Column inner diameter dimensions

The selection of column characteristics is determined by solvent resistance, the need to visually inspect the bed, the pressure rating of the system, and the dimensions [column inner diameter (i.d.) and length (L)] required from productivity considerations. Productivity considerations will vary if the requirement is based on the amount of information per unit time (analytical gel filtration) or the amount of substance per unit time (preparative gel filtration). 

A compact sensor of greatly reduced dimensions (outer diameter x length 36 x 46 mm) has been constructed and is shown in Fig. 2. In order to conveniently accommodate enzyme columns and to ensure isolation from ambient temperature fluctuations, a cylindrical copper heat sink was included. An outer Delrin jacket further improved the insulation. The enzyme column (inner diameter x length 3x4 mm), constructed of Delrin, was held tightly against the inner terminals of the copper core. Short pieces of well-insulated gold capillaries (outer diameter/inner diameter 0.3/0.2 mm) were placed next to the enzyme column as temperature-sensitive elements. Microbead thermistors were mounted on the capillaries with a heat-conducting epoxy. Two types of mini system has been constructed as discussed below. 

Column dimensions—length (L) and column inner diameter (dc or i.d.)— control column performance (N, speed, sensitivity, sample capacity) and its operating characteristics (flow rate, back pressure). Designations of various column types based on column inner diameters and their associated characteristics are shown in Table 3.1. Note that void volume, sample capacity, and operating flow rate are proportional to (dc)2, while detection limit, or sensitivity, is inversely proportional to (dc)2. Note also that prep columns (>10mm i.d.), microbore (micro columns (<0.5 mm i.d.) will require specialized HPLC instruments (see Chapter 4). There is a definitive trend toward the increased use of shorter and smaller inner diameter analytical columns due to their higher sensitivity performance and lower solvent usage.9"11 This trend will be explored later. 

The use of miniaturized systems might provide a feasible approach for speeding up the separations (given that smaller column dimensions, in terms of both the inner diameter and the length, decrease the dilution). However, miniaturization is not necessarily synonymous with fast separations, since problems often arise with dead volumes, caused by the connections. Nano-LC has been used with UV or MS detection for the analysis of atenolol in urine [143]. A homemade column with an internal diameter of 75 jm containing diol silica modified with teicoplanin was used as the CSR... 

Column volume. X. The total volume of the column which contains the stationary phase. (IUPAC recommends the column dimensions be given as the inner diameter and the height or length of the column occupied by the stationary phase under the specific chromatographic conditions. Dimensions should be given in millimeters or centimeters.)... 

The dimensions of columns are given as length x inner diameter d0 dP). 

Merely, the choice of column dimension demonstrates the awareness of cost reduction for organic solvents as well as analytical run time and thus of sample throughput and economic efficiency. Only 2 % of published reports make use of a column with an inner diameter (I.D.) as small as 1 mm [12] corresponding to a flow of 50 ul/min. Columns with an I.D. of 2.0-2.1 mm are used in 48 % of reports determining a flow between 200 and 500 ul/min and half of all applications is performed with a column I.D. between 3.0 and 4.6 mm and a flow ranging from 500 to 1,000 ml/min (Tables 5-8). 

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.)...

Figure 2 shows a schematic drawing of how the SDS-removal column is attached to the reversed phase column. To prepare this column setup, a fused silica tubing with the desired dimensions (360 im outer, 250 )xm inner diameter and 200 mm length for LC-MS analysis) was connected to a transfer tubing (180 im outer and 50 pm inner diameter) holding a frit in place. The column was filled with reversed phase support as described in... 

The usefulness of the SDS removal precolumn was demonstrated using an LC-MS system on a micro capillary column with an inner diameter of 250 pm. SDS-removal precolumns can be used on micro capillary columns of larger dimensions as well. Our experience has shown that it is... 

NPC with RPC, the immiscibility of the employed mobile phase can cause peak broadening in the second dimension. As recently demonstrated for the analysis of carotenoids, NPC x RPC can be performed with immiscible mobile phases, by adjusting the column dimensions and flow rates, for example, using a microbore column in the first dimension and a standard (4.6 mm ID (inner diameter)) analytical column in the second dimension in order to minimize the effects of band broadening.65,73,74... 

The basis of the considerations is an HPLC column of typical dimensions, 25 cm in length Lc and 4.6 mm inner diameter d, which is packed with a stationary phase of 5 (tm particle diameter d. Let us investigate what can be calculated from these and... 

The size of the column (resin bed) is selected according to the quantity of ions to be retained in the column. The depth of the resin bed in the column should be 10-20 times its diameter. Columns 8-10 mm in inner diameter are often used in laboratories. When the quantities of ions retained are in the microgram or milligram range, columns 3-5 mm in inner diameter are sufficient. In columns of the dimensions given above, 30-50 mesh or 100-200 mesh resins may be used [125... 

The effect of capillary inner diameter on column efficiency is quite predictable the column efficiency increases as the diameter decreases. However, this increased performance is at the expense of sample capacity. Capillary columns that are most commonly used today have inner diameters between 0.2 and 0.3 mm. While the sample capacity corresponding to such column dimensions is adequate for the combined GC/MS, wide-bore capillary columns are required for most remaining peak identification techniques. The wide-bore (0.5-0.7 mm, i.d.) columns may tolerate up to microgram amounts. The column technologies for the wide-bore and conventional capillary columns frequently differ, as an extensive geometrical modification of the column inner surface is needed for the former column type. 

The conclusions about column dimensions and configuration can be summarized as follows straight glass and metal columns with a length of 10-25 cm, an inner diameter of 3-5 mm and a wall thickness of half the inner diameter for metal columns and equal to the inner diameter for glass columns seem to be a good... 

In GC xGC, the first-dimension columns are commonly 15 to 60 m long, with an inner diameter in the range of 0.25-0.53 mm and a film thickness of the order of 0.25-1 gm. These columns provide conventional peak widths of 5 to 30s [13]. The first dimension is in fact not different from those typically used in conventional ID GC. The main reason is that it is desirable to have rather large peak widths when entering the modulator to ensure proper sampling of potentially co-eluting analytes prior to their separation in the column. This point is discussed in detail in Section 3. 

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