Technology derailment, evidence that these two devices did their job. Cars carrying flammable materials also have been retrofitted with extra insulation designed to delay their blowing up long enough for emergency workers to prepare for it. All of the cars containing flammable gases on the Livingston train had this extra insulation. Although two cars did thermally rupture, the first one (containing tetraethyllead) did not blow up with the tremendous explosive power that can accompany such an occurrence, and the second (containing vinyl chloride) did not explode until two days after the fire started. "In the same situation 10 years ago [before the cars were retrofitted]," Zercher says, "the seven cars that contained vinyl chloride almost certainly would have gone up in the first four and a half hours of the [fire's duration]." As it was, only one of these cars blew up at all and that was well after people had been evacuated from the area. Other recommendations of the 1978 task force included development of large-scale training programs for emergency response personnel, such as those in which the Louisiana police participated, and development of a permanent teleconferencing "bridge" at CHEMTREC. This system allows on-site personnel to be in simultaneous communication with experts at several chemical companies who can advise them on particular hazards; it was used several times during the emergency. Although the firefighters have left and the residents of Livingston have returned to their homes, the Livingston derailment is by no means over. Environmental monitoring of the area continues, for example. Reports so far indicate no adverse residual levels of phosphoric acid, one of the most important potential environmental hazards. And the lead levels in Livingston, which might have been elevated due to the explosion of the car containing tetraethyllead, are lower than control readings in an adjacent county. The railroad is continuing its investigation of the incident, focusing particularly on the conduct of its employees. The National Transportation Safety Board, too, is continuing its investigation of the causes of the incident. And the state of Louisiana continues to develop its case against the people who have been arrested. The question of whether alcohol was a contributing factor to the derailment is one of particular con30
C&EN Nov. 1, 1982
Zercher: one big social disruption
cern to the safety board. There currently are no federal regulations forbidding railway personnel from drinking while on the job or from driving a train while intoxicated—a situation that the safety board has been on record as wanting to change since 1974. "The record of alcohol misuse in the railroads is incredible," says Ira Furman, a spokesman for the board. He cites, among other data, a 1978 study conducted for the Federal Railroad Administration that found an average of 33 railway workers every day who considered themselves to be "very drunk" on the job. About 12% of the 234,000 railroad workers surveyed said they drank at least once while on duty in 1978. Another issue that may have affected the Livingston incident that the safety board is concerned about is the arrangement of full and empty cars on a train. At present, the cars on a train are arranged according to the order in which they will be dropped off at their destination. Thus, it is quite likely that cars containing the same hazardous material will be scattered throughout a train with no regard to the contents of adjacent cars. (The only exception is a requirement that cars that contain railroad personnel be separated from those containing hazardous materials by at least five cars.) None of the concerned parties— the chemical shippers, the railroads, and the safety board—is seriously considering trying to group chemical tank cars by their content on freight trains; the rearrangements that procedure would entail at each transfer point would be too formid-
able. But the safety board is concerned about the differences between full cars and empty ones in a derailment. It is investigating the effect of a car's weight on its crash dynamics to see if trains might be safer if the empty cars were grouped together and arranged so that loaded cars would not crash into them. The interindustry task force that recommended many of the tank car changes that were so useful at Livingston presently is in a "second incarnation" as Cox calls it. The group was reformed last summer to suggest further improvements in the safe transportation of hazardous materials and the handling of spills. Although its report is not expected for several months, Cox says the task force this time is not really focusing on major derailments like the one at Livingston. Rather, it is directing its attention to the small spills that account for almost all of the incidents that occur. Although major derailments attract the most public attention, Cox says, most spills are much smaller and involve only the breakage of a bottle or two or a single leaky container. The task force is looking specifically at areas such as the loading process, inspection procedures, and the small-scale releases that sometimes occur at safety valves. It also is considering whether the rail and chemical industries need to improve their public image when major incidents do occur, perhaps by having a public relations person at the scene. D
New system eliminates spectral interferences A just-introduced atomic absorption spectrometer, Instrumentation Laboratory's Video 22, employs a new background correction system that, the company says, offers significant advantages over deuterium-arc and Zeeman-effect systems. In the new approach, the AA instrument's hollow cathode lamp serves as its own background corrector. As chemists have known for a long time, when a high current is passed through a hollow cathode lamp, its emission line is broadened and atomic absorbance by the sample is reduced greatly. The phenomenon, called self-reversal, generally is regarded as something to be avoided. However, it occurred to Stanley B. Smith, director of R&D for IL's analytical instrument division, and Gary M. Hieftje, a chemistry professor at
Technology
Polymer Chemists! Look to Stepan...We're Specialists in Surfactants for the Polymer Industry.
