GCR Laser Diffraction Particle Size and Shape Analyzer
This user guide is under construction
II. Sample Preparation
Sample preparation methods vary widely based on the sample type and end goal of the project. For example, some researchers may want only the terrigenous fraction of marine sediments and need to remove all biogenic carbonate, silica and organic matter, while others may focus on the silt-sized fraction of their samples, sieving and discarding everything coarser than their required sizes. Highly water-soluble samples or particles with low wettability may need to be dispersed using an organic solvent. You can adjust the amount of dispersant solution to be prepared according to the number of samples.
A. Preparing the Dispersant
Several dispersants may be used during particle size analyses using the Bettersizer. We discuss a few in the section below:
Sodium Hexametaphosphate (SHMP): Add 40 g of SHMP/100ml of water
Sodium Hexametaphosphate (SHP) + Sodium carbonate (SC)/Calgon: Add 33g of SHC+7g SC/1 l of water
Dish Soap
B. Sample Preparation Steps for Marine Sediments:
1. Pre-treatment Disggregation (for all samples)
Add 1.5 g of sample to a 50ml centrifuge tube.
If your sample is highly cohesive or lithified, you may need to disaggregate it before treatment with any chemicals. Add~20 ml of SHMP+SC solution (Calgon) to the sample.
If your sample is highly cohesive or consolidated, place it in an ultrasonic bath and sonicate it. The sonication time depends on how cohesive the sample is, so you may need to examine your sample vial regularly to check ifthe particles have disaggregated.
You can also place the sample vial on a shaker table for several hours, stabilizing them by placing them in a small beaker or on a test tube rack.
Typically, samples are dispersed overnight or for 48 hours for more cohesive samples.
After disaggregation, cap vials tightly and centrifuge at 3000 rpm/5 minutes. Make sure that centrifuge is balanced. If you have odd number of vials, fill up an empty vial to balance the centrifuge.
After centrifugation, use a 5 ml pipette to carefully draw out the overlying solution (supernatent) without disturbing the sediment below.
Rinse the sediment at the bottom of vial with 20-25 ml DI water. . For this step, pour the DI water into the vial, cap tightly and mix the sediment and water thoroughly using a vortex mixer. Centrifuge the vial at 3000 rpm for 5 minutes and remove the overlying solution carefully with a pipette. Repeat this rinsing process 2-3 times.
2. High Carbonate, Low Opal Samples
a) Decalcification:
Prepare ~300 ml dil. HCl for this step and set aside. You can adjust the amount of HCl according to the number of samples.
Add 15 ml dil. HCl (10 %). Add the HCl slowly using a clean 5ml pipette, allowing bubbles of CO2 to escape without overflowing the vial, leading to sample loss.
Cap vials tightly and centrifuge at 3000 rpm/5 minutes. Make sure that centrifuge is balanced. If you have odd number of vials, fill up an empty vial.
After centrifugation, use a 5 ml pipette to carefully draw out the acid (supernatent) without disturbing the sediment below.
Rinse the sediment at the bottom of vial with 20-25 ml DI water. For this step, pour the DI water into the vial, cap tightly and mix the sediment and water thoroughly using a vortex mixer. Centrifuge the vial at 3000 rpm for 5 minutes and remove the overlying solution carefully with a pipette.
Dip a pH strip into the vial. If the solution is acidic (pH strip comes out red), more rinsing is required.
Repeat this rinsing process till the overlying solution is neutral (usually, this takes three rinses.)
b) Organic Matter Removal:
You will need ~300ml H2O2 (34%) for this step. You can adjust the amount of H2O2 according to the number of samples.
Take a clean 5ml pipette and rinse it with DI water.
Add 15 ml H2O2 (34%) to the decalcified and washed samples using a clean pipette. Add the reagent slowly to avoid excessive bubbling and sample loss as the organic matter and H2O2 react.
Transfer the vials to a boiling water bath for 1 hour. Make sure that the vials are loosely capped to allow gasses to escape the vial.
After the heating step, remove the vials from the water bath and allow them to cool down. Then, cap vials tightly, and centrifuge at 3000 rpm/5 minutes. Make sure that the centrifuge is balanced.
After centrifugation, remove the overlying H2O2 carefully using a pipette.
