**SW-846 Update V 9014 - 1 Revision 1 July 2014**  **METHOD 9014**

**CYANIDE IN WATERS AND EXTRACTS**

**USING TITRIMETRIC AND MANUAL SPECTROPHOTOMETRIC PR OCEDURES** 

**SW-846 is not intended to be an analytical training manual. Therefore, method procedures**  **are written based on the assumption that they will be followed by analysts who are formally**  **trained in at least the basic principles of chemica l analysis and in the use of the subject**  **technology.**

**In addition, SW-846 methods, with the exception of required method use for the analysis of**  **method-defined parameters, are intended to be guida nce methods which contain general**  **information on how to perform an analytical procedu re or technique which a laboratory can use as**  **a basic starting point for generating its own detai led standard operating procedure (SOP), either**  **for its own general use or for a specific project a pplication. The performance data included in this**  **method are for guidance purposes only, and are not intended to be and must not be used as**  **absolute QC acceptance criteria for purposes of lab oratory accreditation.** 

**1.0 SCOPE AND APPLICATION**

**1.1 This method can be used for measuring free (non -complexed) cyanide and**  **hydrocyanic acid in drinking water, natural surface waters, domestic and industrial wastewaters,**  **and in soil extracts. This method may also be used as a determinative step for quantifying total**  **and amenable cyanide in the alkaline distillates fr om Method 9010.** 

**1.2 The titration procedure of this method uses sil ver nitrate with** 

p **-dimethylaminobenzalrhodanine indicator and is used for measuring concentrations of cyanide**  **exceeding 0.1 mg/L (0.025 mg/250 mL of absorbing li quid).** 

**1.3 Prior to employing this method, analysts should consult the disclaimer statement at**  **the front of the manual and the information in Chap ter Two for guidance on the intended flexibility**  **in the choice of methods, apparatus, materials, rea gents, and supplies, and on the responsibilities**  **of the analyst for demonstrating that the technique s employed are appropriate for the analytes of**  **interest, in the matrix of interest, and at the lev els of concern.** 

**In addition, analysts and data users are advised th at, except where explicitly required in a**  **regulation, the use of SW-846 methods is** not **mandatory in response to Federal testing requirements. The information contained in this me**  **thod is provided by EPA as guidance to be used by the analyst and the regulated community in**  **making judgments necessary to generate results that meet the data quality objectives for t**  **he intended application.**

**1.4 This method is restricted to use by, or under s upervision of, appropriately**  **experienced and trained personnel. Each analyst mu st demonstrate the ability to generate**  **acceptable results with this method.**

**2.0 SUMMARY OF METHOD**

**2.1 This method provides two options for the determ ination of cyanide; namely, a**  **manual spectrophotometric (colorimetric) procedure or a titrimetric procedure.** **SW-846 Update V 9014 - 2 Revision 1 July 2014**  **2.2 In the colorimetric measurement, the cyanide is converted to cyanogen chloride**  **(CNCl) by reaction of cyanide with chloramine-T at a pH less than 8. After the reaction is**  **complete, color is formed on the addition of pyridi ne-barbituric acid reagent. The absorbance is**  **read at 578 nm for the complex formed with pyridine -barbituric acid reagent and CNCl. To obtain**  **colors of comparable intensity, it is essential to have the same salt content in both the sample and** 

**the standards.**

**2.3 The titration measurement uses a standard solut ion of silver nitrate to titrate cyanide**  **in the presence of a silver sensitive indicator.**

**3.0 DEFINITIONS**

**Refer to Chapter One, Chapter Three, and the manufa cturer's instructions for definitions**  **that may be relevant to this procedure.**

**4.0 INTERFERENCES**

**4.1 Solvents, reagents, glassware, and other sample processing hardware may yield**  **artifacts and/or interferences to sample analysis. All of these materials must be demonstrated to** 

**be free from interferences under the conditions of the analysis by analyzing method blanks.**  **Specific selection of reagents and purification of solvents by distillation in all-glass systems may**  **be necessary. Refer to each method to be used for specific guidance on quality control**  **procedures and to Chapter Three for general guidanc e on the cleaning of glassware.** 

**4.2 Interferences are eliminated or reduced by usin g the distillation procedure.**  **Chlorine and sulfide are potential interferences in this method.** 

**4.3 Oxidizing agents such as chlorine decompose mos t cyanides in solution. Chlorine**  **interferences can be removed by adding an excess of sodium arsenite to the waste prior to**  **preservation and storage of the sample to reduce th e chlorine to chloride which does not interfere.** 

