  In this article, a practical procedure for absolute intensity calibration for
SAXS studies on liquid microjets is established, using a gold nanoparticle
suspension as standard so that the intercept at $Q=0$ of the SAXS scattering
curve would provide a scaling reference. In order to get the most precise
extrapolation at $Q=0$, we used an extension to the Guinier approximation, with
a second-order term in the fit that adapts to a larger $Q$-range.
