In the Classroom
Learning Quality Assurance/Quality Control Using U.S. EPA Techniques An Undergraduate Course for Environmental Chemistry Majors Susan M. Libes Department of Chemistry, Coastal Carolina University, Conway, SC 29526;
[email protected] Effective in 1994, environmental chemistry was added to the list of undergraduate chemistry degree options available for program approval by the American Chemical Society. The curricular requirements specify “at least two semesters [i.e., courses] of advanced work in chemistry of the environment, including some aspects of aquatic, atmospheric, and geochemistry” (1). Interest in teaching environmental chemistry has led to the recent publication of several textbooks covering theory and observational results (2–7). In comparison, only two texts and one lab manual are available for teaching undergraduates some of the elements of how to make reliable and defensible environmental measurements (8–10). Comprehensive treatments of this topic are available only in texts designed for postgraduate workshops (11, 12). This deficiency is problematic, as high-quality environmental measurements are critical to the success of modeling efforts and risk assessment. Because both are increasingly used in formulating policy, the U.S. EPA has promulgated a data validation system that relies on standardized plans and activities referred to collectively as QA/QC (quality assurance and quality control). (NOTE: the abbreviations and acronyms used in the paper are defined in Box 1.) Instruction in quality control largely has been neglected throughout the chemistry curriculum despite its widespread use in industry, health care, and the environmental realm (13, 14). As a result, chemistry majors are not well prepared to either defend their laboratory results or conduct research or hence work in the “real” world. Thus the incorporation of QA/QC Box 1. Abbreviations and Acronyms ANOVA APHA PE CAA CFR CLP CERCLA CWA FIFRA GLP IDC LFB MCL MDL NELAP NEPA QA/QC RCRA SARA SDWA SOP SOW TSCA U.S. EPA
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analysis of variance American Public Health Association performance evaluation Clean Air Act Code of Federal Regulations Contract Laboratory Program Comprehensive Environmental Response, Compensation and Liability Act Clean Water Act Federal Insecticide, Fungicide and Rodenticide Act Good Laboratory Practices initial demonstration of capability laboratory fortified blanks maximum concentration level method detection limit National Environmental Laboratory Accreditation Program National Environmental Policy Act Quality Assurance/Quality Control Resource Conservation and Recovery Act Emergency Planning and Community Right-to-Know Act Safe Drinking Water Act standard operating procedure statement of work Toxic Substances Control Act United States Environmental Protection Agency
in the undergraduate curriculum is of general interest and has led to the development of some laboratory exercises for traditional analytical and quantitative analysis courses as well as a project-based capstone course (13–16 ). In the case of the relatively new environmental chemistry degree option, students would be well served if one of their two required advanced courses focused on QA/QC. Such a course is described below and is based largely upon the U.S. EPA guidelines. Interestingly, only two of the five ACS-approved environmental chemistry programs require a course in environmental analysis; such a course is optional in two others. Most of these courses focus on instrumental analysis and hence do not necessarily cover standard QA/QC procedures or sampling design. Most also focus on one matrix (viz., analysis of aqueous samples). Doing high-quality, defensible field and lab work requires more than knowledge of QA/QC methodology. Also needed is a commitment on the part of the sampler and analyst to be ever vigilant as well as honest. The structure of the course described below is designed to elicit this commitment by having students discover the importance of QA/QC through communally critiquing several weeks of analytical results produced by relatively undisciplined sample collection and analysis. In this way, students can be led to discover and reinvent the major objectives and techniques of QA/QC. What Is QA/QC and Why Should Students Learn to Use It? Quality Assurance is an integrated system of management activities that ensures data quality meets specified standards. Quality Control includes all the activities that generate quantitative measures of the success of an analytical procedure. In the environmental realm, this includes activities associated with sampling; sample preservation and storage; method validation; and analysis involving solids, liquids, and gases, as well as combinations of these phases. A course covering these topics, entitled Analytical and Field Methods in Environmental Chemistry, has been taught at Coastal Carolina University since 1994 in support of a new area of emphasis in environmental chemistry. Curricular development has been funded by the National Science Foundation’s Instrumentation and Laboratory Improvement Program and the Academic Research Infrastructure Program. This course is a companion to a relatively traditional course in environmental chemistry. Prerequisites include completion of the first-year chemistry courses. Statistics is recommended but not required. The objective of the course is to teach students the QA/QC techniques in most common use in the environmental field. Hence, the student acquires an immediately marketable job skill. Table 1 contains recent examples of advertisements for
