Chromolith Performance

It is of much interest to compare polymer monoliths with monolithic silica columns for practical purposes of column selection. Methacrylate-based polymer monoliths have been evaluated extensively in comparison with silica monoliths (Moravcova et al., 2004). The methacrylate-based capillary columns were prepared from butyl methacrylate, ethylene dimethacrylate, in a porogenic mixture of water, 1-propanol, and 1,4-butanediol, and compared with commercial silica particulate and monolithic columns (Chromolith Performance). 

FIGURE 9.6 The peptide and small protein map from a 100 pL human plasma injection. Columns sample preparation SCX RAM analytical column chromolith performance RP-18, 100 x 0.1 mm I.D. Minute fractions were analyzed using MALDI-TOF MS. Fraction numbers correspond to the time scale. Dot size is related to signal intensity. 

The liquid chromatograph Zarghi et al. used consisted of a Wellchrom K-1001 pump, Rheodyne 7125 injector, Eurochrom 2000 integrator, and K2600 fluorescence detector. The stationary phase was a Merck Chromolith Performance RP-18e column (100 x 4.6 mm). The mobile phase consisted of 0.01M dibasic sodium phosphate buffer and acetonitrile (60 40 v/v) adjusted to pH 3.5. The flow rate was 2 mL/min. The detector operated at an excitation wavelength of 240 nm and an emission wavelength of 340 nm. Letrozole served as the internal standard (IS). 

Another recent trend focused on supports in the shape of monolithic columns having the goal to benefit from the high permeability and the improved mass transfer characteristics of such structures. With this goal in mind, Lubda and Lindner [75] prepared enantioselective silica monolith columns with tert-butylcarbamoylquinine surface modification. A commercial sol-gel-derived Chromolith Performance Si (100 X 4.6 mm ID) monolith (1.9 tim macropore diameter, 12.5 nm mesopore... 

Kromasil 100 Cl 8 (25x0.46 mm, 5 pm) First dimension Hot Sep micro bore Nucleosil 100-5 SA (15x0.1 cm, 5 pm) Second dimension Chromolith Performance RP18 (10x0.46cm)... 

Zarghi et al. [76] developed an HPLC method, using a monolithic column, for quantification of omeprazole in plasma. The method is specific and sensitive with a quantification limit of 10 ng/ml. Sample preparation involves simple, one-step extraction procedure, and analytical recovery was complete. The separation was carried out in reversed-phase conditions using a Chromolith Performance (RP-18e, 100 x 4.6 mm) column with an isocratic mobile phase consisting of 0.01 mol/1 disodium hydrogen phosphate buffer-acetonitrile (73 27) adjusted to pH 7.1. The wavelength was set at 302 nm. The calibration curve was linear over the concentration range 20-1500 ng/ml. The coefficients of variation for intra- and interday assay were found to be less than 7%. 

On the same time, the simple, reliable and reproducible HPLC and extraction methods were developed for the analysis of tadalafil in pharmaceutical preparation [30]. The column used was monolithic silica column, Chromolith Performance RP-18e (100 mm x 4.6 mm, i.d.). The mobile phase used was phosphate buffer (100 mM, pH 3.0)-acetonitrile (80 20,v/v)at the flow rate of 5 mL / min with LTV detection at 230 nm at ambient temperature. Extraction of tadalafil from tablet was carried out using methanol. Linearity was observed in the concentration range from 100 to 5000 ng/mL for tadalafil with a correlation coefficient (R2) 0.9999 and 100 ng/mL as the limit of detection. The values of linearity range, correlation coefficient (R2) and limit of detection were 50-5000 ng/mL, 0.9999-50 ng/mL, respectively for sildenafil. Parameters of validation prove the precision of the method and its applicability for the determination of tadalafil in pharmaceutical tablet formulation. The method is suitable for high throughput analysis of the drug. 

Herbicide separations were carried out using a Chromolith Performance RP-18e column with 100 mm x 4.6 mm from Merck, protected using Onyx SecurityGuard cartridges (4 x 3.0mm) from Phenomenex. All sample analysis were performed with a flow rate of 1 ml/min at gradient mode. The eluents were acetonitrile/water solutions (solution A 35/65 solution B 90/10), adjusted to pH = 2.8 using a formic acid solution (Panreac, 98%). 

Packing material classical CIS columns (e.g.. Symmetry CIS, SunFire), monolith (e.g., Chromolith Performance and HR), hybrid materials (e.g., XBridge ClS/Shield, Gemini-NX), Fused Core (e.g., Kinetex, Accucore, Ascentis Express), Mixed Mode Phases (e.g., Primesep C, Obehsc N/R). 

Better resolution is achieved, especially in the first part of the chromatogram. The last apolar peak is slightly delayed by the polar CN material, but this small increase in run time is a price worth paying. Moreover, we have been able to separate tricyclic antidepressants and their metabolites (a total of 12 peaks) in one isocratic run using Zorbax Bonus/Chromolith Performance and AQUA/ Zorbax Extend coupled in series. 

One uses six completely different columns, e.g., one of moderate hydro-phobicity but elevated polarity (e.g., SynergiFUSION RP), a monolith (e.g., Chromolith Performance), one with a long alkyl chain and hydrophilic endcapping (e.g., Develosil), one with incorporated ionic groups (Primesep A), and two high-speed columns (20-30 mm, 2-3 mm, 1.5-2 pm). 

However, a comment on the expected clustering of two different types of phases is first necessary. In Chem. 24, two clusters are obvious. The upper cluster. Symmetry Shield to Nucleosil Nautilus, contains embedded phases. The lower cluster, XTerra MS to Chromolith Performance, contains phases with a classical coverage. 

Special phases for fast separations Chromolith Performance RP18e (fast separations with high flow rates)... 

The obtained difference between the Chromolith Performance RP-18e column and the SpeedROD 50 mm or SpeedROD 100 mm columns... 

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