analysis 4

• ACS grade meets or exceeds purity standards set by the American Chemical Society (ACS). This grade is acceptable for food, drug, or medicinal use and can be used for ACS applications or for general procedures that require stringent quality specifications and a purity of ≥95%.
• Reagent grade is generally equal to ACS grade (≥95%) and is acceptable for food, drug, or medicinal use and is suitable for use in many laboratory and analytical applications.
• USP grade meets or exceeds requirements of the United States Pharmacopeia (USP). This grade is acceptable for food, drug, or medicinal use. It is also used for most laboratory purposes, but the USP being followed should always be reviewed prior to beginning to ensure the grade is appropriate for that methodology.
• NF grade meets or exceeds requirements of the National Formulary (NF). The USP and the NF (USP– NF) jointly publish a book of public pharmacopeial standards for chemical and biological drug substances, dosage forms, compounded preparations, excipients, medical devices, and dietary supplements.
• Laboratory grade is the most popular grade for use in educational applications, but its exact levels of impurities are unknown. While excellent for teaching and training, it is not pure enough to be offered for food, drug, or medicinal use of any kind
• Purified grade, also called pure or practical grade, meets no official standard; it is not pure enough to be offered for food, drug, or medicinal use of any kind.
• Technical grade is used for commercial and industrial purposes; however, like many others, it is not pure enough to be offered for food, drug, or medicinal use of any kind.
• Solutions are prepared with raw materials that meet or exceed requirements of the American Chemical Society.
• Where no A.C.S. specifications exist, chemicals of highest purity available are used.
• All aqueous solutions are prepared using high purity, deionized, water which meets requirements for American Society for Testing and Materials (ASTM) type 1 Reagent Grade Water.
• Exact production and quality control records are maintained providing traceability of raw materials.
• Lot samples are maintained for a minimum of five years.
• All solutions are guaranteed to meet label specifications.
• All Reagents branded solution labels meet or exceed all (International Organization for Standardization) ISO, DOT and Occupational Health and Safety Administration (OSHA) regulations and include the following information:

  • Expiration Date
  • Date of Manufacture
  • Standard Reference Material used
  • Actual Lot Analysis
  • Space for date received and date opened
• INDICATORS – are complex organic compounds used:

  • to determine the end point in neutralization process,
  • to determine hydrogen-ion concentrations pH,
  • to indicate that a desired change in pH has been affected.
• MIX INDICATORS – used to sharpen up the color change.
• Physicochemical – attributes the color of certain ions , an increase in which causes the appearance of a new color, a decrease in which causes the disappearance of a color or appearance of a diff color.
• Organic theory – attributes the color of indicator to certain groupings of the elements in a compound and the change in color to a change in molecular structure
• Colloidal – assumes that indicator form colloidal solutions the change in color of which in dependent upon change in size of the colloidal particle.
• Use 3 drops of indicator test solution for a titration unless otherwise directed.
• When a strong acid is titrated with a strong alkali, or a strong alkali with a strong acid, methyl orange, methyl red, or phenolphthalein may be used.
• When a weak acid is titrated with a strong alkali, use phenolphthalein as the indicator.
• When a weak alkali is titrated with a strong acid, use methyl red as the indicator.
• A weak alkali should never be titrated with a weak acid, or vice versa, since no indicator will give a sharp end point.
• The appearance of a color is more easily observable than is the disappearance. Therefore, always titrate where possible to the appearance of a color.
• pH indicators detect the presence of H+ and OH-
• They react with H+ and OH- because they are weak acids and bases themselves
• If an indicator is a weak acid and is colored, and its conjugate base has a different color, deprotonation causes a color change