December 6, 2010
How to Wash Dishes
Posted by Evelyn Mervine
|Teflon beakers in Aqua Regia.|
Some days, I feel that I do nothing but wash dishes… I wash dishes in lab and then go home and wash more dishes. Below is my guide to washing dishes, both at home and in lab.
|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
You do acid washes in pyrex beakers? Doesn't that let the A-R leach all the trace elements out of the pyrex? I've always used plastic or teflon for acid washes. But then, I think only the PGE people use A-R. Us normal schlubs go HCl, HNO3, HF, from what I recall (obviously HF can't be done in glass).Also, there are some very senior geochemists who have determined that the REE blanks in good tap water are low enough to run Sm Nd without any special water purification at all. Obviously they'll never admit it in print, thoguh, since it doesn't look good.
Chuck: This is how I was taught… we've never had blank issues for the elements I've worked with: U, Th, Nd, Sr, Pb… but perhaps using plastic beakers is better if you do whole suites of trace elements.Interesting about the tap water… I believe it, depending on where you live!There are some crazy stories of the "old days" of geochemistry… I've heard a rumor that one famous geochemist (who I won't name) used to chainsmoke while doing all of his chemistry! A little dangerous around the methanol, I suppose, but apparently it didn't affect his blanks at all.
Dear Evelyn,My apartment inherited a set of very nice florence flask-shaped decanters, previously in use at a company that makes, among other things, popular brands of bleaches & detergents. I came to your blog in searching for an idea as to whether the pyrex (Kontes/Kimex) in the flasks might gradually be releasing tiny amounts of things that will turn my chromosomes into unfortunate shapes or the like. I recognize that the reasonable, safe course of action here would be to recycle these or return them to a lab, & just buy fresh, clean ones, but I'm curious – what are the odds I'm still drinking smatterings of organic solvents or heavy metals, now that they've been properly cleaned?Thanks for your input. Hope you remain sane through to the end of your PhD & beyond!