III. TYPES OF LABWARE
The objective of this module is to introduce you to the types of labware typically found in biological research laboratories. We use the term "labware" rather than "glassware" because much of modern bioresearch is done with "plasticware"! Work in the Techniques Facility will involve the use of both plastic and glass vessels, pipettes, etc. Some of the labware used in modern laboratories is disposable, i.e., it is used once and then discarded in the proper waste container. However, some of labware is not disposable! Do not dispose of any labware without first checking that it is, in fact, disposable! In the Tech Facility the proper containers for discarding disposable labware are those with red bags in them and labeled "INFECTIOUS WASTE".
In this module, you will review examples of different types of Labware.
EXERCISE #1: DEMONSTRATION LABWARE:
Find the cabinet or shelf labeled "Demonstration Labware" and remove the box of Tech Facility demonstration Labware, placing it onto the bench top. Read the labels on each item, as well as the notes that pertain to it in this module. Perform additional exercises as you get to them below.
TYPES AND USAGE OF LABWARE
Below is a summary description of the types of Labware commonly used in bioresearch laboratories.
A. BEAKER (glass or plastic; glass ones not disposable, plastic ones sometimes disposable)
USAGE: Used for dissolving, mixing, and heating of various substances. Normally, is not used for long-term storage.
NOTES: Do not leave beaker open to the air before or during use. Cover it with Parafilm or some other stretchable laboratory film, or store it upside-down on a clean surface. This will keep it clean and ready for use, or, in the case of a Parafilm cover, will protect the contents from contamination during use.
EXERCISE #2: USING PARAFILM
"Parafilm" is a popular type of plastic protective film, and is usually used in rolls. Look for a roll of Parafilm on one of the Tech Facility benchtops (there are several). Note that one side of the film (the underside, as it unrolls) is covered with protective paper. This is the clean side of the film; the exposed upper surface is dirty!
1. Obtain the 100ml beaker from the box. Note that it is already covered with Parafilm. You are going to uncover and re-cover it.
2. Peel off its Parafilm cover.
3. Using a scissors, cut off a piece of Parafilm just large enough to fit across the beaker opening.
4. Carefully peel off the paper backing from the piece you have cut, taking careful note of which side is the clean side.
5. Stretch the film slightly as you place the clean side in contact with the beaker, and pull it down tightly against the edge of the beaker.
6. Stretch the overhanging film slightly as you complete the wrapping process. Then put the beaker back in the box.
B. ERLENMEYER FLASK (glass; not disposable)
USAGE: Frequently used in preference to beakers, for dissolving and mixing substances. The relatively narrow opening permits plugging or capping in various ways when sterilization of contents is required.
NOTES: Mixing can be accomplished manually by gently swirling the flask, and the narrow opening prevents spillage (unlike a beaker).
C. VOLUMETRIC FLASK (glass; not disposable)
USAGE: Used to measure liquid volumes in unit volume amounts (e.g., 100ml, 250ml, 1000ml) with high precision. Most volumetric flasks come with glass stoppers.
NOTES: Flask must be kept covered with its stopper or a piece of Parafilm or equivalent before or after use. A volumetric flask is a relatively expensive item because of precise calibration required in its manufacture, and should be treated with care. For example, avoid putting it in any unstable position to drain after washing.
D. GRADUATED CYLINDER (glass and plastic; not disposable)
USAGE: Used to measure liquid volumes, but with less precision than with a volumetric flask. However, the graduated cylinder permits measurement of intermediate volumes (say, 32ml, 97ml), unlike volumetric flasks.
NOTES: A glass graduated cylinder is used for measuring liquids that may dissolve plastic. However, because water or watery solutions tend to adhere to glass, the complete volume measured in a glass graduated cylinder (i.e., contained in it) will not be delivered from it when the liquid is poured out into another vessel. Thus, glass graduated cylinders are marked "TC", which means "to contain". If you measured, say, 100 ml in a 100ml cylinder, the volume that you pour out into another vessel might be only 99ml.
A plastic graduated cylinder, on the other hand, will deliver the entire volume that it contains. Thus, it is marked "TC/TD" ("to contain, to deliver"). If you measured 100 ml in a 100ml plastic cylinder, the volume that you pour out into another vessel would be 100ml, assuming that you were careful to shake out the last droplet.
E. PETRI DISH (glass or plastic; glass ones not disposable, plastic ones usually disposable)
USAGE: A special type of covered dish, usually used as a container for growing bacteria and other microorganisms on or within a semi-solid culture medium, or eucaryotic cells in a liquid medium. The Petri dish design facilitates observation of microorganism growth characteristics or of the growth of eucaryotic cells. Petri dishes are frequently used for other general purposes, such as storage of small lab items.
NOTES: When using a Petri dish for cell culture, don't forget to label it! Include name of your culture medium, your initials and a date. It is very important to label a Petri dish on both sides, i.e., on the lid and the bottom side. If the lid accidentally became separated from the dish, you would still be able to identify your culture by looking at the label on the bottom.
F. REAGENT BOTTLE (glass and plastic; not disposable)
USAGE: Used for long or short-term storage of various solutions. A glass reagent bottle is used to store solutions that may dissolve or react with plastic and therefore cannot be stored in plastic reagent bottles. Reagent bottles are equipped with screw caps or sometimes glass stoppers in the case of glass bottles.
NOTES: Reagent bottles should be kept closed with a glass stopper or screw cap, and opened only during use. For further protection against slow evaporation, Parafilm or other types of stretchable plastic film can be used to wrap the stopper or cap.