**4.4 Sulfide interference can be removed by adding a n excess of bismuth nitrate to the**  **waste (to precipitate the sulfide) before distillat ion. Samples that contain hydrogen sulfide, metal**  **sulfides, or other compounds that may produce hydro gen sulfide during the distillation should be**  **treated by the addition of bismuth nitrate.**

**4.5 High results may be obtained for samples that c ontain nitrate and/or nitrite. During**  **the distillation, nitrate and nitrite will form nit rous acid, which will react with some organic**  **compounds to form oximes. These compounds, once fo rmed, will decompose under test**  **conditions to generate HCN. The possibility of int erference of nitrate and nitrite is eliminated by**  **pretreatment with sulfamic acid just before distill ation. Nitrate and nitrite are interferences when**  **present at levels higher than 10 mg/l and in conjun ction with certain organic compounds.** 

**4.6 Thiocyanate is reported to be an interferent wh en present at very high levels; levels**  **of 10 mg/L or less were not found to interfere.**

**4.7 Fatty acids, detergents, surfactants, and othe r compounds may cause foaming**  **during the distillation when they are present in hi gh concentrations, and may make the endpoint** 

**for the titrimetric determination difficult to dete ct. They may be extracted at pH 6-7 to eliminate** 

**this interference. SW-846 Update V 9014 - 3 Revision 1**  **July 2014 5.0 SAFETY** 

**5.1 This method does not address all safety issues associated with its use. The**  **laboratory is responsible for maintaining a safe wo rk environment and a current awareness file of**  **OSHA regulations regarding the safe handling of the chemicals specified in this method. A**  **reference file of material safety data sheets (MSDS s) should be available to all personnel involved**  **in these analyses.**

**WARNING : KCN and NaCN are highly toxic. Avoid skin and e**  **ye contact and inhalation.**

**5.2 Because of the toxicity of cyanide, exercise gr eat care in its handling. Acidification**  **of cyanide solutions produces lethal, toxic hydroge n cyanide (HCN) gas. Prepare all**  **cyanide-containing solutions within a ventilation h ood. Wear hand and eye protection at all times**  **when working with cyanide.**

**6.0 EQUIPMENT AND SUPPLIES**

**The mention of trade names or commercial products i n this manual is for illustrative**  **purposes only, and does not constitute an EPA endor sement or exclusive recommendation for**  **use. The products and instrument settings cited in SW-846 methods represent those products**  **and settings used during method development or subs equently evaluated by the Agency.**  **Glassware, reagents, supplies, equipment, and setti ngs other than those listed in this manual**  **may be employed provided that method performance ap propriate for the intended application has** 

**been demonstrated and documented.**

**This section does not list all common laboratory gl assware (e.g., beakers and flasks) that**  **might be used.**

**6.1 Spectrophotometer - Suitable for measurements a t 578 nm with a 1.0 cm cell or** 

**larger.**

**6.2 Hot plate stirrer/heating mantle.**

**6.3 pH meter.**

**6.4 Refrigerator.**

**6.5 5 mL microburette.**

**6.6 Class A volumetric flasks - 1000, 250, and 100 mL.** 

**6.7 Erlenmeyer flask - 500 mL. SW-846 Update V 9014 - 4 Revision 1**  **July 2014 7.0 REAGENTS AND STANDARDS** 

**7.1 Reagent-grade chemicals must be used in all tes ts. Unless otherwise indicated, it**  **is intended that all reagents conform to the specif ications of the Committee on Analytical**  **Reagents of the American Chemical Society, where su ch specifications are available. Other**  **grades may be used, provided it is first ascertaine d that the reagent is of sufficiently high purity t**  **o permit its use without lessening the accuracy of th**  **e determination. Reagents should be stored in glass to prevent the leaching of contaminants from**  **plastic containers. Note, however, that sodium hydroxide solutions of relatively moderate s**  **trength (i.e., 4.1 g/L and greater), should be stored in HDPE plastic containers whenever possible** 

**.**

**7.2 Reagent water -- Reagent water must be interfer ence free. All references to water**  **in this method refer to reagent water, unless other wise specified.** 

