LaMotte DC1600 Colorimeter - Manual (Page 35)

CYANIDE
PYRIDINE-BARBITURIC ACID METHOD CODE 3660
QUANTITY CONTENTS CODE
60 mL Cyanide Buffer 2850PS-H
5 g *Cyanide Cl Reagent *2794DS-C
5 g *Cyanide Indicator Reagent *2793DS-C
15 mL *Hydrochloric Acid, 1N *6130-E
15 mL *Sodium Hydroxide, 1N *4004-E
2 Spoons, 0.1 g, plastic 0699
1 Pipet, plastic, 1.0 mL 0354
1 pH Short Range Test Papers, pH 9 - 14 2955
1 Rod, plastic, stirring 0519
*WARNING: Reagents marked with * are considered hazardous substances. Material Data Safety Sheets (MSDS) are supplied for these
reagents. For your safety, read label and accompanying MSDS before using.
APPLICATION: Low level concentrations in drinking and surface waters; domestic and industrial waters. This
method determines only those cyanides amenable to chlorination.
RANGE: 0 – 0.5 ppm Cyanide
METHOD: Cyanides react with a chlorine donor to form cyanogen chloride, which subsequently reacts
with Pyridine and Barbituric Acid to form a red-blue compound in proportion to the amount
of cyanide originally present. The concentration of the red-blue compound is determined
spectrophotometrically.
SAMPLE HANDLE
& PRESERVATION: Cyanide solutions tend to be unstable and should be analyzed as soon as possible. Samples can
be stabilized by adjusting the pH to greater than12 with NaOH. However, the pH will have to
be readjusted to pH 10.5 before performing the test.
INTERFERENCES: Oxidizing agents and aldehydes can react with cyanide, while reducing agents, such as sulfite,
react with the chlorine donor; both can cause negative interferences. Thiocyanate and
cyanogen chloride both react as cyanide in this test and will give a positive interference. Color
and turbidity can also interfere.
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