Rinse the sediment at the bottom of vial with 20-25 ml DI water. For this step, pour the DI water into the vial, cap tightly and mix the sediment and water thoroughly using a vortex mixer. Centrifuge the vial at 3000 rpm for 5 minutes and remove the overlying solution carefully with a pipette.
c) Opal Removal (<5wt% opal):
Prepare 200 ml of 10% NaoH solution for this step. You can adjust the amount of NaOH according to the number of samples.
Add 10 ml of 10% NaOH to the sediments carefully using a clean 5ml pipette.
Transfer the vials to a boiling water bath for 30 mins.
After the heating step, remove the vials from the water bath and allow them to cool down. Then, cap vials tightly, and centrifuge at 3000 rpm/5 minutes. Make sure that the centrifuge is balanced.
After centrifugation, remove the overlying NaOH carefully using a pipette.
Rinse the sediment at the bottom of vial with 20-25 ml DI water. For this step, pour the DI water into the vial, cap tightly and mix the sediment and water thoroughly using a vortex mixer. Centrifuge the vial at 3000 rpm for 5 minutes.
Before removing the overlying solution, check its pH by dipping a pH strip into the vial. Blue color indicates that the solution is basic, and the sample needs to be rinsed further. Repeat the rinsing step till the pH strip indicates neutral pH (this should take ~4-5 rinse cycles).
3. High Opal Samples
a) Organic matter removal:
You will need ~400ml H2O2 (34%) for this step. You can adjust the amount of H2O2 according to the number of samples.
Add ~3 of sample to a 100ml beaker.
Take a clean 5ml pipette and rinse it with DI water.
Add 20ml H2O2 (34%) to the decalcified and washed samples using a clean pipette. Add the reagent slowly to avoid excessive bubbling and sample loss as the organic matter and H2O2 react.
Place the beakers on a shaker table for 24 hours for the reaction to take place.
Wet sieve the sediment to the <63um fraction.
b) Opal removal (>5wt% opal):
Prepare ~400 ml of 20% NaoH solution for this step. You can adjust the amount of NaOH according to the number of samples.
Add 20 ml of 20% NaOH to the sediments carefully using a clean 5ml pipette.
Place the beakers on a magnetic stirring+heating plate and THEN start heating it to 85oC. Hold the temperature at 85oC for EXACTLY one hour, stirring continuously with a clean stir bar during the entire process.
After the heating step, remove the vials from the water bath and allow them to cool down.
Transfer the samples to a 50ml centrifuge tube. Then, cap vials tightly, and centrifuge at 3000 rpm/5 minutes. Make sure that the centrifuge is balanced.
After centrifugation, remove the overlying NaOH carefully using a pipette.
Rinse the sediment at the bottom of vial with 30-35 ml DI water. For this step, pour the DI water into the vial, cap tightly and mix the sediment and water thoroughly using a vortex mixer. Centrifuge the vial at 3000 rpm for 5 minutes.
Before removing the overlying solution, check its pH by dipping a pH strip into the vial. Blue color indicates that the solution is basic, and the sample needs to be rinsed further. Repeat the rinsing step till the pH strip indicates neutral pH (this should take at least 4 rinse cycles).
c) Decalcification:
Prepare ~150 ml dil. HCl for this step and set aside. You can adjust the amount of HCl according to the number of samples.
Add 15 ml dil. HCl (10 %) to your sample. Add the HCl slowly using a clean 5ml pipette, allowing bubbles of CO2 to escape without overflowing the vial, leading to sample loss.
Place the vials within small beakers on a shaker table for 24 hours.
After this, cap vials tightly and centrifuge at 3000 rpm/5 minutes. Make sure that centrifuge is balanced. If you have odd number of vials, fill up an empty vial with an equal amount of water as your sample vial and place it so that the number of vials on opposite sides of the centrifuge are equal.
After centrifugation, use a 5 ml pipette to carefully draw out the acid (supernatent) without disturbing the sediment below.
Rinse the sediment at the bottom of vial with 20-25 ml DI water. For this step, pour the DI water into the vial, cap tightly and mix the sediment and water thoroughly using a vortex mixer. Centrifuge the vial at 3000 rpm for 5 minutes.
