Easily portable automatic polarographic analyser - esp for determn of formaldehyde concn in vehicle exhaust gases

摘要

Polarographic analyser is of the type in which a sample to be analysed is diluted in an electrolyte inside a cell contg. a reference electrode and an indicator electrode between which a scanning voltage is applied which varies as a linear function with time, a measurement of cell potential being related to an evaluation of active ions in the sample. The indicating electrode is of fixed area, the proportion of active ions in the sample is held low enough to keep electrode response within linear range, the voltage scanner producing an inter-electrode current which is passed via a transformer to a limiting voltage circuit using a condenser and diode to register a stable period reading on a voltmeter. Used for repetitive, quantitative, polar graphic analyses of multiple samples to determine the concn. of active ions which are oxidizable or reducible by electrolysis, e.g. most metals and some org. functional gps. such as aldehyde ketone, amino and mercaptan. Device is used esp. to check concn. of formaldehyde in combustion prods., trapped from the exhaust systems of internal combustion engine vehicles. The appts. is easily portable, robust and simple to operate without extensive training. It is also inexpensive compared with its predecessors and produces accurate results at high speed.