Fre~niu$' Journal of

Fresenius J Anal Chem (1995)352:152-t 56

@ Springer-Verlag 1995

Use of reference materials in coastal monitoring quality assurance A.Y. Cantillo, G.G. Lauenstein NOAA/NOS/ORCA21, 1305East West Hwy., 10614, Silver Spring, MD 20910,USA

Received:2 August 1994/Revised:26 September 1994~Accepted: 28 September 1994 Abstract. The NOAA National Status and Trends (NS&T) Program determines the current status of, and changes over time in the environmental health of U.S estuarine and coastal waters. Concentrations of organic and inorganic contaminants are determined in bivalves, bottom-dwelling fish and sediments. The quality of the analytical data generated by the NS&T Program is overseen by the performance-based Quality Assurance Project, which is designed to document sampling protocols, analytical procedures, and laboratory performance, and to reduce intralaboratory and interlaboratory variation. All NS&T cooperating laboratories are required to participate in yearly intercomparison exercises. The analysis of reference materials, such as the National Research Council of Canada's Certified Reference Materials (CRMs) and National Institute of Standards and Technology's (NIST) Standard Reference Materials (SRMs), and of control materials, is required. Because of the need for marine matrix reference materials and standards, NOAA contributed to the production of eight NIST SRMs and seven internal standard solutions. Analytical data from all control materials and all matrix reference materials are reported to the Program once.

United States, including Alaska. This effort has been primarily performed by NOAA's National Marine Fisheries Service. The MWP collects and analyzes bivalve mollusks and associated sediments from around the United States, including the Great Lakes, Alaska, Hawaii, and Puerto Rico. This effort is administered by NOAA, with collection and analyses being performed under contract. From 1986 through 1994, the Geochemical and Environmental Research Group, Texas A&M University, College Station, TX, collected and analyzed samples from the Gulf coast. During this time the Battelle Memorial Institute, Duxbury, MA, and Sequim, WA, collected and analyzed samples from the U.S. East and West Coasts, including sites in the Hawaiian Islands and Alaska. During 1986-t989 samples from along the California and Hawaiian coasts were collected and analyzed by Science Applications International Corporation, Inc. The analytes include 24 polycyclic aromatic hydrocarbons, 20 polychlorinated biphenyl congeners, DDT and its metabolites, 9 other chlorinated pesticides, organotins, 5 major elements, and 12 trace elements (Table 1).

Quality assurance project NOAA national status and trends program

In response to the need for information on effects of human activities on environmental quality in coastal and estuarine areas, and to the need to develop management strategies to deal with these conditions, the National Oceanic and Atmospheric Administration (NOAA) initiated in 1984 the National Status and Trends (NS&T) Program for Marine Environmental Quality. The purpose of this program is to determine the current status and detect changes in the environmental quality of our nation's estuarine and coastal waters. The NS&T Quality Assurance (QA) Project is one of the seven components of the Program and applies to the two monitoring projects: the National Benthic Surveillance Project (NBSP) and the Mussel Watch Project (MWP). The NBSP collects and analyzes benthic fish and sediments from sites around the coastal and estuarine Correspondence to: A.Y.Cantillo

The QA Project of the NS&T Program assures that despite differences in the analytical methodologies used, data are comparable between all participating laboratories. Details of the QA Project can be found in Cantillo and Lauenstein [1]. The QA Project is not limited to NS&T Program laboratories, but is made available to other laboratories quantifying estuarine and coastal contamination. The QA Project has been in existence since t985. Since 1990, the Environmental Protection Agency's (EPA's) Environmental Monitoring and Assessment Program-Estuaries (EMAP-E) has been a cosponsor and contributor to the QA Project. The NS&T Program does not prescribe specific analytical methods but encourages the use of state-of-the-art procedures. This allows the use of new or improved analytical methodology or instrumentation without compromising the quality of the data sets. It also encourages the contractor laboratories to use the most cost-effective methodology while generating data of documented quality. The methods used by the various laboratories contributing to the NS&T monitoring effort have been

