Dichloropentafluoropropanes as solvents for size exclusion chromatography.

We have found that HCFC225s (HCFC225ca: 3,3-dichloro-1,1,1,2,2-pentafluoropropane, HCFC225cb: 1,3-dichloro-1,1,2,2,3-pentafluoropropane) are superior mobile phases for size exclusion chromatography (SEC). As alternatives of CFC113, they have been shown to possess a number of excellent properties, such as low flammability, low viscosity, low cost, high purity, and environmental and operational friendliness. In addition, they have distinct advantages for the SEC measurement, because they solubilize some kinds of acrylate such as poly(methyl methacrylate) (PMMA) and commercial monodispersed PMMA can be used to prepare calibration curves necessary for the measurement of equivalent molecular weight of some polymers. Furthermore, we propose an HCFC225/1,1,1,3,3,3-hexafluoroisopropanol mixed solvent for use in the SEC of poly(ethylene terephthalate) (PET) and polyamides. Poly(2-(perfluorooctyl)ethyl acrylate), whose PMMA equivalent weight average molecular weight was 118,100 Da, was evaluated by a multi-angle laser light scattering (MALLS) detector to have an absolute molecular weight of 439,000 Da. The difference can be attributed to the molecular size of the polyfluorinated polymer compared to the non-fluorinated one. The possible application of this novel mobile phase system for molecular size and molecular weight characterization of perfluoropolyethers, PET, nylon 6 and nylon 6,6 are also discussed.

The history of DBCP from a judicial perspective.

The efforts of workers in less-developed countries who have been exposed to 1,2-dibromo-3-chloropropane (DBCP) to obtain redress through the courts for damages suffered from these exposures are reported. The authors, who are lawyers, have represented more than 26,000 such workers. Evidence of the culpability of the U.S. manufacturers and the corporate users of DBCP, particularly Standard Fruit Company in Costa Rica, is presented. The damaged-worker plaintiffs are stymied by the application by the U.S. judicial system of forum non conveniens, which works in the defendants' favor by shunting the cases back to the plaintiffs' home countries, where the judicial systems are inadequate to deal with such cases and unlikely to be able to enforce judgments against the defendants.

Exporting DBCP and other banned pesticides: consideration of ethical issues.

Many developed countries permit the export of pesticides that are banned, restricted, or unregistered within their own borders. This practice, which leads to the exposure of agricultural workers in developing countries to high levels of pesticides that are not permitted in the country of manufacture, raises many ethical issues as well as economic, social, political, and public health issues. Worldwide attempts to control export of such pesticides, through the FAO/UNEP Prior Informed Consent program, moves this issue in the right direction. This article explores the current U.S. and international practices, using the specific example of export of DBCP to banana-producing countries. The actions taken by multinational corporations, manufacturers of the pesticides, and public health officials in both the exporting and importing countries are explored, along with the impacts on workers, local economies, governments, and the environment.