[Nagenyleveable]

A biological sample was sent for phosphate analysis to determine the total amount of phosphate. In the laboratory 0.10g of sample was digested in acid and heated. on average, the digestion process is successful in solubilising 97% of the total phosphate content. On colling the sample was filtered and made up to 5ml. An automated flow injection analysis system was used in an absorbance assay for phosphate. the volume of sample injected, 10 µl, produced an absorbance change of 0.1. Injection of the same volume of a control solution, containing 12ppm phosphate, yielded an absorbance change of 0.06. calculate the percentage mass of phosphate in the sample.


Please help me with this. I have a sample question that is similar which I am using as a guide but im still totally lost.
Thanks

[Borek]

Show us what you tried.

[Nagenyleveable]

The question im working off differs in that it contains the addition of reagents and this is what is creating the problem for me.

97% solubilised therefore 0.097g

0.01ml x 20= 0.2

0.2ppm=0.1

0.06= 0.12ppm

1ppm=1mgdm-3


Dilution factor= final/initial

[Borek]

No, 97% of total phosphate content gets solubilized, that means you have to calculate phosphate content first, than to assume what you have calculated is 97% of the real value.

No idea what you are calculating.

Start calculating concentration (in ppm) of phosphates in the sample injected.

[Nagenyleveable]

i don't understand the question or the sample im working from. I wouldn't have posted the question if I didn't need help.The exam is in a few days so by knocking what ive done already without any indication of help really does nothing for my confidence.

[Borek]

Do you know how the absorbance depends on the concentration? If so, do you know how to convert given absorbance to concentration?