Basic Laboratory Skills

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Basic Laboratory Skills
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LIQUID VOLUMES ARE MEASURED WITH

• Graduated Cylinders liters
• milliliters
• Beaker liters milliliters
• Flasks liters milliliters
• Pipettes milliliters
• Micropipets microliters

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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)

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Graduated Cylinders

• Use to measure volumes gt 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

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Pipettes(Straw with Graduations)

• Use when measuring volumes lt 10 mL
• Select smallest pipette for job to lt error
• Pipettes maybe volumetric (deliver specific
  volume)
• 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

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Micropipettes

• Micropipettes measure volumes lt 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

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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

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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

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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
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SECTION TWO
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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)

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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

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MASS / VOLUME

• ____ G / mL x ____ mL ____g of solute
• concentration volume to be
  weighed out
• desired desired
  dissolved 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
  

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MASS / VOLUME

• __9__ _______
• PERCENT VALUE DECIMAL
  VALUE OF g / mL
  
• OR
• _______ X ________ _______g of solute
• Decimal value Volume
  measured added to
• (g/ mL) Desired
  volume desired
• OR
• 0.09 x 100 mL
  9 g NACL
• decimal value desired total
  measure mix with
• (g/mL) (mL)
  solvent up to 100 mL

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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)
  

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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 mL or V1 1000mL / 100
  10mL
• 100mg/ml or
  10ml to 990 ml solvent

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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
  theyre 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

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PPE PERSONAL PROTECTIVE 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.