Methods of Glucose Measurement Flashcards
separate cells within 1hr, further delay will cause
false ↓
if delayed specimen testing use ___ to prevent glycolysis
sodium flouride (NaF)
SST
storage consideration:
↓ 7mg/dL/hour
Room Temperature (RT)
storage consideration:
↓ 2mg/dL/hour
4degC
hemolyzed sample will cause
dilutional effect = false ↓
effects of dextrose contamination
↑ plasma glucose by 500mg/dL
reduction of cuprous iron to cuprous ion
Copper Reduction
Cu2+ + phosphomolybdic acid -> phosphomolybdenum
Folin-Wu
Cu2+ + arsenomolybdic acid -> arsenomolybdenum
Nelson-Somogyi
Cu2+ + neocuproine -> Cu-neocuproine complex
Neocuproine
Folin-Wu and Nelson-Somogyi end product
blue
Neocuproine end product
yellow-orange
- aka Hagedorn Jensen method
- inverse colorimetry
Ferric Reduction
ferricyanide + glucose -> ferrocyanide
Ferric Reduction
ferricyanide color
yellow to orange
ferrocyanide color
colorless
uses ortho-toluidine (aromatic amine)
condensation
glucose + o-toluidine -> Schiff’s base
end product?
green
H2O2 + chromogen -peroxidase-> oxidized chromogen + H2O
Peroxidase-coupled/Trinder Reaction
absorbance of Peroxidase-coupled/Trinder Reaction
↑ A 500 nm
measurement of the degree of oxygen consumption using a pO2 (Clark) electrode
polarographic method
polarographic method requires addition of ____ and iodide or ____ ethanol
molybdate
iodide
reference method for glucose determination
hexokinase method
hexokinase
____ reaction is highly specific
coupling
hexokinase
effect of hemolyzed/icteric sample ____ glucose level
falsely ↓ glucose level
glucose + NAD -glucose dehydrogenase-> gluconolactone + NADH + H+
glucose dehydrogenase; UV method
NADH + tetrazolium dye -diaphorase-> NAD + formazan blue
glucose dehydrogenase; c/s method
