December 6, 2010
|Teflon beakers in Aqua Regia.|
|Appropriate set-up for washing dishes at home.|
How to Wash Dishes at Home (Graduate Student Version):
Definition of dishes: An eclectic assortment of plates, bowls, cups, mugs, and utensils gathered from your mom, grandmother, friends who graduated/got married, and discount stores.
Supplies Needed: Divided sink or sink + bucket, dish soap, sponge, steel wool, water, dishrack.
1. Allow dishes to accumulate for 3 to 5 days. If you have a non-graduate student housemates and/or spouse, reduce accumulation time to 1 to 2 days.
2. Give the dishes a thorough rinse under the sink faucet, especially if they’ve been accumulating for 3+ days. Scrape excess food particles/goo into the trash or garbage disposal.
3. Fill the sink with hot, soapy water. Fill the other half of the sink (or a bucket) with hot water.
4. Scrub the dishes with the sponge and steel wool in the soapy water.
5. Rinse the dishes in the hot water.
6. Place on dishrack to dry.
7. Let dishes sit on dishrack until needed for eating food.
How to Wash Dishes at Home (Graduated Student Version):
Definition of dishes: Beautiful matching sets of plates, bowls, cups, mugs, wine glasses, and utensils that you obtained as wedding gifts and/or bought from a nice store (Pier 1, Ikea, Target- pronounced “Taarjaay” to sound fancier) with your “real job” money.
Supplies Needed: Sink, dishwasher, dish soap.
1. Allow dishes to accumulate for 0-1 day.
2. Give the dishes a quick rinse under the sink faucet.
3. Place dishes in dishwasher.
4. When full, add soap and run dishwasher.
5. Put dishes away shortly after the dishwasher is done running.
|Appropriate set-up for washing dishes in lab.|
|Freshly-washed lab dishes.|
How to Wash Dishes in Lab:
***Disclaimer: Please only follow these directions in a geochemistry lab under proper supervision and with proper safety equipment. This is my dish washing protocol. Note that every geochemistry lab has its own protocol.***
Definition of dishes: Teflon beakers used for geochemistry.
Supplies Needed: Ultrapure (MilliQ) water, pure nitric acid, pure hydrochloric acid, methanol, kimwipes, sink rated for disposal of trace amounts of acid, large glass beakers (2L works well), watch glass lids for glass beakers, teflon tongs, large fume hood, large hotplate, nitrile gloves, chemical-resistant bodysuit, plastic lab clogs, safety glasses, face shield, permanent marker.
1. Allow dirty dishes (from chemistry) to accumulate. There are always dirty dishes, and it takes several days to clean them, so it’s best to move the cleaning along every day.
2. Don appropriate safety gear. For steps 3-4 the clogs, chemical bodysuit, nitrile gloves, and safety glasses are fine. After step 4, add the face shield and a second pair of gloves, preferably gloves that come up to your elbows.
3. Remove “permanent” marker labels from dirty teflon beakers using kimwipes (laboratory tissue) and methanol. Remove any gritty sample residue from inside of beakers using kimwipes. Then, place the teflon beakers in a 2L glass beaker.
4. Rinse the beakers thoroughly in ultrapure (okay to use less pure) water. Pour this water into the sink.
5. Add 50% hydrochloric acid to the glass beaker. Make this by adding concentrated pure hydrochloric acid to ultrapure water. ALWAYS WORK WITH ACIDS IN FUME HOODS. Use teflon tongs to push down any beakers that float to the surface. Be sure to rinse the tongs thoroughly in ultrapure water after use (to remove the acid). BE SURE TO LABEL THE BEAKER AS CONTAINING ACID UNLIKE MANY LAB VISITORS/INTERNS. IF YOU DON’T LABEL YOUR ACID BEAKERS I WILL LEAVE THREATENING NOTES AROUND LAB AND ON YOUR DESK.
6. Put beaker on hotplate and let sit overnight at a temperature of ~100 deg C. Boiling the hydrochloric acid for 1 hour is also recommended.
7. Pour the hydrochloric acid into another 2L glass beaker. You can use this acid for the next batch of beakers to be cleaned- I generally reuse my acids 8 times.
8. Rinse the beakers 3x in ultrapure water. Be sure to dispose of this water (which has trace acid in it from the rinsing) in a waster beaker or properly set-up sink.
9. Add Aqua Regia “Royal Water”, a mixture of pure nitric acid and pure hydrochloric acid in a 1:3 ratio. Be careful! Aqua Regia is called royal water because it can dissolve noble metals such as gold. This is strong stuff… which is good because we want superclean beakers. When you first form aqua regia it will bubble like crazy, so be extra careful when working with freshly-made aqua regia. DO NOT PUT AQUA REGIA ON THE HOTPLATE. DO NOT BOIL AQUA REGIA. DO YOU HEAR ME, INTERN?
10. Let beakers sit in aqua regia (cold) overnight.
11. Pour out the aqua regia into another glass beaker. Again, the aqua regia can be used up to 8 times.
12. Rinse the beakers 3x in ultrapure water. Be sure to dispose of this water (which has trace acid in it from the rinsing) in a waster beaker or properly set-up sink.
13. Add 50% nitric acid. Make this by adding concentrated pure nitric acid to ultrapure water.
14. Put beaker on hotplate and let sit overnight at a temperature of ~100 deg C. Boiling the hydochloric acid for 1 hour is also recommended.
15. Pour out the 50% nitric acid into another glass beaker. Again, the nitric acid can be used up to 8 times.
16. Rinse 3x in ultrapure water. Be sure to dispose of this water (which has trace acid in it from the rinsing) in a waster beaker or properly set-up sink.
17. Fill beaker up with ultrapure water and add ~1mL of ultrapure nitric. Let boil for 1 hour.
18. Cool, then rinse 1 more time in ultrapure water.
19. Check every beaker for sticky spots using a drop of ultrapure water. If the drop sticks/hesitates anywhere on the beaker, wash the beaker again. If the drop moves smoothly around the beaker, put the beaker in a clean place (I use a flowbox) to dry. You don’t want it to accumulate dust while it dries!
Below is a link to a fun video of gold dissolving in aqua regia, but note the (oh the horror!) ungloved hand moving the beaker around. ALWAYS WEAR GLOVES WHEN WORKING WITH AQUA REGIA.
Aqua Regia Video