Narrow bore packed columns

Narrow bore packed columns are characterised by having i.d. in the range 

2 mm and particle size of 3-30 pm. Ishii and co-workers [115] evaluated several types of column materials, for instance, stainless steel, Pyrex glass, PTFE and fused silica glass, and concluded that the latter gave the best column efficiency. 

Using proprietary packing techniques detailed by Verzele [116] microparticulate columns of up to 2 m can be prepared. For columns of 200 pm 

---

It Is the purpose of this manuscript to compare four types of mlcrobore columns reported In the literature. The utilization of the narrow-bore packed column HPLC In terms of Instrumentation requirements for Injection valves, pumping systems, and detectors are also discussed. 

Narrow-Bore Packed Column Pyrex Glass PTFE Fused-Slllca Glass Stainless Steel 100-500 3-10 0.1-2 0.1-20... 

Narrow-bore packed-column HPLC, as reported by Yang utilized fused silica columns of OOO pm I.D. packed with 3-, 5- and 10-pm particles. A proprietary packing technique yields high... 

The low mobile phase flow rates (0.1 to 20 ui /min) used In narrow-bore packed columns allow not only between 50 and 500 times solvent saving compared with columns operated at... 

To utilize the available potential of narrow-bore packed columns, the liquid chromatograph Including Injector, hydraulic pumping system, and detectors must have a matching level of performance. 

There Is no doubt that narrow-bore packed columns pose very stringent requirements on the design of the liquid chromatograph. Modifications of existing commercial equipment for the practice of narrow-bore packed column HPLC are given below ... 

For high pressure narrow-bore packed column HPLC, a splitter... 

Figure 2. The modified Valeo 0.5 p 1 internal loop sampling valve for split injection in narrow-bore packed column HPLC (Reproduced with permission from Ref. 12, copyright Elsevier Sci. Publ. Co.)...

The design of hydraulic systems for narrow-bore packed column HPLC Is particularly challenging because of the low flow rate used In narrow-bore packed columns. The potential performance of narrow-bore packed columns Is greatly reduced by the constraint of operable constant low flow rates and the operable pressure limit. 

A high pressure syringe pump operated under constant pressure mode Is often used for low flow rate operation In narrow-bore packed column HFLC. Flow rates as low as 0.05 Mi /nln can be obtained. The drawback of constant pressure operation Is the potential flow rate variation due to a flow resistance change In the column. 

Because of the small elution peak volume obtained from narrow-bore packed columns, conventional concentration dependent detectors such as UV-vlslble absorbance, fluorometrlc, and electrochemical detectors must be purged with makeup solvent or miniaturized to allow minimum extra-column contribution to peak spreading. A cell volume 0.1 i Is desirable for narrow-bore packed columns of I.D. Ishll et. al. reported the reduction of an UV detector cell volume to OAiiZ by using a quartz tube of... 

The use of FT-IR as a narrow-bore packed column PLC detector has also been Investigated by Jlnno et. 

Figure 5. Schematic diagram for on-column fluorescence detection in conjunction with fused-silica narrow-bore packed column.

---