Environmental Express MicroBloc - Manual (Page 13)

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HotBlock: Operation and Instruction Manual MicroBlock TM Distillations
Total Cyanide Distillation with the MICROBLOCK TM Continued
4.4 Sulfamic Acid – if Nitrates and Nitrites are present
4.5 Potassium Cyanide
4.6 Potassium Hydroxide
4.7 Reagent Water ASTM Type II or Equivalent
4.8 Boiling Chips – Environmental Express # C5249
Note: The toxicities 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 EQUIPMENT AND SUPPLIES
5.1 The MicroBlock distillation glassware setup and tubing connections are shown in Figure 2 (Cyanide Style #1).
Part Number Description
C5012 Reaction/Absorption Flask
C7110 Snip & Pour, 1.25N NaOH, 50 x 10mL
C5210 Cold Finger
C5217 Absorption Impinger
C5216 Distillation Head
5.2 Helpful Accessories (Part# BT844004)
5mL delivery Repipette for 18N H
2
SO
4
addition
5mL delivery Repipette for Mg2Cl addition
6.0 REAGENT PREPARATION – DISTILLATION ONLY
6.1 Sodium Hydroxide Solution, Stock, 1.25N
Dissolve 50g of NaOH in reagent water and dilute to 1L.
6.2 Sodium Hydroxide Solution, Working, 0.25N
Dilute 200mL of 1.25N stock solution to 1L with reagent water.
6.3 Sulfuric Acid, 18N
Place a 1L glass container in an ice bath with a magnetic or mechanical stirrer. Add 500mL of reagent water. Slowly add
500mL of concentrated Sulfuric Acid drop-wise while stirring. Replenish ice in the ice-bath if required. Exercise caution
when preparing this reagent because of the exothermic nature of the reaction. After all the sulfuric acid has been
added, dilute to 1L with reagent water and mix thoroughly. Cool to room temperature before use.
6.4 Magnesium Chloride Reagent
Dissolve 510g of MgCl2:6 H
2
O in reagent water and dilute to 1L.
Note: This reagent is required if it is known that refractory iron-cyanide complexes are present.
6.5 Sulfamic Acid
Dissolve 20g of reagent grade sulfamic acid in reagent water and dilute to 1L.
Note: This reagent is required if it is known that nitrates-nitrites are present.
6.6 Potassium Cyanide, Stock Standard
Dissolve 2.51g of KCN in reagent water containing 2.0g of KOH. Dilute to 1L. Concentration of 1 mL = 1mg CN.
Standardize with 0.0192 N AgNO
3
on a monthly basis. Refer to US EPA method number 335.4 paragraph 7.9 for the
AgNO
3
preparation.
6.7 Potassium Cyanide, Intermediate Standard
Dilute 10mL of Stock Cyanide Standard to 100mL with reagent water. Concentration of 1mL = 100.0µg CN.