U.S. DEPARTMENT OF COMMERCE National Technical Information Service PB-261 260 Chemical Analyses for Water Pollutants National Training & Operational Technology Or., Cincinnati, OH. Nov 76 ------- NOTICE THIS DOCUMENT HAS BEEN REPRODUCED FROM THE BEST COPY FURNISHED US BY THE SPONSORING AGENCY. ALTHOUGH IT IS RECOGNIZED THAT CER- TAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RE- LEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE. ------- •{ b b 0 8 4 PB 261 260 EPA 430/1 IS 013 CHEMICAL ANALYSES FOR WATER POLLUTANTS TRAINING MANUAL U.S. ENVIRONMENTAL PROTECTION AGENCY OFFICE OF WATER PROGRAM OPERATIONS NAT|ON.V. "ECHNICAL INFC *'.••••' :>. SERVICE ------- BIBLIOGRAPHIC DATA SHEET 1. Report No. eport No. EPA-4UO/1-75-013 3. Recipient's Accession No. J!£L '4. Title and "Subtitle Chemical Analyses for Water Pollutants 5. Report Date November 1976 '. Author(s) ^ Audrey E. Kroner 8- Performing Organization Kept. ! No. " 1 '. Performing Organization Name and Address U.S. Environmental Protection Agency, OWPO Municipal Operations and Training Division .National Training & Operational Technology Center Cincinnati, Ohio 45268 10. Project/'TasK, Work Unit No. ; 11. Contract/Grant No. 12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered 14. 15. Supplementary Notes 16. Abstracts This training manual contains outlined information used by Lecturers when presenting topics in EPA-NTOTC Course 100. 3, "Chemical Analyses for Water Pollutants. " The contents concern individual constituents found in water (e. g. dissolved oxygen) and information useful to analysts (e.g. statistics). A section of laboratory procedures adapted for class groups is included. 17. Key Words and Document Analysis. 17a. Descriptors Acidity, Alkalinity, Ammonia, Biochemical Oxygen Demand, Carbon, Dissolved gases. Hardness, Inorganic nitrates, Nitrites, Nitrogen cycle, Oxygen, Phosphorus, Quality Assurance, Statistical Analysis, Data Collection and Evaluation. 17b. Identifiers/Open-Ended Terms 17e. COSATI Fie Id/Group 19. Security Class (This |21. "No. of Pages Report) ' j UNCLASSIFIED j 18. Availability Statement Release to public 20. Security Class (This Page UNCLASSIFIED 1 NTIS-35 IRdV. 3-7ZI USCOMM-OC r ------- EPA-430/ 1-75-01 3 December 1975 CHEMICAL ANALYSES FOR WATER POLLUTANTS This course is designed for chemists or technicians who will perform chemical analyses for water pollutants. The student will learn about analyses listed in the guidelines developed pursuant to Section 304(g) of the Federal Water Pollution Control Act Amendments of 1972 for NPDES permit applications and reports and also for certifications issued by the States. The student will learn theoretical concepts and perform laboratory exercises pertaining to the following: Acidity and Alkalinity Determinations, pH Measurement, Biochemical Oxygen Demand, Dissolved Oxygen (Winkler and Probe), Calcium and Magnesium Hard- ness Determination, Nitrogen Analyses (Ammonia, Kjeldahl, Nitrate, Nitrite), Phosphorus Determinations, Total Organic Carbon Analysis, Total Solids Deter- mination. Discussion periods are scheduled after each laboratory assignment is completed. Time is divided about equally between classroom and laboratory work. Persons attending should have fundamental knowledge of inorganic chemistry and quantitative analysis. They should also be able to use an analytical balance, volu- metric glassware and titration assemblies. U. S. ENVIRONMENTAL PROTECTION AGENCY Office of Water Program Operations TRAINING PROGRAM ------- FOR KW OK l> These mainuals are prepai-ed for reference use of students enrolled in scheduled training courses of the Office of Water Program Operations. Environmental Protection Agency. Due to the limited availability of the manuals it is not appropriate to cite them as technical references in bibliographies or other forms of publication. References to products and manufacturers are for illustration only; such references do not imply product endorsement by the Office of Water Program Operations, Environmental Protection Agency. The reference outlines in this manual have been selected and developed with a goal of providing the student with a fund of the best available current information pertinent to the subject matter of the course. Individual instructors may provide additional material to cover special aspects of their own presentations. This manual will be useful to anyone who has need for information on the subjects covered. However, it should be understood that the manual will have its greatest value as an adjunct to classroom presentations. The inherent advantages of classroom presentation is in the give-and- take discussions and exchange of information between and among students and the instructional staff. Constructive suggestions for improvement in the coverage, content, and format of the manual are solicited and will be given full consideration. ------- CONTENTS Title or Description