G. CULTURE TUBES - ALSO CALLED "TEST TUBES" (glass; usually disposable)
USAGE: Glass culture tubes are used both as all-purpose test tubes and as culture tubes for growth of microorganisms. For the latter purpose they are sterilized before use and are equipped with special caps or stoppers. Disposable culture tubes come in different sizes, specified by length and diameter. Look for one that is 13 X 100mm, and another that is 18 X 150mm.
H. "SNAP-CAP" TUBES (plastic; disposable)
USAGE: These are also good "all-purpose" tubes, useful for holding and storing small amounts of solid chemicals or of fluid volumes in the refrigerator or freezer.
NOTES: The most common error in using "snap-cap" tubes involves forgetting to snap the cap!
EXERCISE #3: SNAPPING THE CAP!
1. Pick up the 13ml snap-cap tube, and pull its cap off (it is not a screw cap).
2. Put the cap back on, pressing very slightly. Note that it appears to be back in place, but it is not on correctly, and the tube is actually still open!
3. Jiggle the cap back and forth; it still has some freedom of movement. Now give it an extra hard downward push. It will snap into its true closed position.
If left unsnapped during storage, tube contents will either spill out or evaporate. This seemingly minor problem is at best annoying, and can cause loss of time and money. At worst, it can be dangerous, depending upon tube contents.
I. CENTRIFUGE TUBES (plastic; disposable)
USAGE: This tube is used for centrifugation of various substances. It may also used for storing compounds, in which case proper labeling is required.
NOTES: These tubes may be purchased sterile or non-sterile. Always check to make sure that you are using the appropriate tube for your purpose.
J. MICROCENTRIFUGE TUBES (plastic, disposable)
USAGE: This tube is used for relatively high speed centrifugation of small volumes and sometimes for storage of small quantities of compounds or solutions.
K. WEIGHING DISH (plastic; disposable)
USAGE: Disposable weighing dishes are preferred to weighing paper for handling chemicals because:
a) there is less chance of spillage,
b) the dish is flexible and can be bent slightly to produce
a pointed "snout" for transferring the weighed-out
chemical to a mixing vessel, and
c) the dish is readily rinsed with deionized water to
transfer any residual chemical traces (usually
fine powder) to the mixing vessel.
ADDITIONAL NOTES ON USE OF LABWARE
In general, only reagent bottles (or capped test tubes) are to be used for long-term storage. Beakers cannot be capped or sealed very tightly, and are thus not good for storage. In general, beakers should be used only as described in A (above). Graduated cylinders and volumetric flasks are NOT to be used for storage unless you are specifically directed to do so. They are designed for volume measurement, and must be available for re-use at all times.
When freezing solutions for storage, remember to use a bigger storage container than needed. For example, do not store 50ml of solution in a 50ml container, because the volume of a watery solution expands when frozen. When defrosting, you may use a warm water bath method. Place the container with its frozen contents into a beaker or bucket of warm water, being careful not to use too high a water level (otherwise your reagent bottle may tip over). Monitor the melting periodically, so that the solution does not become too warm for its intended use after thawing.
Stored solutions must be labeled properly (for additional material on storage and labeling see Tech Facility workbook, Module VIII,).
WASHING OF LABWARE
In the Tech Facility each labware user will wash what he or she uses. Do not leave dirty labware on the bench top; always place it in the proper wash bucket (filled with wash solution) as soon as you have finished using it. When you work in a research lab, you may not have to wash the glassware, but you should know how the washing of experimental labware is done.
Instructions on proper washing of labware are given in the Tech Facility workbook, Module VI, part B.
DISPOSING OF LABWARE
On the Labware Cabinet and also in these instructions there is a list of disposable Labware. These are items that should be discarded immediately after use, and not washed for re-use.
Remember: Broken glass and other sharp things ("sharps") are disposed of in a container labeled "SHARPS ONLY-BIOHAZARD".
PLEASE BE CAREFUL WHEN WORKING WITH GLASSWARE! BROKEN GLASSWARE MUST BE CLEANED UP IMMEDIATELY AND DISPOSED OF PROPERLY.
Other lab waste and items which are listed as disposable go into the waste box that has a red bag in it. This box will later be sealed with tape, and disposed of as Infectious Waste. Take a look at one of these Hazardous Waste boxes; all of them must have the Address, name of Research Supervisor and the date prior to disposal. For additional information on disposal, see the Tech Facility workbook, Module II, - Waste Disposal.
EXERCISE #4: QUESTIONS
Review the types and usage of Labware by answering these questions:
1. What is a volumetric flask used for?
2. What is one advantage of using a plastic graduated cylinder instead of a glass one? When it is necessary to use a glass graduated cylinder?
3. What is an Erlenmeyer Flask used for?
4. What labware should be used for storing solutions?
5. What is the difference in usage of glass and plastic reagent bottles?
6. What is the basic use of beakers?
7. Why should you not store 250-ml of solution in a 250-ml storage bottle in the freezer?
8. List Labware that is usually considered disposable.
9. Why it is necessary to label a Petri Dish on top and bottom?
10. When should you wash glassware that you have used in the Tech Facility?
EXERCISE #5: CLEANING UP!
In the Techniques Facility, just as in any laboratory, you must clean up your work area and restore it to order before leaving. Otherwise the laboratory can become chaotic, leading to loss of efficiency and productivity (productivity in a research lab = completion of experimental work and ultimate publication of results in a professional journal). When you are finished with this module, put all of the demonstration labware back into the box, and put the box back in its original location.