air, water and land pollution chapter 5: methodology and quality assurance/quality control of...

Air, Water and Land Pollution

Chapter 5:Methodology and Quality

Assurance/Quality Control of Environmental Analysis

Copyright © 2010 by DBS

Contents

• Overview of Standard Methodologies• Selection of Standard Methods• Field Quality Assurance/Quality Control (QA/QC)• Analytical Quality Assurance/Quality Control

Methodology and QA/QC of Environmental Analysis

Overview of Standard Methodologies

• Method – a body of procedures and techniques for performing an activity, systematically presented, in the order in which they are executed

• Regulatory methods – approved by EPA

• Consensus methods – published by professional organizations (e.g. ASTM, APHA, USGS, AOAC)

• Differences may be minor since EPA adopts consensus methods all the time

ASTM = American Society for Testing MaterialsAPHA = American Public Health AssociationUSGS = US Geological SurveyAOAC = Association of Official Analytical Chemists



• Standard US EPA methods:– Scope and application– Summary of method– Interferences– Safety– Apparatus and materials– Reagents– Calibration– Quality control– Sampling– Extraction– Instrumentation– Qualitative identification– Calculations– Method performance (MDLs)



U.S. EPA Methods for Air, Water, Wastewater, and Hazardous Waste

• Office of Air Quality Planning and Standards (OAQPS), Office of Water (OW), and the Office of Solid Waste (OSW)

• Index to EPA Test Method http://www.epa.gov/fem/methcollectns.htm

• National Environmental Methods Index http://www.nemi.gov

http://www.epa.gov/fem/methcollectns.htm

http://www.nemi.gov/



http://www.nemi.gov

http://www.nemi.gov/




Air Test Methods• EPA test methods under authority of the Clean Air Act

(http://www.epa.gov/ttn/)

– Ambient air - http://www.epa.gov/ttn/amtic/ (criteria, air toxics, and inorganics)– Stationary Sources - http://www.epa.gov/ttn/emc– Workplace air - http://www.cdc.gov/niosh/nmam/ and

http://www.osha.gov/dts/sltc/methods/toc.html

http://www.epa.gov/ttn/

http://www.epa.gov/ttn/amtic/

http://www.epa.gov/ttn/emc

http://www.cdc.gov/niosh/nmam/

http://www.osha.gov/dts/sltc/methods/toc.html




Water Test Methods• EPA test methods under the water program (The Federal Water Pollution Control Act)

and drinking water program (The Safe Drinking Water Act)

– Method 100 to 400 Series ‘Methods for Chemical Analysis of Water and Wastes, MCAWW)

– Method 500 Series ‘Methods for the Determination of Organic Compounds in Drinking Water’

– Method 600 Series ‘Test Methods for Organic Chemical Analysis of Municipal and Industrial Wastewater’

– Method 900 Series ‘Prescribed Procedures for Measurement of Radioactivity in Drinking Water’

– Method 1000 Series – a set of microbiology and toxicity procedures




Waste Test Methods• SW-846 – ‘Test Methods for Evaluating Solid Waste, Physical/Chemical Methods’• http://www.epa.gov/epaoswer/hazwaste/test/main.htm

http://www.epa.gov/epaoswer/hazwaste/test/main.htm



Other Applicable Methods: APHA/ASTM/OSHA/NIOSH/USGS/AOAC

APHA Methods• ‘Standard Methods for the Examination of Water and Wastewater’

– First published 1905 (before EPA existed)– ‘Mother’ of all methods




ASTM Methods• ‘Annual Book of ASTM Methods’• Updated yearly• 77 volumes, 12,000 standard methods• Use has decreased due to cost

http://www.astm.org/BOOKSTORE/BOS/section11.htm

http://www.astm.org/BOOKSTORE/BOS/section11.htm




OSHA/NIOSH Methods• Occupational Health and Safety Administration and national Institute for occupational

Safety and Health• Created in 1970 to protect workers’ safety and health• Methods for air sampling and analysis• ‘NIOSH Manual of Analytical Methods (NMAN)’ - http://www.cdc.gov/niosh/nmam/

http://www.cdc.gov/niosh/nmam/




USGS Methods• Large number of reports and methods• ‘Techniques of Water Resource Investigations (TWRI) - http://pubs.usgs.gov/twri

AOAC Methods• Association of Official Agricultural Chemists, changed its name to Association of

Official Analytical Chemists, then to Association of Analytical Communities• ‘Official Methods of Analysis of AOAC International’ - http://www.eoma.aoac.org/

http://pubs.usgs.gov/twri

http://www.eoma.aoac.org/




Soil Methods• American Society of Agronomy (ASA) and the Soil Science Society of America

(SSSA)• Used principally by soil scientists and engineers




Other Methods• Dept. of Energy (DOE)• National Oceanographic and Atmospheric Administration (NOAA)• Other countries environmental agencies• See Lee (2000) and Smith (1997) for cross-references