Outline Number I DATA COLLECTION AND EVALUATION Sample Handling - Field Through Laboratory 1 Statistics for Chemists 2 Accuracy-Precision-Error ^ Interlaboratory Quality Control Studies 4 II STANDARD SOLUTIONS, ACIDITY, ALKALINITY Volumetric Analysis of Water Quality 5 Acidity. Alkalinity, pH and Buffers 6 Alkalinity and Relationships Among the Various Types of Alkalinities 7 III OXYGEN TESTS Dissolved Oxygen - Factors Affecting DO Concentrations in Water 8 Dissolved Oxygen Determination (Winkler lodometric Titration and 8 Azide Modification) Dissolved Oxygen Determination - Electronic Measurements 9 Biochemical Oxygen Demand Test Procedures 10 BOD Determination - Reaerated Bottle Probe Technique 10 Effect of Some Variables on the BOD Test 10 Mathematical Basis of the Biochemical Oxygen Demand (BOD) Test 10 IV SELECTED ANALYSES Sources and Analysis of Organic Nitrogen 11 Ammonia, Nitrites and Nitrates 11 Total Carbon Analysis 12 Determination of Calcium and Magnesium Hardness 13 Solids Relations in Polluted Water 14 Phosphorus in the Aqueous Environment 15 100.3. 11.75 II ------- 2 C o n_t e n t s Title or Description Outline Number V LABORATORY PROCEDURES Biochemical Oxygen Demand Test - Dilution Technique 16 Laboratory Procedure for Dissolved Oxygen (Winkler-Azide Procedure) 17 Determination of Kjeldahl Nitrogen 18 Determination of Nitrate-Nitrite Nitrogen 19 Laboratory Procedure for Total Solids 20 Laboratory Procedure for Total Hardness 21 Laboratory Procedure for Phosphorus 22 Acidity 23 Laboratory Procedure for Total Alkalinity 24 ------- SAMPI.K HANDLING - KII-: LP THROmi f I \HOK\TOKY I PLANNING A SAMPLING PROGRAM A Factors to Consider: 1 Locating sampling sites 2 Sampling equipment 3 Type of sample required a grab b composite 4 Amount of sample required 5 Frequency of collection 6 Preservation measures, if any B Decisive Criteria 1 Nature of the sample source 2 Stability of constituent(s) to be measured 3 Ultimate use of data II REPRESENTATIVE SAMPLES If a sample is to provide meaningful and valid data about the parent population, it must be representative of the conditions existing in that parent source at the sampling location. A The container should be rinsed two or three times with the water to be collected. B Compositing Samples 1 For some sources, a composite of samples is made which will represent the average situation for stable constituents. 2 The nature of the constituent to be determined may require a series of separate samples. C The equipment used to collect ;nc sample is an important factor to consider. ASTM* ' has a detailed section on various sampling devices and techniques. D Great care must be exercised when collecting samples in sludge or mud areas and near benthic deposits. No definite procedure can be given, but careful effort should be made to obtain a rep- resentative sample. Ill SAMP LE IDENTIFICATION A Each sample must be unmistakably identified, preferably with a tag or label. The required information should be planned in advance. B An information form preprinted on the tags or labels provides uniformity of sample records, assists the sampler, and helps ensure that vital information will not be omitted. C Useful Identification Information includes: 1 sample identity code 2 signature of sampler 3 signature of witness 4 description of sampling location de- tailed enough to accommodate repro- ducible sampling. (It may be more convenient to record the details in the field record book). 5 sampling equipment used 6 date of collection 7 time of collection 8 type of sample (grab or composite) 9 water temperature 10 sampling conditions such as weather, water level, flow rate of source, etc. 11 any preservative additions or Techniques 12 record of any determinations done in the field 13 type of analyses to be done in laboratory WP.SUR.sg. 6. 3.74 1-1 ------- Sample Handling - Field Througji Laboratory IV SAMPLE CONTAINERS A Available Materials 1 glass 2 plastic 3 hard rubber B Considerations 1 Nature of the sample - Organics attack polyethylene. 2 Nature of constituents) to be determined - Cations can adsorb readily on soine plastics and on certain glassware. Metal or aluminum foil cap liners can interfere with metal analyses. 3 Preservatives to be used - Mineral acids attack some plastics. 