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Environmental Express
• 7
SimpleDist® Micro Heating Block:
Operation & Instruction Manual
Distillation Methods
Total Cyanide Distillation with the SimpleDist® Micro Heating Block
4.4 Sulfuric acid/magnesium chloride solution - Add 277 mL of reagent water to a 500 mL
beaker. Add 80.5 g MgCl
2
•6H
2
O (4.3) and stir to completely dissolve. Slowly add 189 mL
of sulfuric acid (4.2) while stirring. This should be done in a hood as toxic fumes may be
released. Once the solution is cool you should have 500 mL of total volume.
4.5 Potassium cyanide
4.6 Potassium hydroxide
4.7 Reagent water ASTM Type II or equivalent
Note:
The toxicity for each of the reagents used in this procedure are not fully documented.
Treat each chemical as a potential health hazard and limit exposure. Exercise good laboratory
technique with an emphasis on safety.
5.0 Procedure (Note: Standards must be distilled in a like manner as the samples for this
method)
5.1
Set the temperature of the Heating block to 120°C and allow the heat to stabilize. This
should take approximately 30 minutes. If all reagents are ready to use this should be
sufficient time to set up and prepare a full batch of 20 samples and all necessary QC.
5.2
Place one collector tube for each sample, standard, QC, or other aliquot needing to
be distilled in a test tube rack with the “Measure” end up. Add 1.59 mL of 0.95 M
NaOH solution (4.1) to each tube.
Note:
After final distillate dilution this will give a
concentration of 0.25 M NaOH. The initial concentration may be adjusted to provide
alternate final concentrations as needed by the analytical method of choice.
Cap the
tubes with one membrane and cap. Ensure that the membrane is not torn and shows
a visible edge all the way around the tube.
5.3
Place one sample tube for each sample, standard, QC, or other aliquot needing to be
distilled in a test tube rack and add 6.0 mL of sample/standard to each tube. The tubes
may be labeled with permanent ink to aid in sample identification. Do not add any
label to the tube as this will interfere with the fit in the block as well as heat transfer
during the distillation process. If solid samples are being distilled add 0.5 to 1.0 g of
the sample to the tube along with approximately 5 mL of reagent water. Samples high
in organic content such as sludge should tend toward the lower sample mass while
samples that are relatively free of organic material can use the higher end. The total
amount of cyanide present in the tube should be less than 600 µg.
5.4
Add 0.75 mL of the sulfuric acid/magnesium chloride solution (Step 4.4) to the first
sample tube. Immediately place the ‘Distill’ end of a filled and capped collector tube
(Step 5.2) over the open end of the sample tube. Press the two pieces together to form
a rough fit. You will not be able to hand press a tight seal.
5.5
Place the distillation unit in the tube press. Hold the collection tube by the break joint
to give support during the sealing procedure. Firmly press the two pieces together with
one motion. The collection tube should be flush with the ring around the edge of the
sample tube. If the pieces are at a visible angle the assembly will not fit all the way in
the block.
5.6
Repeat Steps 5.4 and 5.5 for all prepared sample and collection tubes.
