What should you do if you get too much chemical out of the reagent bottle?

Figure 1: The transfer of a large amount of solid.

Figure 2: The transfer of a small amount of solid.

Figure 3: Using a piece of weighing paper to transfer a solid.

It is usually easier to transfer solids to a wide mouthed container such as a beaker. Take a labeled beaker to the reagent shelf where the chemicals are kept. When you take the top off the reagent bottle, don't lay it down (risks contamination). Many solid chemicals can be easily transferred by tipping the bottle and slowly rotating the bottle back and forth. Don't tip the bottle up high and let the contents pour out. If a spatula is provided at the reagent bottle, you may use it. Never use your own spatula. Be sure to put the right lid on the right bottle and return the bottle to its place on the shelf. Take an appropriately sized, labeled beaker to the reagent shelf. The stopper of the reagent bottle should be held during transfer or, if it is flat, placed upside down on the counter. Carefully pour the amount of reagent that you will need, not extra, into the beaker and then close the reagent bottle. Graduated cylinders are unstable so transfer liquids into the labeled beaker first and then pour from the beaker into your graduated cylinder. It is a good idea to make this latter transfer over a sink.

Figure 4: Pouring a liquid or a solution from a glass-stoppered bottle.

Always return the stopper to the bottle and the bottle to the reagent shelf. Never put your dropper or pipet into a reagent bottle. If the reagent bottle is equipped with a dropper, use that dropper, being careful not to touch the walls or contents of your receiving vessel with the dropper.

Reagents are expensive and are a significant cost to your lab. You know what to do to keep others from stealing your reagents. But contamination, improper storage and “lost” batches will all eat into your stock of reagents, bump up your consumables costs and waste your precious time. Unless you take steps to prevent them, that is.

Here are some ideas on how to help make your reagents last longer than ever before:

1. Make an inventory of your reagents. Name, open date, expiry date, quantity, storage location. Even the most simple list helps everyone recall what stock is on hand. That way your lab can avoid wasting money on reordering something frightfully expensive when the inventory shows that it already exists in the lab. Somewhere. Probably in my drawer (sorry)…I’ll put it back on the shelf.

2. Aliquot reagents upon delivery. If there’s only one thing to do, this is it! There is always a risk of contamination when drawing from primary containers; all it takes is one absent-minded dip of a used pipette tip to spoil a freshly opened bottle. Pre-measured aliquots are a great approach to eliminating source contamination whether or not the reagent will be shared amongst others. Aliquots also help to keep reagents stable longer because individual tubes will travel through temperature effects of freezing and melting once, maybe twice. And that’s it.

3. What comes out of the bottle, stays out of the bottle. When measuring out a chemical, you realise you have taken out a little too much in your pipette/cylinder/spatula. To prevent wasting it, you put it back into the container, right? Wrong! There is always a risk of contamination after you have removed it from the container and if you put it back in, you risk transferring the contamination back in there and ruining the whole batch. So make a hard and fast rule for yourself: if you take more out that you need, discard it. Let’s call it the angel’s share.

4. Share an aliquot, not a bottle. Collaboration helps advance everyone’s research, but think about measuring out a volume to give away when a new neighbor comes knocking to borrow a cup of sugar. The principle behind this is that the lab is your home and they are a welcomed guest. Unless you’re willing to train them to your lab’s standards and supervise, there is little sense in allowing free reign where anyone can help themselves. Sharing the secrets about where the best reagents are stored may indirectly contribute to their occasional disappearance. Hmmm…

5. Cover with foil. Protect light sensitive chemicals by wrapping bottles and tubes in an opaque material like aluminum foil. While it may not always be essential for items stored in your own lab refrigerator, do remember what’s stored under bright fluorescent lights in the shared, high-traffic walk-in refrigerator.

6. Use powder. Liquid reagents, liquid gold. Bottles can sit abandoned for weeks, growing their own science experiment inside, precipitating out or evaporating. Some even outlast the researchers themselves! Consider a switch to powdered reagents and mix up just the right amount when you need it to save money and the hassle of replacing old stock. Try your hand at quality control with this simple batch method by Nick Oswald if you make the switch and do let us know how well it works for you.

That’s six things our lab does to prolong the life of various reagents. What does your lab do?