**7.3 Reagents for spectrophotometric determination**

**7.3.1 Sodium hydroxide solution (0.25N), NaOH - Di ssolve 10 g of NaOH in 1 liter** 

**of water.**

**7.3.2 Sodium phosphate monobasic (1M), NaH 2**  **PO 4**  • **H 2**  **O - Dissolve 138 g of**

**NaH 2**  **PO 4**  • **H 2**  **O in 1 liter of water. Refrigerate this solution.**

**7.3.3 Chloramine-T solution (0.44%), C 7**  **H 7**  **ClNNaO 2**  **S - Dissolve 1.0 g of white,**

**water-soluble chloramine-T in 100 mL of water and r efrigerate until ready to use.** 

**7.3.4 Pyridine-barbituric acid reagent, C 5**  **H 5**  **N** • **C 4**  **H 4**  **N 2**  **O 3**  **- Place 15 g of barbituric acid in a 250-mL volumetric flask and add just enou**  **gh water to wash the sides of the flask and wet the barbituric acid. Add 75 mL of pyridine**  **and mix. Add 15 mL of concentrated hydrochloric acid (HCl), mix, and cool to room temp**  **erature. Dilute to 250 mL with water. This reagent is stable for approximately six months**  **if stored in a cool, dark place.**

**7.3.5 Stock potassium cyanide solution (1 mL = 1000** μ **g CN**

− **), KCN - Dissolve 2.51 g of KCN and 2 g of KOH in 900 mL of water. S**  **tandardize with 0.0192N silver nitrate, AgNO**  **3 . Dilute to appropriate concentration to achieve 1**  **mL = 1000** μ **g of CN**

−

**.**

**NOTE : A detailed procedure for AgNO**  **3 standardization is described in Standard** 

**Methods for the Examination of Water and Wastewater , 18th Edition, 1992, "Method** 

**4500-CN D."**

**7.3.6 Intermediate standard potassium cyanide solut ion (1 mL = 100**  μ **g CN**

− **), KCN. Dilute 100 mL of stock potassium cyanide solu**  **tion (1 mL = 1000** μ **g CN**

− **) to 1000**

**mL with water. 7.3.7 Working standard potassium cyanide solution (**  **1 mL = 10** μ **g CN**

− **), KCN. Prepare fresh daily by diluting 100 mL of intermedi**  **ate standard potassium cyanide solution**

**and 10 mL of 1N NaOH to 1 liter with water.**

**7.4 Reagents for titration procedure**

**7.4.1 Rhodanine indicator - Dissolve 20 mg of p-dim ethylamino-benzal-rhodanine,** 

**C 12**  **H 12**  **N 2**  **OS 2**  **, in 100 mL of acetone.**

**7.4.2 Standard silver nitrate solution (0.0192N), A gNO**  **3 - Prepare by crushing**  **approximately 5 g of AgNO 3**  **and drying to constant weight at 40** ° **C. Weigh out 3.2647 g of SW-846 Update V 9014 - 5 Revision 1**  **July 2014 dried AgNO**  **3 . Dissolve in 1 liter of water.** 

**NOTE : A detailed procedure for AgNO**  **3 standardization is described in Standard Methods** 

**for the Examination of Water and Wastewater , 18th Edition, 1992, "Method 4500-CN D."** 

**8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE**

**Sample collection, preservation and storage require ments may vary by EPA program and**  **may be specified in a regulation or project plannin g document that requires compliance**  **monitoring for a given contaminant. Where such req uirements are specified in the regulation,**  **follow those requirements. In the absence of speci fic regulatory requirements, use the following**  **information as guidance in determining the sample c ollection, preservation and storage**  **requirements.**

**8.1 See the introductory material in Chapter Three, "Inorganic Analytes."** 

**8.2 Samples should be collected in plastic or glass (preferably plastic) containers that** 

**are either amber or covered with aluminum foil so a s to filter light at 400 nm and below and**  **prevent photodecomposition of cyanide complexes. A ll containers must be thoroughly cleaned**  **and rinsed prior to use. All sample containers mus t be prewashed with acids, water, and**  **metal-free detergents, if necessary, depending on t he use history of the container. For further**  **information, see Chapter Three.**

**8.3 Aqueous samples for cyanide analysis should be preserved under alkaline**  **conditions by adjusting the pH to 12 or greater usi ng sodium hydroxide. Solid waste samples** 

**should be stored at** ≤ **6 oC after collection and prior to extraction.**

**8.4 Store all sample matrices at** ≤ **6 oC for no longer than 14 days. Solid phase sampl es**  **must be extracted within 14 days of sample collecti on. Bring the samples to room temperature**  **prior to analysis. Analysis of aqueous samples and solid phase extract solutions must be**  **performed within 14 days of sample collection or ex tract generation.** 

**8.5 Distillates that are not analyzed immediately s hould be stored in tightly sealed flasks** 

**at** ≤ **6** ° **C.**

**9.0 QUALITY CONTROL**

**9.1 Refer to Chapter One for guidance on quality as surance (QA) and quality control**  **(QC) protocols. When inconsistencies exist between QC guidelines, method-specific QC criteria**  **take precedence over both technique-specific criter ia and those criteria given in Chapter One,**  **and technique-specific QC criteria take precedence over the criteria in Chapter One. Any effort**  **involving the collection of analytical data should include development of a structured and**  **systematic planning document, such as a Quality Ass urance Project Plan (QAPP) or a Sampling**  **and Analysis Plan (SAP), which translates project o bjectives and specifications into directions for**  **those that will implement the project and assess th e results. Each laboratory should maintain a**  **formal quality assurance program. The laboratory s hould also maintain records to document the**  **quality of the data generated. All data sheets and quality control data should be maintained for**  **reference or inspection. SW-846 Update V 9014 - 6 Revision 1**  **July 2014 9.2 Initial demonstration of proficiency (IDP)** 

**Prior to the analysis of samples an initial demon stration of method proficiency is**  **accomplished through the successful calibration of method-specific instruments according to**  **project requirements and criteria set forth in the applicable analytical methodology. This initial**  **demonstration should be performed prior to independ ently running an analytical method, and**  **should be repeated if other changes occur (e.g., in strument repair, significant change in**  **procedure). Documentation of IDP should be maintai ned by the Quality Assurance Manager.**  **The laboratory must also repeat the demonstration o f proficiency whenever new staff members**  **are trained or significant changes in instrumentati on are made. See Method 8000 for information**  **on how to accomplish an initial demonstration of pr oficiency.** 

**An analytical instrument is said to be calibrated when an instrumental response can be**  **related to the concentration of an analyte. This r elationship may be depicted graphically, and** 

**referred to as a “calibration curve.” Initial cali bration curves must be established based upon the**  **requisite number of standards identified within the method for each target analyte (and surrogate**  **for organic compounds). All reported concentration s for target analytes should be within the high**  **and low initial calibration standards. Data genera ted above the high standard should be diluted**  **into the calibration range and reanalyzed. The freq uency requirements for the initial calibration**  **vary among the individual methods.**

**Most analytical methods require multipoint (three o r more) calibration that may include**  **calibration blanks and higher levels so that unknow ns fall within the calibration range and are**  **bracketed by calibration points. The number of cal ibration points, the calibration range, and the**  **frequency requirements should be specified in the Q APP.** 

**9.3 Before processing any samples, the analyst shou ld demonstrate that all parts of the**  **equipment in contact with the sample and reagents a re interference-free. This is accomplished**  **through the analysis of a method blank. As a conti nuing check, each time samples are**  **extracted, cleaned up, and analyzed, and when there is a change in reagents, a method blank**  **should be prepared and analyzed for the compounds o f interest as a safeguard against chronic**  **laboratory contamination. If a measurable absorban ce is observed at or in close proximity to the**  **measurement wavelength of the target analyte that w ould prevent the accurate determination of**  **that analyte, determine the source and eliminate it , if possible, before processing the samples.**  **The blanks should be carried through all stages of sample preparation and analysis. When new**  **reagents or chemicals are received, the laboratory should monitor the preparation and/or analysis**  **blanks associated with samples for any signs of con tamination. It is not necessary to test every**  **new batch of reagents or chemicals prior to sample preparation if the source shows no prior**  **problems. However, if reagents are changed during a preparation batch, separate blanks need**  **to be prepared for each set of reagents.**

**The laboratory should not subtract the results of t he method blank from those of any**  **associated samples. Such "blank subtraction" may l ead to negative sample results. If the**  **method blank results do not meet the project-specif ic acceptance criteria and reanalysis is not**  **practical, then the data user should be provided wi th the sample results, the method blank results,** 

**and a discussion of the corrective actions undertak en by the laboratory.** 

**9.4 Sample quality control for preparation and anal ysis** 

**The laboratory must also have procedures for docum enting the effect of the matrix on**  **method performance (precision, accuracy, method sen sitivity). At a minimum, this should**  **include the analysis of QC samples including a meth od blank, a matrix spike, a duplicate, and a**  **laboratory control sample in each analytical batch. Any method blanks, matrix spike samples,** **SW-846 Update V 9014 - 7 Revision 1 July 2014**  **and replicate samples must be subjected to the same analytical procedures (Sec. 11.0) as those**  **used on actual samples.**

