\begin{table}%t4
\caption{\label{table:4}Hardness ratio analysis results.} 
%\centering
\par
\begin{tabular}{ c c c c } 
\hline\hline 
\noalign{\smallskip}
Name$^{(1)}$  & $N_{\rm{H}}$$^{(2)}$  \\ 
\hline  
2QZ J003814.3-273130 & $\rm 12.05^{+3.50 }_{-4.10 }$ \\ 
SDSS J004206.18-091255.7 & $\rm 3.00^{+2.2 }_{ -2.00 }$ \\ 
XMMU J010316.7-065137 & $<$0.10 \\ 
SDSS J010941.97+132843.8 & $\rm 0.98^{+0.25 }_{ -0.35 }$ \\ 
$[$WFM91$]$ 0226-1024 & $\rm 5.60^{+1.60 }_{ -1.50 }$ \\ 
SDSS J024230.65-000029.6 & $\rm 65.00^{+40.00 }_{ -20.00 }$ \\ 
SDSS J072945.33+370031.9 & $<$0.10 \\ 
SDSS J073405.24+320315.2 & $\rm 1.30^{+0.20 }_{ -0.4 }$ \\ 
SDSS J083633.54+553245.0 & $\rm 1.55^{+0.25 }_{ -0.35 }$ \\ 
SDSS J091914.23+303019.0 & $\rm 1.30^{+0.30 }_{ -0.35 }$ \\ 
SDSS J092138.45+301546.9 & $\rm 8.80^{+3.40 }_{ -3.60 }$ \\ 
SDSS J092142.57+513149.4 & $<$0.10 \\ 
SDSS J092345.19+512710.0 & $\rm 1.30^{+0.70 }_{ -0.60 }$ \\ 
SDSS J093918.07+355615.0 & $<$0.10 \\ 
SDSS J094309.56+481140.5 & $\rm 5.20^{+4.50 }_{-3.00 }$ \\ 
SDSS J095548.13+410955.3 & $<$0.10 \\ 
SDSS J095942.08+024103.1 & $\rm 19.60^{+10.00}_{ -12.00 }$ \\ 
SDSS J095944.47+051158.3 & $\rm 6.90^{+2.50 }_{ -3.00 }$ \\ 
SDSS J100038.01+020822.3 & $\rm 6.50^{+2.00 }_{ -4.00 }$ \\ 
SDSS J100145.15+022456.9 & $\rm 1.40^{+0.70 }_{ -0.40}$ \\ 
SDSS J101614.26+520915.7 & $<$0.10 \\ 
SDSS J101954.54+082515.0 & $\rm 20.00^{+8.30 }_{ -10.00 }$ \\ 
SDSS J104433.04-012502.2 & $<$0.10 \\ 
SDSS J110637.16+522233.4 & $\rm 1.90^{+1.00 }_{ -1.00 }$ \\ 
SDSS J110853.98+522337.9 & $<$0.10 \\ 
SDSS J111859.56+075606.5 & $\rm 5.20^{+3.20 }_{ -4.00 }$ \\ 
SDSS J112300.25+052451.0 & $\rm 15.90^{+2.00 }_{ -4.00 }$ \\ 
UM 425                & $\rm 1.20^{+0.1 }_{ -0.2 }$ \\ 
SDSS J112432.14+385104.3 & $\rm 13.00^{+5.70 }_{ -2.50 }$ \\ 
SDSS J113537.67+491323.2 & $<$0.10 \\ 
SDSS J114111.61-014306.6 & $\rm 2.50^{+1.00 }_{ -0.60 }$ \\ 
SDSS J122637.02+013015.9 & $\rm 6.00^{+1.90 }_{ -2.20 }$ \\ 
SDSS J122708.29+012638.4 & $\rm 1.40^{+1.00 }_{ -0.80 }$ \\ 
SDSS J123637.45+615814.4 & $\rm 1.50^{+0.40 }_{ -1.00 }$ \\ 
LBQS 1235+1807B & $<$0.10 \\ 
SDSS J124559.59+570053.1 & $<$0.50  \\ 
SDSS J132401.53+032020.6 & $\rm 12.70^{+6.40 }_{ -4.00 }$ \\ 
SDSS J132827.07+581836.9 & $\rm 29.00^{+12.00 }_{ -9.00 }$ \\ 
SDSS J133639.40+514605.2 &  $<$0.10 \\ 
SDSS J134059.24-001944.9 & $<$0.10 \\ 
HELLAS2XMM J140049.1+025850 & $\rm 11.00^{+5.00 }_{ -5.00 }$ \\ 
SDSS J142555.22+373900.7 & $<$0.10 \\ 
SDSS J142652.94+375359.9 & $\rm 0.95^{+0.50 }_{ -0.30 }$ \\ 
SDSS J144625.48+025548.6 & $\rm 7.60^{+3.50 }_{ -4.50 }$ \\ 
SDSS J150858.15+565226.5 & $\rm 3.20^{+0.45 }_{ -1.00}$ \\ 
SDSS J151729.70+001652.6 & $<$0.10 \\ 
SDSS J153322.80+324351.4 & $\rm 0.90^{+1.20 }_{ -0.30 }$ \\ 
SDSS J203941.04-010201.6 & $\rm 3.00^{+2.00 }_{ -1.50 }$ \\ 
SDSS J231850.79+002552.6 & $\rm 8.30^{+5.00 }_{- 4.00 }$ \\ 
\hline 
\end{tabular}
\par
\tablefoot  {Column~(1): Source name;  Col.~(2): Neutral hydrogen column density estimated from hardness ratio. Errors correspond to 1$\sigma$ confidence intervals and estimated from the count-rate errors.} 
\end{table}