4 Mailing Requirements - Containers should be large enough to allow extra volume for effects of temperature changes during transit. All caps should be securely in place. Glass containers must be protected against breakage. Styrofoam linings are useful for protecting glassware. C Preliminary Check Any question of possible interferences related to the sample container should be resolved before the study begins. A preliminary check should be made using corresponding sample materials, con- tainers, preservatives and analysis. D Cleaning If new containers are to be used, prelim- inary cleaning is usually not necessary. If the sample containers have been used previously, they should be carefully cleaned before use. There are several cleaning methods available. Choosing the best method in- volves careful consideration of the nature of the sample and of the constituent(s) to be determined. i Phosphate detergents should r.oi bo used to clean containers for phosphorus samples. '2 Traces of dichromatic cleaning solution will interfere v, ith metal analyses. L Storage Sample containers should be stored and transported in a manner to assure their readiness for use. V SAMPLE PRESERVATION Every effort should be made to achieve the shortest possible interval between sample collection and analyses. If there must be a delay and it is long enough to produce significant changes in the sample, preservation measures are required. At best, however, preservation efforts can only retard changes that inevitably continue after the sample is removed from the parent population. A Functions Methods of preservation are relatively limited. The primary functions of those employed are: 1 to retard biological action 2 to retard precipitation or the hydrolysis of chemical compounds and complexes 3 to reduce volatility of constituents B General Methods 1 pH control - This affects precipitation of metals, salt formation and can inhibit bacterial action. 2 Chemical Addition - The choice of chemical depends on the change to be controlled. Mercuric chloride is commonly used as a bacterial inhibitor. Disposal of the mercury-containing samples is a problem and efforts to find a substitute for this toxicant are underway. 1-2 ------- Samp!<• Handling - I'lciii Tlinuigh I To dispose of solutions of inorganic mercury salts, a recommended procedure is to capture and retain the mercury salts as the sulfide at a high pH. Several firms have tentatively agreed to accept the mercury sulfide for re-processing after preliminary con- ditions are 3 Refrigeration and Freezing - This is the best preservation technique avail- able, but it is not applicable to all types of samples. It is not always a practical technique for field operations. C Specific Methods The EPA Methods Manual includes a table summarizing the holding times and preservation techniques for several analytical procedures. This information also can be found in the standard refer- ences (!» 2» 3) as part of the presentation of the individual procedures. VI METHODS OF ANALYSIS Standard reference books of analytical procedures to determine the physical and chemical characteristics of various types of water samples are available. A EPA Methods Manual The Methods Development and Quality Assurance Research Laboratory of the Environmental Protection Agency, has published a manual of analytical procedures to provide methodology for monitoring the quality of our Nation's Waters and to deter- mine the impact of waste discharges. The title of this manual is "Methods for Chem- cal Analysis of Water and Wastes. "<2> For some procedures, the analyst is referred to Standard Methods and/or to ASTM Standards. B Standard Methods The American Public Health Association, the American Water Works Association and the Water Pollution Control Federation prepare and publish a volume describing methods of water analysis. These include physical and chemical proceaures. The title of this book is "Standard Methods for the Examination of Water and Waste - water. "<3> C ASTM Standards The American Society for Testing and Materials publishes an annual "book" of specifications and methods for testing materials. The "book" currently con- sists of 33 parts. The part applicable to water is a book titled, "Annual Book of ASTM Standards, Part 23. Water; Atmospheric Analysis". ' D Other References Current literature and other books of analytical procedures with related in- formation are available to the analyst. E NPDES Methodology When gathering data for National Pollutant Discharge Elimination System report purposes, the analyst must consult the Federal Register for a listing of approved analytical methodology. There he will be directed to pages in the above cited reference books where acceptable pro- cedures can be found. The Federal Register also provides information con- cerning the protocol for obtaining approval to use analytical procedures other than those listed. VII ORDER OF ANALYSES The ideal situation is to perform all analyses shortly after sample collection. In the practical order, this is rarely possible. The allowable holding time for preserved samples is the basis for scheduling analyses. ------- Sample Handling - Field Through Laboratory A The allowable holding time for samples depends on the nature of the sample, the stability of the constituent(s) to be de- termined and the conditions of storage. 1 For some constituents and physical values, immediate determination is required, e.g. dissolved oxygen, pH. 2 Using preservation techniques, the holding times -for other determinations range from 6 hours (BOD) to 7 days (COD). Metals may be held up to 6 months.