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such jobs. In 1996 (latest data available), the United States had 1200 environmental analysis labs, which employed 14,000 analysts. This represents a $1.2 billion per year industry (18). Some jobs are entry level and recent graduates are often hired as temporary help before receiving permanent employment (19, 20). Some colleges and universities maintain certified environmental quality labs to meet regional needs and enhance teaching and research opportunities. These labs can provide hands-on experience for students pursuing degrees in environmental chemistry. There are also intrinsic benefits to learning QA/QC such as improvement of problem-solving skills (13–16 ). By focusing on data quality, students also have a unique opportunity to discover the limitations of analytical methods and sampling plans and to learn how to defend and critique the quality of their scientific data. Legislative Context: Why EPA-Approved Analytical Methods Exist and How to Find Them A course in QA/QC should begin with a short discussion of the legal mandates that motivate most environmental work. A short overview of environmental law in the United States is available at the Commission for Environmental Cooperation’s World Wide Web site (21). Also useful is the World Wide Web site maintained by the United States Environmental Protection Agency (U.S. EPA) (22). In the United States, the U.S. EPA administers most environmental regulations. This agency was
created by the National Environmental Policy Act of 1969, which gave the U.S. EPA wide executive powers to protect and enhance environmental quality. The formal mechanisms for this are laid out in 12 major acts (Table 2). Most of these require demonstration of compliance with federal or state environmental regulations. The U.S. EPA administers these laws through separate program offices (the Offices of Air, Water, Solid Wastes, etc.). These offices oversee all activities in their program areas that include promulgation of new environmental standards, enforcement and management, and research and development. The last has included development of sampling, analytical, and toxicological protocols. As a result, separate sets of methods have been created for most program areas. In addition, some states have adopted more stringent standards and hence maintain their own sets of protocols. The administrative details of the federal laws listed in Table 2 are published under Title 40 of the Code of Federal Regulations (40 CFR), which is entitled “Protection of Environment”. A searchable version of 40 CFR is located on the World Wide Web (23). These laws specify what analytes are to be monitored and how they are to be monitored, including sampling, QA/QC, and analytical directives. For example, 40 CFR Pt 136, Appendix A, contains analytical methods for measuring organic compounds in waste water, and Appendix B contains the protocol for determining method detection limits (MDLs). Some methods are published separately
Table 1. Job Advertisements for Environmental Chemistry Analysts Research Assistant I Chem. Eng. News (Jun 29, 1998, p 91) The Mississippi State Chemical Laboratory, a state regulatory laboratory located at Mississippi State University, is seeking applicants for a Research Assistant I with a BS in Chemistry, Biochemistry, or Physical/Biological Sciences with a strong analytical chemistry background for an entry level position. Experience in wet instrumental analysis, AA and high performance [sic] liquid chromatographic analysis of drug, vitamin additives and chemical contaminants in food is desirable.... Environmental Chemist Environmental Careers Bulletin (May 5, 1998, p 16) Assist with a variety of analytical and environmental chemistry-related tasks. Reqs: bachelor‘s degree in chemistry with coursework in chemical fate. 1–3 years experience in an analytical laboratory conducting metals analyses; familiarity with EPA analytical methods; experience conducting data validation; good writing, communication, and problem solving skills; proficiency in quantitative and statistical data analysis; and experience working on multiple assignments with many challenging deadlines.
Laboratory Analysts Applicant requires a minimum BS in chemistry or natural sciences and 3–5 years experience in the analysis of environmental samples. Requires comprehensive knowledge of environmental chemistry and EPA methodologies. Troubleshooting skills and/or supervisory experience highly desired. Laboratory Project Managers Applicant requires a minimum BS in chemistry or natural sciences with 3–5 years environmental laboratory experience. Extensive experience in client services, technical support and data management required. Successful applicants will be responsible for coordination and oversight of both short term and long term projects. Laboratory Managers/Directors Applicants are required to possess a minimum BS in chemistry, MS preferred, with 10+ years experience in laboratory management, CLP and/ or DOE/DOD contract experience highly desired. Successful applicants will be responsible for management of regional lab facilities and technological improvements for a nationwide laboratory network.
Environmental Careers Bulletin Online (Jul 1998) (17 ) Chemist Environmental Careers Bulletin (Sep 9, 1997, p 13)
Chemist Environmental Careers Bulletin (May 5, 1998, p 14)
…[seeking] an individual to conduct chemical analyses. Oversee various projects; and maintain communication with clients. Reqs: 2 years environmental laboratory experience; familiarity with EPA testing methods and calibration procedures; PC literacy; expertise using HPLC and GC for analyses; and a bachelor’s degree. Exposure to computer data acquisition systems a plus.
