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Posts tagged ‘petri dish’

Agars, Buffers, and Broths

Nutrient Agarhas been a staple in both the classroom and the lab, it is used

Bacteria Experiment Kit

Bacteria Experiment Kit - Agar!

as a bacteria growing medium – happily feeding the source bacteria you swab through it from whatever experiment you’ve dreamed up. Be it the ‘is my dog’s mouth cleaner than mine, to testing the 5 second rule.  We’ve sold lots of gelled Agar over the years, in both bottle or kit.

But sometimes people prefer to mix their own agar rather than have it pre-gelled. Sometimes this is for storage reasons (dehydrated agar does last longer on the shelf). Also, people may have need for other kinds of Agar or lab mixes.

Specialty Agar

Specialty Agar

So we have added some new agars and will be adding more! We’ve added a 500g bottle of dehydrated Nutrient Agar, as well as bottles of Technical Agar (which has a much lower amount of ‘stuff’). We’ve also added MacCornkey Agar, which is used in identifying bacteria that can ferment lactose. The MacCormley Agar will be available dehydrated or as a prepared plate.

In addition to Agar, we are also adding D/E Neutralizing Broth, which is

D/E Neutralizing Broth

D/E Neutralizing Broth

used to determine the effectiveness of bactericidal properties of disinfectants, etc.  This comes in convenient tubes in packs of 100.  In addition we are now carrying bottles of Butterfield Phosphate Buffer, which is used as a dilutant in wastewater & food testing.

These new chemicals, being mostly biological or used in biological applications, are made on demand to maximize shelf life. As a result they cannot be rush ordered.

Spectrum Scientifics will be adding more of these items in the future. Keep an eye out!




Laboratory Glassware -A Primer Part 3

Continued from Part 2

Having covered flasks and other basics, there are a few more common types of lab glassware to discuss.

Test Tubes: Test tubes come in a variety of sizes, but overall that have the

same shape: A long tube with a rounded bottom. Test tubes are not meant to stand on their own, but to he held in the hand or stored is test tube racks. Test tubes are low cost and low volume, making them convenient for storage, side-by-side reactions, small quantity heating over a flame, and hundreds of other uses. They are probably one of the most common types of labware.  Most test tubes are made of borosilicate glass so they can be heated, but sometimes test tubes are made of plastic.

Petri Dishes: Petri dishes are more used in biology than chemistry, but they have a place in the chemistry lab as well. The most frequent use of petri dishes is for growing bacteria cultures in an agar (nutrient) mix. Petri dishes are often considered disposable, so they most often made of plastic. However they can also be made of glass for situations where heat may need to be applied.  Petri dishes typically have a simple bottom-and-top arrangement, and some designs may have grid patterns for measuring density and growth and others may be bisected into sections for comparison or simple space efficiency.


Reagent Bottles and Media Bottles: These bottles are used to store liquid

or powder chemicals. They are not made for reactions. They can be made of glass or sometimes plastic. Almost as important to the material the cap or lid. Some designs may use a glass stopper, others may have a screw-on cap depending on the reagent/media being held.



Distilling & Condensing Systems There are a huge number of distillation systems and apparati. They often have different purposes but the most basicone is to make distilled water by boiling it (and leaving the impurities behind) and then have a section where the evaporated water condenses again – either by having a jacketed sleeve, or condensing tube where cold water is pumped in fresh to cool & condense the steam back into water. There are many variations on this and going into them is beyond the scope of this article. Some systems are designed to distill other liquids, or separate them by heating. As one may expect, distilling and condensing systems are made of glass as plastic can rarely stand the heat involved.

Continued in Part 4.