What are ion pairing reagents?
What are ion pairing reagents?
Ion Pairing Reagents are use as mobile phase additives, which allow the separation of ionic and highly polar substances on reversed phase HPLC columns.
Why phosphate buffer is used in HPLC?
A buffer maintains the pH when a small amount of acid or base is added. The most popular buffers for HPLC with UV detection are phosphate and acetate. Phosphate and acetate are particularly useful buffers because they can be used at wavelengths below 220 nm.
What are the three types of ion pairs?
The hydration of ions must be considered when studying their interactions in solution. There are three different ion pairs based on different states of hydration between cations and anions: solvent separated ion pair, solvent-shared ion pair, and contact ion pair (52).
How does ion suppression work?
Abstract Ion-suppression is a reversed phase technique suitable for ionisable compounds, in particular weak acids or weak bases. Ion Suppression Chromatography (IS) works for polar, weak acidic or basic compounds, using a standard RPLC column. Buffering to a lower pH decreases the fraction of un-dissociated acid.
Which buffer is used in HPLC?
Examples of acceptable volatile buffers are ammonium acetate, ammonium formate and ammonium citrate….When should you use a buffer for HPLC, how does it work and which one to use?
| Buffer | pKa | Operating pH range |
|---|---|---|
| Phosphate, pk1 | 2.1 | 1.1-3.1 |
| pK2 | 7.2 | 6.2-8.2 |
| pK3 | 12.3 | 11.3-13.3 (not advisable) |
| Citrate, pK1 | 3.1 | 2.1-4.1 |
When to add an ion pair reagent to the mobile phase?
The purpose of adding an ion pair reagent to the mobile phase is usually to change the retention time of ionic analytes.
How are ion pairing reagents used in HPLC?
The use of ion-pair reagents can be a handy tool in improving retention and peak shape of ionizable compounds in HPLC (typically reversed phase). Here’s how:
How can ion pair reagent increase the retention factor?
By varying the mobile phase concentration of the ion pair reagent, the retention factor for an oppositely mono-charged analyte can be continuously increased by a factor of 10–20 compared to the value with no added ion pair reagent.
Which is the ion pairing agent in lcspray?
Here, TFA is added to the mobile phase to act as the ion-pairing agent, for the determination of amphetamine in urine samples by reversed-phase liquid chromatography-electrospray (LC-ES)-MS/MS.