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- Buehler Grinder/Polisher
- Diamond grinding disk disc
- Sample Beaker
Each sample will correspond to one beaker; collect as many beakers as needed. Beakers need to be cleaned (DI water and isopropyl alcohol) and labeled (ex. 1, A, or sample label).
Next start the grinding process using the Buehler grinder located in the Xray prep X-Ray preparation area of the thin section lab Thin Section Lab (Figure 1).
Note: The diamond disc is attached to a magnetic disc which is then placed on the wheel plate. Diamond disks are located on the stud shelf in ICP prepthe X-Ray preparation area of the Thin Section Lab. Use the silver or purple diamond diskdisc.
Figure 1: Buehler Grinder Polisher. A. On/Off switch B. Power Indicator light C. Timer On/Off button D. Water On/Off switch E. Water flow control knob F. Disc speed control. G. Stop/Start. H. Emergency Stop.
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Polish the rocks with a Breuler diamond disc (Figure 2) until they're completely smooth and round on all edges. The purpose of grinding on a diamond disc is to remove any possible contaminates caused by the drilling mud (or drill bit) or the rock saws in the splitting room. There should be no pits or jagged corners. Put the rock into a labeled beaker (Figure 3). Before polishing the next sample, clean the diamond disc with a dressing stone. Dressing stones are found in the Splitting Room of the Core Lab. Do this for all samples and then move on to 'Cleaning Samples'.
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See XRD Sample Preparation Hard Rock
Part in blue below to be deleted
The X-Press is a motorized hydraulic press that crushes samples into smaller pieces.
First, clean the X-press with simple green and isopropyl alcohol. Clean the work area and all materials with isopropyl alcohol for each sample. Place a large KimWipe on your working surfaces for your clean materials. Next collect the following supplies that make up the 'crushing unit' of the X-press (Figure 7). Materials are located in the drawer labeled 'X-PRESS SUPPLIES' in the X-Ray Prep Area in the Thin Section Lab.
- Weighing Paper 6" x 6"
- Core liner
- Two delrin discs
- Stainless steel base
- Aluminum Die
Figure 7: Materials needed for assembly of ‘crushing unit’. A) Weighing Paper 6”x6”. B) Core Liner. C) Two Delrin Discs. D) Stainless Steel Base. E) Aluminum Die.
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- Grab the stainless steel dish. This is the base for the crushing unit (Figure 8).
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- Place a piece of Weigh Paper on the Base (Figure 9).
Figure 9. Dish with Weigh paper
- Put one Delrin disc on top of the weigh paper (Figure 10).
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- Place the sample on top of the Delrin Disc (Figure 11). These discs can fracture leaving Teflon flakes in the sample so arrange the sample such that the two flattest surfaces are the top and bottom.
Figure 11. Sample Added
- Now place the second delrin disc on top of the sample (Figure 12). Again make sure the disc rests flat against sample (as flat as it can be).
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- Put the aluminum die on top of the delrin disk, holding it until you slip the core liner over the unit (Figure 13).
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- Now slip the piece of core liner over all the pieces and sit it inside the stainless steel base (Figure 14).
Figure 14. Core Liner added
- The crushing unit is now assembled and we can start crushing samples (Figure 15).
Figure 15: Overview of the X-Press. A) Metal platform sample rests on. B) Jacksrew. C) Pressure Relief Handle. D) ‘On’ toggle. E) Pressure Gauge.
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Crush the sample by continuously holding down the toggle switch (Figure 15D). The motor and pump can be heard and the pressure will rise (Figure 15E). Once pressure is about 5tons the toggle can be released and the sample will sit under that pressure. For most samples ~5 tons of pressure is enough force to crack it. If you find the need to go near 10 tons, try rotating the sample onto another side and repeat the process again. Taking the pressure up greater than 10 tons can cause the disks and the core liner to shatter. Contaminating the samples and creating a safety hazard.
Safety Note: Always wear safety glasses. Do not stand directly in front of the X-Press while it is operating. Never leave the X-Press unattended while using. Do NOT take the instrument above 10 tons of pressure.
