March 15 (LAB) Flashcards
Condensation method
Ortho-toluidine (dubowski method)
Condesation of glucose with witha primary aromatic amine in glacial acetic acid, forming an equilipibrium mixture of a glycosylamine and the corresponding schiff base
Ortho-toluidine
glycosylamine + schiff’s base
Ortho-toluidine
Colormetric glucose oxidase method (saifer gerstenfield method)
Glucose oxidase method
Polarographic glucose oxidase
Glucose oxidase method
Whole blood is __ lower than serum or plasma
11%
leukocytosis (increased WBCs) is up to __ mins
90 mins
is present in the gray tube
which is used for glucose determination
Sodium fluoride
inhibits the glycolytic enzyme
enolase which acts as an anticoagulant
Sodium fluoride
There is also __ which inhibits the
glycolytic enzyme, glyceraldehyde-3-phosphate
dehydrogenase
acetate
Glycolysis decreases serum glucose by approximately
__ (5 to 10 mg/L) in normal
uncentrifuged coagulated blood at room temperature
5% to 7% in 1 hour
Refrigerated (___C)
○ Serum or Plasma: stable up to ___
○ Whole blood: 2mg Na fluoride per mL of whole
blood (48 hrs)
2-8*C, 48 hrs
Refrigerated (___C)
○ Serum or Plasma: stable up to ___
○ Whole blood: 2mg Na fluoride per mL of whole
blood (48 hrs)
2-8*C, 48 hrs
Different lab methods to determine glucose levels in the
sample
○ Chemical method
○ Enzymatic method
A. Oxidation-Reduction Method
1. Alkaline Copper Reduction Method:
a. Folin Wu Method
b. Nelson Somogyi Method
c. Neocuproine Method
d. Benedict’s Method
- Alkaline Ferric Reduction Method
a. Hagedorn Jensen
B. Condensation Method
a. Dubowski Method
Principle: reduction of cupric ions to cuprous
ions forming cuprous oxide in hot alkaline
solution by glucose
Alkaline Copper Reduction Method
The glucose reduces cupric ions present in the
alkaline copper reagent to cuprous ions or the
cupric sulfate is converted to cuprous oxide
which reduces the phosphomolybdic acid to
phosphomolybdous acid
Folin Wu Method
Sugars with reducing properties are rising out
of the presence of the potential aldehyde or
keto group called the reducing sugars
● Ex of reducing sugars
Nelson Somogyi Method
The reducing sugars when heated with the
alkaline copper tartrate reduce copper from the
cupric state and cuprous oxide is formed
Nelson Somogyi Method
When cuprous oxide is heated with
arsenomolybdate, there will be reduction of ___ to ___
which has the color ___
molybdic acid to molybdenum, blue
420 nm
Folin Wu method
The copper in oxidation state reacts with
neocuproine forming a complex, this complex is
extracted into a chloroform methanol mixture
giving a yellow or yellow-orange solution
Neocuproine method
Used for detection and quantitation of reducing
substances in body fluids like blood and urine
Benedict’s method