**The following should be included within each analyt ical batch:** 

**9.4.1 Method Blank - For each batch of samples anal yzed, at least one method**  **blank must be carried throughout the entire sample preparation and analytical process,**  **including exposure to all glassware, equipment, sol vents, filtration, and reagents that are**  **used with field samples. Analysis of a method blan k is used to assess contamination**  **from the laboratory environment, equipment, and/or reagents. Any free cyanide** 

**measured in the method blank that exceeds the lower limit of quantitation (LLOQ) (Sec.**  **9.7) indicates that contamination is present. The source of the contamination should be**  **determined and corrected prior to performing any sa mple analysis. Any sample included**  **in an analysis batch that has an unacceptable metho d blank concentration should be**  **reanalyzed in a subsequent batch after the contamin ation problem is resolved.** 

**9.4.2 Matrix Spike (MS)/Duplicate - Documenting the effect of the matrix should**  **include the analysis of at least one MS and one dup licate unspiked sample or one matrix**  **spike/matrix spike duplicate (MS/MSD) pair. Both a queous samples and solid sample**  **extracts should be represented by a minimum of one MS sample for each respective**  **matrix. The decision on whether to prepare and ana lyze duplicate samples or a**  **MS/MSD must be based on knowledge of the samples in the sample batch. If samples**  **are expected to contain the target analyte, laborat ories may use a matrix spike (MS) and**  **a duplicate analysis of an unspiked field sample. If samples are not expected to contain**  **the target analyte, the laboratories should use a M S/MSD pair. Consult Method 8000**  **for information on developing acceptance criteria f or the MS/MSD.** 

**9.4.3 A laboratory control sample (LCS) should be i ncluded with each analytical**  **batch. The LCS consists of an aliquot of a clean ( control) matrix similar to the sample**  **matrix and of the same weight or volume. The LCS i s spiked with the same analytes at**  **the same concentrations as the matrix spike, when a ppropriate. When the results of the**  **matrix spike analysis indicate a potential problem due to the sample matrix itself, the**  **LCS results are used to verify that the laboratory can perform the analysis in a clean** 

**matrix. Consult Method 8000 for information on dev eloping acceptance criteria for the** 

**LCS.**

**9.4.4 Also see Method 8000 for the details on carry ing out sample quality control**  **procedures for preparation and analysis. In-house method performance criteria for**  **evaluating method performance should be developed u sing the guidance found in** 

**Method 8000.**

**9.5 Initial Calibration Verification (ICV)** 

**Immediately after the calibration standards have b een analyzed, the accuracy of the**  **calibration must be verified by the analysis of an ICV standard. The ICV is prepared in the same**  **manner as a calibration standard (i.e., the sample is NOT processed through distillation) at a**  **concentration level within the calibration range of the method and using a second source standard**  **(prepared using standards different from the calibr ation standards) spiked into 0.25N sodium**  **hydroxide (see Sec. 10.1). The control limit for t he ICV is ±15% of the true value. When the ICV**  **exceeds the control limits, the analysis should be terminated, the problem corrected, the**  **instrument recalibrated, and the calibration re-ver ified.** **SW-846 Update V 9014 - 8 Revision 1 July 2014**  **9.6 Continuing Calibration Verification (CCV)**

**Once the calibration curve has been established, t he continuing accuracy must be verified**  **by analysis of a CCV after every tenth field sample , and at the end of the analysis sequence.**  **The CCV is equivalent to or prepared in the same ma nner as a calibration standard (i.e., the**  **sample is NOT processed through distillation) at a concentration level within the calibration range**  **of the method and using the same source standard (p repared using the same source standards**  **as those used to prepare the calibration standards) spiked into 0.25N sodium hydroxide (see Sec.**  **10.1). CCV concentrations alternating between the low- and mid-range calibration standard** 

**concentrations are recommended. The control limit for the low-range CCV is ± 50%**  

### and for **the mid-range CCV is ± 15% of the true value. When the**  **CCV exceeds the control limits, the analysis should be terminated, the problem correcte**  **d, the instrument recalibrated, and the calibration re-verified using an ICV analysis. Sam**  **ples that are not bracketed by acceptable CCV runs must be reanalyzed.** 

**9.7 Lower Limit of Quantitation (LLOQ) check stand ard** 

**The laboratory should establish the LLOQ as the low est point of quantitation which, in**  **most cases, is the lowest concentration in the cali bration curve. The LLOQ should be verified by**  **the analysis of at least 7 replicate samples, spike d at the LLOQ and processed through all**  **preparation and analysis steps of the method. The mean recovery and relative standard**  **deviation of these samples provide an initial state ment of precision and accuracy at the LLOQ.**  **In most cases the mean recovery should be +/- 35% o f the true value and RSD should be <**  **20%. In-house limits may be calculated when sufficient d**  **ata points exist.**

