Infrared device, concentration measurement

Many industries regularly conduct repeat insult patch tests on human volunteers to evaluate topical irritancy. Groups of human volunteers are patched with test substance. One to five concentrations can be tested simultaneously, a wide enough range to yield results relevant to the usage. Cumulative skin irritancy is measured by applying patch applications each day for 3 weeks. Skin irritation is usually assessed visually, but blood flow and skin temperature can be measured objectively by laser Doppler flowmetry, ultrasound Doppler, heat flow disk measurement, sensitive thermocouple devices, or noncontact infrared radiative techniques. In these tests, dose-response curves can be obtained. Skin thickness can be measured with calipers as a measure of edema formation. 

Several measurement techniques exist for the determination of short-term concentrations. Depending on the exposure situation, there is a choice of easily usable, directly indicating sampHng devices (see Section 6.9.3.1), e.g., substance-unspecific analytical instruments Hke photoionization detectors (PID), flame ionization detectors (FID), infrared analyzers (see Section G.9.3.4), and specific sampling techniques based on adsorption on a substrate and thermodesorption (Section 6.9.4). 

The extent of reaction ( is determined by mass balancing the open system in steady state. The concentrations of carbon monoxide and carbon dioxide are measured by non-dispersive infrared spectroscopy (Binos, Rosemount), oxygen is determined by use of a magnetic device (Magnos 3, Hartmann fz Braun). 

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