I think AAS or ICP/MS are the best solutions.

nregards,

Allow use of UV for analysis of Al in the mud, it's just more complicated because it requires a standard and be done repeatedly to determine the maximum absorbance

Using AAS may seem to be more modest, but because of the disruption Na, while using ICP-OES are also possible but too wasteful seems if just want to know the content of Al

Thank you, everyone, for their replies towards my query. 

Dear  Sebastian Hippmann,

Thank you for your recommendation for using the Morin method for aluminum. I have used the mentioned method but its results are very different from ICP - OES results. It showed 2 times higher concentration than the original results (using ICP - OES). 

I have tried several times and with using different scheme but no difference in results. 

Can anyone suggest me the possible reasons for not getting similar results and secondly how can I fix it? 

Dear Dr. Sebastian Hippmann, 

Thank you so much for your comprehensive answer. I have again checked with pH 3.0. But the results are not changed although pH 3.0 showed low concentration than pH 6.0 .  I have also checked with different quantities of Morin solution and results showed with the increase in Morin quantity aluminum concentration increased which reflects that optimum quantity of Morin solution is 5 ml / 25 ml final sample.  

 The concentration of Fe and Cu is very low in my samples although the PO43- is high and I think that caused the problem. Could you send me the article with other reagents and appropriately the method which don't interfere with PO43- ?

Thank you so much 

regards, 

umair