By Anonymous on Wednesday, April 10, 2002 - 12:55 pm:
Anyone have a method they would recommend to assay this compound by HPLC? Any hints would be great
By Anonymous on Wednesday, April 10, 2002 - 02:58 pm:
Waht detectors do you have?
By Anonymous on Thursday, April 11, 2002 - 09:27 am:
I only have variable wavelength UV and RI detectors -- thx
By Jim Gorum on Thursday, April 11, 2002 - 09:21 pm:
No Name,
Try a C-18 column and a water/acetonitrile gradient with detector set at 200 to 210 nm.
Change to an isocratic method if you get very good separation.
Jim
By Anonymous on Monday, April 15, 2002 - 01:45 pm:
Jim - I've tried C18 with various proportions of ACN/water @ wavelengths of 190 to 230. Matrix is difficult to dissolve. . had to end up using THF. I've also tried MeOH as part of mobile phase. Any other ideas?
NN
By A.Nonymous on Tuesday, April 16, 2002 - 08:54 am:
Is it neccesary to dissolve your matrix, isn't it just enough to dissolve your N-octa...
Have you got any response for N-octa... @ different wavelengts and different proportions of ACN/water?
By Anonymous on Thursday, April 18, 2002 - 03:46 pm:
Ion pair Chromatography?? use a C-18 column and anions suppressor ... conductivity detector !!!
By Chris Pohl on Friday, April 19, 2002 - 08:20 am:
An ion of this sort cannot be directly detected in the UV (Jim, believe it or not there are some analytes that don't absorb at this wavelength). While this compound is readily detected by conductivity detection, if you are stuck with choosing between UV detection or refractive index detection your best bet would probably be refractive index. Although there are literature references to indirect UV detection, this technique is rather difficult to routinely apply to molecules of this sort. While I was unable to find any readily available references for a your specific compound, conditions suitable for the analysis of molecules of this sort can be adapted from references describing the separation of alkyl sulfonates. Try using an ammonium acetate buffer (10-20 mM, pH4) with 40-50% acetonitrile. Your sensitivity with refractive index won't be all that great but it should be workable provided you aren't trying to deal with determination of trace levels. Regarding your sample solubility problem, try adjusting the pH of your sample. You should be able to solublize it by adjusting the pH to around 7. At this pH it should be soluble even in water although it might help to that a bit of solvent.
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