Focus
Fusion Energy Research
Tylenol Analysis Food & Drug Administration (FDA) field laboratories throughout the nation were involved in the analysis of Tylenol samples collected from homes, store shelves, and warehouses in October after a series of deaths from adulteration of the popular analgesic with cyanide. Cyanide in sufficient amount kills quickly because of its ability to combine with important respiratory enzymes, thus inhibiting cellular respiration. According to Arvin P. Shroff, director of FDA's Division of Field Science, FDA scientists were able to analyze about 2 000 000 capsules of regular and extra-strength Tylenol in a short period of time, using a combination of visual inspection and chemical analysis. It is not difficult to detect gross substitution of KCN for acetaminophen. Tylenol is a free-flowing powder, while KCN is crystalline, with a granular texture. In addition, KCN can be distinguished from Tylenol by a characteristic odor. Visual inspection was thus used for primary screening of the Tylenol samples. If cyanide was detected visually, the capsules were analyzed individually to determine adulterant concentrations. These concentration values were important, Shroff explains, since they could potentially provide information relating to how the pills were tampered with. But even if no KCN was found by visual inspection, the capsules were analyzed in composite samples, with the powder from 5-10 cap-
sules combined to make up each composite. "Our goal," says Shroff, "was to analyze each and every pill." FDA scientists quickly developed a number of analytical methods to deal with the crisis: • colorimetry, including a modified USP method; • X-ray spectrometry, using either grain inspection or clinical mammographie X-ray instrumentation; and • polarography. The polarographic technique, developed at FDA's New York City district laboratory by research chemist Walter Holak, was used for the bulk of the analyses, since the X-ray methods required instruments that were not widely available and the colorimetric methods were primarily for qualitative analysis. The polarographic technique involved differential pulse polarographic reduction of cyanide at about - 0 . 3 V vs. SCE, with quantitation by standard addition. Holak's technique is a modification of a differential pulse polarographic procedure he found in a Princeton Applied Research Corporation application note on cyanide. "All these things had to be done in a very short period of time," Shroff explained. "Most of our people worked day and night on these analyses, as you can imagine. "A lot of people don't recognize that analytical chemistry crosses many disciplines," he continued. "In the area of food and drugs, almost everything we do pertains to analytical chemistry."
1474 A · ANALYTICAL CHEMISTRY, VOL. 54, NO. 14, DECEMBER 1982
Analysis inside working tokamaks is now a reality, thanks to research that has been done at a number of fusion energy research facilities in the U.S. and overseas. Much of this research has involved the detection of pesky impurities that make their way into the plasma from the walls of the tokamak. These impurities tend to cool the plasma, making it difficult to attain the high temperatures necessary for fusion. A tokamak is a toroidal reactor vessel used in magnetic confinement fusion, in which strong magnetic fields keep the hot plasma away from the walls of the reactor vessel. Line radiation is one of the principal energy loss processes that plague tokamaks. Light elements in the center of the plasma are totally stripped of electrons, but heavier elements frequently retain some of their innershell electrons. The energy of the hot plasma excites these electrons, and the radiation resulting from deexcitation can carry energy away from the plasma at a high rate. Precisely the same sort of fluorescence process is what makes it possible for researchers to detect plasma impurities, except that with laser-induced fluorescence spectroscopy (LFS) the atoms are raised to excited electronic states by the laser instead of the plasma. The emission wavelengths are then detected and studied to determine what species are doing the emitting. The initial experiments were performed on the ISX-B tokamak at Oak Ridge National Laboratory in 1979 by J. B. Roberto's group in conjunction with investigators from KFA Juelich in West Germany, and simultaneously by scientists from General Atomic in California. Roberto's group is using LFS to understand plasma impurity 0003-2700/82/A351-1474$01.00/0 © 1982 American Chemical Society
