Glassware cleaning

2. Introduction
⚫Laboratory procedures require specific ,sensitiveand
precise methods fora reliable result .
⚫These methods should involve good glassware
cleaning toensureexcellent laboratory results.
⚫In all instances laboratory wares should be physically
clean, chemical residue free, grease free and be sterile.
⚫Laboratoryglassware area variety of materials made
of glass used forscientific experimentsand analysis in
all fields of science especially the diagnostic and
research field of medicine.

3. Types of Laboratory Glassware
⚫Merck glassware
⚫Duran glassware
⚫Rankem glassware
⚫Borosil R glassware
⚫Borosilicate qualityglassware
⚫Hydrometer
⚫Thermometer
⚫Crucibles-silica
⚫Zeal Thermometer
⚫Exampleof glassware items include beakers, f lasks, test
tubes, microscope slides, glass petri dishes, pipettes,
graduated cylinders, jars etc.

4. Laboratory Glasswares

5. Glassware cleaning
⚫Glasssware cleaning isdependenton the typeof glassand
theagent to be cleaned off theglass.
⚫In lieu of this , therearedifferent method of glassware
cleaning.
1. Initial Glass Cleaning
⚫This is the first step in glassware cleaning.
⚫If theglassware isn’tclean after these initial stepsyou can
goon to moreaggressivecleaning protocols.
⚫Method
⚫Scrapeawayany thick solid material from theglass if
possible.

6. Glassware cleaning(Methods)
⚫Wipeaway anygrease from theglass joints with a solvent
likeacetone which can be used to help remove thegrease.
⚫Put theglassware in awarm cleaning solution of detergent
and water.
⚫Usea brush orcleaning pad to clean any residueor
contamination.
⚫Rinsewith tapwater first, followed bydeionized waterand
allow todry
.
⚫Most new glass is slightly alkaline and should be washed
upon receipt and generally can be soaked in a 1% HCL or
HNO3 solution before wash , rinse in tap followed by DI
waterand allow todry
.

7. Glassware cleaning(Methods)
2. Mild Cleaning Methods
⚫If the initial cleaning method fails trygentle solvents
for long term soaking.
⚫When dealing with the gentle aqueous solutions heat
soaking or, in some instances, mechanical agitation
such as stirring, shaking, orsonicationcan enhance its
productivity.
⚫Thecommongentleaqueouscleaning mixtures are
described below.

8. Common Gentle Aqueous Cleaning Mixtures and their
Uses
⚫ Deionized water
⚫ Dilutesurfactants
For diluting out absorbed ions – passive soaking.
Solubilizing lipid material – agitation, brushing, rubbing
orsonication.
⚫ Protein or saccharide hydrolyzing enzymes Breaking largerstructures into
soluble molecules – passivesoaking.
⚫ Metal chelating compounds
⚫ Dilutestrong acids
Insoluble salts become more so by removing
the metal ion – passivesoaking.
Insoluble salt’s anion is solubleas its acid form
– soak or agitation.
⚫ Concentrated weak acids Insoluble salt’s anion is solubleas its acid form
– soak or brush.
⚫ Dilute solutionsof: Phosphates, Carbonates or Ammonia All create low levels of
hydroxide ions for
solubilizing weak
insoluble acidicsolidsor
hydrolyzing ester bonds
– soak, agitateor brush.

9. Glassware cleaning(Methods)
3. Using Organic Solvents
⚫ Organicsolventsareoften used to removecontaminants from
glass.
⚫ Basically, if itcan be readilydissolved in an organicsolvent it
can be removed by these means.
⚫ The useof organicsolvents iscomplicated due to their
flammability and toxicity.
⚫ When working with solvents properventilationand
appropriate PPE (suitableglovecompatibilitywith the
solvent) are necessary.
⚫ Moistening a cloth with solvent is good foreasilyaccessed
surfaces.
⚫ Agitating solvent insideof aglasscontainer isanother

10. Glassware cleaning(Methods)
4. Aggressive Cleaning Methods
⚫If the mild ,aqueous and organic solvent methods
described above are not effective then aggressivecleaning
method is adopted.
⚫This method involve releasing the adhered
material/contaminant by removing the top layerof silicon
oxideof theglass.
⚫Itcan also be done by oxiding the material itself from the
glasssurface.
⚫This can be achieved by soaking the glass in 2%
hydrofluoricacid ora base bath (sodiumor potassium
hydroxide in eitherethanol or isopropanol) before rinsing
and cleaning in detergent.