After the sample has cracked remove the crushing unit. To remove the unit, loosen the 'pressure relief handle' (Figure 15C) by rotating it counter clockwise and press down on the toggle switch. The pressure gauge should read zero and the metal platform will lower down. Do not leave the platform up, always make sure to lower it back down after crushing a sample (you can use the jackscrew to lower the metal platform if it does not automatically fall once pressure is released). When the platform is level with the surface let go of the toggle and start unscrewing the jackscrew. Then open the door and remove the sample crushing set up. The pieces can be poured into a labeled bottle that will eventually hold the finely ground powder. From here the pieces will then be put into the Shatterbox vessels.
If pieces are still too large to fit in the shatter box vessel (see Figure 21) then repeat the same setup and crush it again. Look out for and remove any pieces of the Delrin Discs that may have chipped off and gotten into the sample. Leaving pieces of the Delrin Discs in the sample will cause contamination.
Grinding Samples in the Shatterbox
See XRD Sample Preparation Hard Rock
The shatterbox takes the crushed pieces from the X-Press and grinds them into a very fine powder. The Spex shatterbox is capable of grinding three standard size samples or one large sample. Our grinding vessels used are tungsten carbide.
Apparatus and Materials
- Shatterbox
- Tungsten Carbide Vessels: Vessel, Puck, and Lid
- Samples
- 1oz Sample Vials
- Sample Labels
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Determining LOI
Loss on Ignition, or 'LOI', compares a mass measurement taken before and after a sample is subjected to extreme heat. Petrologists use LOI as an indication of degree of alteration. Low LOI values suggest relatively fresh, unaltered basalt; whereas high LOI numbers suggest alteration (clay, alteration minerals, etc.). LOI is determined by weighing a small amount of the sample (~5 g) before and after ignition. Samples typically lose weight as water is driven off, though an iron-rich, water-poor sample may gain weight.
LOI is not required for all types of ICP Preparation. Check with the science party to determine if LOI is a desired measurement. If the science party does not want an LOI measurement move on to the section Making the Sample Bead.
Loss on Ignition
Determining a sample LOI comprises three procedures:
- Pre-ignition weighing
- Igniting samples
- Post-ignition weighing
Advice on LOI Procedures (from Exp. 366 Methods)
Shipboard sample preparation and LOI determination procedures described in Murray (2000) and updated in recent IODP Proceedingsvolumes (e.g., Reagan et al. [2015] for Expedition 352) are appropriate for a range of sediment and rock compositions, but some care must be taken with unusual sample matrixes. As an example, attempting sample ignitions on carbonate-rich materials can lead to spurious results and issues with contamination if quartz crucibles are used for sample ignitions because carbonates will react with quartz upon heating to both devitrify and decompose the crucible. Alumina ceramic crucibles may be better for carbonates but risk contamination for Al and potentially other elements due to spallation over time. Maximum ignition temperatures of 1000°C and higher are appropriate for ultramafic and some
Figure 16. Shatterbox. A. Power switch. B. Cover. C. Control panel.
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Figure 17. Small vessel components. A. Container B. Puck. C. Lid.
The large grinding vessel holds between 20 – 60mLs of material and has five components: a container, puck, inner ring, O-Ring and lid (Figure 18).
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Figure 19. Large Vessel components. A. Container B. Inner Ring C. Puck D. O-Ring E. Lid.
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Figure 19. Three-pinned rack plate to hold three small vessels in Shatterbox
Figure 20. Single-pinned rack plate to hold one small vessel in Shatterbox
The three-pinned plate will hold three vessels while the one-pinned plate will only hold one. If two samples need to be crushed select the three-pinned plate. The large vessel will sit directly in shatterbox without an additional plate below it.
Loading the Shatterbox
Transfer the sample pieces into the grinding vessel. Pour sample pieces between the puck and the wall of the vessel (Figure 21). There can't be any material on top of the puck or inside the sealing ring; otherwise the vessel will not seal properly and the sample can spill inside the shatterbox. If any pieces are on top of the puck or ring, use gloves, tongs, or a KimWipe to move the sample into the vessel. Put on the lid and start assembling the shatterbox.