**9.7.1 The LLOQ verification is recommended for ea ch project application or, at a**  **minimum, on a quarterly basis to validate quantitat ion capability at low analyte concentration**  **levels. This verification may be accomplished eith er with clean control material (e.g., reagent**  **water, method blank, Ottawa sand, diatomaceous eart h, etc.) or a representative sample matrix**  **(free of target compounds). Optimally, the LLOQ sh ould be less than or equal to the desired**  **regulatory action levels based on the stated projec t-specific requirements.** 

**9.7.1.1 The determination of LLOQs using spiked cle an control material**  **represents a best-case scenario, and does not evalu ate the potential matrix effects of**  **real-world samples. For the application of LLOQs o n a project-specific basis, with**  **established DQOs, a representative matrix-specific LLOQ verification may provide a more**  **reliable estimate of the lower quantitation limit c apabilities.** 

**9.7.1.2 Alternatively, a representative sample matr ix may be spiked with**  **the analytes of interest at the predicted LLOQ conc entration levels. This LLOQ check is**  **carried through the same preparation procedures as the environmental samples and other**  **QC. Individual LLOQs are verified when each respec tive analyte is recovered at ±50% of**  **the predicted LLOQ concentration or established DQO criteria. This check may also be**  **applied towards establishing the individual analyte reporting limit(s).** 

**9.7.2 In-house limits may be calculated when suffic ient data points exist.** 

**9.8 It is recommended that the laboratory adopt add itional QA practices for use with this**  **method. The specific practices that are most produ ctive depend upon the needs of the**  **laboratory and the nature of the samples. Whenever possible, the laboratory should analyze**  **standard reference materials and participate in rel evant performance evaluation studies.** 

**9.9 The method of standard additions must be used f or the analysis of all samples that** **SW-846 Update V 9014 - 9 Revision 1 July 2014**  **suffer from matrix interferences such as samples wh ich contain sulfides.** 

**10.0 CALIBRATION AND STANDARDIZATION**

**10.1 Standard curve for samples without sulfide**

**10.1.1 Prepare a series of standards by pipetting s uitable volumes of working**  **standard potassium cyanide solution into 250-mL vol umetric flasks. To each flask, add**  **50 mL of 1.25N sodium hydroxide and dilute to 250 m L with water. Prepare using the**  **following table. The sodium hydroxide concentratio n will be 0.25N.** 

**mL of Working Standard**

**Solution (1 mL = 10**  μ **g CN**

− **) Concentration**  **(** μ **g CN**

− **/L)**

**0**

**1.0**

**2.0**

**5.0**

**10.0**

**15.0**

**20.0 Blank** 

**40**

**80**

**200**

**400**

**600**

**800**

**10.1.2 After the standard solutions have been prepa red according to the table**  **above, pipet 50 mL of each standard solution into a 100-mL volumetric flask and proceed** 

**to Sections 11.2.2 and 11.2.3 to obtain absorbance values for the standard curve. The** 

**final concentrations for the standard curve will be one half of the amounts in the above**  **table (final concentrations ranging from 20 to 400** μ **g/L).**

**10.1.3 Prepare a standard curve ranging from 20 to 400**  μ **g/L by plotting absorbance of standard versus the cyanide concentration** 

**10.2 Standard curve for samples with sulfide**

**10.2.1 It is imperative that all standards be disti lled in the same manner as the**  **samples using the method of standard additions. St andards distilled by this method will**  **give a linear curve, at low concentrations, but as the concentration increases, the**  **recovery decreases. It is recommended that at leas t five standards be distilled.** 

**10.2.2 Prepare a series of standards similar in con centration to those mentioned in**  **Sec. 10.1.1 and analyze as in Sec. 11.2. Prepare a standard curve by plotting**  **absorbance of standard versus the cyanide concentra tion.** 

**11.0 PROCEDURE**

**11.1 If the manual spectrophotometric determina tion will be performed, proceed to**  **Sec. 11.2. If the titration procedure will be perf ormed, proceed to Sec. 11.3.** **SW-846 Update V 9014 - 10 Revision 1 July 2014**  **11.2 Manual spectrophotometric (colorimetric) dete rmination** 

