203 Sample Collection for Metals Analysis 14.1 GENERAL CONSIDERATIONS IN SAMPLING The quality of any analytical system depends primarily on the sample analyzed. A sample must be representative of the environmental system from which it is taken so that chemical analysis results, in turn, represent the system. 14.1.1 FACTORS AND REQUIREMENTS OF SAMPLING PROGRAM TO BE CONSIDERED • Parameters of interest with method number and references • Duration of survey • Frequency of sampling • Number of samples • Sample matrices • Sample source • Site identification • Grab or composite samples (see Section 14.1.4) • Manual and automatic sampling (see Section 14.1.5) • Field measurements • Quality control (QC) requirements 14.1.2 PREPARATION FOR SAMPLE COLLECTION • Understand the sampling plan; all information should be written and discussed with field personnel. • Prepare, clean, and calibrate sampling equipment so that it is ready to use. • Check, calibrate, and prepare equipment for field tests. • Prepare sample containers. • Prepare preservative and dispose in a safe container. • Collect labels and markers, field notebook, pH paper, and small disposable cups to check pH of preserved samples. • Prepare all blanks. • Check all calibration standards and expiration dates for freshness. If necessary, prepare new ones. • Check QC samples for availability, and check dates for freshness. If necessary, prepare new ones. Determine whether sample should be spiked and discuss concentration of the spikes. Calculate the volume of the added spike stock solution for each spiked parameter. 14 © 2002 by CRC Press LLC 204 Environmental Sampling and Analysis for Metals • Collect pipets with suitable volumes and pipet bulbs. • Collect empty bottles for splits, duplicates, and so on. • Collect glassware for field tests and check cleanliness of glassware. • Make sure that thermometers are stored in protective carriers to avoid breakage. • Check spike stock solutions and check dates for freshness. If necessary, prepare new ones. • Collect soap for cleaning sampling equipment and for washing hands, paper towels, soft tissues, and bottles with DI (deionized) water. 14.1.3 PREFIELD PROCEDURES Several prefield procedures must be considered prior to the sampling activities: • Selection of proper sampling equipment (preferred materials for sampling and purging equip- ment for metals analysis include Teflon, polypropylene or polyethylene, and stainless steel) • Decontamination of sampling equipment • Selection of sample bottles • Preservative preparation • Preparation and calibration of field analytical instruments • Preparation of sample labels, chain-of-custody forms, field notebook, waterproof ink, and so on 14.1.4 TYPES OF SAMPLES 14.1.4.1 Grab or Individual Samples Samples collected at a particular time and place are called grab or individual samples. This type of sample represents conditions at the time it was collected. Therefore, a grab sample should not be used as a basis for decision making about pollution abatement. However, some sources are quite stable in composition, thus single-grab samples would be considered representative. 14.1.4.2 Composite Samples If results for an entire source system are to be reported, a series of small samples are collected in a sin- gle container and blended for analysis. The mixing process averages variations in sample composition and minimizes analytical effort and expense. These types of samples are called composite samples. When a time factor is being taken into consideration, grab samples are collected at suitable intervals according to expected changes. Composite samples reflect average characteristics during the sampling period, and in most cases a 24-h period is standard. Subsample volume should be constant and at least 200 ml. 14.1.5 MANUAL AND AUTOMATED SAMPLE COLLECTION 14.1.5.1 Manual Sample Collection When collecting samples for immediate field tests or when automatic samplers are not available, col- lect samples directly into a sample container. If a sample cannot be placed directly into the container, an intermediate vessel should be used. The intermediate container must be as clean as the sample container and must be made from the required material for parameter of interest. The sample is col- lected by lowering a properly cleaned device on a rope, pole, or chain into the sample medium. In some cases, using a power or hand-operated pump is necessary to withdraw the sample. When collecting samples for metals analysis, rinsing the sampling device three times is sufficient, except if the bottles are prepreserved. © 2002 by CRC Press LLC Sample Collection for Metals Analysis 205 14.1.5.2 Automated Sample Collection A wide variety of automatic samplers are commercially available. When sampling a large number of locations, automatic samplers are more practical, help reduce human error, and are able to keep the samples cool to 4°C during the time spent gathering samples. Automatic samplers, however, are ex- pensive. 