Selection of Standard Methods

• Summary:– EPA methods for compliance or regulatory monitoring– USGS methods for water resource related surveys– AOAC methods for food and agricultural products

• In some cases there is a choice since several methods exist e.g. table above shows several choices for water monitoring

• Within EPA methods several protocols are available

• Investigator should consider:– Objective– Ease of use– Availability of instruments– MDLs– Costs



Methods for Sample Preparation• Pretreatment is required first step prior to trace analysis (except for pristine natural waters)

e.g. EPA 3000 series: Digestion Methods for Metals (SW-846)– Method 3005A: Digestion of water for analysis by FLAA or ICP (dissolved metals)– Method 3010A: Digestion of water for analysis by FLAA or ICP (susp. soilds)– Method 3015: Microwave digestion for aqueous samples– Method 3020A: Digestion of water for analysis by GFAA– Method 3031: Digestion of soils for analysis by AA or ICP– Methods 3050B: Digestion of sediments, sludge, and soils



Methods for Sample Preparation

e.g. EPA 3500 series: Extraction of Liquid and Soil Samples for Nonvolatile/Semivolatile Compounds (SW-846)

• Classical liquid-liquid extraction uses 1 L sample and methylene chloride (CH2Cl2)

• For solids Soxhlet extraction is used



Methods for Sample Preparation

e.g. EPA 5000 series: Headspace or Purge-and-Trap for VOCs• Previous methods cannot be used since they use open containers

• P & T is carried out by purging the sample with inert gas (N2) and then trapping the volatile materials

• Trap is heated to desorb materials



Methods for Physical, Biological, and General Chemical Parameters• EPA 100 and 300 Series: Physical Properties, Inorganic and Nonmetallics, • EPA 200, 6000, and 7000 Series: Metals• EPA 400 Series: Aggregate Organic Analytes• APHA 8000-10000 Series: Biological Parameters and Testing

Methods for Volatile Organic Compounds• EPA 500, 600, and 8000 Series (esp. EPA624: VOCs via GCMS)• APHA 6000• USGS O-xxxx-xx

Methods for Semivolatile Organic Compounds (SVOCs)• EPA 500, 600, and 8000 Series, APHA 6000, USGS O-xxxx-xx• Can also be analyzed via either GC or HPLC



Methods for Other Pollutants and Compounds of Emerging Environmental Concerns• Contaminant Candidate List (CCL) – chemicals that may require regulation in the

future


Field Quality Assurance/Quality Control (QA/QC)

• Errors can be quantified and minimized through design and implementation of a quality program



• Errors can be quantified and minimized through design and implementation of a quality program

– Quality control (QC) and quality assurance (QA)– QC is a system of technical activities to control data quality (blanks and spikes)– QA is a management system that ensures QC is working as intended– QA may include viewing data, evaluating parameters, taking corrective actions,

planning for process and personnel involved– QC and QA together help to produce data of a known quality (e.g. precision,

accuracy) and enhance the credibility of results



• Formal QA/QC program is called Quality Assurance Project Plan (QAPP)• Should be prepared and approved before sample collection begins• Should include:

– Project description– Project organization and responsibility– QA objectives for measurement data (precision and accuracy)– Sampling procedures– Sampling custody– Calibration procedures– Analytical procedures– Data reduction/validation and reporting– Internal quality control checks– Performance and system audit– Specific routine procedures used to assess data precision/accuracy and completeness– Corrective actions– QA report and management



Types of Field QA/QC Samples

• Errors from:– Analyte carryover from sampling equipment– Incomplete decontamination of sample equipment between samples– Cross-contamination between samples– Absorption of volatile chemicals from air during transport and storage

• To test for the presence/absence of these errors the following QC samples are required:

– Equipment blank – detect contamination from sampling equipment– Field blanks – undergoes the full handling and shipping process of an actual

sample. Detects sample contamination during field operation and shipping– Trip blanks – used for VOC analysis only, prepared prior to field trip by filling

containers with clean water or sand – used to evaluate error associated with shipping and handling



Types of Field QA/QC Samples

• Several other QC samples may be required depending on specific data quality objectives (DQOs)

– Field replicate samples – field samples obtained from one sampling point, homogenized and divided into separate containers, treated as separate samples throughout the remaining processes – used to assess error associated with heterogeneity, methodology and analytical processes

– Background samples – used to assess contaminant concentrations, collected upstream of contaminated areas



Numbers of Field QA/QC Samples

• Equipment blanks – one per type of sampling device per day. At least one for every 20 samples per parameter group and per matrix.

