Lab glass cleaning

Lab Glass Cleaning
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com

Advice
for clean and
residue-free
residue free
laboratory
equipment

© Dr. Weigert & DURAN Group 2012

Good practice– type of glass
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Selection of right types of glass
 a high quality of the raw materials and their
composition
ii
 wall thickness distribution in order to attain
a good resistance to temperature and
g p
changes in temperature,
high level of mechanical stability
 a very high hydrolytic resistance
(corresponds to class 1 according to ISO 719).
 very small expansion coefficients, a high level
of resistance to quick changes in temperature


Good practice– conformity to standards
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• Why should attention be paid to conformity to
standards?
 standards set the properties and
geometries for laboratory glass products ->
products can be still be obtained with the
same characteristics and dimensions
even after many years
 characteristics which are decisive for safety
such as distribution of wall thickness in
beakers, are given in the standards for many
articles


Good practice– instruction for use
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• What is important when selecting a glass item for use?

 before each use the glass surface should be
checked for damage such as scratches,
cracks or chips
 vessels should only b used when they are in
l h ld l be d h h
a flawless condition, this is particularly
important for work under pressure or at high
temperatures
 damaged glass may not be used for safety reasons.


Cleaning – cleaning process
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The advantage and disadvantages of
• manual cleaning
 greater risk of injury
 slower and less economical when there
are lots of items to be washed
 time consuming when the laboratory
appliances have a complex geometry
 is clearly quicker if only single laboratory
glass items are being cleaned
 flexible in terms of duration of cleaning
and selection of cleaning agent


Cleaning – cleaning process
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Advantages and disadvantages of
• cleaning in a washer/disinfector
 reduced breakage risk
 reduced risk if injury
 saves staff resources
 quicker and more economical for
large quantities of items to be
washed
 inflexible in terms of duration of
cleaning and selection of cleaning
agent


Cleaning – type of soiling
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Type of soiling
• Organic soiling
peptides/ proteins, fats/oils,
carbohydrates/ polysaccharides,
organic colourings, pigment residues
colourings
and felt tip residues, resins and
paraffin


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Type of soiling

• Inorganic soiling
g g
carbonates, salts, metal oxides,
watery solutions of inorganic acids
(HCl,
(HCl H2SO4)/
alkali (NaOH, KOH),
salt solutions
(NaCl, NaNO3, FeCl2 etc.)


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Type of soiling

• Microbiological residue
g
growth media, cell cultures and
tissue residues, nutrient broth,
microorganisms
i i


Cleaning - cleaning agents
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Which cleaning agents are suitable for which soiling?
• Alkaline cleaning agents
 are suitable f th d t i and removal
it bl for the denaturing d l
of residues which contain protein, fat and
carbohydrates
• Acid cleaning agents
 are effective against inorganic salts,
lime and other carbonates.
• Bleaching agents
 help with the removal of paints and with disinfection.


Cleaning - cleaning agents
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• What requirements must a cleaning agent meet?
 The selection is linked to the type of soiling to
be
b removed and th f
d d the framework conditions (ti
k diti (time,
material properties and mechanical system, quality
of water)
 fundamental requirements: • Which resources can be used?
 good ability to remove dirt abrasive materials (steel wool)
 high dirt carrying capacity
dirt-carrying must not be used -> these will
 suitable for most surfaces cause surface damage to the
 good rinsing properties
g gp p glass
 not hazardous to health  soft sponges, cloths and brushes
 very cost-effective are suitable
 environmentally friendly


Cleaning – parameters of cleaning
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• Chemistry (=cleaning agents)
 helps with the decomposition of dirt
components and th simplifies
t d thus i lifi
the removal of dirt from surfaces
 the surfactants contained in cleaning
agents improve the wetting of the item
to be cleaned and the dirt-carrying
capac ty o the ate
capacity of t e water
 the selection of the cleaning agent to
be used depends on the dirt to be
removed,
removed the material of the items to be
cleaned and the quality of water used for
automated cleaning


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• Temperature
 high temperatures can accelerate physical,
chemical and enzymatic processes and
h i l d ti d
thus benefit removal of contaminations
 temperatures which are too high can,
 however, reduce enzyme activity
 Another disadvantage of excessive temperature
is the
i th conversion of carbonic acid contained i
i f b i id t i d in
the water to carbonate via hydrogen carbonate
which is then precipitated as a poorly soluble
compound with the water hardening salts magnesium
and calcium. This results in stubborn ‘lime deposits’.


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• Time
 an extended reaction time for the
cleaning solution makes th removal
l i l ti k the l
of dirt from the surface easier due
to better swelling of the contaminants
and a stronger chemical decomposition
of the dirt components


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• Mechanics
 The use of mechanical agents such as the
use of b h or pressurized water jets
f brushes d
enables bonding forces between dirt
and surface to be overcome so that
dirt can then be removed more easily.

 Chemistry temperature, time and mechanics are the four components
Chemistry, temperature
of the so-called Sinner’s Circle which describes the mode of action of the
cleaning process and which was named after the chemist Dr. Herbert
Sinner.
Sinner


Cleaning – Dr. Sinner´s Circle
Sinner s
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Dr. Sinner’s Circle

Each parameter is variable in size. However, if one factor is changed this
will affect the size of at least one other factor if the cleaning performance
is to remain the same. This means that a longer reaction time is necessary
if there is a lower temperature in the rinsing process for example. A
reduced parameter is thus compensated by the increase of another.


Cleaning – quality of water
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Quality of water
 defines
• microbiological factors (germ count)
• the degree of water hardness, given in °GH (German hardness)
(magnesium and calcium ions in the water )
 If water with a high degree of hardness is used for cleaning, significant
residues may be deposited on the cleaned surfaces
 Depending on the water quality (e.g. deionised water or softened water)
different effects are achieved in combination with the used cleaning
agents. These affect the material compatibility and the cleaning results.


Advice and Tips
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• How can laboratory glass be stored correctly
whilst saving as much space as possible?
• Marking – what has to be observed?
• How can stubborn residues be avoided?
• How should the glass be disposed of?
• What should you know about volumetric
glassware?
• How should you clean cover glass and slides?

All this and more at :
www.labglasscleaning.com


Laboratory Glass Cleaning
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From experts for experts –
p p
www.labglasscleaning.com
Pictures by Karin Gerdes
http://www.karingerdes.de

Lab glass cleaning

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