The little Chem/ Meter : big on accuracy Take a look at all the outstanding features in our Series 20 C h e m / M e t e r hydraulic diaphragm metering p u m p : Metering accuracy w i t h i n - 1%. Steady, continuous feeding of clear fluids. Capacities of 14.7 M L / m i n . Pressures to 1500 psi. Zero to 100% capacity adjustment while operating. Totally enclosed, leakproof design. Wetted parts made of corrosive resistant stainless steel with sapphire ball-seats and teflon diaphragms. Measures only 10>?" x 5" x 3Y?". The Series 20 C h e m / M e t e r is ideal for machinery that requires the injection of precisely measured liquids. These include plastics, pharmaceuticals, chemical process, foods, beverages and fertilizers. For larger measuring requirements from 23 to 3024 M L / m i n we have the Series 200 Chem/Meter. You can get all the de tails on the reliable C h e m / M e t e r line by calling or w r i t i n g Crane Co., C h e m p u m p Division, Warrington, Pa. 18976.
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Automated Measuring Saves Lab Time. If you measure viscosity with the capillary m e t h o d , there's a SCHOTT AVS System for y o u . If you don't, maybe you s h o u l d . The fully automated AVS/PA will test up to 30 different samples w i t h o u t operator supervision. Select the program and let it g o ! Variable program capabilities include: number of rinses, number of repeat measurements, test temperature, sample temperature c o n d i t i o n i n g period, suction rates and more. Standard-temperatures up to 150°C; High Temperature-up to 220°C. Measuring accuracy 0.1 % with a range up to 500 c ST Semi-Automated models also available. Building block concept allows expansion from basic unit to fully automated unit.
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11 EAST 26TH STREET, NEW YORK, N.Y. 10010/(212) 679-8535 CIRCLE 198 ON READER SERVICE CARD
1332 A . ANALYTICAL CHEMISTRY, VOL. 5 1 , NO. 13, NOVEMBER 1979
blood sugar level. Many physicians be lieve an improved ability to prevent swings in blood sugar may prevent the usual complications of diabetes, in cluding heart disease, blindness, cata racts, blood vessel damage, nerve dis orders, and kidney damage. Such improvement in control is af forded by the use of reagent strips produced by a number of manufactur ers. In one type of reagent strip, a drop of blood is placed on a semi-per meable membrane. Blood cells do not pass through the membrane, but blood filtrate is exposed to the reagent system underneath. Glucose oxidase in the reactive area dissolves in the fil trate, converting any glucose present to gluconic acid. Hydrogen, removed from the glucose in the glucose oxi dase reaction, combines with atmo spheric oxygen to form hydrogen per oxide. In the presence of peroxidase, the hydrogen peroxide oxidizes chromogen indicator, producing gray to blue-purple colors. The color may be visually compared to a color chart or analyzed in a reflectance colorimeter. In the Rockefeller University study, patients were taught to monitor their own blood glucose with the reagent strips and were encouraged to main tain their blood glucose level between 70 and 140 mg/dL. They were also taught to calibrate exercise, food, and insulin in terms of their effects on blood glucose levels. For example, a given type of candy would be found to increase a patient's blood sugar by about 20 mg/dL. The patient could then use three of these candies to cor rect a hypoglycemic episode. Patients were encouraged to perform similar experiments with various types of foods. And blood glucose response to exercise and to particular doses of in sulin was tested in a similar fashion by each patient. They were encour aged to perform blood tests before and one hour after each meal and to adjust their glucose levels when necessary with the variables at their command. At the end of the study, Peterson concluded that improved control of blood glucose through the program of patient-monitored blood sugar had been demonstrated and that systolic blood pressure, alkaline phosphatase concentration, and nerve conduction abnormalities had been ameliorated. Peterson also suggested that the pro gram was cost effective through the avoidance of diabetes-related hospi talizations that would occur in the ab sence of the close control made possi ble by the patient self-monitoring. As Peterson puts it, "It gives people a chance to do something about their condition. That's what makes people with chronic diseases depressed—the sense of helplessness and hopelessness that comes with any chronic disease."