Figure 21. Small vessel filled with sample pieces. No sample material is on the top the puck or in the lid ring.
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Figure 22. The inside of the Shatterbox. A. The lever arm B. The clamp arm C. The inner capsule.
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Figure 23. Inside the Shatterbox with the bottom three-pinned rack plate resting inside the inner capsule.
Now load vessels onto the plate (Figure 24). The divet in the bottom of the vessels will settle onto the pins and fit firmly in place.
Figure 24. Three samples loaded into the Shatterbox.
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Figure 25. The top rack plate sitting on top of the three samples. A. Clamp arm. B. the “boss” of the rack plate, where the clamp arm will attach.
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Figure 26. A. The lever arm inserted into the end of the clamp arm. B. The clamp arm pushed over the lever arm.
The resistance in the lever arm is very important and must be adjusted before use. There should be moderate resistance in the arm while pushing it down. If the resistance is too low the containers can shake free; whereas, if it's too strong the clamp can break. Ideal tightness is just past the point where the vessels can be rotated while the clamp is down. Adjust the resistance by raising the clamp arm and pushing on the 'locking pin.' Hold the locking pin and turn the guide (Figure 27A). Rotating the guide clockwise decreases resistance; whereas counterclockwise increases resistance.
Figure 27. The lever arm and the guide. A. Retractable locking pin being pushed to allow adjustment of the 'guide' length.
Now close the lid and turn the emergency stop switch to 'On'. This does not start the shatterbox but does enable operation. If an emergency shutdown is needed, flip this switch to 'Off' and all shaking will stop even though the timer will continue to count down.
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Figure 27. A. Current operating time. B. Minute button. C. Second button. D. Start button. E. Pause/Stop button.
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Normal Sounds: The shatterbox is extremely loud. The foam and strap surrounding the shatterbox helps keep it in place and minimize some of the noise.
Abnormal Sounds. If there are any metal on metal sounds shut off the shatterbox immediately. Something inside the shatterbox has probably come loose and will damage the inside of the container.
When the shatterbox cycle is done open the lid and remove the vessels, placing them on the counter. Open the grinding vessel and with clean tweezers take a bit of the powder and feel it against the inside of your wrist. The sample should feel like talc powder, if it does not, repeat the shatterbox cycle.
Transfer powder into Vial
Disassemble the vessel carefully wearing 'Powderless Nitrile' gloves. Clean off any powder on the lid or puck with clean gloves or a Kim Wipe. Carefully remove the puck from the vessel. Pour the sample onto a clean weighing paper. If any powder remains, use a clean plastic spatula, brush, or your finger to dislodge it.
Note: Never use metal to dislodge sample material, as any grooves or scratches in the vessels will increase the risk of contamination.
Cleaning the Grinding Vessels
Vessels must be cleaned in between samples and after all samples have been run for the day. Vessels should never be put away wet. This alters and tarnishes the vessel.
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- Wearing nitrile gloves, wash the individual pieces of the grinding vessels with DI water and a small piece of a scouring pad (no soap).
- After each washed piece piece immediately spray it with isopropyl alcohol and wipe it down with a Kim Wipe. Do not use the ship's compressed air line to dry pieces as the air is too dirty.
- Lay the pieces on, and cover vessels with Kim Wipes.
After the last run for the day
- Take a scoop of quartz sand and put it in your vessel and run it as you would a sample for several minutes.
- Remove the vessel and empty out the sand. Scrub the pieces with DI water and a scouring pad. Then spray with isopropyl alcohol and wipe down with Kim Wipe.
If your vessel is particularly dirty run a combination of quartz sand, a little hot water and detergent (Borax). This can be run for several minutes. A thick paste will form and you clean it with DI water and isopropyl as in the other cases.
