This document provides information on cleaning laboratory glassware. It discusses the importance of clean glassware for reliable laboratory results. It describes different types of glassware and various cleaning methods from initial cleaning to more aggressive techniques using solvents or oxidizing agents. The methods section explains steps for initial cleaning, mild aqueous solutions, using organic solvents, and oxidative cleaning. It also covers neutralizing waste, common glass cleaners, ultrasonic cleaning, drying and sterilization. Safety precautions are emphasized when handling cleaning chemicals.

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