Glass-lined columns

Acryflc acid, alcohol, and the catalyst, eg, sulfuric acid, together with the recycle streams are fed to the glass-lined ester reactor fitted with an external reboiler and a distillation column. Acrylate ester, excess alcohol, and water of esterification are taken overhead from the distillation column. The process is operated to give only traces of acryflc acid in the distillate. The bulk of the organic distillate is sent to the wash column for removal of alcohol and acryflc acid a portion is returned to the top of the distillation column. If required, some base may be added during the washing operation to remove traces of acryflc acid. 

Only trace amounts of side-chain chlorinated products are formed with suitably active catalysts. It is usually desirable to remove reactive chlorides prior to fractionation in order to niinimi2e the risk of equipment corrosion. The separation of o- and -chlorotoluenes by fractionation requires a high efficiency, isomer-separation column. The small amount of y -chlorotoluene formed in the chlorination cannot be separated by fractionation and remains in the -isomer fraction. The toluene feed should be essentially free of paraffinic impurities that may produce high boiling residues that foul heat-transfer surfaces. Trace water contamination has no effect on product composition. Steel can be used as constmction material for catalyst systems containing iron. However, glass-lined equipment is usually preferred and must be used with other catalyst systems. 

A glass distillation column cracked, and water was sprayed onto the crack. A spark was seen to Jump from the metal cladding on the insulation. which was not grounded, to the end of the water line. Although no ignition occurred in this case, the incident shows the need to ground all metal objects and equipment. They may act as collectors for charges from steam leaks or steam or water Jets. 

Iodoethanes are separated on a glass-lined, stainless-steel column (2mx3.2mm o.d.) packed with 10% OV-101 on Chromosorb W HP (150— 190m), using flow-rates of 90ml min-1 for the carrier gas (N ) and 35 and 350ml min-1 for H and air, respectively, for the flame-ionisation detector. Set the injection port, detector and column temperatures at 140, 130 and 60°C, respectively. 

With the advent of capillary GC, [50-54] the need for separators and the concomitant risk of suppression of certain components vanished. Capillary columns are operated at flow rates in the order of 1 ml min and therefore can be directly interfaced to EI/CI ion sources. [48,49] Thus, a modem GC-MS interface basically consists of a heated (glass) line bridging the distance between GC oven and ion source. On the ion source block, an entrance port often opposite to the direct probe is reserved for that purpose (Chap. 5.2.1). The interface should be operated at the highest temperature employed in the actual GC separation or at the highest temperature the column can tolerate (200-300 °C). Keeping the transfer line at lower temperature causes condensation of eluting components to the end of the column. 

One can find 1-mm glass-lined stainless steel columns or fused silica capillary columns. Fused silica is available with 75-yU.m, 100-/xm, or 320-/xm internal diameter by 20-cm, 25-cm, or 30-cm length. Fused silica is a glass tubing with an outside polyimide coating to prevent breakage. 

M. Konishi, Y. Mori, and T. Amano, High-performance packed glass-lined stainless steel capillary column for microcolumn liquid chromatography, Anal. Chem., 57 2235-2239 (1985). 

Inorganic, methyl, and n-butyl tin compounds may be converted to volatile hydrides, and the latter separated on a chromatographic column prior to detection of tin by AAS.58 In this particular study, an electrically heated absorption cell was used, although a flame-heated quartz cell could have been employed equally well. Balls59 used on-line cryogenic trapping on a silanized glass-wool column to separate dibutyl tin and tributyl tin in sea water prior to transport to a quartz-tube atomizer for determination by AAS. 

Chromatographic System Use a gas chromatograph equipped with a flame-ionization detector and a 2-m x 4-mm (id) borosilicate glass column, or equivalent, packed with 2% to 5% methylpolysiloxane gum on 80- to 100-mesh acid-washed, base-washed, silanized, chromatographic diatoma-ceous earth, or equivalent materials. The column should have a glass-lined sample-introduction system or on-column injection. Maintain the column isothermally between 240° and 260°, the injection port at about 290°, and the detector block at about 300°. Use a dry carrier gas with the flow rate adjusted to obtain a hexadecyl hexadecanoate peak approximately 18 to 20 min after sample introduction when using a 2% column, or 30 to 32 min when using a 5% column. 

---