153 Table 1. Organic contaminants, and major and trace elements determined as part of the NOAA National Status and Trends Program Polycyclic aromatic hydrocarbons Low molecular weight PAHs (2- and 3-ring structures) 1-Methylnaphthalene 1-Methylphenanthrene 2-Methylnaphthalene 2,6-Dimethylnaphthalene 1,6,7-Trimethylnaphthalene Acenaphthene Acenaphthylene Anthracene Biphenyl Fluorene Naphthalene Phenanthrene

High molecular weight PAHs (4-, 5-, and 6-rings) Benz[a]anthracene Benzo[a]pyrene Benzo[b]fluoranthene Benzo[e]pyrene Benzo[ghi]perylene Benzo[k]fluoranthene Chrysene Dibenz[a,h] anthracene Fluoranthene Indeno [1,2,3-cd]pyrene Perylene Pyrene

Chlorinated pesticides 2,4'-DDD 4,4'-DDD 2,4'-DDE 4,4'-DDE 2,4'-DDT 4,4'-DDT Aldrin cis-Chlordane

Dieldrin Heptachlor Heptachlor epoxide Hexachlorobenzene gamma-HCH Mirex trans-Nonachlor

Polyehlorinated biphenyl congeners (IUPAC numbering system) PCB 8, PCB 18, PCB 28, PCB 44, PCB 52, PCB 66, PCB 77(110), PCB 101, PCB 105, PCB 118, PCB 126, PCB 128, PCB 138, PCB 153, PCB 170, PCB 180, PCB 187, PCB 195, PCB 206, PCB 209

Major and trace elements A1, Si, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Sn, Sb, Ag, Cd, Hg, T1, Pb Organotin species Monobutyltin trichloride, dibutyltin dichloride, tributyltin chloride, tetrabutyltin

documented by Lauenstein and Cantillo [2]. All NS&T laboratories are required to participate in a continuing series of intercomparison exercises utilizing a variety of solutions and natural matrix materials. The organic analytical intercomparison exercises are coordinated by the National Institute of Standards and Technology (NIST), and the inorganic exercises by National Research Council (NRC) of Canada. The analysis of reference materials, such as the NRC Certified Reference Materials (CRMs) and NIST Standard Reference Materials (SRMs), and of control materials generated for use by NS&T labs as part of the sample stream, is required. A minimum of 8 % of the organic analytical sample string consists of blanks, reference or control materials, duplicates, and spike matrix samples. The use of control materials does not entirely replace the use of duplicates and spiked matrix samples. A minimum of 2% of the standard inorganic sample string consists of calibration materials and reference or control materials. Analytical data from all control materials and all matrix reference materials are reported to the NS&T Program office. These data are stored at the NS&T Program office. In NS&T trace organic analytical procedures, internal standards are added at the start of the analytical procedure, specifically at the sample homogenization step, and are carried through the extraction, clean-up and instrumental analysis. The internal standards when taken through the extraction and clean-up steps and then used for quantification account for analyte losses. Acceptable recovery rates must be higher than 50%. Analysts are

responsible for monitoring recovery rates and determining acceptability based on variation of these rates. The results of calibration checks performed at the beginning and end of each typical sample string are required to be within _+ 10% of the accuracy-based value for standards in order to consider the instrument used to be within calibration. The results of spike blank analysis are required to be within + 20% of the correct value in order for the method to be considered in a state of control. All samples must be quantified within the calibration range. Quantification based on extrapolation is not acceptable. Method Detection Limits (MDLs) are calculated and reported annually on a matrix and analyte basis. Since 1989, the method used for calculating MDLs is that used by EPA and is described in detail in the 7/1/88 edition of the Federal Register (Definition and Procedure for the Determination of the Methods Detection Limits - Revision 1.11). If the EPA method is not used or is modified, the procedure used for MDL calculation is described in detail. Separate MDLs are calculated for mussels and oysters. Acceptable limits of precision for organic control materials are _+ 30% on average for all analytes, and +_ 35% for individual analytes. These limits apply to those materials where the concentrations of the compounds of interest are at least 10 times greater than the MDLs. The application of these guidelines in determining the acceptability of the results of the analysis of a sample is a matter of professional judgement on the part of the analyst, especially in cases where the analyte level(s) are near the limit of detection.