• Field blanks – one per day• Trip blanks – one with each shipment. At least one for each VOC method.• Field replicates – at least one sample per matrix type during each sampling event, or

10 % of the samples, whichever is greater.• Background samples – at least one per matrix type


Analytical Quality Assurance/Quality Control

Quality Control Procedures for Sample Preparation

• Significant errors occur during sample preparation– Digestion for metals– Extraction for semivolatile and nonvolatile organics

• These include:– cross-contamination from glassware or chemicals, – contaminant loss owing to sorption or volatilization, – matrix effects, – incomplete digestion or extraction of the analyte (improper procedure)



Quality Control Procedures for Sample Preparation

• Two types of ‘spiking’ QC samples are used for the QA/QC purpose to assess sample preparation procedures:

– Spiked sample/matrix spike: a small sample of a known concentration of analyte stock solution is added to the sample before sample preparation. In general the spike should produce 10-100 x instrument detection limit. Results are evaluated based on % recovery

– Surrogate spikes: surrogates are organic compounds that are similar to analytes of interest but are not formally found in the environment. Used to trace organic determination methods such as GC/GCMS and HPLC



Quality Control Procedures During Analysis

• Types of Laboratory QA/QC Samples:

(a) blanks – used to assess contamination

(b) spikes – used to obtain percentage recovery (accuracy)

(c) replicates – used to determine analytical precision




Types of Laboratory QA/QC Samples:

1. Blanks - analyte free water. Used to detect introduction of contaminants. Preparation/method blanks - blanks used throughout the entire preparation and analysis

Instrument blanks - analyte free reagents inserted between high and low concentration samples

2. Reagent water spikes - analyte free water spiked with the analyte of interest. Used to monitor the effectiveness of the method





3. Performance evaluation samples – contain known identities and concentrations of target analytes

4. Matrix spikes and matrix spike duplicates (MS/MSDs) – field samples spiked in the lab using the same spiking chemicals as above. Predetermined quantities of stock solutions of certain analytes are added to a sample matrix prior to extraction/digestion and analysis

5. Laboratory duplicates – aliquots of the same sample prepared and analyzed at the same time

6. Reference materials – obtained from an independent source with known analytical levels – measure and validate the analytical system and operator performance





7. Calibration standards – used to obtain calibration curves, include a calibration blank and a series of several concentrations

8. QC check standards – standard solutions with known concentrations. Used to verify that the standards and calibrations are accurate, also to confirm the calibration curve




Number of QA/QC Samples:

• Batch – a group of samples that behave similarly and are processed as a unit• Group of up to 20 samples• EPA sets 1 per 20 (5%) frequency as default• For each batch, there should be a QC sample (blank, spike, duplicate etc.)• Total number of QC samples should be around 25 % of all samples



The hexane extract contains 10 mL/10 µL = 104 µL/10 µL = 1000x the portion of extract = DFPortion of extract contains 0.45 mg/L x 10 µL x 1 L / 106 µL = 4.5 x 10-6 mgTherefore, hexane extract of soil contains 4.5 x 10-6 mg x DF = = 4.5 x 10-3 mg

References

• Clement, R. and Yang, P.W. (2001) Environmental Analysis. Analytical Chemistry, Vol. 73, pp. 2761-2790.

• Lee, C.C. (2000) Sampling, Analysis, and Monitoring Methods, 2nd edition, Government Institute, Rockville, MD.

• Smith, R-K. (1997) Handbook of Environmental Analysis, 3rd edition, Genium Publishing Corporation, Amsterdam, NY.

• Richardson, S.D. (2001) Water Analysis. Analytical Chemistry, Vol. 73, pp. 2719-2734.• Richardson, S.D. (2002) Environmental mass spectrometry: Emerging contaminants and

current issues. Analytical Chemistry, Vol. 74, pp. 2719-2742.• Richardson, S.D. (2003) Water Analysis: Emerging contaminants and current issues.

Analytical Chemistry, Vol. 75, pp. 2831-2857.

Questions

• 2. Which of the following is used for the acid digestion of samples containing metals:(a) EPA 3000 series, (b) EPA 3510 series, (c) EPA 3540 series, (d) EPA 3560 series

14. From the online data base from National Environmental Method Index (NEMI). (a) Find a list of TOC in water methods by all agencies; (b) What is EPA method 425.1? Download a copy of method 425.1

16. What is the primary difference between quality assurance (QA) and quality control (QC)?

21. The table below has a list of QC parameters and the primary means of general QC procedure. Match the right column of each corresponding procedure to the left column. Explain.

Questions

21. The table below has a list of QC parameters and the primary means of general QC procedure. Match the right column of each corresponding procedure to the left column. Explain.

QC Parameter Place letter here QC Procedure

1. Accuracy a. Analysis of blanks

2. Precision b. Analysis of matrix spikes

3. Cross-contamination

c. Analysis of replicate samples

4. Extraction efficiency

d. Analysis of reference materials

Questions

22. A 100 micro-liter stock solution containing 1000 mg/L Pb was added to a 100-mL groundwater sample as the matrix spike and acid digested. The Pb concentration measured by ICP-MS was 0.095 mg/L after a tenfold dilution. Calculate the percentage recovery.

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