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Why do smaller particle size columns improve resolution?
Small particle HPLC columns can offer faster analysis times but only if the particle size distribution is
tightly controlled. Restek’s 1.9$m Pinnacle™DB columns have tight, symmetric particle size
distributions and contain no particles less than 1$m. Herewe demonstrate how our stringent quality
requirements translate into faster, more reproducible results compared to competitor columns. Greater
column efficiency and reproducibilitymean faster throughput andmore consistent results.
Explaining the Small Particle Advantage
Tomake column selection for residual solvents easy, Restek has benchmarked the ICH Class 1, 2 and 3
residual solvents on ourmost popular OVI columns.
Organic Volatile Impurities: Retention Time Index
Non-steroidal anti-inflammatory drugs (NSAIDs) are typically separated on C18 phases. Separations on
our Allure® Biphenyl HPLC column are based on pi-pi interactions, resulting in optimized retention and
selectivity. Increased retention requires higher organic content in themobile phase, increasing
desolvation efficiency in LC/MS. Simplemobile phase changes enhance selectivity, making this column
a great alternative to conventional phenyl phase columns, especially inmethod development.
Separating NSAIDs through Aromatic Selectivity
Among hydroxybenzoic acids, hydroxyl groups on the benzene ring vary by position and number,
creating differences in overall polarity and solubility. The unique bonding chemistry of the Ultra
Aqueous C18 phase assures high resolving power, the best separations across a broad range of analyte
polarity, and compatibilitywith 100% aqueousmobile phases.
Optimized RP-HPLCMethod for Hydroxybenzoic Acids
An Rxi®-5ms column and a wool-packed inlet liner provide the stability and inertness needed for these
basic, active analytes. Chromatography from a six-replicate system suitability analysis was well within
normal acceptance criteria. USP tailing factors were approximately 1.00 for all analytes; retention times
and area responses were very stable.
Assaying Local Anesthetics by GC/FID
Single-injection, dual-column detection/confirmation assay is feasible for regulated solvents in
pharmaceutical products, but no temperature program provides sufficient resolution on both columns.
Using a Restek G43/G16 column pair and independent temperature programs in aGerstel MACH
column heating system, we analyzed and confirmed 23 Class 2 solvents in 8minutes.
8-Minute GC Analysis of Residual Solvents
Two Restek columns provide good retention, selectivity, and peak shape for SSRIs, without ion-pairing
chromatography. Choose an Allure™ Basix column and neutral pH conditions, or an Ultra PFP column
and acidic conditions— either will improve performance for these basic compounds, relative to alkyl
phases.
RP-HPLC Analysis of Selective Serotonin Reuptake Inhibitors
Relative to phases that separate via hydrophobic or polar interactions, the Allure™ Biphenyl stationary
phase offers better retention, selectivity, and efficiency, when analyzing compounds with differences in
the numbers and locations of unsaturated bonds in the hydrocarbon ring structure.
Using
π
-
π
Interactions to Enhance Selectivity for Unsaturated
Compounds
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