Determining LOI
Loss on Ignition, or 'LOI', compares a mass measurement taken before and after a sample is subjected to extreme heat. Petrologists use LOI as an indication of degree of alteration. Low LOI values suggest relatively fresh, unaltered basalt; whereas high LOI numbers suggest alteration (clay, alteration minerals, etc.). LOI is determined by weighing a small amount of the sample (~5 g) before and after ignition. Samples typically lose weight as water is driven off, though an iron-rich, water-poor sample may gain weight.
LOI is not required for all types of ICP Preparation. Check with the science party to determine if LOI is a desired measurement. If the science party does not want an LOI measurement move on to the section Making the Sample Bead.
Loss on Ignition
Determining a sample LOI comprises three procedures:
- Pre-ignition weighing
- Igniting samples
- Post-ignition weighing
Advice on LOI Procedures (from Exp. 366 Methods)
Shipboard sample preparation and LOI determination procedures described in Murray (2000) and updated in recent IODP Proceedingsvolumes (e.g., Reagan et al. [2015] for Expedition 352) are appropriate for a range of sediment and rock compositions, but some care must be taken with unusual sample matrixes. As an example, attempting sample ignitions on carbonate-rich materials can lead to spurious results and issues with contamination if quartz crucibles are used for sample ignitions because carbonates will react with quartz upon heating to both devitrify and decompose the crucible. Alumina ceramic crucibles may be better for carbonates but risk contamination for Al and potentially other elements due to spallation over time. Maximum ignition temperatures of 1000°C and higher are appropriate for ultramafic and some mafic igneous materials but may result in sample sintering and/or sticking to some Si- or Ca-rich materials. Ignition temperatures of <850°C are inadequate to decompose carbonate minerals in sediment samples, even if samples are held at temperature for several hours. In general, igniting samples to at least 900°C as a maximum temperature is advisable to decompose all volatile-bearing phases and obtain reliable measures of LOI.
Pre-ignition Weighing
Apparatus and Materials
- Mettler Toledo Dual Balance
- Acid Washed Quartz Crucibles
- 4x4 Weigh Paper
- Reference Weights
- Thermolyne Muffle Furnace
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Graphical Measurement Window: Shows a line graph of the live-time measurement weight and the running average weight.
Final Weight Panel: Displays the Final Weight after all measurement counts have been made.
Statistics Panel: Shows the average weight adjusting with time.
Counter Weight: Enter in the reference weight Counts: The elapsed amount of measurements
Tare: Shows and applies the tare or 'zero' value.
Sample ID: Name the sample being measured.
Commands Panel: Executable commands
Weigh: Starts measurement
Tare: Determines the 'zero' weight. This value is applied to the final weight.
Halt: Stops a measurement before it has gone through all counts
History Panel: Shows statistics on all measurements taken. This file can be exported into an excel file by using the 'Export' button. Note: The 'Export CSV' file does not work.
Options Panel: Editable measurement parameters. We measure using the 'Counts' feature. 'Counts' is active when the dot is blue. Change the number of counts or measurements the balance takes here.
At the beginning of a series of measurements, tare the balances. To do this first make sure that the 'Counter Weight' field is set to '0' and then set the 'Count' value. The 'Count' is dependent of the sea state: 600 for calm waters and 1000 counts for rough waters. If seas are too rough than wait until the weather settles before continuing to measure.
A rule of thumb is that the measurement of a known reference mass shouldn't have a larger deviation than the accuracy desired. For example, our accuracy is +/- 0.05 grams; weigh a reference mass in the unknown balance that is close to the masses you are measuring (e.g., 25 grams) and perform the measurement with the appropriate counterbalance mass in the reference balance pan. You should get a final mass of 24.95—25.05 grams.
Once parameters are set, select the 'Tare' button. When the tare is complete the 'Final Weight' Section turns orange and the 'History' Section updates (Figure 31). 
Figure 31. Mettler Balance program window showing a tare calculation.
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Figure 32. Reference weights. A: Weights. B: Tweezers.
Weighing Crucibles
The quartz crucibles have three sections: an outer (or large) crucible, an inner (or small) crucible, and a lid (Figure 33).
