PLASTICS:
Lenses for Eyeglasses
Instrumented Buoys Could Help Control Pollution Lockheed Aircraft Corp.'s Oceanics division has equipped this aid-to-navigation buoy in San Diego Bay with specially designed sensor systems which measure water and air temperature, wind speed and direction, barometric pressure, and other environmental conditions every six minutes and transmit the information to a shore-based computer center. The company hopes a network of instrumented buoys anchored off the coasts could provide information for weather forecasting, pollution control, and industry.
BIOCHEMISTRY:
Test for Body Sugar Babies who suffer from inherent defects in their carbohydrate metabolism face the almost certain possibility that such disorders will lead to mental retardation if they go undetected and untreated. Unfortunately, quantitative analytical tests for a variety of sugars in body fluids are unreliable at best, a fact that is the principle underlying reason for the scanty knowledge that exists about inborn errors of carbohydrate metabolism. What promises to be a simple clinical assay technique for saccharides in urine could radically change this picture. The novel gas-liquid chromatographic technique is adaptable to a routine procedure. And it not only detects monosaccharides at the nanogram level, but also differentiates between each sugar in a mixture, Dr. Arthur Furst, director of the Institute of Chemical Biology at the University of San Francisco, and Dr. Jacob Shapira at the biotechnology division of NASAAmes Research Center, Moffett Field, Calif., revealed to attendees at the Pacific Conference on Chemistry and Spectroscopy in San Francisco. Moreover, there's a strong likelihood that the method can be adapted for use in the assay of di- and polysaccharides in urine. It may, in fact, become a rapid, standard routine test for children during their early years, the California biochemists believe. In its current stage of development, the assay entails treating a urine sam-
ple with urease to destroy urea, deproteinating it with zinc sulfate, and then passing it through an ion exchange column to remove salts and other materials. After evaporation to dryness, sodium borohydride is used to reduce the sugars to polyols. These, in turn, are interacted with trifluoroacetic anhydride in acetone nitrile solvent. Using standard gas-liquid chromatographic analysis, the TFA derivatives of the polyols are separated and identified. The entire operation can be carried out within a few hours. On average, the urine samples assayed show 19 major, discrete peaks, Dr. Furst and Dr. Shapira note. They claim to have identified the monosaccharides corresponding to 15 of these peaks, many of which hadn't been identified in urine before now.
Dr. Arthur Furst Detecting inborn errors
The Food and Drug Administration's newly proposed regulation to require that only impact-resistant lenses be used in eyeglasses will have little effect on plastics' slow encroachment on this market. Although the prescription eyeglass market has been moving to greater use of tougher materials, tempered glass is the method of choice for most customers and opticians. Plastic lenses still have the disadvantage of being easily scratched and marred. Only PPG Industries' CR-39 monomer—allyl diglycol carbonate—has had much effect on the use of glass for prescription use, and that has been a steady but slow growth for the past few years. However, PPG doesn't see any great increases in demand for CR-39 if the proposed regulations take effect. Price is probably a factor. CR-39 costs $1.00 a pound in large lots; glass eye lens blanks cost 6 cents a pound. PPG does report greater marketing success in Europe. The greatest success has been in large French cities where CR-39 is capturing about 50% of the glass lens replacement business and about 90% of the plastic lens replacement market. The advantage of CR-39 over polycarbonate, acrylic (used extensively for contact lenses), and other plastics for lens use is greater mar and scratch resistance, but still somewhat below that of glass. The PPG plastic also is easily tinted and finds use in prescription sunglasses. The advantage that tips the balance for plastic in some cases is its light weight. The proposed FDA action is the first step ever taken by a federal agency to set regulatory standards for all eye lenses. Alaska and Connecticut have already enacted legislation requiring the prescribing of impactresistant lenses. Contact lenses and "those instances where the physician feels that the impact-resistant lenses would not meet visual requirements" are exempted. According to FDA, its final regulations will make the sale of soft-glass eye lenses a violation of the Food, Drug, and Cosmetic Act. FDA hopes to "drastically lower the annual toll of eye injuries resulting from accidents to the 100 million Americans who wear prescription glasses." About 20,000 school-age children and 100,000 adults are injured each year because of broken eyeglass lenses. The FDA regulations will include an impact test standard; it consists of dropping a V 8 -inch steel ball weighing 19 grams onto the lens from a height of 50 inches. A minimum thickness will also be specified. OCT. 12, 1970 C&EN 9
