Part 1: Bkgd And RCP Flashcards
Mo-99 causes what?
Higher patient dose
Al3+ causes what?
Colloid formation and clumping of sulphur colloid and RBCs
What can wrong pH cause?
Colloid formation
What type of range would you expect for Tc-99m RPs?
pH on the more acidic side or more neutral
Why is the range of tc-99m RPs typically more acidic?
To eliminate the possible hydrolyzed reduce impurity
What is done if QC for the RP fails?
- retest
- if it fails twice, don’t use
- if multiple kit vials of the same lot fails, contact manufacturer
What does radiochemical purity describe?
The ratio of radioactivity in the desired chemical form compared to the total radioactivity in the preparation
What are radiochemical impurities?
Free pert, hydrolyzed reduced tech, other kit dependent impurities
% labelling efficiency, % bound, %RCP, %tag means the same thing
Two methods to test rcp?
- Thin layer chromatography
- Solid phase extraction
Goal of TLC?
Separate different radiochemical species along length of paper
To analyze counts at different locations on the strip to determine % impurities and % bound rp
Stationary phase
Paper/thin layer strip
Mobile phase
Solvent
Origin
Bottom where the RP is placed
Solvent front
Line or distance the solvent travelled up the strip
Species are separated on TLC based on the _______ of the stationary phase and ______ of the mobile phase.
Electrostatic forces - Stationary
Polarity - mobile phase
the degree of ______ and _____ will determine how far the species will travel with the solvent.
degree of miscibility and attraction will determine
hydrophilic = ?
polar, aqueous
lipophilic = ?
non-polar, organic
examples of hydrophilic solvents?
saline, water, HCl
examples of lipophilic solvents?
chemicals ending in “one” or “ol”
acetone, ethanol
chloroform, dichloromethane, tetrahydrofuran
relative front
distance that a radiochemical travels relative to the distance that the solvent travels
formula for rf
rf = distance travelled by sample/distance travelled by the solvent
rf = 0
radiochemical species remained at origin
rf = 1
radiochemical species travelled to the top of the strip with the solvent front
rf = 0.5
radiochemical species travelled halfway to top of the strip with the solvent front
free pert (TcO4-) in chromatography
rf = 1 (travels up the solvent front)
hydrolyzed reduced (TcO2) in chromatography
rf = 0 (stays at origin)
“bound” tc-complex is (in/dependent) on solvent used and the characteristics of the rp
bound tc-complex is dependent on solvent
in an organic solvent:
hydrophilic RP - bound Tc will _______
lipophilic RP - bound Tc will ________
organic - hydrophilic “opposite” therefore, stay at origin
organic - lipophilic “like” therefore, will travel to the solvent front
in an aqueous solvent:
hydrophilic RP - bound Tc will _______
lipophilic RP - bound Tc will ________
aqueous - hydrophilic “like” therefore, will travel to the solvent front
aqueous - lipophilic “opposite” therefore, stay at origin
how do we analyze RCP?
determination of counts at each location
1) cutting strip into pieces
2) using a radiochromatograph
radiochromatograph
specialized piece of equipment that scans the length of the strip and forms a graph of the counts at each point
formula to determine % bound by two strips in TLC
% bound = 100 - %TcO4- - %HR
which RPs always stay at the origin?
particles - MAA and SC
since particles (do/not) travel with any solvent. can we calculate % of HR?
particles don’t travel with any solvent
- can’t calculate % HR
which RP uses only one strip for TLC? where do you find the bound? where do you find the impurities?
Mibi
- bound at solvent front
- impurities at origin
which RP uses 3 strips for TLC?
HMPAO
in solid phase extractions, if the species has an affinity for the solid it will (remain/exit) the cartridge
remain inside
in solid phase extractions, if the species has an affinity for the solvent it will (remain/exit) the cartridge
exit the cartridge
