Laboratory Assistance, Safety, and Equipment Handling
This is the technical heart of the Lab Attendant post: correct handling of glassware and instruments, chemical and biological safety, and accurate record-keeping.
Safety rules
- PPE first: lab coat, goggles, closed shoes and nitrile gloves; use a fume hood for volatile or toxic work.
- Dilute acids by adding acid to water slowly with stirring, never water to acid.
- Never pipette by mouth; use a bulb or pipette filler.
- Label every container with name, concentration, date and preparer, and keep the safety data sheet accessible.
- Balance the centrifuge with equal-weight tubes placed opposite each other, and never open the lid while it spins.
- Autoclave conditions for routine sterilization: 121 degrees Celsius at 15 psi for 15 to 20 minutes.
- Biomedical waste colours: yellow for soiled and human/animal waste, red for contaminated recyclable plastics, white for sharps, blue for broken glass.
Worked example
Prepare 250 mL of 0.1 M NaCl. Step 1, moles needed = 0.1 mol/L x 0.250 L = 0.025 mol. Step 2, mass = 0.025 x 58.44 g/mol = 1.461 g. Step 3, weigh 1.461 g, dissolve it in about 150 mL distilled water, transfer to a 250 mL volumetric flask, rinse the beaker into the flask, then make up to the mark and mix. Record all three numbers in the register.
Traps
Rounding the molar mass too early; filling to the mark before the solute has dissolved; forgetting to tare the balance; storing acids above bases; drying glassware mouth-up so dust collects.