Anions: analytical methods, detection limits, and holding times - USEPA/SuRGE GitHub Wiki
Dissolved anions were added to SuRGE in 2020. Samples collected by ADA were analyzed in ADA, all others were analyzed at CIN. 2020 and 2021 IC analysis in CIN was performed by Kit Daniels, 2022 and 2023 were analyzed by TTEB. The two CIN labs have different detection limits. The anion analysis (ion chromatography) provides quantification of bromide (br), chloride (cl), sulfate (so4), nitrite(no2), nitrate (no3), and phosphorus (op). no2, no3, and op are also measured via colorometric methods which have a lower detection limit that ion chromatography. no2, no3, and op are documented below, but will only be incorporated in the SuRGE chemistry data file if the colorometric data are not available or somehow compromised.
Analyte detection limits (dl) are assessed annually by each lab. Detection limits may differ by lab and year of analysis. Separate tables are provided below for ADA, CIN-Daniels, and CIN-TTEB.
Please note that the analyte names and units used below are consistent with the SuRGE chemistry data objects, but may differ from those in the data files provided by the laboratories. See Wiki page Chemistry units, names, and data sources for the official list of analyte names and units to be used in the SuRGE data objects.
Detection and reporting limits taken from data files provided by ADA. For 2022 SO4, the June data reports include a MDL and RDL of 0.266 and 1.0, respectively, with a determination date of 2/16/2022. These values are quite high and are inconsistent with September data reports that include a MDL and RDL of 0.022 and 0.5, respectively, also with a determination date of 2/16/2022. We assume the lower ML and RL are correct.
The final data file of 2023 (EPAGPA108_148_147_anions.xlsx) had new detection limits, quantified on 8/30/2023. They are slightly lower than those used for the rest of the year and the original (higher) values are reported below and used for this project.
| Analyte | Analyte Container and volume | Analytical method | Year | Detection limit | Reporting Limit | Preservation and Holding times | Lab |
|---|---|---|---|---|---|---|---|
| br | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 0.041 mg_l MDL determination on 7/16/2021 |
0.1 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| cl | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 0.026 mg_l MDL determination on 7/16/2021 |
0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| so4 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 0.151 mg_l MDL determination on 7/16/2021 |
0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| f | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 0.014 mg_l MDL determination on 7/16/2021 |
0.1 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| no2 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 19 ug_n_l MDL determination on 7/16/2021 |
xx ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| no3 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 49 ug_n_l MDL determination on 7/16/2021 |
xx ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| op | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2021 | 54 ug_p_l MDL determination on 7/16/2021 |
xx ug_p_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| br | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 0.034 mg_l MDL determination on 2/16/2022 |
0.1 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| cl | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 0.068 mg_l MDL determination on 2/16/2022 |
0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| so4 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 0.022 mg_l MDL determination on 2/16/2022 |
0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| f | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 0.035 mg_l MDL determination on 2/16/2022 |
0.1 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| no2 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 6 ug_n_l MDL determination on 2/16/2022 |
100 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| no3 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 14 ug_n_l MDL determination on 2/16/2022 |
500 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| op | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2022 | 54 ug_p_l MDL determination on 2/16/2022 |
xx ug_p_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| br | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 0.013 mg_l MDL determination on 9/22/2022 |
0.1 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| cl | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 0.015 mg_l MDL determination on 9/22/2022 |
0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| so4 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 0.022 mg_l MDL determination on 9/22/2022 |
0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| f | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 0.011 mg_l MDL determination on 9/22/2022 |
0.1 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| no2 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 6 ug_n_l MDL determination on 9/22/2022 |
100 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| no3 | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 14 ug_n_l MDL determination on 9/22/2022 |
500 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
| op | A single 125 mL HDPE bottle | The Determination of Inorganic Anions Using the Dionex ICS-2100, G-GWERD-SOP-3329-0 | 2023 | 16 ug_p_l MDL determination on 9/22/2022 |
100 ug_p_l | Filtered not acidified. Stored @ 4oC up to 28 days | ADA |
Method detection limits provided by Mailly Pham [2/9/2022 email]. Reporting limits are generally assumed to be lowest standard in curve, unless otherwise indicated. The lowest standards for Br, F, NO2, NO3, and OP used in this analysis (see Daniels_Anions_2021.xls) are much higher than that used by TTEB on the same machine. We will adopt the lowest standard reported by TTEB (see below) or Kit Daniels, whichever is lowest, for these data.
| Analyte | Analyte Container and volume | Analytical method | Year | Detection limit | Reporting Limit | Preservation and Holding times | Lab |
|---|---|---|---|---|---|---|---|
| br | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 0.02 mg_l MDL determination on 11/17/2020 |
0.05 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
| cl | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 0.03 mg_l MDL determination on 11/17/2020 |
0.4597 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
| so4 | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 0.025 mg_l MDL determination on 11/17/2020 |
0.423 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
| f | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 0.005 mg_l MDL determination on 11/17/2020 |
0.05 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
| no2 | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 15 ug_n_l MDL determination on 11/17/2020 |
50 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
| no3 | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 4 ug_n_l MDL determination on 11/17/2020 |
50 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
| op | A single 30 mL HDPE bottle | EPA Method 300 | 2021 | 15 ug_n_l MDL determination on 11/17/2020 |
50 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-Daniels |
Minimum detection limits are taken from first row of data reports. Reporting limits are assumed to be equal to lowest standard and were provided by David Griffith [9/22/2022 e-mail]. These can also be extracted from some of the raw data files that include standard curves. I noted some minor deviations from the nominal reporting limits provided by David's e-mail and those in the data files, but the nominal values are very close and will be used in this project.
| Analyte | Analyte Container and volume | Analytical method | Year | Detection limit | Reporting Limit | Preservation and Holding times | Lab |
|---|---|---|---|---|---|---|---|
| br | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 0.008 mg_l | 0.05 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |
| cl | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 0.03 mg_l | 0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |
| so4 | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 0.05 mg_l | 0.5 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |
| f | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 0.007 mg_l | 0.05 mg_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |
| no2 | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 5 ug_n_l | 50 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |
| no3 | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 6 ug_n_l | 50 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |
| op | A single 30 mL HDPE bottle | EPA Method 300 | 2022-2023 | 11 ug_n_l | 50 ug_n_l | Filtered not acidified. Stored @ 4oC up to 28 days | CIN-TTEB |