New PPB techniques exploit X-Ray emission, improve trace-element determination! There's no real question of the feasibility of doing P P B techniques with x-ray emission. For petroleum, pharmaceuticals, metal lurgy or other process industries — General Electric X R D equip ment delivers analyses in the parts-per-billion range — with precision and consistent reproducibility. T h e petroleum appli cation cited here (see chart) demonstrates a repeatability in the range of 5 to 50 P P B , for copper, iron, nickel and vanadium. Still another chemical processor uses X R D equipment for an alyses of lighter elements — Al through Ti — over a range from ten to a few hundred P P M . General Electric supplies X R D with widely diverse applications to perform P P B studies with flexibility and minimum detectability *j High wattage characteristics with up to 100-ma sample excitation give minimum percentage quantities U Choice of six tube targets offers selective excitation If Thin x-ray tube window (.010" Be) provides long wave length output for light element analyses fl Twin counter tubes with ultra-thin windows for widest spectral range efficiency U Samples u p to 2*4" square or 3" diameter and 1 ^ " thick can be conveniently presented U And, all these advantages can be obtained on programmed equipment. For further details on applications, and methods already proven in use, write Room UU-74, X-Ray Department, General Electric Co., Milwaukee 1, Wisconsin.
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CONCENTRATION RANGES AND REPEATABILITY OF METHOD Element Copper Iron Nickel Vanadium
Concn. range (PPM)
Standard Deviations*
0.003-0.03 0.03 -0.1 0.04 -0.4 0.4 -5.0 0.01 -0.1 0.1 -0.5 0.01 -0.1 0.1 -0.5
-0.003 ±0.011 -t-0.033 ±0.51 + 0.005 ±0.011 -i-0.006 ±0.010
*Based on differences between the two values in respect ve duplicate determinations on 10 samples in each concentration range. For the high range, relative accuracy at Pure Oil Company in determining the amount present varies approximately 2%—in the lowest range up to 50%.
General Electric XRD equipment at Pure Oil Company Re search Center (Crystal Lake, III.) analyzes refinery feed stocks for trace-metal concentrations from 0.003 to 5.0 PPM.
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