Difference between revisions of "Lab tips & tricks"

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Any experienced chemist knows plenty of secrets on how to work better, faster or more effective in his lab or outside. Knowing important lab tips and tricks can help you to work more efficient, and even solve problems that you may face.

Lab space

• Make sure there is a clear way from your bench to the exit, in the event of an accident
• Always keep chemicals and chemistry separate from food and cooking
• Make sure there's always some ventilation in the lab, to prevent a build-up of gasses and volatile chemicals
• Have a functional washing sink in the event of an accident close to the work bench and make sure there is a clear way towards it, but if you can afford one, get an eyewash station, usually in the form of sterile saline eye washing liquid
• Keep cardboard boxes on a dry shelf, never on the floor, as in the event they get wet, their bottom will disintegrate, which can be disastrous if you have fragile items inside, as when you take away the box, the items will fall out of the box and break
• "Coat" the bottom of the cardboard boxes with duct tape, that way, the bottom will hold in the event of a spill
• Have MSDS in printed form for all your reagents, and make sure you keep the in a readily accessible location

Lab item organization

Glassware

• Stackable transparent plastic containers are good for storing glassware and they're cheap, and you can store separate types for each container (beakers in a drawer, condensers in another, etc.) or mixed (beakers with flasks, etc.)
• If your lab space is spacious, suitable and you can afford, get some drawer units and keep the glassware in drawers, separated by types (beakers in a drawer, condensers in another, etc.)
• To prevent the glassware from bumping into each other when you open/close the drawers or containers, place a bubble wrap sheet or foam on the bottom of the drawer/container, then place the glass item on the bubble wrap/foam sheet
• If you do not have enough drawers or you have none, group your glassware items based on their size to fit better
• While you can keep your glassware and fragile objects on a shelf nailed to the wall, there's always the risk of falling and breaking your lab items, always keep them "grounded"

Plasticware

• If your plastic item is heat resistant and you want to dry it in an oven, make sure you thoroughly wash it and properly rinse it with lots of distilled water, as while the plastic will survive high temperatures, whatever organic impurities are present on its surface may decompose and stain your plastic, often irreversible
• Write down the date when you fist acquired the plastic item, and then the date when the first signs of degradation appear, that way you will know how long you can safely use it
• Do not keep plastic items in direct contact with sunlight or UV light

Metalware

• Place all of your small metal items (keck clip, scoopula, spatula, wire gauze) in one drawer, while larger items (clamps, jacks, tripods) in separate locations, unless you prefer to sort your items by function rather than material
• Items not made of corrosion resistant alloys should be coated in protective paint (Plasti Dip is a good choice)
• Place your tools in a drawer or on a tool board, but keep them away from areas with volatile (and corrosive) reagents

Working in the lab

Personnel safety

• Always have clean and working safety equipment (the lab coat, goggles, gloves must be intact and not worn if possible) or at least some form of protection when doing lab work (unless you want to get your street clothes dirty or contaminated), though this is more important when doing dangerous reactions with corrosive or toxic reagents, and less when doing something as simple as a recrystallization from water or a low-toxic solvent, performing a simple distillation, filtering a suspension, transferring reagents in another container, handling glassware, etc., and when washing your glassware, wear something so your clothes won't get wet
• Make sure your windows or doors (if you have any) can be opened easily
• Turn on your ventilation/fume hood when working with toxic or smelly gasses, regardless of the scale you work with

Performing an experiment

• Do not rush things - slow and steady wins the race, as they say
• Before you try an experiment, make sure you can find a good reference from a proper source
• Draw a sketch of your process and setup
• Assemble the hardware parts of your setup before doing anything to see if you're doing it right
• Round objects should be placed on a support, to prevent them from falling
• Use a cork ring to hold items that cannot be safely placed on flat surfaces (like chromatography reservoir flasks)
• Take a good look at the reaction/process, and if something doesn't seem right, do not proceed until further research
• Keep notes of your experiment, preferably in a paper notebook, and also note any significant observations
• When drying a salt, to see if there are any water vapors coming off, hold a piece of glass above the vessel with the hot salt and see if any vapors condense on the glass, for the salt to be dry there should be no condensation
• Microwave is probably the fastest way to heat up water
• Elemental bromine is better than iodine at initiating Grignard reactions, and 1,2-dibromoethane is just as good
• If your cooling consists of a water bucket and a water pump, add some ice in the bucket to keep the water cool
• To get an even colder cooling fluid, add some antifreeze in the water before adding ice
• When doing a reflux reaction that needs distilling afterwards, you can connect a 3-way distillation connecting adapter with same size joint to the flask, then attach a small female stopper to the side arm and a Liebig condenser as a reflux column; after the reflux is over, remove the female stopper and the Liebig condenser, replace it with the Liebig condenser and place a male ground glass stopper on the upper female joint where the condenser was
• If you're distilling compounds that attack the rubber seals of on ordinary thermometer adapter, instead of getting fancy ground glass thermometers or a teflon adapter, wrap one or more layers of PTFE tape around the thermometer, then just poke it down into the adapter and thread the cap on top, sealing the teflon against the glass
  • Note that this might not always work, and the screw thread might break down as well, depending on the type of chemical you're distilling, best to do a smoke test before to see if any vapors come out through the PTFE seal
• When distilling volatile chemicals, a reflux condenser can be placed above the distillation receiver, like here
• Place a paperclip at the bottom of an oil bath vessel to act as a magnetic stirrer when using a hotplate or heating mantle with magnetic stirring, that way the you can get homogenous heating of the oil
• Pre-chilled sulfuric acid is practical for dilution - in most cases adding it to a reaction mixture is highly exothermic so the pre-chilling helps a lot
  • You can easily do this by keeping or storing your sulfuric acid in the fridge or freezer and only take it out before performing the dilution
• For making very cold cooling bath, keep the brine salt in the freezer before using it
• To make a stable filter funnel stand/support, drill a hole in a plastic or cardboard box and place it over the beaker
  • If your funnel is not very stable, place a larger funnel in the hole, glue it to the stand to hold it into place, then place your funnel in the large funnel

