Philip J. Koerner | Authors


Extend uHPLC µm Column Lifetime with KrudKatcher Ultra In-line Filters

For many years, the use of guard columns has been advocated by column manufacturers and other experts to protect and extend column lifetime and performance of analytical columns from potential damage caused by the presence of chemical contaminants and microparticulates in the sample and mobile phase.

Development of a High-Throughput LC–MS-MS Assay for 13 Commonly Prescribed Pain Management Drugs from Urine with Cleanup Using Solid-Phase Extraction

Fast turnaround time is critical in the clinical testing environment. Here, fast liquid chromatography (LC) technologies were utilized for the comprehensive assay of commonly prescribed pain management drugs in under 2 min. The use of fast LC also provided significantly improved sensitivity. A mini-validation for these analytes in human urine was performed and acceptable values for accuracy, precision, linearity, lot-to-lot variability, and matrix effects were demonstrated for each analyte.

Using pH-LC to Control Selectivity of Acidic and Basic Compounds on Gemini-NX

The use of mobile phase pH to control analyte ionization states (pH-LCâ„¢) in reversed phase HPLC separations is a highly effective way to change selectivity. The ionized species of an analyte is shown to have higher polarity (less hydrophobicity) than the neutral species, which results in a loss of expected retention for that analyte. This can be attributed to less interaction with the hydrophobic stationary phase and greater affinity with the aqueous portion of the mobile phase. Ionized species also participate in ionic interactions with exposed and activated silanols, which impact peak shape and reproducibility.

Increasing LC–MS-MS Sensitivity with Luna® HILIC

The analysis of polar compounds in support of clinical and preclinical pharmacokinetic studies requires an analytical methodology capable of achieving ultra-low detection and quantification limits. The high sensitivity afforded by coupling HPLC with tandem mass spectrometry (MS-MS) has made it the technique of choice in this environment, but it is subject to the following limitations when reversed phase liquid chromatography (RPLC) is used: