular calibration
environmental interference of POCT
temperature , humidity and contamination
What are the two phases in chromatography
Stationary phase and mobile phase
what do molecular interactions between two phases in chromatography rely on
polarity - polar compounds are most attracted to polar stationary phase and move slower than non polar compounds that arent attracted to the phase and move faster
Volatility -compounds with high volatility interact less with the phases and elute faster
Size and Shape of molecules
large molecules move slower
Thin layer chromatography
qualitative use
-uses thin layer of silica or alumina coated on surface so sample is placed on the plate and it travels up the mobile phase by capillary action
-polar compounds move slower while less polar move faster
Gas chromatography
sample is vaporized and injected into a column with stationary phase
the mobile phase is an inert gas like nitrogen or helium that carries sample through the column
compounds are separated based on volatility and affinity for the stationary phase
HPLC
high resolution technique used to separate, identify, and quantify components in liquid mixtures.
liquid mobile phase is pushed through the stationary phase
-operates under high pressure
-separation is based on polarity, solubility and size of molecules
What plays a key role separation in chromatography
mobile phase
higher flow rate = faster separation but less resolution
slow flow rate -= better separation but takes up time
changing polarity, mobile phase composition , temperature and pressure affect the rate compounds elute
What are methods of detection
UV- Visible Absorption - HPLC for detecting compounds that can absorb light in UV or visible spectrum
Fluorescence- for compounds that naturally fluoresce or can fluoresce with reactions
Mass spec- powerful
identification and quantification of samples based on mass to charge ratio
a signal is detected and a chromatogram is generated
how are results analyzed on a chromatogram
y axis- intensity of detection; response of the detector
x -axis = time or volume of elution
Peaks
Height /area = quantity of analyte and retention time tells you the ID
Shape of peak tells you the nature of the sample
symmetrical -=clean separation
distorted peak = interferences
Integration of peaks quantifies amount of each component
Area UNDER peak is directly proportional to conc of analyte
Ensure you have a correct baseline and integration bounderies. If there is overlapping integration has to be manually adjusted
What is used to improve reproducibility in GC
temperature controlled columns
how is chromatography used in the lab
ID biomarkers ; helps with early detection and effective treatment plans
TDM - conc of therapeutic drugs in blood preventing toxicity or confirming drug efficacy
Substance screening- substances like alcohol, drugs , hormones . Helps to detect drug abuse or monitor levels of corticosteroids or contraceptives
Quantification of contaminants- Iding and quantifying contaminants like heavy metals, pesticides, pollutants. Looks at toxins in patients system
how to assess the chromatogram
-visually represents how different components of a sample elute over time
What is peak resolution
abiility to distinguish two peaks that elute close together
-need good resolution
-depends of column type, mobile phase, flow rate and sample volume
peaks cant be too close together
How does sample contamination interfere with chromatography
how to avoid
can occur during collection, preparation or analysis
-can cause extraneous peaks , distort baseline or unusual signals
clean containers and maintain equipment
GLP to avoid contamination from external sources like air or lab equipment
How does column overloading interfere with chromatography
how to avoid
overloading with too much sample can cause poor separation , peak broadening or tailing peaks
This happens because the stationary phase is saturated, preventing proper separation
avoid by using proper sample size
dilute sample before injection
How does mobile phase instability interfere with chromatography
how to avoid
mobile phase variations with pH, ionic strength or solvent ratio can affect chromatography
unstable mobile phase leads to fluctuating retention times or distorted peak
avoid by
Prepare mobile phase as per manufacturer instruction
Ensure that it is fresh
Do pH checks regularly
monitor for instability
How do instrumental issues interfere with chromatography
how to avoid
pump issues or data acquisition errors can distort chromatographic results
-malfunctioning detector can give erratic or baseline drifting signals
avoid by doing
regular calibration and PM
follow SOP