14.1.6 GENERAL RULES IN SAMPLING • Samples must be collected from the least to the most contaminated sampling locations within the site. • Disposable latex gloves must be worn while sampling, and new, unused gloves must be used for each separate sampling point. • For compositing or mixing samples for metals analysis, use a stainless steel or Teflon bowl. • Keep in mind that the order of sample collection is as follows: 1. Volatile organic compounds (VOCs) 2. Extractable organics 3. Total metals 4. Dissolved metals 5. Microbiologicals 6. Inorganic nonmetals • For aqueous matrices, sampling equipment and containers are rinsed with the sample fluid before the actual sample is taken, with the exception of prepreserved containers. • A step-by-step, written sampling procedure should be available. The procedure should contain all sample collection activities. 14.1.7 PROPER MATERIAL FOR SAMPLING DEVICES Devices used for collecting samples for metals analysis should be made of plastic, stainless steel, or Teflon. 14.1.8 ERRORS INTRODUCED DURING SAMPLING Serious errors that may be introduced during sampling and storage are the contamination resulting from improperly cleaned sampling devices and sample containers and loss of metals by absorption or precipitation in sample containers because of failure to acidify the sample properly. 14.1.9 WASTE DISPOSAL IN THE FIELD Wastes generated during sampling are separated into specialized and properly labeled waste con- tainers. Laboratory- and field-generated wastes are disposed of by certified waste management com- panies. The certificate and contract of this company should be recorded. 14.2 AUTOMATIC SAMPLERS 14.2.1 P ROPER OPERATION OF AUTOMATIC SAMPLERS To ensure proper operation of automatic samplers and thus the collection of representative samples, correct maintenance and calibration must be followed: • A maintenance log containing all repair information should be available. • Prior to each field trip, check the sampler for correct operation (proper working order, bat- teries, desiccant, etc.). © 2002 by CRC Press LLC 206 Environmental Sampling and Analysis for Metals • Before sampling, check the constant pumping volume. • After returning from the field, check operation of sampler and repair if necessary. 14.2.2 PREPARATION OF SAMPLING EQUIPMENT Step-by-step cleaning procedures (called decon for decontamination) should be performed. These procedures derive from specific regulations and must be available in written form. Equipment should be cleaned before sampling and in the field between samples. At the end of the field trip, sampling equipment must be labeled as “rinsed, ready for house cleaning.” After being sufficiently cleaned in the laboratory, the equipment should be labeled as “in-house cleaned, ready for field,” accompanied by the date and the signature of the cleaner. Both house and field cleaning should be documented properly. Detergents specified for cleaning include Alconox (or equivalent) with 5% phosphate, or Liquinox (or equivalent), which is free of phosphates and ammonia. The purity and reliability of the analyte-free water used for rinsing and blank preparation are shown in results of tests performed on the blank. 14.2.2.1 In-House Cleaning of Sampling Equipment 1. Wash with hot, soapy tap water and scrub with a brush. 2. Rinse thoroughly with hot tap water. 3. Rinse with 10 to 15% nitric acid (HNO 3 ). Acid rinses should never be applied to stainless steel or metallic equipment. 4. Rinse thoroughly with deionized water. 5. Rinse thoroughly with pesticide-grade isopropanol. 6. Rinse thoroughly with analyte-free water. 7. Air dry completely. 8. Wrap in aluminum foil for storage and transportation. 14.2.2.2 Field Cleaning of Sampling Equipment Use the same procedure as in-house cleaning procedure, with the exception of hot water wash and rinse. Laboratory-pure water rinse is recommended, but optional. Rinsing with sample water is ac- ceptable when proper cleaning of the equipment is impossible. It should be disposed of until effec- tive cleaning is possible. 14.3 SAMPLE CONTAINERS 14.3.1 P REFERRED SAMPLE CONTAINERS • Preferred sample containers for metals analysis are polyethylene bottles with tight, screw- type lids. • Borosilicate glass containers also may be used, but avoid soft glass bottles for samples containing metals in the microgram-per-liter (ppb) range. • Store samples for silver analysis in light-absorbing containers. • Sample containers may be cleaned in-house or in the field or purchased from commercial vendors as precleaned containers. The cleaning grades must meet EPA analyte-specific re- quirements. All records for these containers (lot numbers, certification statements, date of receipt, etc.) and their uses must be documented. © 2002 by CRC Press LLC Sample Collection for Metals Analysis 207 14.3.2 PROPER CLEANING OF SAMPLE CONTAINERS 1. The soap should be metal-free Acationox or equivalent. 2. Wash bottles and caps in hot, soapy water and rinse liberally with tap water until soapsuds are gone. 3. Rinse bottles and caps with 1+1 HCl, followed by tap water rinse. 4. Rinse bottles and caps with 1+1 HNO 3 . 5. Rinse three times with liberal amounts of laboratory-pure water. 