New system can determine antimony in presence of nickel Absorbance 0.15
0.10
0.05
We offer you the most c o m plete line of sophisticated surfactants specifically designed to meet the requirements of the Polymer Industry. There are more than 5 0 products in our Polystep line that have been developec in our specialty Polymer Chemistry laboratory and we are continually innovating new ones. An example is our line of Polystep ether sulfates. These offer remarkably better adhesion, water rem u m particle size and latex stability. Try us. Our outstanding Tech Service is available to assist you in making your product better. We believe you will find we are doing things to benefit you that others are not. For complete information write or call: Stepan Chemical Company, Surfactant Department, Edens & Winnetka, Northfield, IL 6 0 0 9 3 . Tel: 3 1 2 / 4 4 6 - 7 5 0 0 . In Europe: Stepan Europe, 3 8 3 4 0 Voreppe, France. Tel: (76) 5 0 - 8 1 - 3 3 .
Stepan Our Fiftieth Year
Indiana University, that self-reversal could form the basis for a new system of background correction. In the technique developed by Smith and Hieftje, the hollow cathode lamp is run first at a normal, relatively low current; its light is absorbed both by the element of interest and also by the background (mostly broadband absorption caused by undissociated molecules in the sample path and by light scattering). Then a very brief high-current pulse is passed through the lamp, bringing on the self-reversal effect. The broadened emission is absorbed primarily by the background, the same proportion as before, while atomic absorbance by the sample decreases sharply. The correct atomic absorbance is obtained by measuring the difference between the two signals. Compared to conventional deuterium-arc background correction systems, the Smith-Hieftje approach has several advantages, IL says. It works in the visible as well as the ultraviolet portion of the spectrum. It isn't thrown off by structured background caused by vibrational or rotational transitions. It can eliminate at least some spectral interferences. Since there is only one light source, there is no danger of misalignment. The single light source also eliminates the need for a beam-splitter, with its reduction in light throughput, and it reduces the likelihood of baseline drift. As an example of the Smith-Hieftje system's ability to eliminate spectral interferences, IL cites a determination of antimony at the 231.147-nm line in the presence of nickel, which
has an absorbing resonance line at 231.096 nm. With deuterium arc background correction, 10 pg of nickel, measured at the antimony line, has an AA signal comparable to that of 3 ng of antimony. With the Smith-Hieftje system, the nickel interference disappears almost completely. Zeeman-effect background correction systems (based on wavelength shifts caused by a strong magnetic field) share some of the Smith-Hieftje system's advantages over deuterium arcs, IL admits. But it adds that the new system avoids some of the complications of the Zeeman approach. For example, there are no doublevalued working curves, which, in Zeeman systems, can cause two different concentrations to produce the same absorbance reading. Also, the Smith-Hieftje system has no polarizer to reduce light availability and no magnet to encumber either the source or sample area. IL notes that both Smith-Hieftje and Zeeman-effect systems are inherently less sensitive than deuterium-arc systems. However, the relatively simple Smith-Hieftje system costs less than deuterium-arc systems and much less than Zeeman-effect systems. It's not practical to retrofit the Smith-Hieftje background correction system into existing AA instruments, IL says, because major changes in electronics are required. The new IL Video 22 has the system built in. It also uses a new series of hollow cathode lamps with extra insulation to prevent arcing during the high-current pulses. Ward Worthy, Chicago Nov. 1,1982 C&EN
31
