In analysis of cefixime isomer, tetrabutylammonium hydroxide is used in the mobile phase at a concentration of 2.5%. why is it used?
can we use tetramethylammonium hydroxide instead of it.?
Dear Sir. Concerning your issue about the function of tetrabutylammonium hydroxide in the separation of cefixime isomers of an analyte. Tetrabutylammonium hydroxide is the chemical compound with the formula (C4H9)4NOH, abbreviated Bu4NOH with the acronym TBAOH or TBAH. This species is employed as a solution in water or alcohols. It is a common base in organic chemistry. Relative to more conventional inorganic bases, suchas KOH and NaOH , Bu4NOH is more soluble in organic solvents. Bu4NOH is a strong base that is used often under phase-transfer conditions to effect alkylations and deprotonations. Typical reactions include benzylation of amines and generation of dichlorocarbene from chloroform. Bu4NOH can be neutralized with a variety of mineral acids to give lipophilic salts of the conjugate base. For example, treatment of Bu4NOH with disodium pyrophosphate, Na2H2P2O7, gives (Bu4N)3[HP2O7], which is soluble in organic solvents.[ Similarly, neutralization of Bu4NOH with hydrofluoric acid affords an relatively water-free Bu4NF. This salt dissolves in organic solvents and is useful to desilylation. The regeneration of ion-pairing reagent distribution on liquid chromatography columns after gradient elution has been well recognized as the cause for long column equilibration time, a major drawback associated with gradient elution reverse phase ion-pair chromatography. To date, the majority of studies have focused on optimizing the separation conditions to shorten the equilibration time. There is limited understanding of the ion-pairing reagent distribution process between the mobile phase and stationary phase in the course of gradient elution, and subsequent column re-equilibration. The focus of this work is to gain a better understanding of this process. An ion-pair chromatographic system, equipped with a YMC ODS C(18) column and a mobile phase containing tetrabutylammonium (TBA) hydroxide as the ion-pairing reagent, was used in the study. The TBA distribution profile was established by measuring its concentration in the eluent fractions collected during the gradient cycle using different column equilibration times with an ion chromatographic method. Furthermore, the analyte retention time was evaluated as the function of the column equilibration time and TBA concentration in the mobile phase. The column equilibration and its impact on the method robustness will also be discussed. I think the following below links and the attached file may help you in your analysis:
https://en.wikipedia.org/wiki/Tetrabutylammonium_hydroxide
https://www.ncbi.nlm.nih.gov/pubmed/22080812
https://www.researchgate.net/profile/Changqin_Hu/publication/259200526_The_selection_of_suitable_columns_for_a_reversed-phase_liquid_chromatographic_separation_of_beta-lactam_antibiotics_and_related_substances_via_chromatographic_column_parameters/links/02e7e52c77ef0a759c000000.pdf?origin=publication_list
Thanks
Article The selection of suitable columns for a reversed-phase liqui...
As an ion-pairing reagent, Bu4NOH can be useful to separate different isomers. If so, you should use it. Tetramethylammonium hydroxide is not good for this purpose. Do you adjust pH with some acids? Otherwise, the pH of mobile phase is too high.
Hi Dr Fuad,
It is used for acidic analytes as ion paring agent to improve separation, the other could be suitable for this purpose, since it is in the same form tetraalkylammonium salt.
this is correct if i dilute in the water can be ionization like this ?
TBAOH TBA+ + OH- ? so how the mass balance ?
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