61-4
BORON, continued
SAMPLING AND STORAGE
Collect samples in polyethylene bottles or alkali-resistant boron-free glass.
REAGENT PREPARATION
Prepare additional BoroVer 3/sulfuric acid solution by mixing one
BoroVer 3 Reagent Powder Pillow per 75 mL of sulfuric acid, ACS,
adding the powder pillows individually with stirring. Preparation of
this solution generates gaseous HCl when the indicator pillow is added
to the concentrated sulfuric acid. Use of a fume hood or other well-
ventilated lab area is strongly advised. This solution will be stable for
up to 48 hours if stored in plastic containers. It should not be stored in
Pyrex or Kimax (borosilicate) vessels for longer than one hour because
the solution will leach boron from these containers. Use soft glass or
polyethylene containers for storage.
ACCURACY CHECK
Standard Additions Method
a) Snap the neck off a Boron Voluette Ampule Standard, 250 mg/L B.
b) Use the TenSette Pipet to add 0.1, 0.2 and 0.3 mL of standard,
respectively, to three 25-mL portions of sample.
c) Perform the above procedure. The boron concentration reading should
increase 1 mg/L for each 0.1 mL of standard solution added.
d) If these increases do not occur, see Standard Additions (Section I) for
more information.
Standard Solution Method
Check the accuracy of the test using Boron Standard Solution, 4 mg/L as
B, listed under Optional Reagents, below. Or, prepare this solution as
follows:
a) Pipet 4.00 mL of the Boron Voluette Ampule Standard, 250 mg/L B,
into a 250-mL volumetric flask.
b) Dilute to volume with demineralized water. Swirl to mix.
Analyze according to the above procedure using either of these solutions
as the sample.
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