Before removing the overlying solution, check its pH by dipping a pH strip into the vial. Red color indicates that the solution is acidic, and the sample needs to be rinsed further. Repeat the rinsing step till the pH strip indicates neutral pH (this should take at 2-3 rinse cycles).
4. Addition of Dispersant to Chemically Processed Marine Sediments (usually > clay/silt size range)
Add ~20 ml of dispersant to the sample vial and mix thoroughly using a vortex mixer. Alternatively, add the dispersant solution to a sample slurry in a beaker and mix well.
Allow the sample + dispersant solution to rest for 48 hours.
5. Addition of Dispersant to Chemically Untreated Marine Sediments (usually fine grained, <clay/silt size range)
Take a clean beaker and label it appropriately with sharpie (Clean the label off later with acetone or ethyl alcohol).
Add a dollop of sediment into the beaker using a spatula.
Add a dollop of SHMP into the beaker.
Add 100 ml of DI water and stir on a magnetic stir plate.
Cover the beaker and store on a plastic container for two days to let the clays disaggregate.
C. Sample Preparation for Soil Samples
Prepare a dispersant solution by adding 33g Sodium Hexametaphosphate + 7g Sodium Carbonate/1000 ml of water
In an appropriately labelled 50ml centrifuge tube, add a dollop of soil sample.
Add 20 ml of dispersant solution using a 5ml pipette. Mix well using a vortex mixer.
Allow the slurry to stand for 48 hours before measurement.
D. Sample Preparation Steps for Metal Powders
To be updated
III. Measurement Set-up
Double-click the Bettersize Laser Particle Size Analysis System V8.20 icon to launch the software.
The software opens to a blank Project page. Right click on the screen and select New Project. Rename the project as appropriate. This creates a new blank project without any measurements inside it.
iii. Double-click on the blank project name to open it. Then, under the Test menu, click on Manual. This opens the the Particle Size Test (Manual) window. Use the Document tab to enter information like sample name, sample number, tester, dispersant, test unit, sample source, sampling method, ultrasonic duration, and rotating speed. This information will be printed in the test report.
iv. Next, set up the measurement parameters by clicking on the Parameter tab (yellow).
v. To set up a new template, click the Setup PMT button to display the PMT Database window, where parameter templates can be created, edited, and selected.
vi. Click on New to create a new set of parameters. Choose the correct parameters for your measurement in the New PMT Window. Use the Save button to create a new template.
NOTE: Refer to the Bettersizer user manual for more information on the specific parameters.
vii. Next, Click on the Water Supply button. This allows water (or your chosen dispersant) to be pumped into the circulation tank, until it reaches the water level sensor.
viii. Click on the circulation button to start circulating water/other dispersant within the instrument.
ix. Bubbles may form during the circulation process, and they can be eliminated by starting ultrasonication. To minimize bubbles, let the water circulate for 3 seconds, then click the Circulation icon to switch it off. After 3 more seconds, switch on the circulation function. Repeat this action 3 times.
x. The circulation and ultrasound settings can be varied to determine the optimum settings for measurement and bubble elimination. The Bettersizer is now ready to measure its first sample
xi. Before beginning the measurement, the instrument should be aligned and any background noise should be eliminated. Click the Auto-Align button to start the automatic alignment procedure to ensure the measurement reliability and accuracy.
xii. Next, Click on the Test tab (green). Here, click the Confirm button to accept the background caused by optic signals that are scattered by pure media and need to be subtracted from the measurement. Once confirmed, these background signals will be removed.
xiii. At this point, the instrument should prompt the user to add sample, in order to reach the appropriate laser obscuration levels to make a measurement. Obscuration levels (in % ) are indicated by a blue bar on the bottom left corner of the test tab under “Obs.” Once the required level of obscuration is reached (green zone), you should get the message “Obscuration is suitable for making test” on the upper right-hand side of the Test tab. See section on Sample addition for further details.
D50 (µm) | >30 | 10-30 | 2-10 | <2 |
|---|---|---|---|---|
Recommended obscuration (%) | 15-20 | 10-15 | 10 +/-3 | 5-10 |
xiv. Click on the Real-time button to observe the particle size distribution results in real time. Wait for the real-time curve to stabilize, then click on Start to perform the measurement.