Oversee EPA emergency and rapid response projects and commercial projects; perform lab packing in accordance with EPA and DOT regulations; and perform hazmat testing of unknown to determine hazardous characteristics. Reqs: knowledge of TSDF packaging and profiling guidelines; bachelor’s degree in chemistry; 2 years experience in oil, petroleum, and hazardous substance clean-up; knowledge of EPA QA/QC data collection protocols, EPA standard methods of analysis of multimedia waste and environmental samples; ability to operate and calibrate field screening instrumentation, and experience in chemical characteristics, of oil, petroleum, and hazardous substances; an ability to determine, develop, and implement waste characterization, bulking, and treatment actions.
Environmental QA Officer Chem. Eng. News (Jun 29, 1998, p 86) Groundwater Analytical currently has an opening for a Quality Assurance Officer. This position requires a BS in Chemistry, a strong knowledge of EPA methods and analytical instruction, 5 or more years of environmental experience and excellent organization, communication and interpersonal skills. Require familiarity with state certification programs and other regulatory approval programs....
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by the U.S. EPA in manuals that can be purchased through National Technical Information Services (see Table 3 for titles and publication numbers) (24). The manuals can be accessed through the U.S. EPA’s World Wide Web site (25–26 ). They are also available from the U.S. EPA (27) and commercial sources on CD-ROM. The methods developed for a particular program area are tailored to data quality needs as well as the nature of the matrix (water, tissues, air, and solid wastes). Thus multiple U.S. EPA methods exist for many analytes. 40 CFR also lists acceptable alternative methods, such as those published by the American Public Health Association (APHA) for drinking water (28 ). Methods from related program areas, such as the Clean Water Act (CWA) and the Safe Drinking Water Act (SDWA), are very similar and hence the U.S. EPA is working to consolidate them. An equally confusing situation exists with regard to data validation procedures. A formal set of national guidelines is available only for the Comprehensive Environmental Response, Compensation & Liability Act (CERCLA) and the CWA. CERCLA work is performed through its National Contract Laboratory Program (CLP). None exist for the CAA, Resource Conservation & Recovery Act (RCRA), or SDWA. In these cases, data validation procedures are administered through less formal arrangements. For example, the U.S. EPA’s Office of Ground and Drinking Water relies on its laboratory certification program to define QA/QC protocols for the SDWA. This certification program dictates minimal QA/QC activities and performance criteria (29). Each state polices its own certification system in which requirements more stringent than those of the U.S. EPA can be enforced. As a result, certain states do not recognize the certification approved by other states. In an effort to enable environmental labs to work across state boundaries, the U.S. EPA is developing a national environmental laboratory accreditation program (NELAP), which emphasizes attainment of performance criteria rather than specific QA/QC practices (30). Getting Started Success in QA/QC relies on documentation. Hence standardized forms, labels, and logbooks are the stock in trade. Spreadsheets are an excellent way to generate forms that can be
printed out for field and lab use. Data can be entered into a spreadsheet for computational and graphing purposes, such as construction of control charts. Spreadsheets are particularly useful for repetitive calculations that involve statistical functions, as programs such as Microsoft’s Excel contain built-in routines for many common operations. Environmental labs are rapidly adopting computerized data entry, albeit as customized templates, over traditional lab notebooks. Rather than use these templates, students are best served by practicing their graphing and computational skills by constructing their own tables and graphs and performing their own statistical tests. Of greatest importance is acquiring the discipline to provide proper annotation on graphs, tables, and computations. Students are introduced to the use of spreadsheets for analytical work as part of their first lab assignment, in which they make field measurements of water quality using an in situ sensor. We use a Hydrolab data sonde that measures temperature (EPA 170), pH (EPA 310.1), dissolved oxygen (EPA 360.1), depth, and conductivity (EPA 120.1). In situ sensors are also available for turbidity, redox potential, chlorophyll, and some ions such as nitrate. The most timeefficient approach is to select readily accessible sites on campus, such as drainage ditches, storm-water retention ponds, reflecting pools, lakes, and streams. Students record their field measurements on a standardized form. Students then create a spreadsheet version of the data table and present their results as bar graphs. Simple statistical functions are used to analyze the data (e.g., mean, standard deviation, minimum and maximum values). In succeeding weeks, the complexity of the analytical work is increased. Students collect their own samples and analyze them with minimal coaching on quality control. Turbidity (EPA 180.1), true color (EPA 110), and alkalinity (EPA 150.1) require little in the way of QA/QC to obtain a useful result. Fluoride (EPA 345.2), as measured with an ionselective electrode, provides a first example of the need for a multipoint calibration. Total hardness is measured with a simple EDTA titration (EPA 130.1) using Erio-T as an indicator. Using murexide as the indicator, calcium concentrations (EPA 215.2) can be measured and used along with pH, temperature, and alkalinity to compute the saturation index (SI) for calcium carbonate (APHA 2330).
