Column packing methods slurry preparation

The most commonly used method to pack capillary columns for CEC utilizes the slurry packing methods typically used in HPLC. The capillary tube with a temporary frit is connected to a packing reservoir, such as a short HPLC column or another viable unit, which is connected to a high-pressure pump for solvent delivery. The slurry at a concentration of 50-100 mg/ml is prepared in a suitable solvent. Table 4.3... 

Reproducibility during column preparation is a significant problem in CEC. Preparation methods involving pumped slurries were all found to produce generally highly efficient (> 200,000 plates/m for 3-pm ODS particles), but within a batch of columns packed by the same method, the relative standard deviation (RSD) of EOF, and migration time and retention factor of a standard were [23], respectively, 7-14%, 5-22%, and 9-30%. These values are particularly relevant to considerations of the transfer of HPLC methods to CEC. 

The preferred method for packing silica gel and alumina columns is the slurry method, whereby a slurry of the adsorbent and the first eluting solvent is made and poured into the column. When nothing is known about the mixture being separated, the column is prepared in petroleum ether, the least polar of the eluting solvents. 

Empty column (25 cm x 1 cm I. D.) assembly was purchased from Phenomenex (USA). The columns were packed with perphenyl carbamoylated beta-cyclodextrin bonded onto silica gel using an Alltech pneumatic liquid pump (Alltech, USA) by slurry packing method. The silica gel was supplied by Eka Chemicals AB (Sweden) with particle size of 16 pm (KR100-16-SIL). The eluent (desorbent) used was a binary mixture containing 60% aqueous buffer solution (1% TEAA, pH=4.5) and 40% methanol. The feed solution was prepared by dissolving raeemate propranolol hydrochloride in the desorbent at... 

Slurry packing techniques are required for the preparation of efficient columns with rigid particles of less than 20 micrometers in diameter. The same general packing apparatus. Figure 4.8, can be used to pack columns by the balanced-density slurry, liquid slurry, or the viscous slurry techniques. Down-fill slurry packing is the method of choice for small bore columns and packed capillary columns. 

Columns consisting of particles of less than 30-50 jum in diameter are prepared most efAciently by slurry packing. Balanced-density slurry packing [11,12] is the most successful of such methods. In this technique, a supporting liquid is used which has the same density as that of the particles. This eliminates sedimentation problems. A typical balanced-density slurry-packing apparatus is shown in Fig.3.42. For the preparation of a... 

The column may be packed with the adsorbent in a number of ways. The objective is to obtain a uniform packing through which the solvent will pass at a reasonable rate. One of the simplest methods of attaining the former objective is to prepare a thin slurry of the adsorbent in the solvent which is to be used, pour this into the tube, and allow the solvent to drain. Another method is to fill the tube with solvent and sift in the dry adsorbent, thus allowing it to settle evenly. 

Particles below 20 pm in diameter cannot be packed in dry form as they tend to become lumpy, thus precluding the preparation of high-performance columns. The material must be suspended in a liquid to give a slurry. A high-pressure pump then conveys the slurry into the column at great speed. There are almost as many methods for wet packing as there are column manufacturers. Proponents are convinced that their own ways and means are the best, making it difficult for the uninitiated to choose between them. Slurry production itself is based on a few essential principles ... 

A packed column for LSC ordinarily consists of a glass tube packed with the adsorbent which is finely divided solid. Packed columns are usually prepared by pouring a slurry of the stationary phase in the mobile phase into a glass tube closed at the bottom by a cottonwool pad or perforated plate having openings too small to permit passage of the solid particles used. The column is then allowed to form by use of one or more of the following methods ... 

Kaminski, M., J. Klawiter, and J. S. Kowalcsyk, Characteristics of the Tamping MeAod for Packing Preparative Columns Part IL J. Chranatogr. 243,225-244 (1982). (characteristics of the slurry method of packing chromatographic columns). 

In the slurry method, the adsorbent is packed into the column as a mixture of a solvent and an undissolved solid. The slurry is prepared in a separate container... 

The stationary phase in LLC can be prepared in different ways, depending on the support particle size chosen. An often-applied preparation technique is the in situ coating method. In this case the stationary phase liquid is pumped through the dry packed (slurry packing) column. Later, the column is flushed with mobile phase to displace excess stationary phase liquid between the particles. 

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