IV. Sample Addition
Appropriately prepared samples can be added to the Bettersizer for discrete measurements or added in batches of up to 60 and measured consecutively using BT-A60 high throughput Autosampler system. For more details on sample preparation, consult the Sample preparation section of this article.
A. Manual Sample Addition
Place the deflocculated samples (see Sample Preparation - Wet Sediment Analysis for fine-grained sediments (Clay/Silt)) on a magnetic stir plate with an appropriate stir bar and generate a stable vortex.
Take a clean pipette and grab an aliquot of the sample from midpoint of the vertical height and radius of the vortex.
Add the pipette’s contents to the circulation tank and repeat till desired obscuration rate is reached.
B. Sample Addition using the Autosampler system (in progress)
Instead of adding sample to a beaker, samples are added to an autosampler vial using a spatula, and DI water is poured into the vial.
Right-click on the main project page and select” New project”. Name the project as appropriate.
Measurement and Results management
Once the sample is added, a large number of particles appear in the video window, and the required laser obscuration is reached (the green zone).For the recommended obscuration levels, refer to the previous section.
After sample addition, click on the Real-time button to observe the particle size distribution results in real time. Wait for the real-time curve to stabilize, then click on Start to perform the measurement.
At this stage, the instrument disperses the sample over 30s (or for the time interval set in the SOP). At the end of each measurement, results are displayed in the Serial Test Result window. Click on the Save button, then enter the sample name, sample number and click OK to save the test result under Record page.
Close all testing windows after the measurements are finished. The results are automatically saved in the Record page in the order in which they were measured, and the average value of all three runs per sample is automatically calculated by the software.
Double click on a record to view the test results for particle size. You can check the repeatability of your results by performing replicate measurements of the same sample. You can compare between multiple samples by going to the Comparison tab.
Double click on any of the results to open the Result Page Report.
You can check the repeatability of your results by selecting replicate measurements of the same sample or compare between multiple samples by going to the Comparison tab.
There are several ways to export data from the Bettersizer software.
a) To Export/print a data report, select a test result in the Record page and click the Print button to print the report.
b) Alternatively, right click on the blank part of the Result page to export the report in PDF or Excel formats. To export/print a data report, select a test result in the Record page and click the Print button to print the report. Alternatively, right click on the blank part of the Result page to export the report in PDF or Excel formats.
At the end of each measurement, results are displayed in the Serial Test Result window.
Click on the Save button, then enter the sample name, sample number and click OK to save the test result under Record page.
Close all testing windows after the measurements are finished. The results are automatically saved in the Record page in the order in which they were measured, and the average value of all three runs per sample is automatically calculated by the software.
Double click on any of the results to open the Result Page Report. Right click on the result page to view/export the data in your desired format.
There are several ways to export data from the Bettersizer software.
a) To Export/print a data report, select a test result in the Record page and click the Print button to print the report.
b) Alternatively, right click on the blank part of the Result page to export the report in PDF or Excel formats.
3.Right click on the result and select View Result-Image
4. The Results window appears which has tables, images and plots for single particles, particle statistics, L/D and Circularity data.
At each step, you can use the Setup button to customize the output parameters.
Click on Save. This opens the Save Sample window.
Check if the Sample Name is reflected correctly in the “Save Sample As” box. Also check the Sample parameters and information under “Information”.
Select the Save Individual Particle checkbox.
Next, go to Results Management.
Select the Sample you wish to export. In case of multiple samples, use Shift + Select.
Click “Print” and choose the parameter you want to generate the report of.
Once the a pdf of the report is generated, make sure to go to Print and select “Microsoft Print to PDF”, then click OK. This ensures that the reports are correctly formatted and legible.
Reports for multiple samples can be exported as a single pdf file for the following parameters-
Particle Shape: Particle Size Result (Laser), Mesh Sizes Report
Particle Shape: Particle Shape Result (Image), L/D Result, Circularity Result, Size and Shape
Reports for Graph Grading Results and Circularity by Size Class need to be exported separately for each sample.
To generate reports in Excel, click on the “Excel” button in the Results Management—New Project Window. Note that the Excel format is available only for …. Data, and needs to be exported individually for each sample.
Click on “Export” to copy the Laser and Image data to Excel. You can select which types of data you want to export.