Table 2. Major Environmental Legislation Legislation
Enacted
Methodology
Matrix
Clean Air Act (CAA)
1970
40 CFR 60-61, SW-846, Air CLP-SOW,a TO-1 to 14
Air
National Environmental Policy Act (NEPA)
1970
NA
NA
Clean Water Act (CWA)
1972
SW-846 and EPA series
Water
Federal Insecticide, Fungicide & Rodenticide Act (FIFRA)
1972
EPA 800 series b
Air, soil, and water
Ocean Dumping Act
1972
NA
NA
Safe Drinking Water Act (SWDA)
1974
EPA 100–500, 900 series
Drinking water
Toxic Substances Control Act (TSCA)
1976
EPA 700–800 series
Toxic substances
Resource Conservation & Recovery Act (RCRA)
1976
SW-846
Hazardous wastes
Environmental Research & Development Demonstration Act
1976
NA
NA
Comprehensive Environmental Response, Compensation & Liability Act (CERCLA)
1980
CLP SOWs a
Hazardous wastes
Emergency Planning & Community Right-to-Know Act (SARA)
1986
NA
NA
Pollution Prevention Act
1990
NA
NA
a Contract
Laboratory Program Statements of Work. b A forerunner of QA/QC protocols was established in FIFRA as Good Laboratory Practices (GLP).
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Introducing Students to the Need for QA/QC Once students have accumulated and worked with the concentration data from several analytes, they are experienced enough to make an assessment of the validity of their results. Class discussion can be initiated with a very general question, “How good are your results?” This should lead to general confusion, as the term “good” needs a lot of defining. The teacher can use the following questions to ensure that the major issues are identified. How close were your results to the “real” values? How reproducible were your results? How well do you know the values you have submitted as results? What is the lowest level of analyte you can reliably detect? What is the highest level of analyte you can reliably detect? Did you actually measure the analyte?
Students are led to acknowledge they don’t know the answers to these questions because they don’t have the appropriate information. They can then be asked how to obtain the necessary information. For example, reproducibility can be assessed by performing replicate measurements. Students should then be asked how they would express the results of these repetitions (percent difference) and how they would organize the repetitions. In the case of the latter, they could take replicate samples in the field or replicate aliquots from the same sample bottle. During the course of this discussion, students should also be led to identify potential problems that can compromise
the quality of a measurement, such as matrix effects, analyst performance, machine dysfunction, sample contamination, and out-of-range analyte concentrations. They should then be prompted to propose activities to diagnose and cope with these problems, and hence “reinvent” most of the common techniques used in quality control. Students should also be led to discuss what it is that they have measured and hence to acknowledge that most analyte concentrations determined by environmental methods are operationally defined. Lastly, they should be led to conclude that the same performance criteria and degree of data validation are not necessary for all measurements. The teacher can then introduce the concept of data quality objectives as the minimal qualitative and quantitative specifications for uncertainty, which are best established by the end user of the data. Some time should also be spent talking about the importance of knowing the history of the samples you are analyzing. This discussion can be stimulated by asking the students to create a list of things that could alter the analyte concentration of a sample. This list should include lack of sample preservation, inappropriate storage, dirty sample containers, incorrect sampling techniques, incorrect sample identification, and outright doctoring of samples. Students should then be prompted to recommend procedures for preventing these mishaps and thereby “reinvent” the basic activities associated with maintaining Chain of Custody records. The students should also be able to deduce that these same concerns relate to any commercial labware, such as reagents, standards, reference materials and precleaned sample containers.