Handling lab items and reagents

Lab items

• Round objects should be placed on a support or a plate, to prevent them from rolling and falling over
• Beakers, jars, drinking glasses (not for drinking anymore), egg trays can be used to hold round bottom flasks upright
• Subwoofer speakers can be used to hold RBFs and similar round bottomed items
• Use a cork ring to hold items that cannot be safely placed on flat surfaces (like chromatography reservoir flasks, etc.)
• Pre-weight your bottle or flask, that way you can calculate the weight of your reagent without having to transfer it in another container
• You can weight the empty reagent bottles and write down their weight on the bottle, that way, when you add the reagent in the bottle, you can easily keep tabs on the amount of reagent you have, without having to empty the container

Reagents

• If you're pouring a solid, you can rotate the bottle slightly to get it going
• Dry fine powdered reagents may build up static charge, and when using a spatula, some may stick to it
• Use a funnel to safely transfer liquids from a large bottle to a smaller one
• If you want to empty a beaker to another vessel, especially one with a limited opening, you can use a stirring rod on top to direct the flow
• When transferring corrosive liquids, especially the volatile kind, do this in a fumehood
• When transferring non- or low volatile corrosive reagents (like alkaline solutions and conc. sulfuric acid), place the receiving bottle/flask in the sink, so that any potential spill can be washed from the bottle with water down the drain, and not contaminate the work bench
• If your flask or beaker has a stir bar that you cannot or don't want to remove it, place a small magnet or another stir bar outside the bottom of your beaker to hold the stir bar in the beaker and prevent it from falling out as you pour

Storage

• Never keep your oxidizers together with flammable materials, keep them in separate cupboards/containers
• Store each reagent depending on their category (oxidizer with oxidizer, acid with acid, etc.)
• Keep acid bottles in plastic trays, so that in the event of a spill, the acid will not leak all over your closet
• Smelly reagents (amines, sulfides, etc.) must be kept in another larger box or double bag
• Never overfill the bottle with liquid above its limit, as the bottle may burst if there's a sudden change in ambient temperature
• Cover the openings of your clean flasks or beakers with foil to prevent dust from setting
• Keep extremely hazardous chemicals in plastic bottles, as long as they're compatible, as in the unfortunate event you drop the container on a hard surface, the container must not break, and thus spread the hazardous material all over the floor, which will require cleaning and decontamination. If the hazardous material cannot be stored in a plastic container, and only glass, keep the glass container in a plastic box at all times. This method however is impractical for large bottles, but except for volatile acids you won't usually work with large quantities of hazardous chemicals.

Cleaning

• Try to clean everything you'll need for tomorrow, today
• Use oxidizing mixtures (like chromic acid, aqua regia) to remove persistent stains, but if the item can be easily replaced (like a plastic pipette), this may not be required, as you could be wasting good reagent
• To wash pipettes, take a graduated cylinder of the same length as the pipettes and fill it with washing solution
• Some items, like volumetric flasks, Florence flasks, can be placed upside down near the space between the house radiator and wall (if there is one), when drying the said washed glassware, as the heat helps to dry faster
• Cloth drying racks can also be used for holding wet glassware to let the water drip from them
• Retort clamps can be used to hold various glassware, like round-bottom flasks or Erlenmeyer flasks upside down to dry them
• In the event of a spill, always have kitty litter (silica gel or bentonite), it is very good at absorbing lots of stuff
• To remove the label from a bottle, try to see if it doesn't come off in a single move, as some labels can be easily removed
• For hard to remove labels, you will need to wet them first (if they absorb water or other liquids), then using a knife or cutter to manually scrape off the label, afterwards fill the bottle with hot water, take a paper tower or an old rag, place cleaning powder or baking soda, wet it a bit and manually scrape off the last bits of the label from the bottle
• Toaster ovens can be used to dry glassware

Waste handling

• Acidic wastes can be neutralized with a base, while basic wastes can be neutralized with an acid, preferably a weak and cheap one, like acetic acid or citric acid
• Keep the waste containers near a ventilated place, best in a large tupperware container if possible, to prevent any leaks
• Solid reagents should be separated based on their heavy metal content

Gallery

• 

  To limit the use of washing solution, a graduated cylinder can be used to wash pipettes, stirring rods or other long and thin glass items.

• 

  If you don't have a support where to put your recently washed cylinder, you can use a larger one, provided you don't need the latter for a while.

See also

• Cleaning glassware
• Improvisation
• Proper disposal of chemicals
• Safe handling and storage of chemicals

References

Relevant Sciencemadness threads

• Laboratory Tips and Tricks
• Safety Tips for n00bs/kw3ls