While running HPLC I have prepared 0.1% (v/v) orthophosphoric acid diluted in water, as mobile phase. Does anyone know how can I prepare this?
Well, what do you have to start from? What usually is called "concentrated H3PO4" is an 85 % aqueous solution whereas anhydrous H3PO4 would be a solid at room temperature. Due to the high concentration of the acid in the aforementioned 85 % solution, there will be partial condensation into polyphosphoric acids. As I recall it, the ortho prefix is just used to distinguish H3PO4 from these polyphosphoric acids....so no, there is no difference. At least for dilute solutions, you don't need to worry about any condensation.
If you have access to such a 85 % solution and need a 0.1 % (v/v) solution, transfer 1 ml of the concentrated acid into a 1 L volumetric flask containing some volume of HPLC-grade water while stirring the flask, wait for the temperature to return to room temperature, finally fill to a total volume of 1 L.
Regards,
JR
Orthophosphoric and phosphoric acid are the same you can take 0.1ml of acid + 99.9ml water to get 0.1% (v/v)
Well, what do you have to start from? What usually is called "concentrated H3PO4" is an 85 % aqueous solution whereas anhydrous H3PO4 would be a solid at room temperature. Due to the high concentration of the acid in the aforementioned 85 % solution, there will be partial condensation into polyphosphoric acids. As I recall it, the ortho prefix is just used to distinguish H3PO4 from these polyphosphoric acids....so no, there is no difference. At least for dilute solutions, you don't need to worry about any condensation.
If you have access to such a 85 % solution and need a 0.1 % (v/v) solution, transfer 1 ml of the concentrated acid into a 1 L volumetric flask containing some volume of HPLC-grade water while stirring the flask, wait for the temperature to return to room temperature, finally fill to a total volume of 1 L.
Regards,
JR
In a 0.1% v / v solution of H3PO4 phosphoric acid (also known as orthophosphoric acid) you have 1 mL of H3PO4 per L of solution. It means 1.7 g of it (see chemspider.com). If your concentrated solution of phosphoric acid is 85% wt% (density 1.685 g/L) 1 mL of it contains almost exactly the amount you need to prepare 1 L of your solution. The answer of J-E Raiteman is right, just take 1 mL (1.001 mL to be exact) and dissolve it with water to a 1 L solution.
Hi every one
Is it ok to use sodium-binded form of H3PO4?? such as Na2HPO4 or NaH2PO4? what are their differences and charactristics?
Hi Arladan, If you start with H3PO4 and add a base (NaOH) you get some neutralization of the acid species and form some salts (NaH2PO4, Na2HPO4, and finally Na3PO4). You can see the Na-binded form of H3PO4 as the result of base neutralization. As a conseqeence the solution will have a different pH. On the other hand if you know the pH and the total amount of P you get the corresponding mixture of ionic species in equilibrium.
Orthophosphoric and phosphoric acid are the same.
Trick to identify if two compound are the same are not: Get the CAS number.
CAS number is individually unique.
Phosphoric acid usually come as 85%.
Dilute down from 85% to 1%. Example ~3mL (2.95 mL) of 85% Phosphoric Acid --> 250 mL H2O. Scale as needed.
Then dilute the 1% Solution to 0.1%. 1mL to 10 mL. Scale as needed.
For mobile phase / diluent... Volumetric flasks are not needed.
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