Table 3. U.S. EPA Method Series and Citations Series
Analysis Category
Citation a
1–28
Air Monitoring Methods
40 CFR 60, Appendix A b
101–115
Air Monitoring Methods
40 CFR 61, Appendix B b
100s
Physical Properties
200s
Metals
300s
Inorganic, Nonmetallics
400s
Organics
200–235
Metals
Methods for the Determination of Metals in Environmental Samples (EPA 600/4-91/010, 600/R-94/111)
500–552
Organics
Methods for the Determination of Organic Compounds in Drinking Water (EPA 600/4-88/039, 600/4-90/020, 600/R-92/129, 600/R-94/173, 821/R-93/010B)
600s
Organics
Methods for Organic Chemical Analysis of Municipal and Industrial Waste Water 40 CFR- Part 136, Appendix A (EPA 821/B-96/005)
700s
Chemical Fate, Environmental Effects & Health Effects
40 CFR – Parts 796–798
1600s
Organics
Methods for the Determination of Nonconventional Pesticides in Municipal and Industrial Wastewater (EPA 821/R-93/010A)
900s
Radionuclides
Prescribed Procedures for Measurement of Radioactivity in Drinking Water (EPA-600/4-80-032)
0000s
Air Sampling Methods
1000s
Determination of Hazardous Characteristics
3000s
Sample Preparation Methods
4000s
Field Screening Methods & Drafts
5000s
Volatile and Misc. Sample Preparation Methods
6000s
Multi-metal Instrumental Determinations
7000s
Single-metal Instrumental Determinations
8000s
Organics
9000s
Radionuclide & Misc
Methods for Chemical Analysis of Water and Wastes (EPA 600/4-79/020, 600/R-93-100)
Test Methods for Evaluating Solid Wastes Physical/Chemical Methods (SW-846)
aOnly
major sources are shown. New methods are published often as new analytes are added and old methods are updated. Consult ref 22 for a complete list. See refs 25 and 26 for online copies. bMethods available at http://www.epa.gov/ttn/amtic/, http://www.epa.gov/ttn/emc/, and http://www.epa.gov/superfund/programs/clp/index.htm.
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Finally, the students should be engaged in a discussion of data management and storage. For data to be defensible, a reviewer (or data auditor) should be able to reproduce a computation based on the lab’s data archives. This can be simulated in class by having students exchange spreadsheet printouts. Students should be asked to proofread for transcription errors in addition to computational errors. Thus they can be led to appreciate the value of having a second party check all records and computations, as is required in regulatory labs. The chances are that students will have already had problems with data storage, such as bad disks and viruses, and thus can be engaged in a discussion about problems associated with data storage.
With this background, students should read detailed treatments of these subjects (see Box 2). Unfortunately, no single text is sufficient, so excerpts must be assigned from a variety of sources (8–12, 29). Some of this information has been rewritten and incorporated into an in-house lab manual (31 ). Students should also be given an opportunity to examine samples of regulatory documentation, including labels, forms, and logbooks, as these play a major role in creating defensible data. The best way to do this is to take a field trip to a regulatory lab, where students can see how labs perform chainof-custody activities as well as analytical work. This is also an excellent opportunity for students to meet lab professionals who can serve as both role models and potential employers. Practicing QA/QC
Box 2. Lecture Outline I. Data Quality Objectives A. Legislative Mandates B. Types of Samples and Sampling Plans C. Statistical Techniques II. Data Validation A. Quality Assurance 1. Creating and Maintaining a Quality Assurance Plan 2. Chain of Custody Procedures a. Samples b. Reagents and standards c. Sample containers 3. QC Procedures during Analysis 4. Analytical Procedures (Standard Operating Procedures) 5. Equipment Maintenance 6. Assessment of Quality Control Activities 7. Improvement and Corrective Action Procedures 8. Data Handling and Reporting a. Representative calculations b. Raw data records c. Significant figures d. Reporting below the detection limit e. Verification, data security and back-up B. Quality Control Techniques 1. Sampling a. Sample collection: equipment, containers, blanks, duplicates, preservation b. Chain of custody: sample transfer, storage and disposal 2. Method Validation (Initial Demonstration of Method Capability) a. Detection limits: instrument, method, practical quantitation limit b. Upper range of method: dilutions c. Calibration: regression equations 3. General Lab Practices a. Reagent and standard preparation b. Cleaning of sample containers c. Equipment maintenance and stability 4. Sample Preparation 5. Sample Analysis a. Replicates b. Blanks c. Calibration and calibration checks d. Matrix Spikes: field, lab e. Data quality audits (1) External: performance evaluation samples, interlaboratory calibration (2) Internal: reference materials, check standards, Quality Control samples f. Special topics (1) Methods of known and standard additions (2) Surrogates 6. Control Charts
