Dear All
I am working on photocatalytic degradation of carbofuran. Please, what are the best concentrations for preparing standard curve in HPLC?
Regards,
Dear Amal,
I assume that you are taking appropriate safety precautions, using a relatively pure carbofuran standard, are using an appropriate solvent and making up fresh solutions.
The working concentration range of your standard curve depends on one main factor, the linear response range of your detector signal, to a range of concentrations of your standard. Please see that attached diagram.
Once this is known, you may have to dilute or concentrate your samples, so that the detector signals of typical samples, fall within this determined concentration range.
Kind regards,
Ade Kujore
Marketing
Cecil Instruments Limited
Milton Technical Centre, Cambridge CB24 6AZ
United Kingdom
email:- [email protected]
telephone:- +44 (0) 1223 420821
fax.:- +44 (0) 1223 420475
web site:- www.cecilinstruments.com
Dear Amal,
This depends on the sensitivity of your detector, the concentration and also the injection volume. You first have to do some experiments analysing some standards with different concentrations in your system.
Then check the range of concentrations you are interested in and check the linear range of the kalibration line by analysing different concentrations in a response curve.
It is impossible to predict the concantration for us without knowing the injection volume, concentration and type of detector. MS detectors (TOF, triple quad) are more sensitive then UV/FLU detectors.
Just try to find the right cocentration range for your measurement.
Kind regards,
Gerrit
Thanks for your reply
The type of detector is uv detector and injection volume is 10 micro
Dear All
Thanks for your reply. I always prepare 0.05 g/l of carbofuran and I am sure of preparation accuracy, but sometimes the area for the same concentration differs a lot from 808483 to 655000 , I do not know why this big difference in the area for the same concentration.
Regards,
Dear Amal,
In order to help, it would be useful to have details of your method, of the instrument settings and to see some copies of the chromatograms.
Kind regards,
Ade Kujore
Marketing
Cecil Instruments Limited
Milton Technical Centre, Cambridge CB24 6AZ
United Kingdom
email:- [email protected]
telephone:- +44 (0) 1223 420821
fax.:- +44 (0) 1223 420475
web site:- www.cecilinstruments.com
Dear Dr. Ade
The copies of chromatogram are attached for different measurements of the same prepared conc.. I use Acetonitrile 60% to water 40 % as mobile phase and add 1 ml of phosphoric acid, the pH is 2.2-2.3 and wavelength 220. These conditions are constant. I prepared the concentrations three times with the same weight. Please, i found that the column flow direction is reversed, Does this cause a problem for my area?
Regards,
Dear Dr. Ade
The copies of chromatogram are attached for different measurements of the same prepared conc. at retention time of 5.7. I use Acetonitrile 60% to water 40 % as mobile phase and add 1 ml of phosphoric acid, the pH is 2.2-2.3 and wavelength 220. These conditions are constant. I prepared the concentrations three times with the same weight. Please, i found that the column flow direction is reversed, Does this cause a problem for my area?
Regards,
Dear Amal,
Thank you for your response.
What type of injection technique are you using. Are you using an autosampler or manual technique.
No one will ever achieve 100% peak area precision. 99 % with an autosampler is acceptable.
You attached, five images (peak areas), but one has been duplicated. One of the five peak areas, looks like an outlier, if I exclude it, the coefficient variation for three of those areas is 1.8%. If I include the outlier, the coefficient variation for four of those areas is 9.4%.
Incomplete or incorrect integration may explain the differences in peak areas.
I am unclear if your baseline has been fully integrated, as your signal axis is not shown below 0.000 AU. Often a peak baseline is present below zero AU, so it is useful to be able to view to whole of the baseline from a negative signal level.
In which solvent do you dissolve your sample/standard. How accurately are you able to weigh each sample/standard. How many milligrams per 100 ml, for example.
Often, one is able to use the column in a flow which is the reverse of that indicated by the flow arrow, but it does depend on your column type. I do not have any details of your column.
If the column is becoming too worn, there will be inconsistency in the peak areas.
Kind regards,
Ade Kujore
Marketing
Cecil Instruments Limited
Milton Technical Centre, Cambridge CB24 6AZ
United Kingdom
email:- [email protected]
telephone:- +44 (0) 1223 420821
fax.:- +44 (0) 1223 420475
web site:- www.cecilinstruments.com
Dear Dr. Ade
My concerned compound is in retention time of 5.7
Regards,
Dear Amal,
I noted the retention time yesterday before I made my comments. My comments of yesterday still prevail.
Kind regards,
Ade Kujore
Marketing
Cecil Instruments Limited
Milton Technical Centre, Cambridge CB24 6AZ
United Kingdom
email:- [email protected]
telephone:- +44 (0) 1223 420821
fax.:- +44 (0) 1223 420475
web site:- www.cecilinstruments.com
- Badges
- Science method