11. Glassware cleaning(Methods)
⚫The aggressive method is achievable due to the borosilicate
nature of laboratory glassware as the acid will attach to the
silica layerof theglass.
5. Oxidizing Contaminants from Glassware
⚫Often the residueon glass is insoluble toorganic solvents,
surfactant solutions, or mildlyacidic solutions.
⚫At this point one of thecommon ways toclean glass is to
oxidize thecontaminant in order to render it soluble.
⚫Oxidizing agents include aqua regia(nitric acid and
HCl);Chromic acid which is a sulfuric acid based
agent;Piranha solution (hydrogen peroxide based
agent),fuming sulfuricacid which contains pyrosulfuric
acid.

12. Neutralization and Disposal
⚫Neutralizationof theseaggressive baths is nota trivial
matter.
⚫This is largelydue to thevolumeof the baths
commonlyemployed.
⚫Extremecare must be takenand appropriate PPE must
beworn.
⚫Noone should do these neutralizationswithoutthe
proper training.
⚫The Laboratory Safety Officer/Quality Control officer
will helpwith the process by reviewing the procedures.

13. Glass cleaners
⚫Detergents are the besteg Alconox.
⚫Theycan be used for handwashing, soaking and
automaticwasher.
⚫Alwaysusesoft brushes.
⚫Alwaysrinseglasswell and doa final DI rinse.

14. Glass cleaners
⚫ ChromicAcid or Chromerge
⚫ It is agreatcleanerand also removesorganicresidues.
⚫ Use glovesand well ventilatetheareawhen using chromic acid as
it is acarcinogenand verycorrosive.
⚫ Makesure metal clampsor f langesare removed.
⚫ It is best to fill thevessel orsoak the item in the solution fora
short time in a plastic tub so that you can contain the wash
material,.
⚫ Then rinse immediatelyseveral times before proceeding toa
detergentwash.
⚫ Makesure the residual chromic acid is diluted afteruse and
disposed properlyaccording toyour local orcompany
regulations.

15. Glass cleaners
⚫ Removal of Grease
⚫ Grease is best removed by boiling theglass in aweak solution of
sodium carbonate.
⚫ Acetone oranyotherorganicsolventcan be used also, followed
by several waterand DI waterrinses.
⚫ Otherstains
⚫ Forpermanganatestains usea mixtureof equal 3% sulfuricacid
and 3% hydrogen peroxide.
⚫ ForIron stains use a solution containing one part hydrochloric
acid and one partwater.
⚫ For bacteriological contamination, glasswareshould be soaked
in a disinfectant solution and then steam autoclaved then
followed bya suitablewashing and rinsing.

16. Glassware cleaning(Glass cleaners)
⚫Ultrasonic Cleaners
⚫Ultrasonics isagood method of cleaning glassware.
⚫Ultrasoniccleaners thatare heated will be the bestand
generally with a mild detergent they will clean most
residuesoff of glassware.
⚫Rinsing
⚫Glasswareshould always havea waterrinseafterany
cleaning procedure followed bya DI rinse.
⚫It is best togivesmallerpieces such as test tubesa
soaking rinse followed bya DI soaking rinse.

17. Glassware cleaning(Glass cleaners)
⚫Drying
⚫Ovendrying at 100° C is best forall glassware. If not
convenient, rack drying will work.
⚫Steam Autoclaving or Sterilizing
⚫Proper protocol forsteamautoclaving of borosilicate
glassware is 15-20 minutesat 100-120° C.

18. Safety Precautions in cleaning of laboratory
glassware
⚫When cleaning glassware, full shielding of the eyes is a
minimum requirement becauseeven soap solutionscan
causeeye irritation.
⚫Manyof thechemicals used in cleaning can easily
penetrate the skin, especiallywhen combining them with
organic solvents.
⚫Chemical Splash goggles, plastic aprons and non-
disposable gloves – specificallychosen to handleextended
contact with the chemical - should be worn during any of
theaggressive procedures described above.

19. ⚫ THANK YOU