iLearn: HPLC Training by e-Learning

Help on: Number of Injections for HPLC Columns

MTS HELPDESK

Do you have any problems relating to analytical chemistry for pharmaceuticals or training? Send your questions to the MTS helpdesk using our contact form.

Question:
"How many injections should I expect to get out of my reversed phase C18 HPLC columns?"

Answer:
“Put simply, it depends. This is probably not the definitive answer you were hoping for but there are a number of different factors which influence the total number of injections that you can expect for a HPLC column. These relate to the actual column in question, the way you are using the column (the method operating conditions), and also the nature of the sample which is being injected.

Factors relating to the column include the type of packing, e.g. silica, zirconia, etc., and how the stationary phase, in this case C18, is bonded to the packing. Factors relating to the operating conditions include the pH, temperature, and mobile phase components such as solvents and buffers. Factors relating to the sample include the cleanliness of the sample, the volume, pH, impurities present and the nature of the actual sample molecules. ‘Clean’ samples are usually straightforward preparations such as standards, simple drug formulations and mixtures, whereas ‘dirty’ samples include biological fluids and environmental samples.

You can maximise the number of injections for a column by using it within its recommended operating conditions, e.g. pH and flow rate, and by flushing the column routinely to remove strongly retained impurities. Use of a guard column should also help to prolong column life.

As a rough guide you can expect to achieve at least 1000 injections if the column is used within its recommended range of operating conditions and the sample being injected is ‘clean’. You may even be able to perform 5000 injections for some methods. If using ‘dirty’ samples then you should expect to achieve less than 1000 injections but the actual number can vary considerably and may even be as low as 50 injections.

Of course if you do not count the number of injections performed on your columns then you will not know how many injections are possible. It is helpful to keep a record, if only for budgeting purposes in these lean times. Modern chromatography data systems and autosamplers make it simple to count injections for a particular column as long as you keep a note of a column identifier such as serial number.”

iLearn: e-Learning HPLC Training Course

Mourne Training Services is pleased to announce that our e-Learning HPLC training course is now available in a distance learning option: iLearn. This course introduces the important concepts of HPLC and will enable you to fully understand: the different types of HPLC and how they differ; the different types of available HPLC columns and how they differ; why there are so many different mobile phase components and the ways in which they are combined to effect a chromatographic separation; and how components such as the pump, injector, detector and processor are combined to make a HPLC instrument.

The course is delivered using our virtual environment for learning, e-MTS, and consists of:

1. A series of training videos (totalling over 3 hours where each video is approximately 25 minutes),
2. Exercises on which you will receive feedback from your personal tutor and,
3. An assessment which enables accreditation of the training - It is recognised by the Royal Society of Chemistry for the purposes of continuing professional development.

The cost of this course is only GBP £125 + VAT and includes a copy of our training book, An Introduction to HPLC for Pharmaceutical Analysis (which normally costs GBP £29.27). This is great value for a course which equates to a full day of training.

So, how does it work?

All you need is access to the internet. The training is undertaken over a period of 1 week. You sign up and select a week which suits you. Each day training videos and exercises are uploaded to your virtual classroom which you can watch and submit answers for the exercises. This allows you to access the training materials at a time which suits you within the 24 hour period (you should allow about 90 minutes since there are 2 videos, each of length approximately 25 minutes and the exercises should take about 40 minutes). At the end of each session feedback from your personal tutor and full solutions for the exercises is sent to you by email. The assessment is completed on the last day and a certificate is sent out for your training records.

Contact us if you would like to sign up for this training course or if you would like more information. Full details will be posted on the MTS website soon.

HPLC Calculator for working out how much mobile phase to prepare - Gradient Methods

PEAK SOLUTIONS A resource for chromatographers As promised, the MTS HPLC calculator can now work out how much mobile phase you need to prepare for gradient methods. Simply fill in the gradient table making sure to match up A, B, C & D to the solvent lines on your HPLC instrument and include any solvent holds and re-equilibration steps at the end/beginning of each injection. Let us know your suggestions for HPLC calculations that you would like to be added to the calculator.