problem with nereistoxin thiosultap

[aflores]

I have a problem with thiosultap. I am trying analyzed it with mobil phase acn:h20(+1%H3p04) 80:20 for hplc Uv, but the spectrum is modified with the concentration. ¿Why?, and so I am not analyze. ¿anyone know a diferent mobil phase¿

[tom jupille]

If the spectra are concentration-dependent, one workaround is to look at the spectra for an "isosbestic point" (essentially a "pivot" wavelength around which the absorbance bands shift) and work at that wavelength.