Haloethers, determination

The anomeric effect is also present in acyclic systems and stabilizes conformations that allow antiperiplanar (ap) alignment of the C—X bond with a lone-pair orbital of the heteroatom. Anomeric effects are prominent in determining the conformation of acetals and a-alkoxyamines, as well as a-haloethers. MO calculations (4-3IG) have found 4kcal/mol as the difference between the two conformations shown below for methoxy-methyl chloride. ... 

Haloethers (Method 611). Bis(chloromethyl) ether is known to have a very short half-life in water (38 s). Therefore, it was eliminated from the priority pollutant list and from consideration in EMSL-Cincinnati method studies. Some of the other haloethers are very volatile, and care must be taken to prevent their loss during the concentration step. The haloethers are determined by OHD-GC by using a 1.8-m X 2-mm i.d. glass column containing Supelcoport coated with 3% SP-1000. The temperature is held at 60 °C for 2 min and then programmed at 8 °C/min to 230 °C. 

Figure 4 shows the recoveries of the 19 haloethers. Overall, the recoveries were quite good (averaging around 70 percent across the 19 compounds) but the agreement between the duplicate extractions performed in parallel was not as good as in the case of the nitroaromatics, however, it was within 15 percent for most compounds. To determine if the pressure had any effect upon recovery, we compared experiments 5,6 with experiments 9,10 because they were pairs (performed in parallel at different pressures) and they were performed with sand samples spiked under identical conditions. All recoveries were slightly higher when extractions were performed at lower pressures. This seems to be in contradiction with what we obtained for experiments 7,8 however, in this case the sand was spiked directly in the extraction vessel and therefore, the data from experiments 7,8 cannot be compared with the data from experiments 5,6. 

Chiang, J.S. Huang, S.D. Determination of haloethers in water with dynamic hollow fiber liquid-phase microextraction using GC-FID and GC-ECD. Talanta 2007, 71 (2), 882-886. 

A significant number of chlorinated haloethers, chlorinated hydrocarbons, and chlorinated benzenes are SVOCs. Examples include bis(2-chloroisopropylether), 4-chlorophenylphenylether, hexachloroelhane, isomers of dichlorobenzene, isomers of trichlorobenze, isomers of tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene, to name only a few. A number of nitroaromatic SVOCs are considered enviromnentally significant. Remedial action at an old military installation might reqnire the determination of isomers of nitrobenzene, dinitrobenzene, dinitrotoluene, and trinitrotoluene (TNT) in soil and water samples, because they are indicative of explosives. 

Solid-phase microextraction (SPME) devices constitute a second kind of solid-phase extractor. These make use of very small-diameter devices in which analytes are bonded directly to the extractor walls, then eluted directly into a chromatograph. The use of SPME devices for the determination of haloethers in water has been described. 

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