The Boltzmann-plot ( BPT ) method for laboratory plasma diagnostic was used for a quick estimate of physical conditions in the Broad Line Region ( BLR ) of 14 Active Galactic Nuclei ( AGNs ) .
For the BLR of nine AGNs , where PLTE exist , the estimated electron temperature are in the range T \sim 130000K - 37000K are in good agreement with previous estimates .
The estimated electron densities depend on the opacity of the emitting plasma in the BLR , and they are in range from 10 ^ { 9 } cm ^ { -3 } ( for optically thick plasma ) to 10 ^ { 14 } cm ^ { -3 } ( for optically thin plasma ) .
Although an alternative of PLTE in some AGNs may be very high intrinsic reddening effect , this method may be used for fast insight into physical processes in the BLR prior to applying more sophisticated physical models .