The invention relates to an instrument coupled
speciation measuring method of a gaseous
arsenic compound, solving the problems of sensitive, fast and accurate analysis and measurement of the gaseousarsenic compound. The method is carried out on a gaseous
arsenic compound analyzing and measuring on-line coupled
system comprising a standard generation or
sample collection device, a low-temperaturetrapping device, a vacuum heat-insulation separating tank, a gas-carried pipeline, a
hydrogen generation device, an
atomic fluorescence spectrometer and a
signal recording device and comprises the following steps: a, generating an
arsenic compound or collecting samples; b,
trapping and separating the gaseous
arsenic compound; c, separating the gaseous
arsenic compound; and d, detecting the gaseous
arsenic compound. The invention has the advantages of ideal separating effect on the gaseous arsenic compound, good reproducibility, high sensitivity, good linear independence of the gaseous arseniccompounds with different concentrations, wide
linear range, good stability, low cost, simple operation and low analysis cost.