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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 stirrer/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-nitrophenol in
75 mL DI water, then dilute to 100 mL. (pH indicator)
p-Nitrophenol
0.1% aqueous: dissolve 0.1 g of p-nitrophenol 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
and 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)
Orcein
Mix together 1 g of orcein, 1 mL of concentrated
hydrochloric acid and 100 mL of 100% ethyl alcohol.
Shake to dissolve, let sit over night and filter.
(stain for elastic fibers)
Pancreatin
Dissolve 5.0 g of pancreatin in 500 mL of DI water,
then dilute to 1 L. Add 0.5 M sodium bicarbonate
solution dropwise until solution is neutral. (digestive
studies)
SAFETY REFERENCE RECIPES FOR SOLUTIONS
Phenantholine
See Ferroin Solution, page 717.
Phenolphthalein
1% alcoholic: Dissolve 1 g of phenolphthalein in 50 mL
of 95% ethyl alcohol, then dilute to 100 mL with 95%
ethyl alcohol. For a 0.5% solution, only use 0.5 g of
phenolphthalein. (pH indicator)
Phenol Red
0.02% alcoholic: Dissolve 0.1 g of phenol red in 400
mL of 95% ethyl alcohol, then dilute to 500 mL with
95% ethyl alcohol. (pH indicator)
Phenol Red, Sodium Salt
0.02% aqueous: Dissolve 0.1 g of phenol red, sodium
salt in 400 mL of DI water, then dilute to 500 mL. (pH
indicator)
Phloroglucinol
Mix 0.5 g phloroglucinol and 50 mL of DI water. Add
50 mL of concentrated hydrochloric acid and stir. Use
within 5–7 days. Always add acid to water. (test for
pentose or galactose)
Polyvinyl Alcohol
4% aqueous: Add 40 g of polyvinyl alcohol to 1 L of hot
tap water. Microwave on high for about 2 minutes; stir
and heat for additional 1–2 minute increments until
dissolved. Allow solution to cool before use. (preparation
of “slime”)
Potato Dextrose Agar
Suspend 39 g of potato dextrose agar in 1 L of DI
water. Heat to a boil while stirring constantly. Boil
for 1 minute. Sterilize for 15 minutes at 121 °C (15 lbs
of pressure) in an autoclave or pressure cooker. Cool
to 50–55 °C and pour into sterilized culture dishes.
If using for plate counts of yeasts and molds, adjust
the pH to 3.5 with sterile 10% tartaric acid. (culture
medium for plate counts of yeasts and molds)
Pyrogallol
Dissolve 80 g of potassium hydroxide in 65 mL of DI
water, add 5 g of pyrogallol, stir, then dilute to 100
mL. Poor shelf life, make fresh. (determining oxygen
content)
Resazurin
1% aqueous: Dissolve 1 g of resazurin in 50 mL DI
water, then dilute to 100 mL. Stir and filter if necessary.
(biological stain and pH indicator)
Richard’s Solution
Dissolve 6.6 g of potassium nitrate, 3.3 g of potassium
dihydrogen phosphate, 33.3 g sucrose and 1.7
g of magnesium sulfate in 1 L of DI water. (culture of
molds)
Rhodamine B
1% aqueous: Dissolve 1 g of rhodamine B in 50 mL DI
water, then dilute to 100 mL. Stir and filter if necessary.
(biological stain)
Ringer’s Solution for Frogs
Dissolve 0.14 g of potassium chloride, 6.5 g of
sodium chloride, 0.12 g calcium chloride and
0.2 g sodium bicarbonate in 1 L of DI water. (mounting
fluid and examination of blood cells)
Ringer’s Solution for Mammals
Dissolve 0.42 g of potassium chloride, 9.0 g of
sodium chloride, 0.24 g calcium chloride and
0.2 g sodium bicarbonate in 1 L of DI water. (mounting
fluid and examination of blood cells)
Rose Bengal
1% aqueous: Dissolve 1 g of rose bengal in 50 mL
DI water, then dilute to 100 mL with distilled water.
Stir and filter if necessary. (biological stain)
Sabouraud Dextrose Agar
Suspend 65 g of sabouraud dextrose agar in 1 L
of DI water. Heat to boiling while stirring. Boil for 1
minute. Sterilize for 15 minutes at 121 °C (15 lbs of
pressure) in an autoclave or pressure cooker. Cool
to 50–55 °C and pour into sterilized culture dishes.
(microbiological culture medium)
Safranin O
Dissolve 0.1 g safranin in 75 mL of DI water, then
dilute to 100 mL. Filter before use. (Gram counter
stain)
Saline Solution
0.75% aqueous: Dissolve 7.5 g of sodium chloride in
750 mL of DI water, then dilute to 1 L. (Saline solution
for birds and invertebrates, use 0.8% for frogs
and 0.9% for mammals)
Note: DI water denotes either distilled or deionized water.
RECIPES continued on next page.
Slow Microorganisms
Solutions of methyl cellulose are
com mon ly used in micros copy to slow the
movements of microorganisms—making
them more readily observable. Generally
offered as a 2–3% solution in water, its
high vis cosity physically 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 technique
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.
Recipes for Biological, Histological and Chemical Solutions, continued
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