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Basic Laboratory Skills

Basic Laboratory Skills. LIQUID VOLUMES ARE MEASURED WITH:. Graduated Cylinders – liters & milliliters Beaker – liters & milliliters Flasks – liters & milliliters Pipettes – milliliters Micropipets – microliters. To Convert Between Metric Units of Measurement.

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Basic Laboratory Skills

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  1. Basic Laboratory Skills

  2. LIQUID VOLUMES ARE MEASURED WITH: • Graduated Cylinders – liters & milliliters • Beaker – liters & milliliters • Flasks – liters & milliliters • Pipettes – milliliters • Micropipets – microliters

  3. To Convert Between Metric Units of Measurement • Move the decimal point left when going to a bigger unit • Move the decimal point right when going to a smaller unit Example – 2.50 L = _____ mL (2.50 L x 1000 mL/1L = 2500 mL) Example - 95 mL = _____L (95 mL x 1L / 1000 mL = 0.095 L)

  4. Graduated Cylinders: • Use to measure volumes > 10 milliliters • Read volume markings at eye level • Measurements should be at bottom of the Meniscus (lowest point of concave surface) Graduated Cylinder Sizes: 10 mL, 25 mL, 100 mL, 250 mL, 500 mL, & 1 L

  5. Pipettes(Straw with Graduations) • Use when measuring volumes < 10 mL • Select smallest pipette for job to < error • Pipettes maybe volumetric (deliver specificvolume) • Serological pipettes deliver graduated amounts (i.e. 1.2 mL,1.3 mL,1.4 mL…) • Pipettes range in size from 1 mL – 10 mL • NEVER MOUTH PIPETTE • Use a pipette bulb or pump for pipetting & dispensing the solution

  6. Micropipettes • Micropipettes measure volumes < 1mLor 10 – 100 microliters (μ) 1 microliter (μ)= 1,000,000 L or 1 L = 1000mL & 1 mL = 1000 microliter (μ ) • Micropipettes have 2 stops controlled by a plunger: Press to 1st stop and allow to fill. Evacuate by pressing past 2nd stop. Micropipette Tips are used & disposed of after each use Micropipettes can be checked for accuracy using a balance

  7. Multichannel Pipette • This pipette holds 4 – 16 tips & is controlled with one plunger • It accurately measures and dispenses identical samples at the same time • This saves time and energy

  8. ACCURACY OF MICROPIPETTES • A BALANCE CAN BE USED TO DETERMINE IF A MICROPIPETTE IS ACCURATE • 1.5 mL OF H20 SHOULD WEIGH 1.5 g • 0.25 mL OF H20 SHOULD WEIGH 0.25 g • 0.15 mL of H20 SHOULD WEIGH 0.15 g

  9. Review / Practice: Which instrument would you use to perform The following measurements: 25 μ ? 125 mL ? 2.5 mL ? 450 μ ? 8.5 mL ? MICROPIPETTE GRADUATED FLASK PIPETTE MICROPIPETTE PIPETTE

  10. SECTION TWO

  11. MASS OR WEIGHT • IS MEASURED ON BALANCES OR SCALES • STANDARD UNIT OF MASS IS GRAM • MASS MAY ALSO BE MEASURED IN MILLIGRAM (mg) OR KILOGRAMS (kg) • 1,000 MICROGRAM (μ) = 1 MILLIGRAM (mg) • 1,000 MILLIGRAMS (mg) = 1 GRAM (g) • 1,000 GRAMS (g) = 1 KILOGRAM (kg)

  12. Preparing Solutions: • Solution is one or more solutes dissolved in a solvent • The substance being dissolved is a solute • The solvent is usually a liquid • Water is the most common solvent • Concentration is the proportion of solute to solvent Common units of concentration: Mass / Volume, % Mass / Volume, Molarity and X Concentration

  13. MASS / VOLUME ____ G / mL x ____ mL = ____g of solute concentrationvolumeto be weighed out & desireddesireddissolved in solvent OR 0.12 g / mL x 100 mL = 12 g of NACL Measure 12 g NACL, add to solvent up to 100 mL

  14. % MASS / VOLUME __9__% = _______ PERCENT VALUEDECIMAL VALUE OF g / mL OR _______ X ________ = _______g of solute Decimal valueVolume measured & added to (g/ mL)Desired volume desired OR 0.09 x100 mL= 9 g NACL decimal value desired total measure & mix with (g/mL) (mL) solvent up to 100 mL

  15. MOLARITY [# moles of solute in liter of solution] • 1 mole of NACL = 58.4 (atomic mass units) • 2 moles of NACL = 116.8 “ “ • 1 mole of CACl2 = 111 “ “ Volume X Molarity X Molecular= # grams to wanted(L) Desired Wt. of be dissolved (mol /L)Solute(g/mol) in solvent to volume desired 0.02L x 0.5 mol /L x 111g / mol = 1.1 g CACL2(w/ solvent to 20 ml)

  16. C1V1 = C2 V2 - IS USED TO CALCULATE HOW TO MAKE A SPECIFIC SOLUTION – C1 = CONCENTRATION OF STOCK SOLUTION V1 = VOLUME TO BE USED C2= DESIRED CONCENTRATION OF SAMPLE V2 = DESIRED VOLUME OF DILUTED SAMPLE ? 1 L NaCl from 100 mg/mL concentrated sol. 100mg / mL x V1 = 1 mg/mL x 1000mL V1 = 1 mg/ml x 1000 mLorV1 =1000mL / 100 = 10mL 100mg/ml [ or 10ml to 990 ml solvent]

  17. Labeling Solutions • Procedures & protocols vary slightly from lab to lab, but follow standard protocol • Laboratory techs must come up with specific procedures for developing reagents & buffers • Solutions & reagents must be labeled after they’re prepared to avoid error • All solutions are labeled with at least: Name & concentration of reagent Date, Time & Initials of preparer • Reagents must be stored properly & safely

  18. PPE – PERSONALPROTECTIVE EQUIPMENT • Protect yourself & avoid contamination when working with infectious agents & chemicals. • Wear eye protection, gloves, lab coat & masks. • Dispose of biohazards in proper containers. • Follow Aseptic Technique.

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