Here's a well prepared document of the test of some older analyzers

https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=910123W7.TXT

I'm working with TWD about obtaining his Heathkit

This is one of the units in the study conducted by Southwest Research Institute

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I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.