Attachment 03 - NIH Anions.1714658465645.docx

Attachment 03: NIH Anions (Suppressed Ion Chromatography)

Summary This test method covers the sequential determination of fluoride, chloride, nitrite, ortho-phosphate, bromide, nitrate, and sulfate ions in water by suppressed ion chromatography.

Sample Collection NIH shall collect samples, and the Contractor shall pick up the samples from NIH Bethesda, Building 11. The Contractor shall provide NIH with sampling kits for collecting each sample.

The Contractor’s personnel assigned to pick up the samples shall be trained in sampling procedures, such as wearing gloves and eye protection when collecting samples. The Contractor shall adhere to the correct procedures for sample collection, sample preservation, sample handling, sample identification, and prompt transfer of the sample to the laboratory.

In the event that the Contractor also collects the sample, they shall follow the following procedure:

The Contractor shall rinse the bottle and cap three times with sample water and fill the bottle to within one to two inches from the top. Remove any attachment from the tap such as hoses, filters, screens, or aerators. Flush the water for 2-3 minutes or until the water temperature reaches a constant temperature. Samples shall be collected in plastic or glass bottles. All bottles must be thoroughly cleaned and rinsed with reagent water. Fill a prepared 1000 mL bottle as applicable from a free-flowing sample tap or other sources as applicable. The volume collected shall be sufficient to ensure a representative sample, allow for replicate analysis and laboratory fortified matrix analysis, if required, and minimize waste disposal.

If nitrite, nitrate and phosphate are analytes of interest, samples shall be analyzed within 48 hr. of collection. A longer holding time may be appropriate for chloride, sulfate and sulfide.

The laboratory shall inspect samples and accompanied paperwork (e.g., Chain of custody documents) and reject samples that are not collected in accordance with applicable procedures.

Sample Preservation and Storage The method of preservation and the holding time for samples analyzed by this method are determined by the anions of interest. In each sample, the anion that requires the most preservation treatment and the shortest holding time will determine the preservation treatment. It is recommended that all samples be cooled to 4°C and held for no longer than 28 days.

Sample preservation and holding times for the anions that can be determined by this method are as follows:

· Chloride: No preservation is required, holding time 28 days.

· Nitrate: Cool to 4 °C, holding time 2 days.

· Phosphate, Orthophosphate, Sulfate, and Sulfite: Cool to 4 °C, holding time 28 days.

· Nitrite: To a pH less than 2, temperature and holding time to be determined by the Contractor Comment by Hughes, Casey (NIH/OD/ORF) [E]: What about temperature and holding time? Comment by Adjei, George (NIH/OD/ORF) [E]: For temperature and holding time, it depends on the sample. Some sample will require immediate analysis, and some will require storage and preservation at certain temp. Lab will determine that.

Note: If the determined value for the combined nitrate/nitrite exceeds - 0.5 mg/L as N, a resample shall be analyzed for the individual concentrations of nitrate and nitrite.

Sample bottles: Glass or HDPE (High Density Polyethylene) plastic bottles of sufficient volume to allow replicate analyses of anions of interest.

Method of Shipping and Duration and Receiving The Contractor shall place the sample into a cooler with ice for immediate delivery or shipment to the laboratory. The sample shall be received with a chain of custody (COC). The COC shall have the name of the sample collector, date and time of sample collection, signature or initial of the sample collector, location of the sample and type of sample to be analyzed.

Lab Procedure for Analysis This test method covers the sequential determination of chloride, nitrite, phosphate, ortho-phosphate, nitrate, nitrite, sulfite and sulfate ions in water by suppressed ion chromatography. This test method update approves the use of electrolytically generated eluent, electrolytically regenerated eluent, electrolytic suppression (not autozeroing), and electrolytic trap columns also known as reagent-free ion chromatography.

An aliquot of sample is injected into an ion chromatograph. The sample is pumped through two columns and a suppressor device and into a conductivity detector. The analytical column and the guard column are packed with low-capacity anion exchanger. Ions are separated based on their affinity for the exchange sites of the resin. The suppressor device contains a fiber or membrane-based cation exchanger which is continuously regenerated by a flow of dilute sulfuric acid. The suppressor device reduces the background conductivity of the eluent to a low or negligible level by replacing the cations with the hydrogen ion, thereby converting the anions in the sample to their corresponding acids. The separated anions in their acid form are measured using an electrical-conductivity cell. Anions are identified based on their retention times compared to known standards. Quantitation is accomplished by measuring the peak height or area and comparing it to a calibration curve generated from known standards.

Maintenance Plan for The Instrument The Contractor shall perform maintenance on their equipment as outlined per the manufacturer’s instructions.

The maintenance protocol shall be available and be delivered to NIH upon request.

Calibration Procedure The lab shall prepare a blank and at least three combination anion calibration standards containing the anions of interest. The combination of anion solutions shall be prepared in a volumetric flask. Calibration standards shall be prepared weekly, except for those that contain nitrite and phosphate, which shall be prepared fresh daily. The validity of standards can be confirmed through the analysis of a freshly prepared sample, Comment by Hughes, Casey (NIH/OD/ORF) [E]: Freshly prepared what? Comment by Adjei, George (NIH/OD/ORF) [E]: Samples High range standard calibration solution shall be prepared by adding volumes of each stock solutions and diluting it with 1000 ml of reagent water.

The lab shall prepare the intermediate-range calibration standard solution by diluting 10.0 mL of the high-range calibration standard solution with 100 mL of reagent water.

The lab shall prepare the low-range calibration standard solution by diluting 20.0 mL of the intermediate-range calibration standard solution with 100 mL of reagent water.

Analysis Method and Protocol The Contractor shall follow EPA Method 300.0 for analysis method and protocol.

Interferences Any species with a retention time similar to that of the desired anion will interfere. Large quantities of ions eluting close to the anion of interest will also result in an interference. Separation can be improved by adjusting the eluent concentration and/or flow rate. Sample dilution and/or the use of the method of standard additions can also be used. For example, high levels of organic acids that may interfere with inorganic anion analysis may be present in industrial wastes.

Data Acquisition Using the established calibration curve, the Contractor shall compute the concentration of each analyte in each analysis sample or QC standard based on the peak area response. Most chromatography data analysis software systems perform such calculations automatically.

Reference Environmental Protection Agency, Environmental Monitoring Systems Laboratory, Office of Research and Development, USEPA Method 300.0, "Determination of Inorganic Anions by Ion Chromatography," EPA-600/R-93-100, August 1993.

Annual Book of ASTM Standards, Volume 11.01 Water, "Test Method for Anions in Water by Chemically-Suppressed Ion Chromatography," D 4327-97, 1998.

Standard Methods for the Examination of Water and Wastewater, Method 4110, "Determination of Anions by Ion Chromatography," 18th Edition of Standard Methods, 1992.