The minimum quantity specified is the minimum amount of sample material necessary to perform the analysis. This quantity allows for no margin of error. For some analyses, Groundwater Analytical recommends specific types and numbers of containers (e.g., an Aqueous Volatile Organic sample requires 3 x 40mL Glass Vials w/teflon septum caps). In such cases, the recommended container(s) allow for an adequate margin of error. For other analyses, Groundwater Analytical only recommends a general type of container (e.g., a Solid Semivolatile Organic sample requires a Glass Jar w/teflon liner). In such cases, it is strongly recommended that twice the minimum quantity of sample material be collected in the recommended type of container. For solid samples, in addition to the minimum quantities required for individual analyses, each sample also requires 20g of sample material for a percent solids (or percent moisture) determination. Example: A soil sample collected for TPH-IR (30g), 8 RCRA Metals (2.6g) and PCBs (30g) requires a minimum of 62.6g of material for the desired analyses, and 20g of material for percent solids (or percent moisture), for a total required minimum of 82.6g of material. It is then recommended that this minimum be doubled, and at least 165.2g of sample material be collected in a Glass Jar w/teflon liner. For solid samples, all minimum quantities are calculated net of all foreign objects, such as sticks, leaves and rocks.
Only sample containers pre-cleaned according to US EPA protocols are recommended. Appropriate pre-cleaned and pre-preserved containers are available from Groundwater Analytical. Pre-cleaned sample containers should not be pre-rinsed with sample prior to sample collection. Pre-rinsing may cause elevated results.
Samples should be immediately cooled, stored and shipped refrigerated. 4°C (34°F) is the recommended temperature for most analyses. Refrigeration retards biological degradation, reduces the volatility of compounds, retards the hydrolysis of non-aqueous compounds, reduces absorption effects and prevents continuing chemical reactions.
Adjust to pH <2 with Hydrochloric Acid (HCl). Acidification retards biological action, reduces absorption effects and prevents the formation of precipitates and/or complexes. Sulfuric Acid (H2SO4) or Sodium Bisulfate (NaHSO4) may be substituted for HCl in EPA Methods 8021B, 8011, and 8260B.
Adjust to a pH range of 4.0 to 5.0 with Hydrochloric Acid (HCl), Sulfuric Acid (H2SO4) or Sodium Hydroxide (NaOH).
If sample will not be received by laboratory within 24 hours of collection, then adjust to specified pH range with Sulfuric Acid (H2SO4) or Sodium Hydroxide (NaOH). The pH adjustment may be omitted if it is performed upon receipt at the laboratory within 24 hours, and may be omitted if the sample is extracted within 48 hours of collection.
If free chlorine is present in the sample, then Sodium Thiosulfate (Na2S2O3) should be added. Free chlorine can react with organic compounds to form chlorination by-products. Free chlorine is likely to be found in chlorinated municipal drinking waters and treated wastewaters. Sodium Thiosulfate, a reducing agent, is added to remove the free chlorine. For most levels of free chlorine, add 4 drops of 10% Sodium Thiosulfate to samples in 40mL vials, and add 5mL of 10% Sodium Thiosulfate to samples in 1L bottles.
The listed Holding Time is the maximum time a sample may be held between collection and initiation of analysis or extraction.
Samples must be extracted within 7 days of collection. Extracts must then be analyzed within 40 days of extraction.
Samples must be extracted within 14 days of collection. Extracts must then be analyzed within 40 days of extraction.
Samples for
dissolved metals must be filtered prior to preservation with Nitric Acid (HNO3). Filtration must be done with a 0.45 micron membrane filter. Field filtration and preservation is preferred. However, if field filtration is not possible, samples should be cooled at 4°C and shipped to the laboratory for filtration and preservation. Filtration must be done as soon as practical after collection. Groundwater Analytical recommends that filtration be done within 24 hours of collection. If samples are not going to be field filtered, do not preserve samples with Nitric Acid (HNO3).
Aqueous samples samples for Volatile Organic Analyses (VOA) must be collected without any headspace or air bubbles. Volatile organics dissolved in water tend to volatilize readily and will fill any air bubble available in the vial. Particularly with low level samples, this results in a loss of material upon opening the vial. VOA vials must be filled slowly until the liquid forms a meniscus on the rim of the vial. The cap should then be gently placed on the vial, taking care not to disturb the crown of liquid, and firmly rotated tight. The vial should then be examined to verify the absence of all air bubbles.
Adjust to pH <2 with Sulfuric Acid (H2SO4). Alternatively, Hydrochloric Acid (HCl) may be used.
Maximum holding time is 24 hours when Sulfide is present. Samples may be tested with lead acetate paper before the pH adjustment in order to determine if Sulfide is present. If Sulfide is present, it can be removed by the addition of Cadmium Nitrate powder until a negative spot test is obtained. The sample is then filtered, and NaOH is added to adjust the pH >12.
Adjust to pH <2 with Nitric Acid (HNO3) or Sulfuric Acid (H2SO4). Acidification retards biological action, reduces absorption effects and prevents the formation of precipitates and/or complexes.
Samples should be collected with a minimum of aeration. The sample bottle should be filled completely, excluding all headspace, and capped.
Extractable organic samples are susceptible to Phthalate ester contamination. Phthalate ester contamination is generally caused by sample contact with a plastic material, particularly flexible plastics. Use care to avoid sample contact with any plastic, other than Teflon.
Specified quantities of sample material are for only single phase solid samples (i.e. no free liquids). Liquid phase or multiple phase samples require different quantities of sample material. Contact laboratory for advice prior to collecting liquid phase or multiple phase samples for TCLP analyses.
Samples for TCLP Volatile Organics analysis must be leached within 14 days of collection. The leachate must then be analyzed within 14 days of leaching. Samples for TCLP Metals analysis must be leached within 28 days of collection, if Mercury is being analyzed. The leachate must then be analyzed within 28 days of leaching. If Mercury is not being analyzed, then samples for TCLP Metals must be leached within 180 days of collection, and the leachate analyzed within 180 days of leaching. Samples for TCLP Semivolatile Organics, TCLP Pesticides, and TCLP Herbicides analyses must be leached within 14 days of collection. The leachate must then be extracted within 7 days of leaching. The extract must then be analyzed within 40 days of extraction.
Samples must be analyzed within 7 days of collection. However, if Heptachlor is not being determined, sample holding time to analysis may be extended to 14 days.
Samples must be extracted within 7 days of collection. Extracts must then be analyzed within 14 days of extraction.
Samples must be extracted within 14 days of collection. Extracts must then be analyzed within 30 days of extraction.
Samples must be extracted within
14 days of collection. Extracts must then be analyzed within 28 days of extraction.
Add 40-50mg of Sodium Sulfite to each liter of sample to reduce free chlorine that may be present. Free chlorine can react with organic compounds to form chlorination by-products. Free chlorine is likely to be found in chlorinated municipal drinking waters and treated wastewaters. Alternatively, use 40-50mg of Sodium Arsenite. Do not use Sodium Thiosulfate, as it may produce a residue of elemental sulfur which may interfere with the determination of some analytes.
Samples must be extracted within 7 days of collection. Extracts must then be analyzed within 30 days of extraction.
Add Sodium Thiosulfate to reduce free chlorine that may be present. Free chlorine can react with organic compounds to form chlorination by-products. Free chlorine is likely to be found in chlorinated municipal drinking waters. Use approximately 80mg of Sodium Thiosulfate per liter of sample.
Samples must be extracted within 7 days of collection. Extracts must then be analyzed within 21 days of extraction.
Samples must be extracted within 14 days of collection. Extracts must then be analyzed within 7 days of extraction.