Potassium Phosphate Stock Preparation

Updated 6/12/2015 07:40 PM

by Courtney Lane

Introduction

This protocol describes preparation of both monobasic (KH₂PO₄) and dibasic (K₂HPO₄) potassium phosphate solutions and their combinations.

Note: Solubility in water (20°C):

monobasic - 6.1M

dibasic - 8.5M

Materials

Consumables

potassium phoshate monobasic
potassium phosphate dibasic

Disposables

weigh dishes/paper

Equipment

balance
media bottle
volumetric flask

Procedure

Component Composition

Table1

	A A	B B
1 1	Final Volume (mL)*	500

Final Volume (mL)*

500

Table2

	A A	B B
1 1	Component	Final Concentration (M)*
2 2	monobasic	0.17
3 3	dibasic	0.72

Table3

	A A	B B
1 1	Component	Weight (g)
2 2	monobasic	11.56731
3 3	dibasic	14.807

Table4

	A A	B B	C C
1 1	Component	Stock Concentration (M)*	Volume (mL)
2 2	monobasic stock	2	42.5
3 3	dibasic stock	2	180
4 4	dH2O	-	277.5

Preparation From Solids

Add ~80% of the final volume of dH₂O to a sterile media bottle.

Generally, the capacity of the bottle should be greater than (not equal to) the final volume of media to be prepared in order to prevent the media from boiling over during the autoclave step.

Ensure you have a volumetric flask measuring your desired final volume.

Add the desired amount(s) of potassium phosphate from the calculations above.

Apply autoclave tape to the bottle and autoclave on liquids cycle.

CRITICALLiquids cycle.

Store at room temperature.

Preparation From Stock Solutions

Add the calculated volume of dH₂O to a sterile media bottle.

Add the calculated volumes of each potassium phosphate stock solution

If necessary, apply autoclave tape to the bottle and autoclave on liquids cycle.