^2' (2) 3 The EPA Methods Manual includes a table summarizing holding times and preservation techniques for several analytical procedures. This information can also be found in the standard (123) references ' ' as part of the presentation of the individual procedures. 4 If dissolved concentrations are sought, filtration should be done in the field if at all possible. Other- wise, the sample is filtered as soon as it is received in the laboratory. A 0.45 micron membrane filter is recommended for reproducible filtration. B The time interval between collection and analysis is important and should be recorded in the laboratory record book. VIII RECORD KEEPING The importance of maintaining a bound, legible record of pertinent information on samples cannot be over-emphasized. A Field Operations A bound notebook should be used. Informa- tion that should be recorded includes: 1 Sample identification records (Sec Part UI) 2 Any information requested by the analyst as significant 3 Details of sample preservation 4 A complete record of data on any determinations done in the field. (See B, next) 5 Shipping details and records B Laboratory Operations Samples should be logged in as soon as received and the analyses performed as soon as possible. A bound notebook should be used. Preprinted data forms provide uniformity of records and help ensure that required information will be recorded. Such sheets should be permanently bound. Items in the laboratory notebook would include: 1 sample identifying code 2 date and time of collection 3 date and time of analysis 4 the analytical method used !i any deviations from the analytical method used and why this was done 6 data obtained during analysis 7 results of quality control checks on the analysis 8 any information useful to those who interpret and use the data 9 signature of the analyst 1-4 ------- Sample Handling - Field Through Laboratory IX SUMMARY Valid data can be obtained only from a repre- sentative sample, unmistakably identified, carefully collected and stored. A skilled analyst, using approved methods of analyses and performing the determinations within the prescribed time limits, can produce data for the sample. This data will be of value only if a written record exists to verify sample history from the field through the laboratory. REFERENCES 1 ASTM Standards, Part 23, Water; . Atmospheric Analysis. 2 Methods for Chemical Analysis of Water and Wastes, EPA-MDQARL, Cincinnati, OH 45268. 1974. 3 Standard Methods for the Examination of Water and Wastewater, 13th edition, APHA-AWWA-WPCF, 1971. Dean, R., Williams, R. and Wise, R., Disposal of Mercury Wastes from Water Laboratories, Environmental Science and Technology, October, 1971. This outline was prepared by A. Donahue, Chemist, National Training Center, MPOD, OWPO. EPA, Cincinnati, Ohio 45268. Descriptors: On-Site Data Collections, On-Site Investigations, Planning, Handling, Sample, Sampling, Water Sampling, Surface Waters, Preservation, Wastewater 1-5 ------- STATISTICS FOR CHEMISTS I INTRODUCTION A Statistics may be defined, for our purpose, as a collection of methods which have been developed for handling numerical data pertaining to samples or portions of entire populations. B The statistical methods with which we will concern ourselves deal with the presentation and analysis of numerical data from samples. H FREQUENCY A Definitions 1 Frequency - indicates how many times a particular score occurs in a collection of data Frequency table - a tabular arrange- ment of data, ranked in ascending or descending order of magnitude, together with the corresponding frequencies Frequency histogram - a set of rectangles having bases on a horizontal axis with centers at the given scores and heights equal to the corresponding frequencies (See Figure 1) Frequency polygon - a line graph of frequencies plotted against scores (can be obtained by connecting mid- points of tops of rectangles in the frequency histogram) (See Figure 1) Figure 1 Frequency Histogram & Frequency Polygon Frequency >-> CO GO 4^ O 1 1 1 1 1 X X X X j X ^ V s X \ s \ \ \ 1 1 1 1 1 98 99 100 101 102 Chloride ug/l ST.25b.11.75 2-1 ------- Statistics For Chemists B Application Consider the application of the above definitions to the following set of data, obtained from twelve determinations for chloride in water. Results (tig/1) 100 101 99 101 100 100 99 102 100 98 101 102 numbcT of obscrvntions Hie iiiedian is '-'! * I tin1 :i v t' ra^r < >1 LIi middle two scores. 4 Mean - arithmetic average of all the values in the sample distribution, de- noted by X. The formula for calcula- ting the sample mean is X= *!