Anders Hofer

9 Questions 15 Answers 0 Followers

Questions related from Anders Hofer

What is the best way to express Goodness of fit in nonlinear regression (for Michelis-Menten)?

I have been asked by a reviewer to give Goodness of fits to some curves in a manuscript but I am uncertain what is the most correct way to do it. The data is from non-linear regression of...

13 April 2022 8,319 5 View

Where can I find a more pure source of trichloroacetic acid (TCA)?

I am analyzing nucleotides from TCA-precipitated cell extracts by HPLC coupled to UV detection (270 nm) and there is an interfering peak coming from the TCA itself. I have tried some sources of...

08 June 2020 590 4 View

How stable is Klenow exo- and can the stability be improved?

I wonder how stable Klenow Exo- is in -20 degrees and if the stability can be improved at -80 degrees. The source of the enzyme is from ThermoFischer Scientific and stored in 25 mMTris-HCl (pH...

08 June 2020 9,390 0 View

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...

04 October 2019 7,087 13 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...

28 August 2019 2,221 1 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...

17 July 2019 6,054 15 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...

03 December 2017 9,384 15 View

Does the Stewart acid-base approach violate the law: pH+pOH=14?

I was asked to include Stewart acid-base chemistry into a lecture I have and then I became very confused when I tried to read about it. It is there stated that it is the ion gap between positive...

01 January 1970 9,820 3 View

Is the definition of H+ activity different from activities of other molecules and ions?

I am a bit confused by the definition of H+ activity. I have previously learned that activity and concentration follow each other in diluted solutions but when they get more and more concentrated...

01 January 1970 6,443 0 View