United States Environmental Protection Agency Municipal Environmental Research Laboratory Cincinnati OH 45268 Research and Development EPA-600/S2-81-046 May 1981 Project Summary Analytical Methods Evaluation for Applicability in Leachate Analysis Foppe B. DeWalle, Theodore Zeisig, John F. C. Sung, Donald M. Norman, Jack B. Hatlen, Edward S. K. Chian, Michael G. Bissel, Kim Hayes, and Donald E. Sanning Thirty-two laboratories in the United States and Canada conducted round- robin analyses of leachate samples. Samples were analyzed for up to 28 parameters to evaluate accuracy and precision of the methods employed. The 28 parameters included physical parameters (pH, oxidation reduction potential, conductivity, turbidity, and solids), organics (chemical oxygen demand, total organic carbon, organic nitrogen, and free volatile fatty acids), anions (sulfate, phosphate, chloride, nitrate, and bicarbonate), and cations (alkali metals, alkaline earth metals, transition metals, and heavy metals). Individual parameter coefficients of variation ranged from 32 percent to 210 percent. Significant differences were noted between results from colorimetric methods and from titri- metric and physical methods. The average recovery for spiked parameters varied widely for individual parameters. The most applicable method for analysis of each parameter is recom- mended. Use of the standard addition technique is required in each laboratory to determine the matrix depression or enhancement for each type of leachate sample. The accuracy (i.e., agreement be- tween measured and actual amounts) and the precision (i.e., reproducibility) of different analytical methods were evaluated in depth. Thirty-two labora- tories submitted final analytical results. This Project Summary was developed by EPA's Municipal Environmental Research Laboratory, Cincinnati, OH, to announce key findings of the re- search project that is fully documented in a separate report of the same title (see Project Report ordering informa- tion at back). Technical Discussion Leachate samples were collected from nine locations chosen to represent different climatic conditions, varying site age, and a wide range of chemical oxygen demand (COD). Adoublequantity of leachate was collected from one of the sites so that a spiked sample could also be analyzed. Therefore, the nine sites provided ten leachate samples. The leachate samples were collected, chilled, anaerobically sorted, and im- mediately shipped by air to Stanford University. At Stanford, each sample was emptied anaerobically into a 150- liter vessel, thoroughly mixed, placed in 55 one-liter glass containers and 110 five-hundred-mi polyethylene containers, and chilled for distribution by air freight to the participating laboratories. After complete mixing of the double-quantity sample, half of the sample was spiked with each of the chemical parameters to a concentration of about 25 percent of the original concentration in the un- spiked sample. The participating laboratories recorded analytical information on a Stanford Reporting Form that was manually ------- edited before key punching. All major computations and data file management were performed on the Control Data Cyber 173 and CDC 6400 dual mam- frame system of the Academic Computer Center at the University of Washington. The leachate data base was maintained on disc and magnetic tape files. Most of the data preprocessing programs used for data sorting and the computation of sample statistics were written in FORTRAN, compiled with the University of Minnesota Fortran compiler (Version 5.1), and executed under the CDC NOS/BE (Version 1.2) operating system. The statistical package Minitab II was used extensively in the statistical analysis and plotting of the leachate data. The report concentration levels were processed with a G12.5 format specification for all 28 parameters. A G13.6 format specification was used for the average and standard deviation computed for the concentration levels. The data from each parameter were analyzed using the following approach. The within- and between-laboratory standard deviations were plotted against the concentration level to determine if a transformation of the data was required to make