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By Anonymous on Thursday, June 24, 2004 - 08:47 pm:
Hello, everybody!
I need to analyze low level Cetylpyridinium chloride (0.1%) in a syrup kind sample by HPLC.
The sample also contains Tannic acid (7%), Benzocaine (20%), Benzyl alcohol (4%), Alcohol (24%) and some flavor, dye, oil etc.
The method I am using is: mobile phase: Acetonitrile: water (900:100) plus 5 mL ion pair reagent IPC B6. Phenomenex Primesphere 10u 4.6mm x 250mm column. Wavelength 259nm. Diluent: Acetonitrile.
However, this condition does not work. Firstly, CPC elutes too early at RT.2.3 min.. Secondly, there is a huge peak very close to CPC peak, and resolution is poor. Thirdly, there is a small peak underneath of CPC peak.
I do not like to use IPC B6. It needs long long time for column be equilibriumed before run and be cleaned after run.
Can anybody tell me what the problem of my HPLC condition is? Can you give me any suggestion? Thank you in advance!
p.s. pKa value:
Benzocaine: 8.5
Tannic acid: N/A (pH 3.5)
CPC: N/A (pH 5-5.4)
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By Markus Laeubli, Metrohm on Thursday, June 24, 2004 - 10:37 pm:
Try a cation exchanger column with an acidic eluent.
In Journal of Chromatography A 706 (1995) 99-102 an example chromatogram is shown.
The respective column is replaced by the Metrosep Cation C2, link to (http://products.metrohm.com/default.asp ... =ICColumns) and select "Cation columns ...". As an eluent I would use 3 mMol/L nitric acid, 50 % acetone. Adjusting the organic modifier allows to optimize the retention time.
Detection may be conductivity or UV.
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By MG on Friday, June 25, 2004 - 06:29 am:
If you are running at 1 mL/min, then 2.3 min on that column is at or near the dead volume. You might want to try lowering the acetonitrile content to increase retention.
Hello, everybody!
I need to analyze low level Cetylpyridinium chloride (0.1%) in a syrup kind sample by HPLC.
The sample also contains Tannic acid (7%), Benzocaine (20%), Benzyl alcohol (4%), Alcohol (24%) and some flavor, dye, oil etc.
The method I am using is: mobile phase: Acetonitrile: water (900:100) plus 5 mL ion pair reagent IPC B6. Phenomenex Primesphere 10u 4.6mm x 250mm column. Wavelength 259nm. Diluent: Acetonitrile.
However, this condition does not work. Firstly, CPC elutes too early at RT.2.3 min.. Secondly, there is a huge peak very close to CPC peak, and resolution is poor. Thirdly, there is a small peak underneath of CPC peak.
I do not like to use IPC B6. It needs long long time for column be equilibriumed before run and be cleaned after run.
Can anybody tell me what the problem of my HPLC condition is? Can you give me any suggestion? Thank you in advance!
p.s. pKa value:
Benzocaine: 8.5
Tannic acid: N/A (pH 3.5)
CPC: N/A (pH 5-5.4)
-------------------------------------------------------------------------------------------------------
By Markus Laeubli, Metrohm on Thursday, June 24, 2004 - 10:37 pm:
Try a cation exchanger column with an acidic eluent.
In Journal of Chromatography A 706 (1995) 99-102 an example chromatogram is shown.
The respective column is replaced by the Metrosep Cation C2, link to (http://products.metrohm.com/default.asp ... =ICColumns) and select "Cation columns ...". As an eluent I would use 3 mMol/L nitric acid, 50 % acetone. Adjusting the organic modifier allows to optimize the retention time.
Detection may be conductivity or UV.
-------------------------------------------------------------------------------------------------------
By MG on Friday, June 25, 2004 - 06:29 am:
If you are running at 1 mL/min, then 2.3 min on that column is at or near the dead volume. You might want to try lowering the acetonitrile content to increase retention.
