PREPARATION OF REAGENTS
Reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction
occurs.
In organic chemistry, reagents are compounds or mixtures, usually composed of inorganic or small organic molecules that are used to
effect a transformation on an organic substrate. Examples of organic reagents include the Collins reagent, Fenton's reagent, and Grignard
reagent. There are also analytical reagents which are used to confirm the presence of another substance. Examples of these are Fehling's
reagent, Millon's reagent and Tollens' reagent.
Collins reagent-used to selectively oxidize primary alcohols to an aldehyde
Fenton's reagent-solution of hydrogen peroxide and an iron catalyst that is used to oxidize contaminants
Grignard reagentFehling's reagent-used to differentiate between water-soluble aldehyde and ketone functional groups
Millon's reagent-an analytical reagent used to detect the presence of soluble proteins
Tollens' reagent-a chemical test most commonly used to determine whether a known carbonyl-containing compound is an aldehyde or a
ketone
I.INTRODUCTION
The chemistry reagents play an important role in the correctness of an experiment. If the composition of reagent is not correct, it often
leads to errors in the observations and results. While preparing the chemistry reagents in a laboratory, correct proportion of chemicals and
/or solvents as well as procedure is very crucial.
Safety is also very important, as Chemistry Labs are highly prone to accidents. While preparing reagents, one should be aware of correct
handling, procedure, storage and safety hazards. One of the most common accidents which happen is while opening the bromine capsule
to prepare bromine solution. However, with adequate knowledge and care, accidents can be avoided in the chemistry lab.
II. GENERAL INSTRUCTIONS
Always wear a lab-coat and safety goggles.
Wear disposable gloves while dealing with highly poisonous/irritant chemicals.
Follow the specific procedure and amounts/volumes of chemicals and solvents to be used for the reagent to be prepared.
Use clean and dry glass apparatus while preparing the reagents.
Store the reagents after proper labeling (name of reagent, date of preparation, hazard warning) as per the instructions in clean apparatus.
Dispose off any waste paper or any kind of solid waste properly.
Maintain a safe distance while using the chemicals.
Never touch, taste, or smell any chemical, whatever it may be.
Make sure no flammable solvents are in the surrounding area when lighting a matchstick or a burner.
III. SAFETY SYMBOLS
PREPARATION OF SOME COMMON REAGENTS
ALKALINE POTASSIUMFERRICYANIDE REAGENT
The alkaline potassiumferricyanide reagent is prepared by dissolving potassium ferricyanide (1g) in 100 mL of 20% aqueous NaOH
solution in distilled water, and cooled to ambient temperature. The reagent has a greenish-yellow color and a shelf life of two weeks
HOT ICE (SODIUM ACETATE)
SODIUM Acetate *get the pot then put the 1 L vinegar *then put the 100 g of baking soda (not baking powder) SLOWLY *then after you
put it SLOWLY the product is the SODIUM ACETATE. But it cannot be used to create hot ice because it contains more water. So you have
to boil until the 90% of water GONE. * Now turn on the heat and let the SODIUM ACETATE boil for 1 hour. Then get the CYRSTALS form
in the edges of the pot. Cause you will use it later.
PREPARATION OF BIOSPECIMEN
A biological specimen (also called a biospecimen) is a biological laboratory specimen held by a biorepository for research.
Goals of Specimen Preparation
• Observe specimen near natural state as possible.
• Preservation of as many features as possible.
• Avoid artifacts (changes, loss or additional information)
a. Fixation
The main purpose of fixation is to maintain the original form of the specimen
Typical fixatives-preservative agent
Formalin
Makes it one of the best penetrating of all the fixatives,
And formaldehyde, which is an eye and respiratory irritant at low exposure levels, is classified both as a human carcinogen
Glutaraldehyde
Is the most widely applied fixative in both scanning and transmission electron microscopy.
It can cause discoloration of the fluid and tissue.
Alternatives to common fixatives
Novec Fluids< ethoxy-nonafluorobutane (C4F9OC2H5) is a clear, colorless and low-odor fluid>
Novec fluids offer a unique balance of properties, including:
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Nonflammable
Colorless; non-yellowing
Preserves specimens' natural color
Chemically and thermally stable
Low odor
b. Dehydration
To remove the water in the specimen using the dehydrating agents like alcohol and acetone.
c. Block staining
Putting a stain in to the specimen. The common stains are the uranyl acetate, phosphotungstic acid, or potassium permanganate.
d. Embedding
It is all about how to embed the specimen. In the past it uses paraffin waxes but was found to be too soft to enable sections thinner than
about 1 µm to be cut. But now it uses EPOXY RESIN (ex. EPON 812 & EPON 812 has a part called AQUON)
e. Microtomy
It is all about in cutting specimen using microtome.
f. Section staining
Put again a stain like uranyl acetate, phosphotungstic acid, or potassium permanganate.
g. Sectioning artifacts
You seeing the specimen in the MICROSCOPE either SEM (Scanning Electron Microscope) or TEM (Transmission Electron Microscope)