- x n £ X, Table 1 Frequency Table Chloride (ng/1) 98 99 100 101 102 Frequency 1 2 4 3 2 II MEASURES OF CENTRAL TENDENCY A Definitions 1 Central tendency - the tendency of values to cluster about a particular value in the distribution 2 Mode - that value which occurs most frequently 3 Median - midpoint of an array of scores. If there is an odd number of observations, n, the median is xn +1 where Xn + 2 n+ 1 2 distribution. represents the value in the frequency If there is an even 4 X = —l where there are n number of values. B Aids in calculation of the mean Application of the following two statements can reduce errors and amount of time spent in calculating the mean of a distribution. 1 Adding or subtracting a constant to or from each score in a distribution is equivalent to adding or subtracting the same constant to or from the mean of the distribution. Thus the following formula: X = X± C c where the Xj's are the values in the distribution with mean X, and the Xj ± C's are the_values in the distribution with mean Xc. Multiplying or dividing each score in a distribution by a constant is equivalent to multiplying or dividing the mean of the distribution by the same constant. Thus the following formulas: (1) Xc = CX or (2) Xc = - where the X^s are the values in the distribution with mean X, 2-2 ------- Statistics for Chemists and the CXj's or the —±- "s are the v_alues in the distribution with mean X C Application Consider the application of the above definitions to the previously mentioned set of data, obtained from twelve deter- minations for chloride in water, shown in Table 1. 1 Mode = 100 100 + 100 2 2 2 = inn _ X6 + X7 2 Denote the mean of the distribution in Table 1 by X . If we add 100 to each score in the distribution in Table 2, we obtain the scores in the distribution in Table 1; likewise if we add 100 to the mean, X, of the distribution in Table 2, we obtain the mean, X , of the distri- bution in Table 1. Thus X = X + 100 c X = -= c n 100 - = l(-2) + 2(-l) + 4(0) + 3(1) + 2(2) + X 12 100 X = .25 + 100 = 100.25 c 3 Mean n _ 98 + 2 (99) + 4 (100) + 3 (101) + 2 (102) 12 = 100.25 4 Aid in Calculation Consulting Table 1 and observing that the values are in the neighborhood of 100 we might subtract 100 from each score and obtain the following distribution: Table 2 Frequency Table Chloride (fig/1) Frequency -2 1 -1 2 0 4 1 3 2 2 IV MEASURES OF DISPERSION A Definitions 1 Dispersion - spread or variability of observations in a distribution 2 Range - the difference between the highest value and the lowest value R = max - min 3 Average deviation - the sum of the deviations of the values from their mean, without regard to sign, divided by the total number of data values (n) The formula for calculating the average deviation is: 2-3 ------- Statistics for Chemists Average deviation of the mean (D) - the average deviation of individual data items from the mean (d) divided by the square root of the number of data items (n) The. definition of the average deviation of the mean can be expressed by the formula: d D = Variance - the sum of the squares of the deviations of the values from their mean divided by the total number of data values (n) minus 1 The definition of the variance can be expressed by the following formula: - X)2 n - 1 Standard deviation - the square root of the variance The definition of the standard deviation can be expressed by the following formula: - X)2 However, the formula commonly used because of its adaptability to the hand calculator is the following: a - n - 1 where there are n number of values. The dei'iuil.iim ui' the .stundur deviation of the mean can be expressed by the- formula: S = s n 8 Relative standard deviation - the standard deviation (s) expressed as a fraction of the mean, s X The relative standard deviation is often expressed as a percent. It is then referred to as the coefficient of variation (V): V = ;— X 100 = % X The relative standard deviation is particularly helpful when comparing the precision of a number of deter- minations on a given substance at different levels of concentration. B Aids in Calculation Application of the following statements can reduce errors and amount of time spent in calculating the variance or standard deviation of a distribution. 1 Adding or subtracting a constant to or from each score in a distribution doesn't affect the variance or standard deviation of the distribution. Thus the following formulas: (D 2 2 s = s c Standard deviation of the mean (S) - the standard deviation of individual data items (s) divided by the square root of the number of data items (n) (2) s = s c where the X^'s are the values in the distribution with variance s and standard deviation s, and the X.- + C's are the values in the A — o distribution with variance s and standard deviation s . 2-4 ------- Statistics for Chemists 2 Multiplying or dividing each score in a distribution by a constant is tMjuivnlent to multiplying or dividing the variance of that distribution by the square of the same constant. Thus the following formulas: 9 99 (1) B* * C S C _ 2 s2 (2) s 2 - £» c £•* 2 n 1 2 4 3 2 -* 98 99 100 101 102 X = 100. deviation - d IXi- X| 2.25 1.25 . 25 . 75 1.75 25 nlX 2 2 1 2 3 11 |