Monolithic columns inner diameter

Motokawa, M., Ohira, M., Minakuchi, H., Nakanishi, K., Tanaka, N. (2007). Performance of octadecylsilylated monolithic silica capillary columns with 530 pm inner diameter in high performance liquid chromatography. J. Sep. Sci., 29, 2471-2477. 

Alnouti et al. (2005) used Symbiosis to measure propranolol and diclofenac in rat plasma. Twelve different SPE cartridges were screened. A C18 HD (2 x 10 mm inner diameter, Spark) was chosen because it provided the best recovery and peak shapes. When a Luna C18 (2.1 x 50 mm, 5 /an, Phenomenex) was used, the run time was 4 min it was 2 min when a monolithic Chromolith C18 (50 x 2.1 mm, Merck KgaA) column was used. 

FIGURE 12.1 SEM photographs of monolithic silica columns (A) monolithic silica prepared from TMSO in a test tube (B) 50 /mi inner diameter silica skeleton, size 2 /(m, through-pore size 4.5 (ini. (Source From Ikegami, T. and Tanaka, N., Curr. Opin. Chem. Biol., 2004, 8, 527. With permission from Elsevier Scientific Publishing.)... 

In more demanding separations that require higher plate counts, specially designed rapid analysis columns packed with very high efficiency 2 to 3 /.an porous particles are available from several manufacturers. In addition, monolithic columns with improved flow-through characteristics are also commercially available. Figure 13.4 depicts a comparison of inlet pressure and flow rate for 4.6 mm inner diameter x 50, 100, and 150 mm columns packed with 5 /an particles. 

Monoliths have been prepared in both small (50-500 p.m) and large (3. 6 mm) inner diameter columns, as well as in other attractive formats that include traditional SPE and 96-well disk arrays [39 5]. 

In contrast, photoinitiated free radical polymerization of glycidyl methacrylate and trimethylolpropane trimethacrylate in the presence of porogenic solvent affords a monolithic plug within the column that serves as a frit. This procedure represents a simple approach to reproducible fabrication of frits even in capillaries with large inner diameters. 

Figure 29 Separation of the nonsteroidal anti-inflammatory drugs ibuprofen (peak 1), naproxen (2), ketoprofen (3), and suprofen (4) in anion-exchange CEC mode using a strong anion-exchange monolithic column. Conditions on-column alkylated monolith prepared from mixtures consisting of 8% 2-dimethylaminoethyl methacrylate, 24% 2-hydroxyethyl methacrylate, 8% ethylene dimethacrylate, 20% cyclohexanol, 40% 1-dodecanol UV-initiated polymerization at room temperature for 16 h cfpmode= 1423 nm. Column dimensions inner diameter 0.1 mm, total length 335 mm, effective length 250 mm. Mobile phase 0.4 mol/L acetic acid and 4 mmol/L triethylamine in acetonitrile/methanol (60/40), voltage -25 kV, injection -5 kV for 5 s, temperature 50°C, UV detection at 250 nm. (Reprinted from Ref. 127, with permission.)...

The monolithic structure contains large macropores/gigapores (a few micrometers inner diameter), mesopores (2-50 nm), and small micropores (<2 nm). Due to the large flow-through macropores, the backpressure is lower than that in packed columns, allowing higher linear flow rate or longer columns. 

Similar high separation efficiency was obtained for double-stranded (ds) DNA. The separation of pBR322 DNA-Haelll fragments could in fact be accomplished on monolithic systems using a two-step gradient (Figure 17). There, the amount of DNA material that could be loaded onto a 100 X 3 mm inner diameter (i.d.) column without serious loss in separation efficiency was about 2.5 pg. 

An alternative method for preparing the UV detection window has been suggested by Lin et al. [37]. In this method the column consisted of two capillary columns that were joined. One capillary column contained the MIP monolith. The other capillary column housed the U Vdetection window and was filled with electrophoretic buffer. The two sections possessed the same inner and outer diameters. Therefore, they could be connected by aTeflon tube as shown in Fig. 4. 

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