Column |
Purospher® STAR RP-18 endcapped (3µm) LiChroCART® 55-2 HPLC column |
|---|---|
Mobile Phase A |
0.1% acetic acid in acetonitrile |
Mobile Phase B |
0.1% acetic acid in water |
Gradient |
From 25% A to 50% A in 3 min, then isocratic |
Flow rate |
300 µL, without split |
Detection |
UV 220 nm, Ion Trap MS |
| Temperature | Ambient |
Inj. volume |
1 µL |
| Sample | Ketoprofen, Fenoprofen, Ibuprofen; 0.1 µg/µL |
| MS Conditions | |
| Ionization | ESI(-) |
| Nebulizer | 36 psi |
| Dry gas | 8.5 L/min |
| Dry temperature | 330°C |
| Smart mode optimization |
Target mass 205 |
Ion charge control |
Target 50.000, max 50 ms |
| Scan mode | Standard/Normal |
| Scan range | 50-600 m/z |
 |
|
Purospher® STAR RP-18 Endcapped for LC-MS Applications |
"Ghost" mass peaks present a challenge frequently encountered in gradient LC-MS. It is impossible to determine whether ghost peaks originate from an unknown compound in the sample, from an impurity in the mobile phase, or from bonded phase leaching. However, a three-step procedure can help you avoid spurious LC-MS peaks and ensure consistent ghost-peak-free HPLC separations. The simple process includes cleaning the columns and choosing appropriate solvents for LC-MS. These steps increase ionization efficiency, thus improving the sensitivity and reproducibility of LC-MS results.
Simple, 3-Step Process for Optimized Performance in LC-MS
- Flush the column for 60 minutes with a special solvent mixture to remove possible trace impurities. The recommended LC-MS wash solvent is 2-propanol with 0.1% formic acid at a flow rate of 0.5 mL/min (for 3 mm ID columns).
- To reduce the LC-MS background signal, work with extremely high-purity solvents. The recommended solvent is LiChrosolv® Hypergrade with special MS specifications.
- Finally, the column must be re-equilibrated with the mobile phase. Best results are obtained when two blank solvent gradients (without sample injection) are run prior to analysis. Purospher® STAR RP-18 endcapped HPLC columns produce very low and stable background signals in LC-MS, simply after washing with 2-propanol / 0.1% formic acid.
Extracted Ion Chromatograms of "Profens" in Negative Ion Mode Separated on Purospher® STAR RP-18 Endcapped
The combination of LiChrosolv® Acetonitrile Hypergrade solvents and Purospher® STAR RP-18 endcapped columns demonstrates ghost-peak-free MS spectra for Ketoprofen, Fenoprofen, and Ibuprofen (100 ng).
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