Manual of basic techniques for a health laboratory - libdoc.who.int

3. General laboratory procedures 81CoverslipsUsed coverslips can be cleaned and reused.1. Make up the following solution in a large beaker:— 200ml of water— 3ml of detergent— 15ml of bleach or 5ml of a quaternary ammonium disinfectant (see pages 84and 85).2. Put the coverslips into the beaker one by one.3. Leave the coverslips to soak for 2–3 hours, shaking gently from time to time.4. Rinse out the beaker containing the coverslips with tap water four times, shakinggently.5. Give a final rinse with demineralized water.6. Drain the coverslips by tipping them out carefully on to a pad of gauze.7. Dry in a hot-air oven at 60°C, if possible.Keep clean, dry coverslips in a small Petri dish. If possible, use special coverslipforceps for taking them out.Reusable syringes and needlesAs soon as a sample has been collected, remove the plunger from the used syringeand rinse both the barrel and the plunger. Fill the barrel with water, insert theplunger and force the water through the needle. Finally remove the needle andrinse the hub cavity.Reusable syringe with blocked pistonTo loosen the piston, choose one of the following methods:● Soak for 2 hours in hot water (about 70°C).● Stand the syringe on its end, piston down. Pipette 50% acetic acidsolution (reagent no. 3) into the nozzle of the syringe with a fine Pasteurpipette (Fig. 3.61). Leave for 10 minutes.After loosening the piston, soak the syringe for several hours in a bowl of1mmol/l hydrogen peroxide.Rinsing and soaking needlesAs soon as the needle has been used, rinse it while it is still attached tothe syringe, then remove it and leave it to soak in hot water.Blocked needlesTo remove the blockage, use a nylon thread dipped in 50% acetic acidsolution (reagent no. 3); alternatively, you can use a stylet.Fig. 3.61 Cleaning a blocked (reusable)syringe using acetic acid3.5.2 Cleaning non-disposable specimen containersNon-disposable containers, such as jars and bottles, may contain stools, sputum,pus, CSF, blood or urine, all of which may harbour potentially infectiousorganisms.