Anders Hofer

9 Questions 26 Answers 0 Followers

Questions related from Anders Hofer

How can ion pairing agents cause peaks to split?

I have previously made a lot of nucleotide analyses with tetrabutylammonium as ion pairing agent but decided out of curiosity to try primary amines instead and then made a strange observation. One...

10 October 2019 4,885 14 View

What is the most proper term for the affinity constant when allosteric effectors are studied in enzyme activity assays?

In Michaelis-Menten experiments the substrate concentration is varied and Km values and Vmax/kcat values are obtained. My question is what corresponding terms are called when it is the allosteric...

09 September 2019 8,749 19 View

Can the loading capacity of ionic compounds on reverse phase HPLC be increased?

I have a good separation of nucleotides on a c18 with tetrabutyammonium ions as ion pairing agent but have a problem that the column so easily get overloaded and the largest peaks get very broad...

08 August 2019 3,263 8 View

How does the solubility of the buffer in the stationary phase affect resolution in ion-pair RP chromatography?

I analyze nucleotides with tetrabutylammonium ions as ion-pairing agent on a C18 column and I have made an observation that the resolution of the peaks often decreases when I use buffers that I...

08 August 2019 8,204 1 View

How does the choice of ion pairing agent affect the chromatography of multivalent anions?

I am analyzing nucleotides from cells and I have then found that the separation is very good on C18 columns with tetrabutylammonium ions as ion pairing agent. But, as I have discussed in an...

08 August 2019 4,748 2 View

How do I know that the fittings in HPLC are optimal?

I usually do not get as high plate numbers as claimed by the manufacturers and been thinking about how I can know if the fittings (nuts + ferrules) are perfectly seated or not. I have used ACE and...

07 July 2019 5,181 16 View

How can I improve the resolution in SPE purification for HPLC?

I am purifying cell samples for HPLC by SPE to analyze nucleotides and want to improve the SPE procedure to get rid of an impurity causing a broad peak in the HPLC analysis. I can get rid of most...

08 August 2018 6,071 4 View

Is there anyway to extend the lifetime of C18 HPLC columns when used in the presence of tetrabutylammonium salts?

I am using C18 HPLC columns to analyze nucleotides but have the problem that their lifetime is so short. I have tried a lot of variatns of ACE columns (C18, C18aq, C18, hexyl-phenyl etc) from...

12 December 2017 2,773 16 View

How can I get ATP ribose?

I have been looking for ATP ribose (2´-phosphoadenosine-5´-diphosphoribose) as a reference compound in HPLC but cannot find any vendor that sells it. It used to be sold by Sigma but not anymore....

01 January 1970 4,018 1 View