Figure 33. Crucible components. A: Outer (large) crucible. B: Inner (small) crucible. C: Lid.
The inner crucible holds the sample material and is the only piece that is weighed. They are assembled as seen below with the inner crucible inside of the outer crucible and the lid sitting over the entire unit (Figure 34). Crucible sets (large, small and lid) are engraved and lettered and should be kept as a set. For example, Crucible lid 'A' should always be run with large and small crucible 'A'. If a crucible is unlabeled use a diamond-tipped pen to etch in an unused lid.
Figure 34. Complete and assembled crucible unit.
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Figure 35. LOI spreadsheet.
The spreadsheet has multiple columns to fill in.'SITE', TEXT ID', 'CORE/SECT/INTERVAL', 'CRUCIBLE ID', 'CRUCIBLE WT', 'CRU+FRESH SAMPLE WT', and 'CRU+IGN SAMPLE WEIGHT'. 'SAMPLE WEIGHT', POST IGNITION LOSS', and '%LOI' are calculated values based on the weights entered in columns E – G.
The first measurement taken will be the initial weight of an empty crucible. To complete this measurement, open the side door and place an empty inner crucible in the center of the 'Unknown' balance (Figure 36). Record the number or letter etched onto the crucible in the excel spreadsheet under 'Crucible ID.'
Figure 36. Weighing an empty inner crucible.
Close the door and click 'Weigh'. Wait for the counts to finish and then record the 'Final Weight' in the spreadsheet under 'Crucible Wt'.
Weighing Sample
Weigh out 5 grams of sample powder into the quartz crucible within +/- 0.05g (Figure 37). The total weight should be the crucible weight + 5 grams within +/- 0.05 grams. For example, a crucible weighs 14.32g, thus the total weight plus the sample will be between 19.27 – 19.37g. We use 5g because it is a good representation of the sample and it fills the crucible appropriately. You will find that you will loose some of the sample due to it sticking to the qtr crucible when you are finished with the LOI.
Note: If there is only a small amount of material, you can use less but the %LOI error will be larger.
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When the sample is close to this range click 'Weigh.' Press 'Halt' to stop the measurement and either add or remove sample if needed, and then click on 'Weigh' again to take a new measurement.
When a sample's final weight is within the allowable range, record the 'final weight' value into the spreadsheet under 'CRU + FRESH SAMPLE WT'.
Carefully remove your sample from the balance. Place your crucible into the larger quartz holder and cover with a lid (Figure 38). Repeat this process for all samples. After all samples have been weighed and recorded, take samples from the desiccator and bring over to the muffle furnace in the Chemistry Lab.
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Igniting Samples
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Using the Muffle Furnace
Bring crucibles over to the Muffle Furnace (Figure 39). There is a wooden tray to assist the transferor crucibles from one lab to the other. Turn the power switch on and the control panel will illuminate.
Figure 39. The Thermolyne Muffle Furnace. A: Power Switch. B: Control Panel. C: Door handle.
Confirm with scientists, what temperature and how long samples should be run for. Below is a quick reference guide:
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Material
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Ignition Time at °C
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Basalts
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4 or 5 hr at 1025°C
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Si-rich sediments
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4 or 6 hr at ~900°C
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Samples with:
- Muscovite
- Biotite
- Amphibole
- Carbonates
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6 hr or more at XXX°C
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statistics on all measurements taken. This file can be exported into an excel file by using the 'Export' button. Note: The 'Export CSV' file does not work.
Options Panel: Editable measurement parameters. We measure using the 'Counts' feature. 'Counts' is active when the dot is blue. Change the number of counts or measurements the balance takes here.
At the beginning of a series of measurements, tare the balances. To do this first make sure that the 'Counter Weight' field is set to '0' and then set the 'Count' value. The 'Count' is dependent of the sea state: 600 for calm waters and 1000 counts for rough waters. If seas are too rough than wait until the weather settles before continuing to measure.
