Titan column performance Titan porous silica particles employ a novel process that does not require a secondary sizing operation, allowing the entire lot of silica or modified silica to be utilized in column preparation. Figure 5 compares performance with a simple test mix for 1.9-um Titan C18 and two popular sub-2-µm porous C18 columns under reversed-phase conditions. Higher column ef- ficiency was observed for Titan than traditional porous silica C18 particles with smaller average size and broader PSD. The same high-performance UHPLC instrument was employed for testing.
Independent studies by Gritti and Guiochon12,13 confirmed that Titan C18
silica columns show reduced plate heights as low as 1.7 and compare very favorably in efficiency and permeability to core-type particles; however, the authors cited reasons other than narrow PSD for such high performance.
A recent paper by Felinger14 strongly supported narrow PSD as an impor-
tant advantage for solid-core particles over totally porous particles with broader PSD. A second paper by Gritti and Guiochon15
confirmed higher
performance for Titan C18 silica particles having different pores of 80 Å and 120 Å and described when using larger pores should be advantageous.
Current HPLC column platforms from Supelco that employ monodis- perse silica particles are summarized in Table 1; silica substrates are chemically modified with a range of useful column selectivities. Fully porous Titan C18 is compared to commercial core-type silica C18 in Figure 6 for separating benzodiazepines and metabolites under gradient LC-MS conditions; as expected, slightly higher retention and equivalent selectivity were observed.
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Figure 5 – High chromatographic performance of monodisperse 1.9-µm Titan C18 compared with two broader-distribution sub-2-µm porous C18 columns. Sample: uracil, diazepam, toluene, naphthalene, biphenyl; col- umns: 50 × 3.0 mm; mobile phase: 60% acetonitrile/40% water; temp: 35 °C, flow rate: 0.9 mL/min (4 mm/sec); detection: 254 nm. New commercial columns were tested as received.
AMERICAN LABORATORY • 11 • AUGUST 2015
www.sartorius.com/vivaspin-turbo
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