**11.2.1 Pipet 50 mL of sample or 50 mL of the scrubb er solution obtained from the**  **distillation procedure in Method 9010 into a 100-mL volumetric flask. If the sample is later**  **found to be beyond the linear range of the colorime tric determination and redistillation of a**  **smaller sample is not feasible, a smaller aliquot m ay be taken. If less than 50 mL is taken,**  **dilute to 50 mL with 0.25N sodium hydroxide solutio n.** 

**CAUTION : Temperature of reagents and spiking solution can**  **affect the response factor of the colorimetric determination. The reagents store**  **d in the refrigerator should be warmed to ambient temperature before use. Samples should not**  **be left in a warm instrument to develop color, but instead they should be aliquoted**  **to a cuvette immediately prior to reading**

**the absorbance.**

**11.2.2 Add 15 mL of 1M sodium phosphate solution an d mix. Add 2 mL of**  **chloramine-T and mix. Some distillates may contain compounds that have chlorine** 

**demand. One minute after the addition of chloramin e-T, test for excess chlorine with**  **KI-starch paper. If the test is negative, add 0.5 mL chloramine-T. After 1 minute recheck**  **with KI-starch paper. Continue to add chloramine-T in 0.5 mL increments until an excess is**  **maintained. After 1 to 2 min., add 5 mL of pyridin e-barbituric acid solution and mix.** 

**11.2.3 Dilute to 100 mL with water and mix again. Allow 8 minutes for color**  **development and then read the absorbance at 578 nm in a 1-cm cell within 15 min. The**  **sodium hydroxide concentration will be 0.125N. See Sec. 10.0 for standard curves. See** 

**Sec. 12.1 for calculation.**

**11.2.4 See Sec. 10.0 for instructions regarding pre paration of a standard curve**  **based on whether the sample contains sulfides.**

**11.3 Titration procedure**

**11.3.1 Transfer the gas scrubber solution or a suit able aliquot from the 250-mL**  **volumetric flask to a 500-mL Erlenmeyer flask. Add 10-12 drops of the rhodanine indicator.** 

**11.3.2 Titrate with standard 0.0192N silver nitrate to the first change in color from**  **yellow to brownish-pink. The titration must be per formed slowly with constant stirring.**  **Titrate a water blank using the same amount of sodi um hydroxide and indicator used in the**  **sample. The analyst should be familiar with the en dpoint of the titration and the amount of**  **indicator to be used before actually titrating the samples. A 5-mL burette may be**  **conveniently used to obtain a precise titration.**

**NOTE : The titration is based on the following reaction**  **:**

**Ag +**  **+ 2CN** → **[Ag(CN) 2**  **]**

−

**When all of the cyanide has complexed and more silv er nitrate is added, the excess** 

**silver combines with the rhodanine indicator to tur n the solution yellow and then brown**  **ish-pink. See Sec. 12.2 for calculation.**

**12.0 DATA ANALYSIS AND CALCULATIONS**

**12.1 If the spectrophotometric procedure is used, calculate the cyanide, in**  μ **g/L, in the SW-846 Update V 9014 - 11 Revision 1**  **July 2014 original sample as follows:** 

**CN**

− **(** μ **g/L) = A x B x C**

**D x E** 

**where:**

**A =** μ **g/L CN**

− **read from standard curve. B = mL of sample after preparation of colorimetric**  **analysis**

**(100 mL recommended). C = mL of sample after distillation (250 mL recomme**  **nded). D = mL of original sample for distillation (500 mL**  **recommended). E = mL used for colorimetric analysis (50 mL recomm**  **ended).**

**12.2 If the titrimetric procedure is used, calcul ate concentration of CN- in**  μ **g/L in the original sample as follows:** 

**where:**

**A = mL of AgNO 3**  **for titration of sample. B = mL of AgNO**  **3 for titration of blank.**  **C = mL of sample titrated (250 mL recommended). D = Actual normality of AgNO**  **3 (0.0192 N recommended).**  **E = mL of sample after distillation (250 mL recomme nded).**  **F = mL of original sample before distillation (500 mL recommended).** 

**12.3 Results must be reported in units commensurat e with their intended use and all**  **dilutions must be taken into account when computing final results.** 

**13.0 METHOD PERFORMANCE**

**13.1 Performance data and related information are p rovided in SW-846 methods only as**  **examples and guidance. The data do not represent r equired performance goals for users of the**  **methods. Instead, performance goals should be dev eloped on a project-specific basis, and the**  **laboratory should establish in-house QC performance criteria for the application of this method.**  **These performance data are not intended to be and m ust not be used as absolute QC acceptance**  **criteria for purposes of laboratory accreditation.**