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With this preparation, students are now equipped to do the real thing but need to start with a relatively uncomplicated analysis so they can focus on QA/QC. Measuring orthophosphate colorimetrically (EPA 365.2) works well because only one reagent needs to be added to the sample. The intensity of the resulting color can be measured within 10 minutes after reagent addition. A colorimeter equipped with a fiber-optic probe eliminates the time-consuming step of working with cuvettes. To give students experience and practice with as many facets of QA/QC as possible, lab work should approach the measurement of phosphate in stages. During the first lab session, students clean their glassware and prepare reagents. In the second session, they make replicate measurements of a single field sample. Thus they can focus on understanding the calibration technique required for Beer’s law as well as on preparing working standards using the method of serial dilutions. They use their spreadsheet’s built-in functions to perform a linear regression on their data and obtain the equation of best fit, which they use to convert their sample’s absorbance to concentration units. Given a sufficient concentration range, the results of the standards can also be used to demonstrate the linear dynamic range of the method and how to extend it via sample dilution. After this exercise, students are familiar enough with the analysis to draft a Standard Operating Procedure (SOP) for this method. SOPs are a more detailed description of the method than that presented in the U.S. EPA manuals and are used to ensure that all analysts in a laboratory conduct analyses in a standard manner. In the third session, students perform an “Initial Demonstration of Capability” (IDC), which documents their ability to meet either the U.S. EPA or state’s performance criteria for a given analyte. An IDC is a requirement for new analysts in certified labs. It is also required when a lab initially applies for certification for a new analyte or switches instruments. The performance criteria for each analyte can be found in U.S. EPA documents as well as commercial publications (12, 29, 32). In the most general sense, the IDC documents an analyst’s ability to achieve adequate precision and accuracy over a specified concentration range, as well as sensitivity and specificity. To do this, an analyst must produce sufficiently low background readings with method blanks, sufficient accuracy with a performance audit sample, and sufficient precision with replicate samples and be able to reliably detect specified low levels of the analyte. The last is demonstrated by measuring the method detection limit (MDL) as per 40 CFR Pt 136,
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Appendix B, in which sets of lab-fortified blanks of successively lower concentration are analyzed to iteratively determine the lowest detectable level of the analyte. (Ideally, the MDL should be determined in the sample matrix, but this is often not practical.) The MDL is defined as the lowest concentration that can be measured and reported with 99% confidence that the analyte concentration is greater than zero. Because the phosphate analysis is rapid, students can easily go through the three or so requisite iterations during a single lab session. (This is an accommodation, since U.S. EPA recommends doing this over a 3-day period.) This exercise is especially nice, as it requires students to perform a statistical analysis after each iteration to devise a serial dilution protocol for preparing the next set of lab-fortified blanks. To expedite this, students need access to spreadsheets in the lab. We use portable personal computers for this purpose. Since the MDL protocol is complex, students need to first practice the computational process. This should be done the week before the lab work is scheduled. At this time, it is best to provide the students with a “translation” of the CFR document along with a representative data set for illustration and computational practice. In the fourth lab session, students analyze samples and perform the following quality control activities: a sample duplicate (reported as percent difference), duplicate matrix spikes (reported as mean percent recovery), several method blanks, and duplicates of a performance evaluation (PE) sample (reported as an average percent recovery). The students perform their sample duplicate analyses first so they can determine an appropriate spiking protocol for the matrix spikes. The PE samples can be purchased or prepared by spiking a large aliquot of sample prior to the lab session. Students should not be told the concentration of the PE sample before analysis. The results of the PE samples can also be used to conduct an interlaboratory calibration study in which each student represents a laboratory and the results are used to establish acceptable confidence limits for accuracy using the 95% confidence level. If a particular result is significantly different from that of the group, the analyst has failed his or her performance evaluation and hence is “not certified” for this method. The absorbance of the method blanks over the three lab sessions can be used to construct a control chart. Twenty measurements are needed to construct the control and warning limits on a control chart. To do this, students can either pool their results or use the U.S. EPA’s specified control limits (12, 29, 32). If the latter is done, a control chart can be posted in the lab and the data from the blanks can be plotted immediately, so students can determine whether their blanks are acceptable (i.e., within the warning limit). If not, they can immediately take corrective action, such as recleaning their glassware. Ideally, a control chart should also be maintained for the mean percent recoveries of laboratory-fortified blanks (LFBs). LFBs are deionized water spiked to a specified concentration and are prepared independently of the working standards used for calibration. Ideally, two kinds of LFBs should be analyzed, with one at the Maximum Concentration Level (MCL) (the minimum concentration that triggers regulatory action) and the other at an intermediate concentration. A reasonable approximation of the latter can be obtained by having the students plot the results of their midconcentration