6. Drain and cap tightly until used. 14.4 SAMPLE PRESERVATION Sample preservation is necessary for all samples (40 CFR, Part 136). Sample preservation may be ac- complished by using ready, prepreserved bottles obtained from the laboratory, but additional preser- vatives must be available in the field if the measured pH of the preserved sample indicates that addi- tional preservative is necessary. If the sample is preserved in the field, the following protocols should be practiced: • Preservative should be prepared from reagent-grade chemical. • Fresh preservative should be used in each sampling trip. • Preservatives transported to the field should be stored in properly cleaned plastic or Teflon containers to avoid breakage. • Chemicals should be segregated from sample containers to avoid accidental contamination. • Preservatives should be added with a pipet or premeasured droppers. • After preservation, the pH of the preserved sample should be measured. Transfer a small quantity from the preserved and well-mixed sample into a disposable container, and de- termine the pH by using a narrow-range pH paper. If the pH value indicates the addition of more preservative, the preservative should be from the same source as used in the orig- inal treatment. The amount of the additional preservative should be documented, and the additional preservative should be added to the corresponding blank as well. • Acid preservation should be done in a well-ventilated area to avoid inhalation of acid fumes and toxic gases. Any unusual reaction should be noted! • In the case of any acid spill, wipe up immediately and flush the area with a great amount of water. 14.5 SPECIAL SAMPLING PROCEDURES Before collecting a sample, decide on the metal fraction to be analyzed: dissolved (filterable), sus- pended (nonfilterable), or total metals. This decision will determine whether the sample is acidified with or without filtration. 14.5.1 TOTAL METALS Total metals are defined as the concentration of metals in an unfiltered sample or the sum of the con- centrations of metals in both the dissolved and suspended fractions. Preserve the sample with 3 ml of 1+1 HNO 3 or 1.5 ml of concentrated HNO 3 per liter. Samples with high buffer capacity and high alkaline samples may require more acid, as indicated by pH measurement. Samples should be trans- ported to the laboratory without cooling. © 2002 by CRC Press LLC 208 Environmental Sampling and Analysis for Metals 14.5.2 DISSOLVED METALS Dissolved metals are defined as the concentration of metals determined in the sample after it is fil- tered through a 0.45- µm filter. Samples must be filtered through a 0.45-µm filter prior to preserva- tion. Filter paper should be acid washed and dried before use. After the sample is filtered, the filtrate will be the sample for dissolved metals and acidified in the same way as for total metals. 14.5.3 SUSPENDED METALS Suspended metals are defined as the concentration of metals determined in the portion of the sample that is retained in a 0.45- µm filter. Unpreserved samples are filtered through a 0.45-µm filter, as men- tioned above for the sample collection of dissolved metals, and the filter paper is retained for further analysis of the suspended or unfilterable metals. The filter paper containing the suspended matter is transferred to the laboratory for determination of suspended metals. Samples should be filtered in the field, or immediately after transport to the laboratory. In the latter case, preserve the filtrate. 14.5.4 SAMPLE COLLECTION OF HEXAVALENT CHROMIUM Materials containing hexavalent chromium (Cr 6+ ) are sampled separately from other metals. Do not add acid preservation to this sample; transport it to the laboratory for analysis as soon as possible. During transportation and storage, samples should be kept at 4°C. “No preservative added” should be clearly written on the sample label in the request for this type of sample. Holding time is 24 h for these samples. 14.6 HOLDING TIME Holding time for most preserved samples is 6 months. For mercury (Hg) determination, holding time of the preserved sample is 28 days. Samples collected without preservation for the determination of hexavalent chromium (Cr +6 ) can be held for only 24 h. A sample holding-time log is illustrated in Figure 14.1. 14.7 FIELD RECORDS Field records are taken for all data generated during sample collection. These records are kept in a chain-of-custody form (Figure 14.2), sample label (Figure 14.3), field notebook (Figure 14.4), sam- ple field log (Figure 14.5), preservative preparation log (Figure 14.6), and QC sample and spike preparation log (Figure 14.7). 14.7.1 CHAIN-OF-CUSTODY All sampling events should be documented and recorded on a chain-of-custody form. This practice ensures that the sample is collected, transferred, stored, analyzed, and destroyed only by authorized personnel. Each custodian or sampler must sign, record, and date the transfer. The form includes the name of the sampling project; collector’s signature; sampling location; sampling site; sampling point, date, and time; type of sample; number of containers; and analysis required. The chain-of-custody form is illustrated in Figure 14.2. © 2002 by CRC Press LLC Sample Collection for Metals Analysis 209 14.7.2 SAMPLE LABEL A sample label (Figure 14.3) should be affixed to all sample containers and serves as an important part of sample identification. The label should be waterproof, and all information should be written in waterproof ink. 14.7.3 FIELD NOTEBOOK The field notebook (Figure 14.4) is specially designed for fieldwork, with waterproof paper and a hard cover. All