154

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To identify suitable reference materials for use by the NS&T Program and following the recommendation of the Intergovernmental Oceanographic Commission/ United Nations Environment Programme/International Atomic Energy Agency (IAEA) Group of Experts of Standards and Reference Materials (GESREM), NOAA compiled in 1986, and currently maintains a compilation of standard and reference materials for use in marine science [3, 4]. In response to the needs of the NS&T Program, NOAA contributed funds to the production of eight NIST Standard Reference Materials (SRMs) and seven internal standard solutions (Table 2). Two SRMs are based on natural matrices and the calibration solutions are for the three chemical classes of analytes quantified by the NS&T Program, at two concentration levels. The latter are used to facilitate the preparation of multipoint calibration curves. The internal standard solutions were prepared at the request of the NS &T contract laboratories and are currently available for purchase from NIST. These SRMs, CRMs, and control materials have been and continue to be used by NS&T contract laboratories to maintain analytical control.

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Intercomparison exercises Control charts The results of the routine analysis of RMs, other control materials, and blanks are reported annually to the NS&T Program office and are used to prepare control charts. Representative 1991 control charts for the analysis of tissue show good accuracy and precision for phenanthrene and pyrene, and the PCBs 66, 105, and 187 (Figs. 1 and 2). Some of the congeners quantified as part of the NS&T Program coelute when using commonly available gas chromatography columns for analyte separation. A discussion of this topic can be found in Lauenstein and Cantillo [2] and Schantz et al. [5]. Similarly results for Ag, A1, As and Cd show good analytical control for Ag, As and Cd but problems with precision and accuracy for A1 (Fig. 3). These results are for two laboratories that have analyzing Mussel Watch Project samples since its inception in 1986.

All the NS&T laboratories are required to participate in the yearly intercomparison exercises for tissue and sediment analyses. Results of the exercises prior to 1991 are described in Cantillo and Parris [6] and Valette-Silver [7], and those of 1991 through 1993 in Cantillo [8]. The exercise materials used for the intercomparison exercises include samples with unknown contaminant concentrations, and SRMs and/or CRMs. Typical results are discussed below. Two sediment and two tissue materials were used for the 1993 intercomparison exercise for trace metals. NRC BCSS-1 and SRM 1566a were the known materials; NRC prepared Sediment T, a freeze-dried Mississippi delta sediment, and Tissue S, a freeze-dried mussel tissue homogenate collected by IAEA in the Mediterranean off the coast of France, were the unknowns. Results of analyses of SRMs and/or CRMs are not compiled and evaluated as part of the trace organic

Table 2. NIST SRMs and internal standard

solutions partially funded by the NS&T Program

SRM SRM SRM SRM SRM SRM SRM SRM

1491 1492 1493 1941 1974 2260 2261 2262

AH PES TCMX HMB COP Spike COP I-STD COP GC Cal.

Aromatic hydrocarbons in hexane/toluene Chlorinated pesticides in hexane Chlorinated biphenyl congeners in 2,2,4-trimethylpentane Organics in marine sediment Organics in mussel tissue (Mytilus edulis) Aromatic hydrocarbons in toluene (nominal concentration 60 Ixg/mL) Chlorinated pesticides in hexane (nominal concentration 2 lxg/mL) Chlorinated biphenyl congeners in 2,2,4-trimethylpentane (nominal concentration 2 #g/mL) Naphthalene-ds, acenaphthene-d, o, benzol-a]pyrene-dz 2, perylene-da 2 1,2,3-Trichlorobenzene, 4,4'-dibr omooctafluor obiphenyl 2,4,5,6-Tetrachloro-m-xylene Hexamethylbenzene Coprostan-3[3-ol 5a-Androstan-3[3-ol Hexamethylbenzene, coprostan-313-ol, 5c~-androstan-3[3-ol

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intercomparison exercises. Rather, unknown materials are prepared by NIST for each exercise. SRMs and CRMs are analyzed as part of the analytical sample string in which the unknown materials are analyzed. These results are part of the control chart information described above. Some of the materials used for trace organic exercises, however, are cuts of the material used to prepare NIST SRMs or are candidate SRMs in the certification process and so are, in effect, unknowns. As part of the 1993 trace organic exercise, a fish homogenate of carp collected in Saginaw Bay was prepared by NRC and provided to NIST. This material was analyzed for the NS&T analytes except for the polycyclic aromatic hydrocarbons since these compounds are found in very low concentrations in fish tissue. Most of the PCB results fall within the range defined as +_ 35% of the consensus value plus or minus one standard deviation.

