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Abstract  

Initial plant scale trials of the nitrosation of an amino acid revealed a number of issues: _ Much lower yield compared to laboratory scale _ Considerable loss of mass balance _ Large excess of nitrosating agent required for complete reaction _ Highly reactive off-gases produced causing fires in the carbon absorber _ Reaction sensitive to agitation speed _ The by-product produces an impurity in the next process stage which has high human toxicity A kinetic and mechanistic study of the nitrosation reaction, using isothermal power compensation calorimetry and GC/mass spectrometry, has been undertaken in order to understand the above observations and to produce an improved manufacturing process - more robust, higher yielding, reduced effluent volumes and toxicity.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Seymour, S. Hinshaw, T. Nashabishi, C. Cox, B. Coyne, P. Sangsingkeow, and W. Graves

Abstract  

Measurements at counting rates above 50,000 counts per second require specialized pulse processing electronics. New preamplifier technology incorporating an injection junction field effect transistor with integral reset gate provides superior throughput with better low energy resolution. Data acquisition at short peaking times permits maximum throughput with minimum pile-up. Over the past ten years, amplifier throughput of unpiled-up pulses improved. Now it is possible to correct the pulse amplitudes as they are processed, improving performance over older methods. Trapping and ballistic deficit are both greater in high rate measurements, where the shorter amplifier peaking times employed result in larger amplitude variations of the amplifier output pulse. Charge trapping may occur in any sized detector. The Goulding-Landis method corrects best for charge carrier trapping while the Hinshaw method works best for ballistic deficit effects.

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