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3. Tools, instruments and reagents
3.1. Tools and instruments
1) Any of the tools or instruments should not affect the
analytical results.
2) Keep all the tools and instruments clean to prevent sample
contamination. It is recommended to assign a dedicated set of
tools and instruments to each particular substance.
A few examples of cleaning treatments for tools and instruments
are shown below:
- Glassware: Heat to 450℃ for at least five hours in an oven.
- Rotary evaporator: Prevent contamination from ambient air by
fitting an active carbon column and air filter to the stopcock
open to air, or by providing a trap ball.
- Gas blower for concentrating sample extracts: Provide a
portion filled with active carbon or Florisil in the gas line.
3.2. Reagents
3.2.1. Standard chemicals
1) Use products of high purity grade.
2) Record the lot numbers of the reagents used according to 5
below.
3.2.2. Reagents
1) Use products of high purity grade (for precision analysis,
dioxin analysis, residual pesticides and PCB analysis, phthalic
acid ester analysis, HPLC grade, etc.).
2) Purify the reagents as necessary by distillation, heating or
cleaning.
3) Confirm that the quantities used in the procedures described
in Part 2 do not affect the quantitative results.
Some examples of reagent purification are given below:
- Purified water: Wash water from a water purifier with n-hexane
as necessary.
- Sulfuric acid: Use products of high purity, e.g. semiconductor
grade. Wash with n-hexane as necessary.
- Anhydrous sodium sulfate: Use products of high purity, e.g.
for residual pesticide analysis. Heat to 450℃ for at least five
hours as necessary.
- Silica gel: Wash silica gel for column chromatography
ultrasonically in methanol, dry under a reduced pressure, and
heat to 130℃ for about 18 hours in a glass beaker. Transfer the
gel into a sealable container and store in a desiccator.
- Active carbon-silica gel: Wash active carbon-silica gel
ultrasonically in acetone, filtrate, and purify by Soxhlet
extraction with toluene. Dry the purified gel in a rotary
evaporator under a reduced pressure, transfer into a sealable
container, and store in a desiccator.
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