Lesson 1-8

Laboratory

Math and Reagent Preparation

Overview

• Laboratory reagents– Chemical purity

• Laboratory reagent water• Pipet use• Safety• Quality assessment• Formulas for preparing solutions• Making dilutions

Terms

• Solution

• Solvent

• Solute

• Dilution

Common Laboratory Reagents

• Disinfectants

• Dilute acids

• Stock solutions

• Working solutions

• Controls

Chemical Purity

• Use reagent or analytical grade

• Ultrapure sometimes required

• Lower grades not used include:– Technical grade– Practical– Commercial

Laboratory Reagent Water

• Types specified by CLSI

• Made by further treatment of– Distilled water– Deionized water– Reverse osmosis water

Laboratory Reagent Water

• CLSI – grades of water– Clinical Laboratory Reagent Water (CLRW)– Special reagent water– Instrument feed water– Autoclave and wash water– Commercially bottled purified water

• See Table 1-34

Pipets

• TD or TC

• Volumetric pipets

• Serological/graduated pipets

Pipetting Aids

• Manual

• Battery or electrical

Micropipetters

• Advantages– Disposable tips– Adjustable volumes– Improved accuracy– Improved reproducibility

Micropipetters

Safety

• Chemical hazards– Consult MSDS

• Biological hazards– biological controls

• Physical hazards

Quality Assessment

• Correct formulas

• Correct calculations

• Pipet techniques

• Selection of labware

• Reagent storage

• Expiration dates

• Test new reagents

Preparing Dilutions

• Using proportion to make a dilution

Preparing Dilutions

• Using a concentrate to make a dilute solution

Preparing Dilutions

• Using ratios to prepare dilutions

Preparing Percentage Solutions

• Weight/volume

Preparing Percentage Solutions

• Volume/volume

• Weight/weight

Preparing Molar Solutions

• Molar (M) solution = moles solute per liter solution (mol/L)– Formula weight– Mole

Serial Dilutions

• Two-fold dilution series

Compound Dilutions