**13.2 The titration procedure using silver nitrate i s used for measuring concentrations of**  **cyanide exceeding 0.1 mg/L. The colorimetric proce dure is used for concentrations below 1**  **mg/L of cyanide and is sensitive to about 0.02 mg/L**

**.**

**13.3 EPA Method 335.2 (sample distillation with tit ration) reports that in a single**  **laboratory using mixed industrial and domestic wast e samples at concentrations of 0.06 to 0.62**  **mg/L CN**

− **, the standard deviations for precision were ± 0.00 5 to ± 0.094, respectively. In a**  **single laboratory using mixed industrial and domest ic waste samples at concentrations of 0.28**  **and 0.62 mg/L CN**

− **, recoveries (accuracy) were 85% and 102%, respecti vely. These data are**  **provided for guidance purposes only.**

**13.4 In two additional studies using surface wa ter, ground water, and landfill leachate** **SW-846 Update V 9014 - 12 Revision 1 July 2014**  **samples, the titration procedure was further evalua ted. The concentration range used in these**  **studies was 0.5 to 10 mg/L cyanide. The detection limit was found to be 0.2 mg/L for both total**  **and amenable cyanide determinations. The precision (CV) was 6.9 and 2.6 for total cyanide**  **determinations and 18.6 and 9.1 for amenable cyanid e determinations. The mean recoveries**  **were 94% and 98.9% for total cyanide, and 86.7% and 97.4% for amenable cyanide. These data**  **are provided for guidance purposes only.**

**14.0 POLLUTION PREVENTION**

**14.1 Pollution prevention encompasses any technique that reduces or eliminates the**  **quantity and/or toxicity of waste at the point of g eneration. Numerous opportunities for pollution**  **prevention exist in laboratory operation. The EPA has established a preferred hierarchy of**  **environmental management techniques that places pol lution prevention as the management**  **option of first choice. Whenever feasible, laborat ory personnel should use pollution prevention**  **techniques to address their waste generation. When wastes cannot be feasibly reduced at the**  **source, the Agency recommends recycling as the next best option.** 

**14.2 For information about pollution prevention tha t may be applicable to laboratories and** 

**research institutions consult** Less is Better: Laboratory Chemical Management for Waste

Reduction **, a free publication available from the American Ch emical Society (ACS), Committee on**  **Chemical Safety. http://portal.acs.org/portal/fileF etch/C/WPCP_012290/pdf/WPCP_012290.pdf** 

**15.0 WASTE MANAGEMENT**

**The Environmental Protection Agency requires that l aboratory waste management**  **practices be conducted consistent with all applicab le rules and regulations. The Agency urges**  **laboratories to protect the air, water, and land by minimizing and controlling all releases from**  **hoods and bench operations, complying with the lett er and spirit of any sewer discharge permits**  **and regulations, and by complying with all solid an d hazardous waste regulations, particularly the**  **hazardous waste identification rules and land dispo sal restrictions. For further information on**  **waste management, consult the ACS publication liste d in Sec. 14.2.** 

**16.0 REFERENCES**

**There are no references directly related to this me thod. References on total and amenable**  **cyanide can be found in Method 9010.**

**17.0 TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION D ATA** 

**There are no tables or figures in this method. SW-846 Update V 9014 - 13 Revision 1**  **July 2014 Appendix A**  **Summary of Revisions to Method 9014 (from Revision 0, December 1996)** 

**1. The entire document was updated to Microsoft Wor d .docx format from the original .WPD**  **and .PDF files. The revision number was changed to one and the date published to July** 

**2014. 2. Minor editorial and grammatical changes were mad**  **e throughout the document, as**

**needed. 3. Graphics in the Figures Section were modified fr**  **om Corel Drawing Objects V.10 to .jpg graphical images (where needed) to remove artifacts**  **from the conversion process. The text titles of each figure was centered and formatt**  **ed. 4. Minor editorial comments from work group notes f**  **or 9013, 9014, 9015 in excel table were checked and were found to already be incorporated i**  **nto the Method. 5. This appendix was added to document changes made**  **during the editorial process.**

**6. The discussion of Initial Demonstration of Profi ciency (IDP) in Section 9.2 was revised per**  **language from Chapter One. 7. Significantly updated and expanded “QUALITY CONT**  **ROL” section for better adherence to current SW-846 method guidelines and for improve**  **d alignment with current universal practices for published analytical methods.**  **8. Inserted Section 9.7 to describe the use and app lication of LLOQ.**