﻿ HPLC, help:) - Chromatography Forum

## HPLC, help:)

Basic questions from students; resources for projects and reports.

### HPLC, help:)

Okay so HPLC is not my strongest subject and I'm baffled hopefully il be able to find some help.

A sample was analysed on an HPLC equipped with a 15cm long column with an internal diameter of 4.6mm and a flow rate of 1ml min-1. the column was packed for 65% with a C18 stationary phase. An unknown peak appears at 0.87 min. Determine the likelihood that this peak has any interaction with the solid phase, show all working out

This is the question I was given, I tried googling but I can't seem to find anything, maybe I'm not googling the right thing, any help would be much appreciated

### Re: HPLC, help:)

innmate2325 wrote:
Okay so HPLC is not my strongest subject and I'm baffled hopefully il be able to find some help.

Yes, gently speaking You posted it in Gas Chromatography corner.

innmate2325 wrote:
A sample was analysed on an HPLC equipped with a 15cm long column with an internal diameter of 4.6mm and a flow rate of 1ml min-1. the column was packed for 65% with a C18 stationary phase. An unknown peak appears at 0.87 min. Determine the likelihood that this peak has any interaction with the solid phase, show all working out

This is the question I was given, I tried googling but I can't seem to find anything, maybe I'm not googling the right thing, any help would be much appreciated

We don't do students homeworks here. Instead we give hints.
Try to google harder - find out what "dead time is" and why analytes separate on a column.

### Re: HPLC, help:)

Bigger Hint: Pretend the column was just a tube, and forget all about chromatography. If you stick something in one end, and pump liquid through at a certain rate, how long will it take before it comes out the other?
To add a bit more sophistication, consider what the situation would be like if some of the volume of the tube were occupied by inert beads (sand or something) so the actual volume is less.

And be happy that you've been set this question . The chromatographic literature would be a better place if more people had done the calculation you're doing. You aren't one of my students by any chance??

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