METHOD 9010A TOTAL AND AMENABLE CYANIDE

1 CD-ROM9010A - 1 Revision 1 July 1992 METHOD 9010 ATOTAL AND AMENABLE AND 9010 is used to determine the concentration of inorganiccyanide (CAS Registry Number 57-12-5) in wastes or leachate. The METHOD detectsinorganic cyanides that are present as either soluble salts or complexes. It isused to determine values for both TOTAL CYANIDE and CYANIDE AMENABLE tochlorination. The "reactive" CYANIDE content of a waste, that is, the cyanidecontent that could generate toxic fumes when exposed to mild acidic conditions,is not distilled by METHOD 9010 (refer to Chapter Seven). However, METHOD 9010is used to quantify the concentration of CYANIDE from the reactivity test. titration procedure using silver nitrate with p-dimethylamino-benzal-rhodanine indicator is used for measuring concentrations of cyanideexceeding mg/L ( mg/250 mL of absorbing liquid).

2 Colorimetric procedure is used for concentrations below 1 mg/Lof CYANIDE and is sensitive to about METHOD was designed to address the problem of "trace" analyses(<1000 ppm). The METHOD may also be used for "minor" (1000 ppm - 10,000 ppm) and"major" (>10,000 ppm) analyses by adapting the sample preparation techniques orcell path length. However, the amount of sodium hydroxide in the standards andthe sample analyzed must be the OF CYANIDE , as hydrocyanic acid (HCN), is released from samplescontaining CYANIDE by means of a reflux-distillation operation under acidicconditions and absorbed in a scrubber containing sodium hydroxide solution. Thecyanide in the absorbing solution is then determined colorimetrically the colorimetric measurement, the CYANIDE is converted tocyanogen chloride (CNCl) by reaction of CYANIDE with chloramine-T at a pH lessthan 8.

3 After the reaction is complete, color is formed on the addition ofpyridine-barbituric acid reagent. The absorbance is read at 578 nm for thecomplex formed with pyridine-barbituric acid reagent and CNCl. To obtain colorsof comparable intensity, it is essential to have the same salt content in boththe sample and the titration measurement uses a standard solution of silvernitrate to titrate CYANIDE in the presence of a silver sensitive are eliminated or reduced by using the distillationprocedure. Chlorine and sulfide are interferences in METHOD - 2 Revision 1 July 1992 agents such as chlorine decompose most interferences can be removed by adding an excess of sodium arsenite tothe waste prior to preservation and storage of the sample to reduce the chlorineto chloride which does not interference can be removed by adding an excess of bismuthnitrate to the waste (to precipitate the sulfide) before distillation.

4 Samplesthat contain hydrogen sulfide, metal sulfides, or other compounds that mayproduce hydrogen sulfide during the distillation should be treated by theaddition of bismuth results may be obtained for samples that contain nitrateand/or nitrite. During the distillation, nitrate and nitrite will form nitrousacid, which will react with some organic compounds to form oximes. Thesecompounds once formed will decompose under test conditions to generate HCN. Thepossibility of interference of nitrate and nitrite is eliminated by pretreatmentwith sulfamic acid just before distillation. Nitrate and nitrite areinterferences when present at levels higher than 10 mg/L and in conjunction withcertain organic is reported to be an interference when present at veryhigh levels.

5 Levels of 10 mg/L were not found to acids, detergents, surfactants, and other compounds may causefoaming during the distillation when they are present in large concentrations andwill make the endpoint of the titration difficult to detect. They may beextracted at pH AND distillation apparatus such as shown in Figure 1 or Figure2. The boiling flask should be of one liter size with inlet tube and provisionfor condenser. The gas scrubber may be a 270-mL Fisher-Milligan scrubber(Fisher, Part No. 07-513) or equivalent. The reflux apparatus may be a Wheaton377160 distillation unit or - Suitable for measurements at 578 nm with cm cell or plate stirrer/heating mL Class A volumetric flasks - 100 and 250 flask - 500 mLCD-ROM9010A - 3 Revision 1 July grade chemicals shall be used in all tests.

