Laboratory Practices
Laboratory Practices
Page 20
5940022LabPrac.fm
Figure 4 Gravity Filtration
Required Apparatus for Gravity Filtration
Description Unit Cat No.
Cylinder, graduated, 100-mL ............................................................................................ each........................508-42
Funnel, poly, 65-mm........................................................................................................... each......................1083-67
Filter Paper, 12.5-cm, pleated............................................................................................ 100/pkg...............1894-57
Flask, erlenmeyer, 125-mL................................................................................................. each........................505-43
2.6 Reagents
2.6.1 Reagent and Standard Stability
Chemicals supplied with the DR/2400 Portable Spectrophotometer and Portable
Laboratory have the maximum shelf life when stored in a location that is cool,
dark, and dry. The product label will specify any special storage needs.
It is always good laboratory practice to date chemicals upon receipt and to rotate
supplies so the older supplies are used first.
Absorption of moisture, carbon dioxide, or other gases from the atmosphere;
bacterial action; high temperatures or light (with photosensitive compounds)
may affect the reagent shelf life. In some cases, reaction with the storage
container or interaction of reagent components may occur.
In its quest for reagent stability, Hach has developed many unique formulations,
methods of analysis, and forms of packaging.
2.6.2 Reagent Blank
In several tests, the contribution of the reagent(s) to the final reading is of such a
magnitude that it must be compensated for whenever the test is performed. The
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