Waters 2998, Обзор и руководство по обслуживанию

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December 5, 2017, 715004753 Rev. B
Page 86
Some solvents prove immiscible with solvents at both ends of the lipophilicity scale. These
solvents receive a dual M-number:
• The first number, always lower than 16, indicates the degree of miscibility with highly
lipophilic solvents.
• The second number applies to the opposite end of the scale. A large difference between
these two numbers indicates a limited range of miscibility.
For example, some fluorocarbons are immiscible with all the standard solvents and have
M-numbers of 0, 32. Two liquids with dual M-numbers are usually miscible with each other.
A liquid is classified in the M-number system by testing for miscibility with a sequence of standard
solvents. A correction term of 15 units is then either added or subtracted from the cutoff point for
miscibility.
C.3 Buffered solvents
When using a buffer, use a good quality reagent and filter it through a 0.45-µm filter.
Do not leave the buffer stored in the system after use. Flush all fluid line pathways with
HPLC-quality water before shutting the system down and leave distilled water in the system (flush
with 90% HPLC-quality water: 10% methanol for shutdowns scheduled to be more than one day).
Use a minimum of 15 mL for sparge-equipped units, and a minimum of 45 mL for in-line vacuum
degasser-equipped units.
C.4 Head height
Position the solvent reservoirs at a level above the HPLC equipment or on top of the pump or
detector (with adequate spill protection).
C.5 Minimum bend radius for tubing
When bending tubing, consult the following table. The bend radius on tubing must not be less than
the arc shown. The scale is 1:1, so that the diagram can be used as a template.
Figure C–1: Minimum bend radius for stainless steel tubing
Tubing size (OD) Minimum bend radius
1/16-inch or smaller tubing 1/4-inch
R