Regeneration, capillary columns

S) values of these test runs were compared to the well-reproducible results (Xo, So) of the regenerated samples, measmed without deactivating pretreatment. Analysis after both runs used a gas chromatograph with a 50-m CP-Sil glass capillary column and FID detector. The same sample - 36 mg of Pt-B, 10.5 mg of EPT and 64 mg of Pt-CEO - was used and regenerated after each test run by exposure to 30 Torr Oz for 2 minutes and then to 100 Torr Hz for 3 min. ... 

Factors Controlling Selectivity Open Tubular Columns Dynamic Coating Static Coating Column Regeneration Capillary Column Design and Choice Stationary Phases for the GC Separation of Chiral Substances Synopsis References Chapter 6... 

Practically it is quite difficult to destroy an ALOT-type of capillary column. The adsorbents are generally not sensitive to oxygen or moisture. Although the retention behavior of several adsorbents is influenced by moisture, columns can be regenerated by proper conditioning (see also Section 7.4.4 Samples containing moisture ). 

FIGURE 3.61 Illustration of regeneration of a capillary column by solvent rinsing with n-pentane. 

Figure 3.59 Regeneration of a capillary column by solvent rinsing with n-pentane (a) fatigued column (b) after rinsing will 30 mL of n-pentane.

The inside capillary wall controls the electroosmotic velocity and provides undesired adsorption sites for multiply charged molecules, such as proteins. A fused-silica capillary should be prepared for its first use by washing for 15 min each (> 20 column volumes) with 1 M NaOH and 0.1 M NaOH, followed by run buffer ( —20 mM buffer). For subsequent use at high pH, wash for 10 s with 0.1 M NaOH, followed by deionized water and then by at least 5 min with run buffer.28 If the capillary is being run with pH 2.5 phosphate buffer, wash between runs with 1 M phosphoric acid, deionized water, and run buffer.29 When changing buffers, allow at least 5 min of flow for equilibration. For the pH range 4-6, at which equilibration of the wall with buffer is very slow, the capillary needs frequent regeneration with... 

Fig. 5. An analysis of a coarse atmospheric aerosol extract by CE and IC [49]. CE conditions a 57 cmX75 xm I.D. capillary, distance to detector, 50 cm. Electrolyte 2.25 mM PMA (pyromel-litic acid), 0.75 mM HMOH (hexamethonium hydroxide), 6.50 mM NaOH and 1.60 mM TEA (triethanolamine), pH 7.7 or 2.0 mM NDC (2,6-naphthalenedicarboxylic acid), 0.5 mM TTAB (tetradecyltrimethylammonium bromide) and 5.0 mM NaOH, pH 10.9 30 kV (PMA) or 20 kV (NDC) pressure injection for 10 s indirect UV detection at 254 nm (PMA) or 280 nm (NDC). IC conditions an IonPac-ASlO column with an IonPac-AGlO guard precolumn conductivity detection using an anion self-regenerating suppressor (ASRS-I) in the recycle mode. Analytes 2, chloride 3, sulfate 5, nitrate 6, oxalate 7, formate 10, hydrocarbonate or carbonate 11, acetate 12, propionate 14, benzoate.

Figure 32 The scheme for a scaled-up unit (1) a column with capillary collectors for solution samples (2) a supplementary section (3) ceramic filter (4,5) pumps (6) tank for treated solution (7) a resin valve (8,9) top and bottom resin tanks (10-13) solution valves (14) tank for regenerated resin (15) tank for solution under treatment (16) resin tank.

For suppressed conductivity detection, the end of the separation column is connected to a tubular ion exchange membrane suppressor surrounded by a reservoir of regenerant solution [512,513]. The electrodes for conductivity detection are located in a separate capillary downstream of the suppressor. The high voltage electrode for the separation is located in the regenerant reservoir. In this way, the detector is decoupled from the electric field for the separation, and the electroosmotic flow generated in the separation column is used to drive the electrolyte solution through the suppressor and detector. The function of the suppressor (see section 5.7.4.1) is to neutralize electrolyte solution ions. 

Most early efforts focused on the development of thin layer matrix precoated membranes, including those made of nylon and other synthetic polymers, nitrocellulose, anion- and cation-modified cellulose and regenerated cellulose. Several manufacturers currently offer 96-well plates with proprietary coatings for LC-MALDI-MS applications. This approach was described in more detail above. As mentioned previously, all of these sample preparation methods were originally developed for pre-purified samples or fractions, not for analytes eluting from an HPLC or capillary electrophoresis column. 

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