iqc

• Reagents can be in pre-packaged "kit" form, reducing the need for reagent preparation
• Chemicals used in laboratories include:

  • Analytic reagent (AR): suitable for most analytic procedures, meeting ACS specifications
  • Ultrapure, chemically pure (CP): used in specific procedures requiring extremely pure chemicals
  • United States Pharmacopeia (USP); National Formulary (NF): used in drug manufacturing
  • Technical or commercial grade: not suitable for clinical laboratory use
• Organic reagents have different grades:

  • Practical grade with some impurities
  • CP with reagent grade chemical purity
  • Spectroscopic and chromatographic grade with purity levels attained by specific procedures
  • Reagent grade (ACS) with impurities below certain levels set by the ACS
• Reference materials include:

  • Primary standard: highly purified chemical with known concentration and purity
  • Secondary standard: substance of lower purity compared to primary standard
• Water purification methods include:

  • Distillation: produces distilled water
  • Ion exchange: produces deionized water
  • Reverse osmosis: produces RO water
  • Other methods: ultrafiltration, ultraviolet light, sterilization, or ozone treatment
• Reagent grade water is classified into 6 categories based on specifications needed for use, not the method of purification
• Water purification techniques:

  • Pre-filtration: removes particulate matter
  • Distillation: vaporizes water and condenses it
  • Ion-exchange: removes mineral ions
  • Reverse osmosis: forces water through a membrane
• Testing procedures for reagent grade water quality include measurements of resistance, pH, colony counts, and various chemical components
• Measurement conversions:

  • SI Units: International System of Units standardizing worldwide measurements
  • Factor label method: solving technique using conversion factors
• The factor label method is a solving technique using conversion factors to transform units from one system to another
• Conversion factors are fractions that relate two kinds of units; for example, "6.0 cm / s" indicates that 6.0 cm are covered in every 1 second that passes
• Glasswares in laboratories must satisfy certain tolerances for accuracy and precision, classified as Class A or Class B by the American Society for Testing and Materials (ASTM)
• Glasswares used in clinical laboratories usually fall into categories like Kimax/Pyrex (borosilicate), Corex (aluminosilicate), Vycor (acid and alkali resistant), High silica, Low actinic (amber colored), and Flint (soda lime glass)
• An Erlenmeyer flask is a laboratory flask with a flat bottom, a conical body, and a cylindrical neck, allowing contents to be mixed by swirling without spillage
• A beaker is a cylindrical container used to store, mix, and heat liquids in laboratories, usually with flat bottoms and a lip around the top
• Graduated cylinders are often used to measure the volume of a liquid and can also measure the volume of a solid indirectly by measuring the displacement of a liquid
• A volumetric flask is a laboratory flask calibrated to contain a precise volume at a certain temperature, used for precise dilutions and preparation of standard solutions
• A pipette is used to transfer a high accuracy measurement of liquid volumes and comes in various designs for different purposes with varying levels of accuracy and precision
• Mohr pipets are designed to contain a measured volume, with a minute amount of liquid left in the tip during dispensing, and they have no rings but may have a colored bar to indicate the volume
• Serological pipets are designed to accurately dispense a measured volume and have an etched or colored ring at the top of the pipet
• A volumetric pipette is designed to transfer a fixed amount of liquid when filled to the mark, generally having only one "fill-line" on the pipet
• Mechanical pipets can be set to draw and dispense different volumes or be preset to deliver an exact volume, used to accurately deliver very small volumes, microliters, of liquid
• Types of solutions based on water as a solvent include aqueous solutions (completely dissolved in water) and non-aqueous solutions (solvent is not water)
• Types of solutions based on the amount of solute added include unsaturated solutions (can dissolve more solute), saturated solutions (reached limit to dissolve solute), and supersaturated solutions (solute present in excess amount)
• Types of solutions based on the amount of solvent added include concentrated solutions (large amounts of solute added) and dilute solutions (small amount of solute in a large amount of solvent)
• Types of solutions based on the concentration of solute in two solvents include hypertonic solutions (higher concentration in beaker than in the cell), hypotonic solutions (lower concentration in beaker compared to the cell), and isotonic solutions (same concentration in both beaker and cell)
• The concentration of a solution is a measure of the amount of solute dissolved in a given amount of solvent or solution
• Percent by volume (%/v/v) is a measure of the concentration of a substance in a solution, expressed as the ratio of the volume of the solute to the total volume of the solution multiplied by 100
• Molarity (M) is a measure of the concentration of a chemical species in terms of a solute within a solution, quantifying the amount of substance per unit volume of the whole solution
• Molality (m) is a measure of the number of moles of solute present in 1 kg of solvent, used in physical chemistry for mathematical convenience with a commonly used unit of mol/kg
• Parts per million (ppm) is a concentration of a solution that contains 1 g solute and 1,000,000 mL solution, resulting in a very small percentage concentration
• In multicellular organisms, specialized exchange surfaces are required for efficient gas exchange of carbon dioxide and oxygen due to the larger distance substances need to cross over
• Analytical chemistry involves four basic disciplines:

  1. Spectrometry, including spectrophotometry, atomic absorption, and mass spectrometry

  2. Luminescence, including fluorescence, chemiluminescence, and nephelometry

  3. Electroanalytic methods, including electrophoresis, potentiometry, and amperometry

  4. Chromatography, including gas, liquid, and thin-layer chromatography
• Spectrophotometry and photometry involve measuring electromagnetic radiation described as photons of energy traveling in waves
• Beer's Law states that the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the log of transmitted light
• Methods to determine the concentration of an analyte include:

  1. Proportionality

  2. Graphing

  3. Beer's equation
• In spectrophotometry, the relationship between wavelength and energy is described by Planck's formula: E = hv, where h is a constant (Planck's constant) and v is frequency
• Spectrophotometry involves the measurement of light transmitted by a solution to determine the concentration of light-absorbing substances
• Atomic absorption spectrophotometry measures the light absorbed by atoms dissociated by heat, using a hollow-cathode lamp as the light source
• Flame photometry, specifically flame emission photometry, measures the light emitted by a single atom burned in a flame