standard in terms of percent recovery. Once again, the class can pool their data or use the U.S. EPA performance criteria to construct the warning and control limits. These QC techniques are practiced throughout the semester while students are learning to perform other analyses, such as the EPA 200 series for dissolved trace metals. This also provides an opportunity to learn other procedures, such as the method of standard additions. The EPA 200 series includes a method for the measurement of metals in sediments and thus provides an opportunity to work with solids and reference materials. Experience working with organic compounds is provided by measuring petroleum hydrocarbons (EPA 1664 using FTIR spectroscopy for detection rather than gravimetry) and chlorinated pesticides (by gas chromatography with detection by electron capture, EPA 508, 608, or by gas chromatography–mass spectrometry, EPA 525 or 625). These methods provide an opportunity to teach students how to use solid-phase extraction procedures. Reporting Results and Grading To encourage students to concentrate on their analytical and computational work, most weekly lab reports are composed of a lab/field data sheet and a copy of a spreadsheet file that includes their data, computations, and graphs. Spreadsheet grading can be used as an opportunity to introduce students to more functions and options in the program and thus needs to be done with a rapid turnaround time. The students can help each other gradually increase their spreadsheet skills by encouraging demonstration of favorite new shortcuts or discoveries during the first 15 minutes of each lecture, using a projector coupled with a personal computer. This also provides an opportunity for students to discuss functions or options that they could not get to work correctly. At the end of the semester, the class’s results are combined into a master spreadsheet and reviewed by conducting a workshop in which each student or pair is assigned an analyte or group of related analytes. Students are given a week to prepare a 10-minute presentation about the class’s results for the analyte(s). Since several years’ data are available, students can determine whether temporal trends are present using ANOVA. They are also required to discuss how their results compare to U.S. EPA water and sediment quality criteria. They are required to present their data with Microsoft’s Powerpoint software, into which they can import their Excel data tables and graphs. On the basis of the comments and discussion following their presentations, the students transcribe their presentation into a written report. The reports are compiled and archived for use in future years. This body of data is also used by students in a traditional environmental chemistry course in support of a lab project that focuses on the preparation of an Environmental Impact Statement (33). The lecture grade, which constitutes 75% of the course, is the average of several in-class exams and take-home problems. The remaining 25% represents the average of all the lab assignments, including the oral presentation and written report. Student Feedback and Other Insights For the most part, student feedback has been positive and graduates have found employment in environmental
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quality labs. The greatest difficulty students encounter is with the statistical computations and interpretation of their data. We have attempted to address this by working with the statistics instructors to include standard tests in the sophomorelevel statistics course required of our science majors. Indeed, one of the reasons why QA/QC is not a traditional part of the chemistry curriculum could lie in the relative rarity of a statistics course in most chemistry degree programs. The incorporation of statistical functions in spreadsheet programs should facilitate the integration of statistics in the chemistry curriculum. While commercial templates are available to convert environmental lab data into results (for example, automated construction of control charts), students will better understand the computation and graphs by doing this work themselves. Another important element in the success of this course is scheduling large blocks of time (5 hours) for lab work. This is achieved by running a lecture session back-to-back with the lab. For some students, this was a new experience and they had to get used to concentrating for an extended period of time. The results generated by this lab can be used for other purposes including student research projects. Our work was undertaken in partial fulfillment of an Army Corps of Engineer’s permit to alter a wetland on campus and thus the results are also used for external administrative review. Acknowledgments I am grateful for support provided by two National Science Foundation Instrumentation and Laboratory Improvement program grants #DUE-9750477 and #USE-8852385 and a National Science Foundation Academic Research Infrastructure Program: Facilities Modernization grant #STI-9602643 for curriculum development, purchase of analytical equipment, and renovation of the department’s environmental chemistry laboratory. Coastal Carolina University (CCU) provided match moneys for all of these. Technical assistance was provided by Kim Weaver, director of CCU’s Environmental Quality Laboratory, which is certified by the state of South Carolina for the analysis of drinking and wastewater. Feedback was also provided by the environmental chemistry students enrolled in Chemistry 402: Analytical and Field Methods in Environmental Chemistry in Fall 1995 and 1997. Literature Cited 1. Undergraduate Professional Education in Chemistry: Guidelines and Evaluation Procedures; American Chemical Society: Washington, DC, 1992. 2. Perspectives in Environmental Chemistry; D. L. Macalady, Ed.; Oxford University Press: New York, 1998. 3. Connell, D. W. Basic Concepts of Environmental Chemistry; CRC: New York, 1997. 4. Spiro, T. G.; Stigliani, W. M. Chemistry of the Environment; Prentice-Hall: Englewood Cliffs, NJ, 1996. 5. Baird, C. Environmental Chemistry, 2nd ed.; Freeman: New York, 1998. 6. Manahan, S. Fundamentals of Environmental Chemistry; CRC: New York, 1993.
