Page 222 - Demo

Safety Reference
Recipes for Biological, Histological, and Chemical Solutions, continued
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Litmus
0.5% aqueous: dissolve 0.5 g of litmus in 80 mL of boiling DI water. Allow solution to cool to room temperature, dilute to 100 mL. Stir, filter if necessary. (pH indicator)
Malachite Green
1% aqueous: Dissolve 1 g of malachite green oxalate in 50 mL of DI water; stir gently to prevent foaming; dilute to 100 mL. Filter if necessary. (pH indicator, stain for plant cytoplasm)
Methyl Cellulose
3% aqueous: Heat 100 mL of DI water to 85 °C (not boiling), shake 3.0 g of methyl cellulose powder into hot water, and stir rapidly while cooling the solution to 5 °C in an ice water bath. Solution is stable at room temperature but store in tightly closed containers. (slowing down protozoa for microscopy)
Methylene Blue
1% aqueous: Dissolve 1 g of methylene blue in 75 mL of DI water, then dilute to 100 mL. (pH indicator and stain)
Methylene Blue, Loeffler’s
Dissolve 0.3 g of methylene blue in 30 mL of 95% ethyl alcohol; add 0.01 g of potas- sium hydroxide and 100 mL of DI water; stir, and filter. (bacterial stain)
Methyl Green
1% aqueous, acidified: Dissolve 1 g of methyl green in 75 mL of DI water, add 1 mL of glacial acetic acid, then dilute to 100 mL with DI water. Stir, filter if neces- sary. Use 1% acidified aqueous solution as a general nuclear stain, plant stain or cytoplasm stain.
Methyl Orange
0.1% aqueous: Dissolve 0.1 g of methyl orange in 75 mL of DI water, then dilute to 100 mL. (pH indicator)
Methyl Red
0.1% alcoholic: Dissolve 0.1 g of methyl red in 75 mL 95% ethyl alcohol, then dilute to 100 mL. (pH indicator)
Methyl Red
0.04% aqueous: Dissolve 0.1 g of methyl red in 11.8 mL of 0.02 M sodium hydrox- ide solution; dilute to 250 mL with DI water. If using Na salt, omit NaOH. (pH indicator)
Methyl Violet 2B, Indicator
0.04% aqueous: Dissolve 0.1 g of methyl violet 2B in 200 mL of DI water, then dilute to 250 mL. (pH indicator)
Methyl Violet 2B, Stain
Dissolve 0.05 g of methyl violet 2B in 100 mL of 0.7% sodium chloride solution and 1 mL of 1 M acetic acid; stir, and filter if necessary. Use 0.9% sodium chloride solution if staining human blood cells. (staining amphibian and human blood cells)
Methyl Violet 6B, Indicator
1% aqueous: Dissolve 1 g of methyl violet 6B in 75 mL of DI water, then dilute to 100 mL. Stir and filter if necessary. (biological stain)
Millon Reagent
Dissolve 1 part by weight mercury in 2 parts concentrated nitric acid; when mercury has dissolved, add to 2 parts water; stir. Note: always add acid to water. (test for proteins)
Molisch Reagent
Dissolve 5 g 1-naphthol in 100 mL of 95% ethyl alcohol. (test for aldehydes, sugars, and carbohydrates)
Neutral Red
Dissolve 0.1 g of neutral red in 60 mL of 95% ethyl alcohol, then dilute to 100 mL with DI water. Stir and filter if neces- sary. (pH indicator and vital stain stock solution)
Nigrosin
Saturated: Dissolve 3 g of nigrosin (water soluble) in 100 mL of DI water. Stir and filter if necessary. (biological stain for protozoa)
Ninhydrin
Add 2.5 g of ninhydrin to 50 mL of n-butyl alcohol in a 600-mL beaker. Gently heat and stir the solution using a magnetic stir- rer/hot plate in a fume hood until all the solid is dissolved. Dilute to 500 mL with n-butyl alcohol. Use extreme caution when heating n-butyl alcohol, extreme fire risk. (test for proteins)
m-Nitrophenol
0.3% aqueous: dissolve 0.3 g of m-nitro- phenol in 75 mL DI water, then dilute to 100 mL. (pH indicator)
p-Nitrophenol
0.1% aqueous: dissolve 0.1 g of p-nitro- phenol in 75 mL DI water, then dilute to 100 mL. (pH indicator)
4-(p-Nitrophenylazo) Resorcinol
Dissolve 0.01 g of 4–(p-nitrophenylazo) resorcinol in 100 mL of 1 M sodium hydroxide solution, stir. (indicator solution for magnesium and molybdenum)
Nutrient Agar
Mix together 23 g of nutrient agar with 1 L of DI water. Sterilize for 15 minutes at 121 °C (15 lbs of pressure) in an autoclave or pressure cooker. Nutrient agar should be sterilized if it is being used as culture media. Cool to 50–55 °C and pour into sterilized culture dishes. (culture medium)
Nutrient Agar (using plain agar)
Dissolve 5 g peptone, 3 g meat extract, and 15 g of plain agar in 850 mL of distilled water. Adjust pH to 7.0. Bring to 1 L with distilled water. Autoclave or filter sterilize.
Orange G
1% aqueous: Dissolve 1 g of orange G in 75 mL of DI water, then dilute to 100 mL. Stir and filter if necessary. (staining plant sections)
Orange IV
0.1% aqueous: Dissolve 0.1 g of orange IV in 75 mL of DI water, then dilute to 100 mL. Stir and filter if necessary. (pH indicator and biological stain)
Note: DI water denotes either distilled or deionized water.
RECIPES continued on next page.
Slow
Microorganisms
Solutions of methyl cellulose are commonly used in microscopy to slow the movements of microorganisms— making them more readily observable. Generally offered as a 2–3% solution in water, its high viscosity physi- cally inhibits the organism. In use, the resulting dilution will depend on the amount of water present on the slide when the slowing agent is added. Some experimentation may be required to find the optimal dilution for a particular organism. One tech- nique involves dropping the methyl cellulose onto a clean slide in the form of a ring. A drop of the culture being studied is then placed into the center of the ring and a cover glass applied. As an alternative, see the listing for polyvinyl alcohol solution.