Performance improvement It has been shown that the performance of laboratories improves with time as the result of experience gained through participation in intercomparison exercises [8-11-1. This improvement can only be demonstrated through the continued analysis of a material such as a CRM, SRM or a control material with known analyte concentrations. The NOAA intercomparison exercises for trace metals for 1991 through 1993 used BCSS-1 as part of

Fig. 3. 1991 results of analysis of SRM 1566a, Oyster Tissue, as control material for Ag, A1, As and Cd by one of the NS&T cooperating laboratories. Notation to the right indicates the certified value, the 95 % uncertainty range, and _~ 35% of the uncertainty range. MDL is the method detection limit (gg/g dry wt.)

the exercise materials. Typical results reported by a laboratory joining the exercise program in 1991 are shown in Fig. 4. The accuracy of the Cr, Zn and Se determinations improved with time, as did the precision of the Se analysis. No CRMs or SRMs are analyzed specifically as part of the trace organic intercomparison exercises, so an evaluation similar to the one done for the trace metal exercises using changes in CRM and SRM results with time is not possible. A measure of improvement of laboratory performance can be made, however, by comparing the performance of a laboratory joining the exercises for the first time and that of a laboratory that has participated for several years. Laboratories newly joining the exercises usually have larger percent errors than the veteran laboratories [1]. Within a year or two, however, the performance of the new laboratories improves and equals those of the veteran laboratories.

Conclusion Quality assurance is an essential part of environmental monitoring programs, especially those that are not

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References 1. Cantillo AY, Lauenstein GG (1993) Performance based quality assurance of the NOAA National Status and Trends Program. In: Parkany M, (ed) Quality Assurance for Analytical Laboratories. Royal Society of Chemistry, Cambridge, UK, pp 34-43

2. Lauenstein GG, Cantillo AY (eds) (1993) Sampling and analytical methods of the NOAA National Status and Trends Program, National Benthic Surveillance and Mussel Watch Projects 1984-1992: Vol. I-IV. Tech memo NOS ORCA 71. NOAA/NOS/ORCA, Silver Spring, MD 3. Cantillo AY, Calder J (1990) Fresenium J Anal Chem 338 : 380-382 4. Cantillo AY (1993) Standard and reference materials for marine science. IOC Manuals and Guides 25, UNESCO, Nairobi, Kenya, 577 pp 5. Schantz MM, Parris RM, Kurz J, Ballschmiter K, Wise SA (1993) Fresenius J Anal Chem 346:766 778 6. Cantillo AY, Parris RM (1993) Quality Assurance Project trace organic intercomparison exercise results 1986 1990. NOAA Tech. memo. NOS ORCA 69, NOAA/NOS/ORCA, Silver Spring, MD 7. Valette-Silver N (1992) Elemental analyses in marine sediment and biological tissues. NOAA Tech. Memo. NOS ORCA 66, Rockville, MD, 39 pp, plus appendices 8. Cantillo AY (in preparation) Quality Assurance Project intercomparison exercise results 1991-1993. NOAA Tech Memo, NOAA/NOS/ORCA, Silver Spring, MD 9. Willie S, Berman S (1991) Fifth round intercomparison for trace metals in marine sediments and biological tissues NOAA/5. Non-published report prepared for NOAA/NOS/ ORCA Ocean Assessments Division, Silver Spring, MD, 40 pp, plus appendices 10. Willie S, Berman S (1992) Sixth round intercomparison for trace metals in marine sediments and biological tissues NOAA/6. Non-published report prepared for NOAA/NOS/ ORCA Ocean Assessments Division, Silver Spring, MD, 44 pp, plus appendices 11. Willie S, Berman S (1993) NOAA 7 Seventh round intercomparison for trace metals in marine sediments and biological tissues. Non-published report prepared for NOAA/ NOS/ORCA Ocean Assessments Division, Silver Spring, MD, 51 pp, plus appendices