By vijay Kumar Verma on Monday, June 7, 2004 - 05:07 am:

Ihave to analyse a sunscreen lotion that contains MBBT i.e Methylene Bis-benzotriazolyl tetramethylbutyl phenol.COULD YOU SUGGEST A SIMPLE RP-18 method.

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By syx_gf on Monday, June 7, 2004 - 06:00 pm:

You may open Sunscreen Analysis on May 10

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By VIJAY KUMAR VERMA on Monday, June 7, 2004 - 11:40 pm:

You are oversimplifying things. Sunscreen analysis does not have any info regarding MBBT.Please give me a specific answer.
Thank you

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By syx_gf on Tuesday, June 8, 2004 - 12:31 am:

You may try it because it is a almost general method of sunscreen. Hope it works on MBBT too.

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By vijay kumar verma on Tuesday, June 8, 2004 - 02:25 am:

I have tried many methods but MBBT does not give peak with usual reagents. Please give me a practical solution.

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By A.Mouse on Tuesday, June 8, 2004 - 07:17 pm:

I don't get it. Why wouldn't it give a peak? It has a good UV absorption.

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By Anonymous on Wednesday, June 9, 2004 - 01:22 am:

Do you analyze in its (near) max abs? See its spectra if you have DAD or using spectrophotometer with dilute solution. As Amouse said, it is used for sunscreen based on its good UV-abs.
Using your RP-18 column, do you have try up to 100% organic solvent (meOH or ACN)for mobile phase?

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By Anonymous on Wednesday, June 9, 2004 - 01:29 am:

Use less non-polar of column packing.

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By VIJAY KUMAR VERMA on Thursday, June 10, 2004 - 12:50 am:

My formulation contains octylmethoxycinnamate,(OMC) and benzophenone-3 and vitamin Eacetate also besides MBBT. Ihave successfully estimated both OMC and Benzophenone-3 by using RP-18 with ACETONITRILE/MeOH :3:7 as mobile phase.What column pack do you suggest. I have only C-18, C-8 and CN columns.
vijay kumar verma

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By A.Mouse on Thursday, June 10, 2004 - 07:17 pm:

You have a strange mobile phase. I suggest you run a gradient from water to acetonitrile / methanol. The MBBT should elute early.

Under your conditions, it is either unretained (if you use a highly deactivated column) or strongly retained due to silanols.