Collaboration helps advance everyone’s research, but think about measuring out a volume to give away when a new neighbor comes knocking to borrow a cup of sugar. The principle behind this is that the lab is your home and they are a welcomed guest. Unless you’re willing to train them to your lab’s standards and supervise, there is little sense in giving them free reign to where they can always help themselves. Giving away the secrets to where the best reagents are stored may also indirectly contribute to the occasional disappearance of your reagents. Hmmm…

General use, care, and how to open a stuck stopper.

Many of our kits include reagent bottles for steeping and storing bitters. This type of bottle has been used to store chemicals for at least 150 years, though the idea for the ground glass stopper dates back to the late 1700s. The combination of glass bottle and stopper makes the container very resistant to chemical corrosion with a few exceptions. Very strong alkali should not be stored in these bottles because the alkali can cause the stopper to corrode and fuse to the neck of the bottle. Also, hydrofluoric acid should never be stored in glass containers because it will actually dissolve the glass.

Reagent bottles that have been used in a laboratory or otherwise used to store chemicals should not be used for storing food or drinks. The bottles in our kits are always brand new but they may contain a white residue from the process of grinding the neck and stopper so they should always be washed before use.

Bottles typically come in two colors: clear and amber. Clear bottles are ideal for displaying items and amber bottles protect the contents from light. Sizes range from 30 ml (1 ounce) up to 20000 ml (about 5 gallons) and the larger ones may be used to store preserved biological specimens in the lab. The large ones also make excellent terrariums or miniature aquariums.

Because glass expands and contracts with changes in temperature, care must be taken when reagent bottles are heated and cooled. When a reagent bottle is heated, the neck expands, allowing the tapered stopper to drop farther into the bottle. When the bottle is then cooled, the neck shrinks around the stopper, locking it in place. The rough surface of the neck and stopper prevents the stopper from sliding up as the neck shrinks. With a large enough change in temperature, the neck of the bottle can actually crack if it shrinks too tight around the stopper. Additionally, if hot liquid is poured into the bottle, the liquid will form an air-tight seal between the stopper and bottle, and as the liquid and steam in the bottle cool and shrink, the stopper will be pulled down into the bottle neck. This is the same principle that makes the center of a canning jar lid pop down until the seal is released.

When pouring hot liquids into a reagent bottle or placing the bottle in the refrigerator, the lid should be propped open with a toothpick or other small object until the liquid and bottle are cool. Another way to seal the bottle while preventing the lid from sticking is to place a sheet of plastic wrap loosely over the bottle neck before pushing the stopper down.

If the lid of your bottle does get stuck, there are ways to rescue it without breaking it. (You may want to wear leather gloves while trying to remove a stuck stopper in case the bottle or stopper breaks.) Stuck stoppers often cause small chips around the mouth of the bottle. Use a small piece of fine grit wet sandpaper to smooth the edges of the chips.

Grasp the bottle in both hands with your fingers around the bottle and your thumbs against the edge of the stopper. Push against the edge of the stopper. Rotate the bottle and try again until you feel a small pop. It may take several rotations and "pops" before the lid is loose enough to remove.
If the first step didn't work, try running the bottle under warm water while keeping the lid dry. The greater the temperature difference between the bottle and stopper, the more likely the stopper will come loose. Once the bottle is warm, dry it and repeat the steps above.
If that still doesn't work, place a slightly crumpled piece of foil on a rack in the middle of an oven. The foil should be about 1.5 times the height of the bottle or larger. Lay the bottle on its side on the foil with enough extra foil under the top of the bottle to keep the lid from hitting the oven rack if it falls out. Heat the bottle gently by starting at 250°. Increase the temperature by 10-20° every 15 minutes until the stopper loosens. You can pull the bottle out and try step one wearing heat-resistant gloves but the lid should eventually get loose enough to fall out on its own.
If all of that fails, let the bottle slowly cool to room temperature. Wearing a heat-resistant glove and safety glasses, hold the bottle upside down over a folded towel, and use a torch to heat the neck of the bottle. The lid should eventually fall out onto the towel. This rapid heating can cause the bottle to crack so use caution.
If none of those things work and you absolutely must get the contents out of the bottle, use a chisel and hammer to gently chip away the neck of the bottle around the stopper. If the contents you are rescuing are your bitters, filter them thoroughly to remove any glass slivers.