field records should be written in waterproof ink. Errors in documents should be deleted by a single-line cross-through, accompanied by the date and initial of the person making the correction. FIGURE 14.1 Sample holding-time log. Sample ID = sample identification number; prep = prepared; anal = analysis; dispo = disposal; rec = received; sign = signature of logger. Holding Time Explanation: prep = number of days between the date sample received and the date sample prepared anal = number of days between the date sample prepared and the date of actual analysis dispo = number of days between the date sample received and the date sample disposed Storage Designations: R. T. = room temperature in designated area Ref. O. = refrigerator, designated for organic samples Ref. I. = refrigerator, designated for inorganic samples Fr. = freezer, designated for special samples Sample ID Matrix Analysis Required prep anal dispo rec prep anal dispo Sample Prepared Sign Holding Time (days) Day of Preparation Storage © 2002 by CRC Press LLC 210 Environmental Sampling and Analysis for Metals Field ID:____________________________________________________ Site Name:________________________________________________________ ______ Date Sampled Received: ______________________________________ Address:___________________________________________________________ ___ Sampler(s): _________________________________________________ Laboratory:________________________________________________________ ______ Sample Container Description FIGURE 14.2 Chain-of-custody form. Relinquished By: ____________ Organization:________________________ Received By: ______________________ Organization: _______________ _________ Date:______________________ Time:________________________ Date: ______________________ Time: ________________________ Relinquished By: ____________ Organization:________________________ Received By: ______________________ Organization: _______________ _________ Date:______________________ Time:________________________ Date: ______________________ Time: ________________________ Delivery Method: ______________________________________________ (attach shipping bills, if any) Use extra sheets if necessary. RemarksTotal Date SampledSample Identity Total Number of Containers © 2002 by CRC Press LLC Sample Collection for Metals Analysis 211 FIGURE 14.3 Sample label. Field Sequence No.___________________________________________________________________________ Field Sample No.____________________Date _______________________Time ________________________ Sample Location _____________________________________________________________________________ Sample Source_______________________________________________________________________________ Preservative Used ____________________________________________________________________________ Analyses Required ___________________________________________________________________________ ___________________________________________________________________________________________ Collected by ________________________________________________________________________________ Remarks ____________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Final pH Checked ____________________________________________________________________________ Additional Preservative Used (If Applicable) _____________________________________________________ ___________________________________________________________________________________________ FIGURE 14.4 Field notebook. Date _____________________________ Time __________________________________________________ Sampler’s name ___________________ Signature __________________________________________________ Other field people ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Sample location ____________________________________________________________________________ ____________________________________________________________________________ Sample type grab __________ composite ______________________ Compositing time ________________________hr Time interval___________________________min Subsample volume _______________________ml Sq. No. = sample sequence number; FID = field identification number; Cond. = conductivity; DO = dissolved oxygen; Cl 2 = chlorine, residual; ppm = parts per million (mg/l). Field conditions: pH check: Additional preservative used: Other observations: Sq. No. FID Preserv. container Analysis required pH T(°C) Cond. (µmhos /cm) DO (ppm) Cl 2 Comment © 2002 by CRC Press LLC 212 Environmental Sampling and Analysis for Metals 14.7.4 SAMPLE FIELD LOG AND PRESERVATIVE PREPARATION LOG Other field records are the sample field log (Figure 14.5) and preservative preparation log (Figure 14.6). Immediately after sampling while still at the sampling point, the correct preservation and proper identification of samples (chain-of-custody and submittal forms, sample labels, etc.) should be checked. 