Cleaning
of glassware which has contained hazardous materials
must be solely undertaken by experienced personal.
2.
Most
new glassware is slightly alkaline in reaction.
For precision chemical tests, new glassware should
be soaked several hours in acid water (1 % solution
hydrochloric acid or nitric acid) before washing.
3.
Glassware
which is contaminated with blood clots, culture
media, etc. must be sterilized before cleaning.
4.
If
glassware become induly clouded or dirty or contains
coagulated organic matter, it must be cleaned
with chromic acid cleaning solution. The dichromate’s
should be handle with extreme care because it
is a powerful corrosive
5.
Wash
glassware as quickly as possible after use but
if delays are unavoidable, the articles should
be allowed to soak in water.
6.
Grease is removed by weak sodium carbonate solution
or acetone or fat solvents. Never use strong alkalis.
7.
Hot water with recommended detergents should be
used and if glass is exceptionally dirty a cleaning
power with a mild abrasive action can be applied,
provided the surface is not scratched.
8.
During
washing all parts of the article should be throughly
scrubbed with a brush selected for the shape and
size of the glassware. Brushes should always be
in good condition to avoid any abrasion of glassware.
9.
When
chromic acid solution is used, the item may be
rinsed with the cleaning solution or it may be
filled and allowed to stand. The amount of time
should depend on amount of contamination on the
glassware.
10.
Special
type of precipitate material may required removal
with nitric acid, aqua regia or fuming sulphuric
acid. These are very corrosive substances and should
be used only when required.
11.
It
is imperative that all soap detergents and other
cleaning fluids be removed from glassware before
use. This is especially important with the detergents,
slight traces of which will interfere with serologic
and culture reactions. After cleaning, thoroughly
rinse with tap water ensuring that containers are
partly filled with water, shaken and emptied several
times. Finally rinse with deionised or distilled
water.
12.
Drying
can be undertaken either in baskets or on pages
in air or at a temperature not exceeding 120°C.
13.
Always
protect clean glassware from dust by use of temporary
closures or by placing in a dust free cabinet. For
cleaning specific type of glassware, please refer
the following pages.
Cleaning
Specific Types of Glassware
Pipettes
Place pipettes tips down, in a cylinder or tall
jar of water immediately after use. Do not drop
them into the jar, since this may break or chip
the tips and render the pipettes useless for accurate
measurements. A pad of cotton or glass wool at
the bottom of the jar will help to prevent breaking
of the tips. Be certain that the water level is
high enough to immerse the greater portion or
all or each pipette. At a convenient time, the
pipettes may then be drained and placed and in
a cylinder or jar of dissolved detergent or, if
exceptionally dirty, in a jar of chromic acid
cleaning solution. After soaking for several hours,
or overnight, drain the pipettes and run tap water
over and through then until all traces of dirt
are removed. Soak the pipettes in distilled water
for at least one hour. Remove from the distilled
water, dry the outside with a cloth, shake out
the water and dry.
Burettes
(with glass stopcock)
1.
Remove
the stopcock key and wash the burette with detergent
and water.
2.
Rinse
with tap water until all the dirt is removed. Then
rinse with distilled water and dry.
3.
Wash
the stopcock key separately. Before the stopcock
key is replaced in the buretts stopcock key are
not interchangeable
4.
Always
cover burettes when not in use.
Culture
Tubes
1.
Culture
tubes which have been used previously must be
sterilized before cleaning. The best general method
for sterilising culture tubes is by autoclaving
for 30 minutes at 121°C (15ib. pressure).
Media which solidify on cooling should be poured
out while the tubes are emptied, brush with detergent
and water, rinse throughly with tap water, rinse
with distilled water, place in a basket and dry.
2.
If
tubes are to be filled with a medium which is sterilized
by autoclaving, do not plug until the medium is
added .Both medium & tubes are thus sterilized
with one autoclave.
3.
If
the tubes are to be filled with a sterile medium
or if they are to be sterilized by the fractional
method then sterilize the tubes in the autoclave
or dry air sterilizer before adding the medium.
Serological
Tube
1.
Serological
Tubes should be chemically clean but need not
be sterile. However, specimens of blood which
are to be kept for some time at room temperature
should be collected in a sterile container. It
may be expendient to sterilize all tubes as routine.
2.
To
clean and sterilize tubes containing blood, discard
the clots in a waste container and place the tubes
in a large basket. Put the basket, with others,
in a large bucket or boiler. Cover with water, add
a fair quantity of soap or detergent and boil for
30 minutes. Rinse the tubes and clean with brush,
rinse and dry with the usual precautions.
3.
It
is imperative when washing serological glassware
that all acid, alkali and detergent be completely
removed, Both acid and alkali in small amounts destroy
complement and in large amounts produce hemolysis.
Detergents interfere with s e r o I o g i c reactions.
4.
Serological
tubes and glassware should be kept separate from
all other glassware and used for nothing except
serologic procedures.
