the efficiency of the mercury absorption by the filter amounts to no less than 99%, the loss of benzene during passing through the filter being not more than 3%. Our experience of work with the filter demonstrates that it retains operability for a long time (as long as a year). Besides mercury, there exist molecules with electron absorption bands in the 254 nm spectral region with partially resolved vibrational-rotational structure, which may give rise to false signals n measuring benzene content.