A rule of thumb is that the measurement of a known reference mass shouldn't have a larger deviation than the accuracy desired. For example, our accuracy is +/- 0.05 grams; weigh a reference mass in the unknown balance that is close to the masses you are measuring (e.g., 25 grams) and perform the measurement with the appropriate counterbalance mass in the reference balance pan. You should get a final mass of 24.95—25.05 grams.
Once parameters are set, select the 'Tare' button. When the tare is complete the 'Final Weight' Section turns orange and the 'History' Section updates (Figure 31).
Figure 31. Mettler Balance program window showing a tare calculation.
Put in a reference weight into the "Reference' balance. With the tweezers, select the 20g weight and place it in the center of the 'Reference' balance (Figure 32). To have a more accurate measurement, the reference weight should be close to the expected 'Unknown' sample weight (roughly ~20g).
Figure 32. Reference weights. A: Weights. B: Tweezers.
Weighing Crucibles
The quartz crucibles have three sections: an outer (or large) crucible, an inner (or small) crucible, and a lid (Figure 33).
Figure 33. Crucible components. A: Outer (large) crucible. B: Inner (small) crucible. C: Lid.
The inner crucible holds the sample material and is the only piece that is weighed. They are assembled as seen below with the inner crucible inside of the outer crucible and the lid sitting over the entire unit (Figure 34). Crucible sets (large, small and lid) are engraved and lettered and should be kept as a set. For example, Crucible lid 'A' should always be run with large and small crucible 'A'. If a crucible is unlabeled use a diamond-tipped pen to etch in an unused lid.
Figure 34. Complete and assembled crucible unit.
Weight measurements are recorded in an excel spreadsheet which will be uploaded to LIMS at the end of an expedition (Figure 35). Open the excel spreadsheet titled 'LOI Template' found in Local Disk > DATA and save the spreadsheet in Local Desktop > XRD-ICP Prep Documents >LOI spreadsheets.
Figure 35. LOI spreadsheet.
The spreadsheet has multiple columns to fill in.'SITE', TEXT ID', 'CORE/SECT/INTERVAL', 'CRUCIBLE ID', 'CRUCIBLE WT', 'CRU+FRESH SAMPLE WT', and 'CRU+IGN SAMPLE WEIGHT'. 'SAMPLE WEIGHT', POST IGNITION LOSS', and '%LOI' are calculated values based on the weights entered in columns E – G.
The first measurement taken will be the initial weight of an empty crucible. To complete this measurement, open the side door and place an empty inner crucible in the center of the 'Unknown' balance (Figure 36). Record the number or letter etched onto the crucible in the excel spreadsheet under 'Crucible ID.'
Figure 36. Weighing an empty inner crucible.
Close the door and click 'Weigh'. Wait for the counts to finish and then record the 'Final Weight' in the spreadsheet under 'Crucible Wt'.
Weighing Sample
Weigh out 5 grams of sample powder into the quartz crucible within +/- 0.05g (Figure 37). The total weight should be the crucible weight + 5 grams within +/- 0.05 grams. For example, a crucible weighs 14.32g, thus the total weight plus the sample will be between 19.27 – 19.37g. We use 5g because it is a good representation of the sample and it fills the crucible appropriately. You will find that you will loose some of the sample due to it sticking to the qtr crucible when you are finished with the LOI.
Note: If there is only a small amount of material, you can use less but the %LOI error will be larger.
Figure 37. Crucible with approximately 5g of sample. Pre-ignition measurement
When the sample is close to this range click 'Weigh.' Press 'Halt' to stop the measurement and either add or remove sample if needed, and then click on 'Weigh' again to take a new measurement.
When a sample's final weight is within the allowable range, record the 'final weight' value into the spreadsheet under 'CRU + FRESH SAMPLE WT'.
Carefully remove your sample from the balance. Place your crucible into the larger quartz holder and cover with a lid (Figure 38). Repeat this process for all samples. After all samples have been weighed and recorded, take samples from the desiccator and bring over to the muffle furnace in the Chemistry Lab.
Figure 38. Complete crucible unit with sample, ready for ignition.