the variability at different levels of the parameter approximately equal. Quantile-quantile plots were then con- structed for the original and transformed data and used to determine if the distri- butions of the original or the transformed data were reasonably close to a normal distribution. To determine if systematic differences exist between the analytical methods used and between laboratories, a ranking procedure was used. Finally, the analysis of variance was used to estimate the between-laboratory, labo- ratory-sample-interaction, and within- laboratory variance components. A statistical evaluation of the data revealed that the overall coefficient of variation (i.e., the standard deviation as a percentage of the average) ranged from 32 percent for the COD determina- tion to 210 percent for the cadmium determination. The between-laboratory component of variation was larger than the within-laboratory component. The largest portion of the variation, however, was due to a sample laboratory inter- action (i.e., the laboratories' relative results change for different leachate samples). Further, the results of the leachate analysis more closely resembled a lognormal distribution than a normal distribution. The standard deviation of the data in the lognormal scale is equivalent to the coefficient of variation of the data in the original scale of measurement as calculated through a first order Taylor expansion. The standard deviations for the different parameters/ variables are shown in Table 1. The overall standard deviation <7R is approxi- mately 1.5 times larger than the be- Table 1. Standard Deviations for All Reporting Laboratories and for Those Reporting Three Replicates Parameter/ Variable pH ORP Turbidity Conductivity Volatile Acids COD TOO Total Residue Volatile Residue Organic Nitrogen Ammonia Nitrogen Sulfate Total Phosphorus Chloride Alkalinity Nitrate Nitrogen Sodium Potassium Calcium Magnesium Barium Iron Zinc Lead Chromium Cadmium Copper Nickel All Reporting O-R 0.349 123 2.01 0.464 1.01 0.324 0.602 0.574 0.764 1.5O 0.89 1.80 1.45 0.923 0.380 1.98 0.545 0.661 0.74 0.594 1.41 0.532 1.35 0.962 1.71 2.16 1.42 1.08 Laboratories O-L 0.152 93 1.47 0.225 0.627 0.20 0.294 0.517 0.638 1.02 0.923 0.603 1.20 0.494 0.222 1.50 0.125 0.388 0.642 0.109 1.05 0.281 1.03 0.648 1.32 1.78 1.14 0.732 Labs Reporting Three Replicates O-LS 0.1 08 68 1.09 0.174 0.855 0.212 0.493 0.185 0.45 0.671 0.69 1.47 0.610 0.80 0.358 1.32 0.578 0.438 0.336 0.676 1.19 0.354 0.797 0.644 0.727 0.440 0.832 0.842 <7w 0.052 30 0.114 0.026 0.151 0.066 0.069 0.062 0.172 0.265 0.110 0.774 0.563 0.055 0.033 0.193 0.037 0.056 0.046 0.036 0.043 0.053 0.103 0.308 0.665 1.04 0.251 0.365 O-R -Overall standard deviation. CTL = Between laboratory standard deviation. ois = Laboratory sample interaction standard deviation. CT\N = Standard deviation within laboratories. ------- tween-laboratory standard deviation component a\_. The overall standard deviation was especially large for the analysis of cadmium, nitrate nitrogen, turbidity, sulfate, chromium, organic nitrogen, copper, zinc, and barium. Since leachate differs from water and wastewater in both content and con- centration, interferences can lead to erroneous results when water and wastewater methods are used for leachate analyses. Table 2 shows the percent variance associated with the following water/wastewater methods: (1) EPA Methods for Chemical Analysis of Water and Wastes (1974); (2) ASTM Part 31: Water (1975); and (3) Standard Methods (1971). Substantial differences existed be- tween different analytical methods, especially between manual and auto- mated methods. Colorimetric methods tended to give values that were some- times different from those of physical methods. Differences likewise existed among instrumental methods. Pretesting of storage time indicated that no time effect existed to produce a variation in the analytical results, nor did the partic- ular dilutions have a major effect on the Table 2. Percent of Variance Ranges for Three Methods Used to Analyze Water and Wastewater Parameter/ Variance pH OfiP Turbidity Conductivity Volatile Acids COD TOO Total Residue Volatile Residue Organic Nitrogen Ammonia Nitrogen Sulfate Total Phosphorus Chloride