14.7.5 INFORMATION AVAILABLE IN FIELD RECORDS The following information should be available in field records: • Name of sample collector and field personnel • Date and time of sampling • Field conditions (weather, important information about the sample site) • Description of sample location (address, exact sampling points) • Sample type (grab, composite). If composite sample, record the time intervals, duration of sampling, and volume of subsamples • Requested analytical parameters, type and number of containers, preservation technique • Preservative preparation FIGURE 14.5 Sample field log. Purpose of Analysis: _____________________Sample Field ID: __________________________________________ Type of Sample:___________ Sampler: ________________________ Date/Time:__________________________ Sample Site Number Sample Source Description Bottle Type Bottle No. Preservative Analysis Required Remarks: * Field Measurements © 2002 by CRC Press LLC [...]... preservation and treated as discussed in Section 14. 5.2 13 Quality control requirements are dependent on the project plan Field quality control checks are listed in Section 14. 8.2 14 Affix the sample labels, fill out the chain-of-custody form, and record all sampling data in the field notebook, as discussed in Section 14. 7.1 14. 9.2 DRINKING WATER SAMPLING 14. 9.2.1 Sampling Potable Well Water When sampling. .. Collection for Metals Analysis 221 The frequency and location of sampling, the number of samples, and the required parameters must be followed as stated in the discharge permit 14. 9.6 COLLECTING DOMESTIC SLUDGE All samples for sludge classification should be representative and taken after final sludge treatment but before disposal The preferred container for metals analysis is plastic, and the sample... of acid as in the sample 11 Samples for hexavalent chromium (Cr6+) do not need preservative Carefully select the sampling container Do not use prepreserved sampling bottle! Complete sample label and transfer to the laboratory as soon as possible © 2002 by CRC Press LLC 218 Environmental Sampling and Analysis for Metals 12 If the analysis request is for suspended and dissolved metal determination, the... Dippers are useful for sampling liquids and free-flowing slurries xxxxx Locking Slopper rod PVC Pipe PVC 152 cm (5' -0 ") SAMPLING POSITION CLOSE POSITION FIGURE 14. 11 Composite liquid waste sampler, colivasa, used in sampling free-flowing liquids and slurries from drums, shallow open tanks, pits, and so on Ensure that the sampler is clean Open and lower into the sample material and let the tube fill... Figure 14. 9 Collect and preserve samples as in Section 14. 9.3 14. 9.3.4 Sediment Samples Sediment samples are usually taken as a part of surface water samples Equipment used for sediment sampling varies according to sample location, water depth, sediment grain size, and water velocity The most common sampling equipment types are scoops, corers, Eckman sampler (for sand, silt, and mud sediments), and the... Environmental Sampling and Analysis for Metals FIGURE 14. 10 Eckman bottom-grab sampler These permits specify the types and amounts of pollutants that may be discharged and are intended to ensure that the effluent content remains within the limits of the relevant groundwater or surfacewater standard Sampling locations should be described in the permit or the project plan 14. 9.4.1 General Criteria for Collecting... preservation, and documentation should be the same as for the collected samples Selection of spiked and split samples may be dictated by the requirements of the site, a previsit evaluation, or on-site inspection © 2002 by CRC Press LLC 216 Environmental Sampling and Analysis for Metals 14. 8.2.7 Validation of Field Measurements Field measurements are validated through precision (based on duplicate samples) and. .. the neck is upright and pointing to the water flow Fill the bottle and return it to the surface 3 Pour out a small quantity of the sample to leave space for adding preservative and mixing 4 Preserve samples and follow activities as discussed in Section 14. 9 © 2002 by CRC Press LLC Sample Collection for Metals Analysis 219 5 Another grab sampling method is to use a pole-mounted flask and follow steps 1... Figure 14. 13 Corrosive Poison Flammable Cancer Warning Water Reactive Air Reactive Explosive FIGURE 14. 13 Safety labels © 2002 by CRC Press LLC Radioactive Cancer Warning Oxidizer 224 Environmental Sampling and Analysis for Metals 14. 9.8.1 Safety Concerns The person collecting hazardous waste samples must realize that these samples are hazardous materials and should be handled with extreme care! Therefore,... be present When sampling flammable materials with a high vapor pressure or low flashpoint, all equipment should be grounded and all sources of ignition should be prohibited As a general rule, avoid eating and smoking during sampling 14. 9.9 SAMPLING FISH TISSUES Fish tissues are usually analyzed for metals and organic pollutants Equipment used for sampling should be scrupulously cleaned and decontaminated . a chain-of-custody form (Figure 14. 2), sample label (Figure 14. 3), field notebook (Figure 14. 4), sam- ple field log (Figure 14. 5), preservative preparation log (Figure 14. 6), and QC sample and spike preparation. Environmental Sampling and Analysis for Metals 14. 5.2 DISSOLVED METALS Dissolved metals are defined as the concentration of metals determined in the sample after it is fil- tered through a 0.4 5- µm filter LLC 218 Environmental Sampling and Analysis for Metals 12. If the analysis request is for suspended and dissolved metal determination, the sample should be filtered prior to preservation and treated