Igniting Samples
Samples are ignited in the Thermolyne Muffle furnace located in the Chemistry Laboratory. The entire ignition cycle takes approximately 20 hours. After ignition, samples need to be taken out when they come down to ~ 50°C-200°C. If the samples sit for too long they will reabsorb moisture and the 'Post-Ignition Weight' will be inaccurate. Time this accordingly.
Using the Muffle Furnace
Bring crucibles over to the Muffle Furnace (Figure 39). There is a wooden tray to assist the transferor crucibles from one lab to the other. Turn the power switch on and the control panel will illuminate.
Figure 39. The Thermolyne Muffle Furnace. A: Power Switch. B: Control Panel. C: Door handle.
Confirm with scientists, what temperature and how long samples should be run for. Below is a quick reference guide:
Material | Ignition Time at °C |
Basalts | 4 or 5 hr at 1025°C |
Si-rich sediments | 4 or 6 hr at ~900°C |
Samples with:
| 6 hr or more at XXX°C |
A common program is an increase in temperature of 3°C/min to a target temperature of 900°C and a hold of one hour. Then ramp up at a rate of 3°C/min to a target temperature of 1025°C and hold for four hours. This ramp cycle is already programmed into the furnace and corresponds to 'Program 1'. To check or edit a program see additional guides attached to the furnace itself. It is also possible to run the furnace manually without a ramp up cycle. Discuss with scientists their preference.
Either enter the desired temperature manually or select your program. If you are running the furnace manually, enter the desired temperature; no other buttons or steps are needed. If selecting a program, press and hold 'Run' (Figure 40).
Figure 40. Control Panel on Thermolyne Muffle Furnace. A. Actual temperature. B. Desired/ Set temperature. C. Run/ stop button. D. Auto run button. E. Page button. F. Scroll button. G. Down button. H. Up button.
When the furnace finishes it's cycle and cools down to ~50°–200°C, remove the crucibles with tongs. Put samples onto a tray and store tray in the desiccator. Keep samples in the desiccator and remove one at a time while weighing. It is very important for the samples to not reabsorb moisture so begin weighing as soon as possible.
Post-Ignition Weighing
Post-ignition measurements should be taken soon (within an hour) after removing crucibles from the furnace. Failure to do so will disrupt the LOI values. Reweigh the crucible plus the ignited sample to determine how much weight was gained or lost. Follow the same weighing procedure as in Pre-ignition Weighing.
- Record the final weight in the excel spreadsheet under 'CRUCIBLE + IGN SAMPLE WT'. The spreadsheet will populate the columns 'Post Ignition Loss' and '%LOI'.
- The formula used to calculate LOI is:
%LOI = 100 x (weight change during ignition)/ (fresh sample weight).
Note: By convention, weight lost during ignition is recorded as a positive LOI value; whereas weight gained is recorded as a negative LOI value. Report the results to 2 decimal places.
Uploading LOI Data To LIMS
Open the Excel File 'LOI Spreadsheet Upload Template' in Local Disk > DATA (Figure 41). Put your LOI information into the spreadsheet following the example format. Fill in the following:
- Text ID: e.g., WDGE11258831 (Note: capital letter matters)
- Analysis: LOI
- Replicate: 1 (usually)
- crucible_number: Crucible ID (e.g., A, B, F...)
- crucible_preignition_mass: crucible mass only (small inner crucible) (component unit: grams)
- crucible_and_preignition_sample_mass: inner crucible with fresh sample before ignition (component unit: grams)
- crucible_and_postignition_sample_mass: inner crucible with ignited sample after ignition (component unit: grams)
- loi_percent: LOI in % (component unit: none; the value is already a percentage)
- reference_mass: sample mass (calculated difference) (component unit: grams)
- comment: specify temperature and time used for LOI (e.g., 950 deg C for 4 hours; used during Exp 391)
Figure 40. Control Panel on Thermolyne Muffle Furnace. A. Actual temperature. B. Desired/ Set temperature. C. Run/ stop button. D. Auto run button. E. Page button. F. Scroll button. G. Down button. H. Up button.
