SEC-SAXS: Data Collection
Blu-Ice SECSAXS tab for automated, continuous and strategic SEC-SAXS data collections and analyses
A graphical user interface for automated, continuous and strategic SEC-SAXS data collections and analyses is available on the “SECSAXS” tab of BL4-2 Blu-Ice, a beamline control software at BL4-2. The tab is quite user-friendly and some preset parameters could support most cases of SEC-SAXS data collections. However it is designed to be as flexible as possible, if needed, the user can define each parameter along with SEC-SAXS data collection (e.g. exposure time per image, total number of images, interval between exposures, washing procedure, some options for strategic data collection, timing of trigger signal to UHPLC, etc.). Currently the user can submit up to 50 runs* simultaneously.
*Total number of both data collection and buffer exchange/equilibration.
The following options for strategic SEC-SAXS data collection are available to evade potential SEC-SAXS radiation damage problems (See the beamline SEC-SAXS paper for more details) :
- X-ray shutter control (Figure 4)
The X-ray shutter can be closed after the end of background data (first 100 images are used for background data by default) to prevent undesired darts on the sample cell (fouling). It can be re-opened just before the fractions of interest and then closed again after the fractions. It can be also automatically re-opened/closed when the UV absorbance of a fraction exceeds the UV threshold value. Both options can be used together.
- Additional sample cell cleaning after buffer data collection
The sample cell can be washed after the buffer data collection (typically the first 100 images). Together with the X-ray shutter control options, accurate background subtraction can be performed at a level equivalent to the conventional equilibrium SAXS method.
- Multiple X-ray positions on the sample cell
The user can select the capillary position to be shot for each data collection. This rotational choice of the shooting positions could mitigate accumulating radiation damages of the capillary. Also this eventually results in giving extra washing cycles at the same spot before use. Note that only BL4-2 staff can select and save the positions (up to 5) during setup. Please ask BL4-2 staff for this option in advance.
Figure 3: “SECSAXS” tab on Blu-Ice. (Top) “SECSAXS” tab is designed for automated, continuous and strategic SEC-SAXS data collections and analyses. In most cases, the user could use preset parameters for multiple SEC-SAXS data collections and analyses. (Bottom) A view of real-time UV and Rg/I(0)/I(qL) plots on “SECSAXS” tab. The user can perform SEC-SAXS data collection with watching real-time analysis of current frame.
Figure 4: X-ray shutter control options. See the beamline SEC-SAXS paper for more details.