Alkalinity Nitrate Nitrogen Sodium Potassium Calcium Magnesium Barium Iron Zinc Lead Chromium Cadmium Copper Nickel Method Electrometric Electrometric Photometric Electrometric Chromatographic Manual reflux IR detection Gravimetric Gravimetric Kjeldahl N Automated Phenate Distillation Selected Ion Electrodes Automated Phenate Direct Nesslerization Direct Phenate Turbidimetric Automated Chloranilate Gravimetric Automated Ascorbic Acid Manual Ascorbic Acid Mercuric Nitrate Ferricyanide Argentometric Potenti Automated Cadmium Reduction Manual Cadmium Reduction Brucine Flame Photometric Direct A. A. Flame Photometric Direct A.A. EDTA Titri metric Direct A.A. Direct A.A. Direct A.A. Direct A.A. Phenanthroline - - - - - - EPA (1974) a (%) 1.6-3.1 — 1.6-26 7-8.2 — 6.58 80-7.8 - - 99-26 24.6-31.8 58-14.5 3.8-2.2 0.35-1.1 - - 26.7-5.9 0.3-1.5 - 47.2-22 30-14.5 9.06-2.96 - - 15.8-4.0 4.1-26.3 - 57.5-17.3 - 1.5 - 10.3-10.2 - 0.3-0.6 4.76-2.5 10.8-6.5 609-21 - 314-34.5 114-33 105-28.4 350-23 81-17 5.5-0.8 ASTM (1975) a (%) a 5-10 mV — — ±13 mg/L 4.2-3.2 - - - - - - - - - 5 - 10 - - 45.3-2.7 0-5.6 - - - - - 65.1-1.7 - 45.9-r.35 - - 20.3-7.3 67.8-8.7 - 56-6.25 - 55-5.3 57-7.4 29.4-9.6 0-8.7 33.8-3.95 52.4-2.6 Standard Methods a (%) — — — 8.6-7.8 — 6.5 5-70 5-9.7 6.5 - - 69.8-27.6 - - 38.7-77.6 39.2-26.0 9.7 - 4.7 - - 3.3 - 4.2 - 0.0-20 96.5-9.2 66.7-75.4 77.3 - 75.5 - 9.2 - 70.5 70 76.5 25.5 8.2 23.5 26.4 27.6-43.8 77.2 - "—Not reported. U US GOVERNMENT PRINTING OFFICE 1981-757-01Z/7134 ------- Table 3. Recommended Methods for Leachate Analysis Leachate Parameter Recommended Method pH Oxidation reduction potential Turbidity Conductivity Free volatile fatty acids Chemical oxygen demand Total residue Volatile residue Organic nitrogen Ammonia nitrogen Sulfate Total phosphorus Chloride Alkalinity Nitrate Sodium and Potassium Calcium, Magnesium, Barium Heavy metals (Fe, In, Pb, Cr, Cd, Cu, Ni) Electrometric method on fresh sample, using glass electrode and temperature correction. Electrometric method on fresh sample, using platinum electrode with the calomel reference electrode. Nephelometric method on a fresh sample. Electrometric method using platinum electrode and temperature correction. Chromatographic method. COD determination should also be conducted. Manual dichromatic reflux method using the ferrous ammonium sulfate titration. Drying method at 104°C. Drying at 550°C without prior filtration of sample. Kjeldahl manual titration. Distillation tritration method. Gravimetric method. Ascorbic acid method using the persulfate digestion step. Potentiometric titration. Potentiometric method with titration to inflection point of about pH 4.5. Cadmium reduction method after separate determination of the nitrite ion. Atomic absorption or manual flame or automated flame emission method. Atomic absorption spectrophotometric. Direct aspiration atomic absorption spectrophotometric method. outcome of the analysis. However, concentration ranges of a leachate con- stituent can produce a major effect on the analysis. This concentration effect was found to be particularly evident in spiked samples (i.e., the recovery rates varied widely for individual parameters). From this study, the authors recom- mend preferred methods for leachate analyses (Table 3), and general reasons are given for selecting a particular analytical method as being the most applicable. This report was submitted in fulfill- ment of Grant R805753 by the University of Washington, Department of Environ- mental Health, and of Grant R804883 by Stanford University, Department of Civil Engineering, under sponsorship of the U.S. Environmental Protection Agency. Foppe B. DeWalle, Theodore Zeisig, John F. C. Sung, Donald M. Norman, and Jack B. Halien are with the University of Washington, Seattle, WA 98195; Michael G. Bissel and Kim Hayes are with Stanford University, Stanford, CA 96205. Donald E. Banning is the EPA Project Officer (see below). The complete report, entitled "Analytical Methods Evaluation for Applicability in Leachate Analysis," (Order No. PB 81-172 306; Cost: $24.50, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Municipal Environmental Research Laboratory U. S. 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