6 Unlessotherwise indicated, it is intended that all reagents shall conform to thespecifications of the Committee on Analytical Reagents of the American ChemicalSociety, where such specifications are available. Other grades may be used,provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the water. All references to water in this METHOD refer toreagent water, as defined in Chapter for sample collection, preservation, and arsenite ( ), NaAsO. Dissolve g NaAsO in22250 mL acid, hydroxide solution (50%), NaOH. acid ( ) CHCOOH. Dilute one part of3concentrated acetic acid with 9 parts of ,2,4-Trimethylpentane, , , for cyanides AMENABLE to hypochlorite solution ( ), Ca(OCl). Combine25 g of calcium hypochlorite and 100 mL of water.

7 Shake before hydroxide solution ( ), NaOH. Dissolve 50 g ofNaOH in 1 liter of arsenite ( ). See Step iodide starch for hydroxide ( ). See Step Bismuth nitrate ( ), Bi(NO) C 5HO. Dissolve 30 g32 Bi(NO) C 5HO in 100 mL of water. While stirring, add 250 mL of glacial 32 acetic acid, CHCOOH. Stir until dissolved and dilute to 1 liter with3 water. acid ( ), HNSOH. Dissolve 40 g HNSOH in2323 1 liter of - 4 Revision 1 July acid (18N), HSO. Slowly and carefully add 50024mL of concentrated HSO to 500 mL of chloride solution ( ), MgClC 6HO. Dissolve2 2510 g of MgCl C 6HO in 1 liter of acetate for spectrophotometric hydroxide solution ( ), NaOH. Dissolve 10 gNaOH in 1 liter of phosphate monobasic (1M), NaHPOC HO. Dissolve24 2138 g of NaHPO C HO in 1 liter of water.

8 Refrigerate this solution ( ), CHClNNaOS. g of white, water soluble chloramine-T in 100 mL of water andrefrigerate until ready to acid reagent, CHN C CHNO. Place 15 g554423of barbituric acid in a 250-mL volumetric flask and add just enough waterto wash the sides of the flask and wet the barbituric acid. Add 75 mL ofpyridine and mix. Add 15 mL of concentrated hydrochloric acid (HCl), mix,and cool to room temperature. Dilute to 250 mL with water. This reagentis stable for approximately six months if stored in a cool, dark potassium CYANIDE solution (1 mL = 1000 g CN), g of KCN and 2 g KOH in 900 mL of water. Standardize silver nitrate, AgNO. Dilute to appropriate concentration to3achieve 1 mL = 1000 g of :Detailed procedure for AgNO standardization is described in3"Standard methods for the Examination of Water and Wastewater",16th Edition, (1985), methods 412C and standard potassium CYANIDE solution, (1 mL =100 g CN), KCN.

9 Dilute 100 mL of stock potassium CYANIDE solution (1 mL-= 1000 g CN) to 1000 mL with standard potassium CYANIDE solution (1 mL = 10 gCN), KCN. Prepare fresh daily by diluting 100 mL of intermediate standard-potassium CYANIDE solution and 10 mL of 1N NaOH to 1 liter with for titration indicator - Dissolve 20 mg of p-dimethylamino-benzal-rhodanine, CHNOS, in 100 mL of silver nitrate solution ( ), AgNO. Prepare3by crushing approximately 5 g AgNO and drying to constant weight at out g of dried AgNO. Dissolve in 1 liter of - 5 Revision 1 July 1992 NOTE:Detailed procedure for AgNO standardization is described in3"Standard methods for the Examination of Water and Wastewater",16th Edition, (1985), methods 412C and COLLECTION, PRESERVATION AND samples must be collected using a sampling plan that addressesthe considerations discussed in Chapter should be collected in plastic or glass containers.

10 Allcontainers must be thoroughly cleaned and agents such as chlorine decompose most cyanides. Todetermine whether oxidizing agents are present, test a drop of the sample withpotassium iodide-starch test paper. A blue color indicates the need fortreatment. Add sodium arsenite solution a few mL at a time until a drop ofsample produces no color on the indicator paper. Add an additional 5 mL ofsodium arsenite solution for each liter of sample. Ascorbic acid can be used asan alternative although it is not as effective as arsenite. Add a few crystalsof ascorbic acid at a time until a drop of sample produces no color on theindicator paper. Then add an additional g of ascorbic acid for each literof sample samples must be preserved by adding 50% sodium hydroxideuntil the pH is greater than or equal to 12 at the time of should be chilled to properly preserved, CYANIDE samples can be stored for up to14 days prior to sample preparation and oily wastes may be extracted prior to analysis by method9013.