Protein Free Filtrates

Question 0

What is the Somogyi method?

Answer 0

Protein is precipitated by use of zinc sulfate and barium hydroxide in which zinc forms an insoluble salt with protein

Question 1

Limitation of TCA

Answer 1

Limited to determinations requiring very high pH

Question 2

Causes of errors in the preparation of a PFF

Answer 2

1 Use of unclear glassware
2 Incorrect volumes
3 Foaming which indicates incomplete protein precipitation

Question 3

What is protein-free filtrate?

Answer 3

Clear, colorless filtrate after protein is precipitated by either acids or salts of heavy metals

Question 4

Choice of precipitating agent depends on _____

Answer 4

the particular analysis to be performed.

Question 5

Folin Wu’s Method

Answer 5

1 Place 1 mL of clear, unhemolyzed serum or plasma in a clean, dry 125 mL Erlenmeyer flask
2 Add 8 mL of distilled water
3 Mix the contents by swirling
4 Slowly add 0.5 mL of 2/3 N sulfuric acid, swirling the flask during addition
5 Add 0.5 mL of 10% sodium tungstate and mix by swirling
6 Cover flask with rubber stopper or parafilm and shake vigorously for a few minutes
7 Allow mixture to stand for 5 minutes
8 Shake once again and filter or centrifuge
9 Place clear PFF in a clean vial, cover and keep in the freezer

Question 6

Advantage of Somogyi filtrates

Answer 6

Absence of non-glucose reducing agents found in tungstic acid filtrates

Question 7

Protein in serum or plasma is precipitated directly by trichloroacetic acid

Answer 7

Trichloroacetic acid method

Question 8

What is the characteristic of the resulting PFF of TCA Method?

Answer 8

Extremely acidic

Question 9

Somogyi method

Answer 9

1 Place 1 mL of serum or plasma in a clean, dry Erlenmeyer flask
2 Add 8 mL of water to the flask
3 Mix contents of flask by swirling
4 Slowly add 0.5 mL of 10% zinc sulfate swirling the flask during addition
5 Slowly add 0.5 mL of 0.5 N Ba(OH)2 swirling the flask during addition
6 Cover flask with a clean rubber stopper or parafilm and shake vigorously for several minutes
7 Filter or centrifuge

Question 10

Criteria for precipitating agents

Answer 10

1 Should not interfere with the substance being determined

2 Must provide the proper pH for the filtrate

Question 11

Causes of foaming

Answer 11

Improper reagent concentrations
Presence of an excess of anticoagulant
Use of improper anticoagulant

Question 12

Disadvantage of Somogyi filtrates

Answer 12

Cannot be used in determination of uric acid, creatinine, and non-protein nitrogen as these are left with the coagulum

Question 13

Trichloroacetic acid method

Answer 13

1 Place 2 mL of serum or plasma in a clean, dry Erlenmeyer flask
2 Slowly add 8 mL of 10% TCA, mixing the contents of the flask during addition
3 Cover the flask with a rubber stopper or a parafilm and shake vigorously for several minutes
4 Filter or centrifuge the mixture

Question 14

Present in greater concentration in blood than any other constituent with the exception of water

Answer 14

Protein

Question 15

Other term for Folin Wu’s Method

Answer 15

Tungstic Acid Filtrate