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Post-Ignition Weighing
Post-ignition measurements should be taken soon (within an hour) after removing crucibles from the furnace. Failure to do so will disrupt the LOI values. Reweigh the crucible plus the ignited sample to determine how much weight was gained or lost. Follow the same weighing procedure as in Pre-ignition Weighing.
- Record the final weight in the excel spreadsheet under 'CRUCIBLE + IGN SAMPLE WT'. The spreadsheet will populate the columns 'Post Ignition Loss' and '%LOI'.
- The formula used to calculate LOI is:
%LOI = 100 x (weight change during ignition)/ (fresh sample weight).
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Uploading LOI Data To LIMS
Open the Excel File 'LOI Spreadsheet Upload Template' in Local Disk > DATA (Figure 46). Put your LOI information into the spreadsheet following the example format. Fill in the Text ID, Analysis, Replicate, Crucible number, and all weights and units including the %LOI.
Figure 41. LOI Spreadsheet Upload Template.
Open up the program ‘Spreadsheet Uploader’ Pinned to the Taskbar (Figure 4142).
Figure 42. Spreadsheet Uploader Icon.
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- Lay a large Kim wipe and a piece of weigh paper down next to the Bead Maker. Unwrap a platinum crucible and place it on the weigh paper. Pour the powder mix into the crucible. The sample should evenly cover the bottom.
- Pipette 10 µL of 0.172 mM LiBr wetting agent into the center of the sample powder.
- Open the Bead Maker lid and place sample inside the sample holder. The short wide crucible will fit directly; whereas, the tall narrow crucible will need an additional ceramic ring (no longer have these?).
- Close the lid. Double check both indicator lights are on. Press 'On' to start the program. The process will take 12 minutes and the sample is heated in three stages:
- Stage 1:700°C for 2 min
- Stage 2:1050°C for 5 min,
- Stage 3: 1050°C in agitation for 5 min.
- Be prepared to remove the crucible as soon as the timer reaches 0. The material hardens very quickly so be ready with safety glasses, gloves, and the platinum tipped tongs before the final stage has finished.
- With the Pt-tipped tongs, lift out the crucible and swirl the contents around to get the entire sample into one bead. Wear eye protection! The bead is very hot and rapid cooling can cause it to shatter and fly out.
- Place the crucible on its cooling rack. When seated properly the red light behind it will start flashing. When the bedmaker beadmaker beeps it should be finished cooling.
- Place a sheet of 6x6 weigh paper on the ceramic plate. Take crucible from the cooling rack and prepare to flip it upside down on the paper to extract the bead.
- With crucible in hand flip over and give it a firm whack on the weigh paper. The bead should pop off without much resistance. Put the bead back into the vial that contained the flux.
- If there are small pieces of bead left behind you can use your Teflon spatula to try pry it off. Do not use too much force. The platinum is malleable and will get scratched and damaged if put under too much force. If it still remains, make a note of the sample number and inform the chemistry technician. The residue (if any) should come off during the cleaning process.
- Repeat process for all samples.
- Hand off all beads to the chemistry technicians to continue on with the ICP analysis.
- off during the cleaning process.
- Repeat process for all samples.
- Hand off all beads to the chemistry technicians to continue on with the ICP analysis.
Using the Bead Maker during transit is not advised, due to power fluctuation which could cause damage to the Bead Maker electronics.
Making beads - protocol used during Exp 391
The process described above was not appropriate to make beads during Exp 391. Some samples had recrystallized parts during cooling. We therefore changed the protocol by doubling the flux quantity (i.e., 400 mg of flux was used) and increasing the sample mass to 125 mg (instead of 100 mg). The temperature of the beadmaker was also "increased" to 1220ºC (see Exp391 X-Ray Tech Report regarding the beadmaker temperature issue)Using the Bead Maker during transit is not advised, due to power fluctuation which could cause damage to the Bead Maker electronics.
Cleaning Platinum Crucibles
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