Adding an HCl acid to the standard and sample

[greg07]

Hello,

can I ask for an explanation, why in the creation of the standard and the sample is added the concentrated acid HCL (32%). It refers to the analysis for fluorescence detector. I don't know what the role play this acid.

Regards
Greg

[tom jupille]

Without details about the compound, the mobile phase, and the fluorescence spectra, it's hard to be specific, but for many compounds the fluorescence spectra are pH dependent.

[greg07]

mobile phase: acetonitrile : 0,05 hydrogenphosfate diammonium (450:550) (V/V) > + Phosphoric acid to pH=3

standard: 27,5g chinagolid + (50ml acetonitrile + 30ml water) + fill up to 500ml with water

10ml of standard fill up to 200 ml with water

8ml above standard fill up to 500ml water and add 6,25 ml concentrated HCl (35%)

Ex =200nm, Em >280nm (by Em =290nm peak hight is 5 times higher)

The peak hight without the acid is higher.

[JI2002]

Are you asking about Quinagolide? If that's the case, the drug is in its HCl salt form.

[greg07]

Yes, it is that case. What for is that acid? Without acid, a RF detector give also an answer, even much higher.

[danko]

Regarding the peak hight – does it get higher without getting narrower?
And in such case the area increases dramatically?
Or does the peak increase in height while decreasing in width?
And in such case the area is roughly the same?

If the area becomes much larger, you should focus on the detection part.
If the area stays the same and you should focus on the chromatography/elution rather than detection.

Best Regards