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7. Bunce, N. Environmental Chemistry; 1991. Wuerz: Winnipeg, MB, Canada. 8. Csuros, M. Environmental Sampling and Analysis Lab Manual; CRC: New York, 1997. 9. Kebbekus, B. B.; Mitra, S. Environmental Chemical Analysis; Blackie Academic & Professional; New York, 1998. 10. Csuros, M. Environmental Sampling and Analysis for Technicians; CRC: New York, 1994. 11. Berger, W.; McCarty, H.; Smith, R-K. Environmental Laboratory Data Evaluation; Genium: New York, 1996. 12. Smith, R.-K. Handbook of Environmental Analysis, 3rd ed.; Genium: New York, 1997. 13. Laquer, F. C. J. Chem. Educ. 1990, 67, 900. 14. Bell, S. C.; Moore, J. J. Chem. Educ. 1998, 75, 874. 15. Perone, S. P.; Englert, P.; Pesek, J.; Stone, C. J. Chem. Educ. 1993, 70, 846. 16. Juhl, L.; Yearsley, K.; Silva, A. J. J. Chem. Educ. 1997, 74, 1431. 17. Environmental Careers Bulletin, Inc. Environmental Careers Bulletin Online; http://www.ecbonline.com (accessed Sep 1999). 18. Johnson, J. Chem. Eng. News 1997, 75(Dec 1), 15. 19. EnviroStaff. http://www.envirostaff.com/enviro.htm (accessed Sep 1999). 20. Environmental Contract Professionals. http://www. ecbonline.com/ ecptop.htm (accessed Sep 1999). 21. Commission for Environmental Cooperation. Summary of Environmental Law in North America; http://www.cec.org/infobases/law/ index.cfm?format=2&lan=english (accessed Sep 1999). 22. United States Environmental Protection Agency, Office of Ground Water and Drinking Water. Drinking Water Standards Program; http://www.epa.gov/safewater/standards.html (accessed Oct 1999). 23. National Archives and Records Administration. Code of Federal Regulations; http://www.access.gpo.gov/nara/cfr/cfr-table-search.html (accessed Sep 1999). 24. National Technical Information Service, U.S. Department of Commerce. Environmental Test Methods and Guidance Publications Available from NTIS; http://www.ntis.gov/yellowbk/1nty791.htm (accessed Oct 1999). 25. U.S. EPA. EPA Publication Titles Sorted by Pub Number; http:// www. epa.gov/clhtml/pubtitle.html (accessed Sep 1999). 26. U.S. EPA. SW-846 On-line Test Methods for Evaluating Solid Waste; Physical Chemical Methods; http://www.epa.gov/epaoswer/hazwaste/ test/main.htm (accessed Oct 1999). 27. U.S. EPA. Methods and Guidance for Analysis of Water; EPA 821C-99-004; U.S. Environmental Protection Agency: Washington, DC, 1999. 28. Standard Methods for the Examination of Water and Wastewater, 20th ed.; Greenberg, A. E., Ed.; American Public Health Association: Washington, DC, 1999. 29. Manual for the Certification of Laboratories Analyzing Drinking Water. Criteria and Procedures Quality Assurance, 4th ed.; EPA 815B-97-001; U.S. Environmental Protection Agency, Office of Water and Office of Ground Water and Drinking Water: Cincinnati, OH, 1997; available at http://www.epa.gov/ogwdw.index.html (accessed Oct 1999). 30. U.S. EPA, OAQPS. National Environmental Laboratory Accreditation Program Conference; http://www.epa.gov/ttn/nelac/ (accessed Sep 1999). 31. Libes, S. Analytical and Field Methods in Environmental Chemistry Lab Manual, 3rd ed.; Coastal Carolina University: Conway, SC, 1998. 32. Wagner, R. E.; Kotas, W.; Yogis, G. A. Guide to Environmental Analytical Methods, 4th ed.; Genium: New York, 1998. 33. Libes, S. J. Chem. Educ. 1999, 76, 1649–1656.
Journal of Chemical Education • Vol. 76 No. 12 December 1999 • JChemEd.chem.wisc.edu
