The Autosampler is fully integrated into the BluIce control system of the beamline. Together with the data reduction and analysis tools (SasTool and SAXSPipe) available at the beamline, the BL4-2 Autosampler is part of a fully integrated solution scattering pipeline.
- 10-30ul sample/buffer volume for a data set 1)
- Minimizing radiation damage by oscillating sample during data collection
- Fast data collection (3-5min/set, 96 samples in 5-8 hours) 2)
- thorough cleaning of capillary, needle and tube (with user customizable cleaning procedure)
- 1.5mm quartz capillary cell
- Sample recovery after data collection (option)
- 96-well plate compatible sample rack with temperature control
- uses VWR 0.2ml 8x PCR strip or half-skirted 96 well-plate:
|type||manufacturer||VWR catalog number|
|0.2ml 8x PCR strip||VWR||20170-004|
|96 well-plate (half-skirted)||VWR||83007-374 , 83007-372|
1) Depending on radiation damage (i.e. total dose on sample). A 30-ul sample volume (our standard) usually provides good results. We encourage the user to bring more volume of sample and buffer (see below).
2) Depending on data collection and washing procedure.
Sample volume and total irradiation to sample are associated with radiation damage. Our standard sample volume for Autosampler is currently 30ul per data acquisition (i.e. per tube). In most case, this provides good result with typical data collection like 10-15 images with 1sec exposure. Please contact BL4-2 staff if you need to minimize sample volume.
We generally recommend taking 3-7 different concentrations of your sample in the same buffer (concentration series). Concentration range is depending on sample (e.g. nucleic acid more scatters X-ray than protein) and sample size. For example, a concentration series from 0.3 to 5mg/ml is good for BSA (~70kDa, Rg=~35 Å), while for Lysozyme (~14kDa, Rg=~14 Å) concentration series of 0.5 to 10mg/ml should be used. To extrapolate zero concentration curve, try to measure the sample with the concentration as low as possible.
You need to aliquot buffer and sample to PCR tube. A PCR strip should be used for a concentration series and identical buffer. Buffer is always applied to the left side (position A) and other tubes are used for sample concentration series (position B-H). Depending on option of buffer data collection described below, you need more than 60ul of buffer in A. Needle height of Autosampler is optimized for VMR 0.2ml 8x PCR strip (catalog number: 20170-004). Do NOT use different PCR tubes! Watch the following video for more details.
[Important!] The BL4-2 Autosampler can deal with such low sample volumes but we encourage the user to bring more volume of sample and buffer, which make it easy to do sample preparation at the beamline (pipetting, centrifugation, filtering, etc.) and could be safe for unexpected sample loss (e.g. sample precipitation, evaporation, etc.).
Buffer data collection option
Following options for buffer data collection are available in Blu-Ice SolSAXS tab for "AlwaysBuffer?" choice:
- checked: taking buffer data sets every time before each concentration. If you have buffer in tube position A and 4 protein concentrations in tube position B-E, you will get 8 data sets (A, B, A, C, A, D, A, E). In this case, you need 120ul (= 30ul x 4) of buffer in tube A.
- unchecked (our standard): taking buffer data sets before and after concentration series. If you have buffer in tube position A and 4 protein concentrations in tube position B-E, you will get 6 data sets (A, B, C, D, E, A). In this case, you need 60ul (= 30ul x 2) of buffer in tube A.
Customizable and powerful cleaning procedure for accurate background subtraction
Accurate background subtraction is critical for subsequent analysis. All data is taken at the exactly same position of the same capillary and thus the capillary should not have any dirt like radiation-damaged sample on the wall. Autosampler equips Hamilton fluid dispenser for sample loading and cleaning. Detergent, bleach, and ethanol are generally used for cleaning procedure. After each data collection, all places sample passed through (capillary, needle and tube) can be perfectly washed with oscillating those solutions for next data set. Since cleaning procedure is very depending on your sample and experiment, it is also customizable by user.
Video tutorial for BluIce SolSAXS tab
Martel A, et al., An integrated high-throughput data acquisition system for biological solution X-ray scattering studies. (2012) J Synchrotron Radiat. 19(Pt 3):431-4.