Gold number: Difference between revisions

Content deleted Content added

Inline

Revision as of 02:38, 17 February 2024

The Gold number is the minimum weight (in milligrams) of a protective colloid required to prevent the coagulation of 10 ml of a standard hydro gold sol when 1 ml of a 10% sodium chloride solution is added to it.^[1] It was first used by Richard Adolf Zsigmondy in 1901.

An electrical double layer is normally present on the gold sol particles, resulting in electrostatic repulsion between the particles. The sodium chloride ions disrupt this electrical double layer, causing coagulation to occur.

The coagulation of gold sol results in an increase in particle size, indicated by a colour change from red to blue or purple. The higher the gold number, the lower the protective power of the colloid, because a greater amount of colloid is required to prevent coagulation.

The gold number of some colloids are given below.

Protective Colloid	Gold Number
Gelatin	0.005-.01
Haemoglobin	0.03-0.07
Egg Albumin	0.15-0.25
Potato Starch	20-25
Gum arabic	0.15-0.25
Caseinate	0.01-0.02
Sodium Oleate	1-5
Dextrin	125-150

References

^ Hadkar, Dr U. B. Physical Pharmacy. Nirali Prakashan. ISBN 978-81-85790-34-3.

[1] Hadkar, Dr U. B. Physical Pharmacy. Nirali Prakashan. ISBN 978-81-85790-34-3.

[1]

@@ Line 1: / Line 1: @@
+The '''Gold number''' is the minimum weight (in milligrams) of a protective colloid required to prevent the coagulation of 10 ml of a standard hydro gold sol when 1 ml of a 10% [[sodium chloride]] solution is added to it.<ref>{{Cite book |last=Hadkar |first=Dr U. B. |url=https://books.google.com/books?id=V3VIaBDTpJ8C |title=Physical Pharmacy |date= |publisher=Nirali Prakashan |isbn=978-81-85790-34-3 |language=en}}</ref> It was first used by [[Richard Adolf Zsigmondy]] in 1901.
-The '''Gold Number''' is the minimum weight (in milligrams) of a protective colloid required to prevent the coagulation of 10 ml of a standard hydro gold sol when 1 ml of a 10% [[sodium chloride]] solution is added to it.<ref>{{Cite book |last=Hadkar |first=Dr U. B. |url=https://books.google.com/books?id=V3VIaBDTpJ8C |title=Physical Pharmacy |date= |publisher=Nirali Prakashan |isbn=978-81-85790-34-3 |language=en}}</ref> It was first used by [[Richard Adolf Zsigmondy]] in 1901.
 An [[electrical double layer]] is normally present on the gold sol particles, resulting in electrostatic repulsion between the particles. The sodium chloride ions disrupt this electrical double layer, causing coagulation to occur.
@@ Line 38: / Line 37: @@
 |-
 |}
 ==References==
 {{Reflist}}