NOx_SM4500_NO3_F_2016_FINAL_01_20_2022

Revised 1/20/2022
NC DEQ/DWR WASTEWATER/GROUNDWATER LABORATORY CERTIFICATION BRANCH
LABORATORY NAME: CERT #:
PRIMARY ANALYST: DATE:
NAME OF PERSON COMPLETING CHECKLIST (PRINT):
SIGNATURE OF PERSON COMPLETING CHECKLIST:
Parameter: Nitrogen, Nitrate + Nitrite
Method: SM 4500 NO3- F- 2016

Note: This is an automated version of SM 4500 NO3- E- 2016. As the verbiage in SM 4500 NO3- F- 2016 is sparse, many of the method references contained in this checklist will refer to the manual method. Equipment:
Automated analytical instrument
Reduction column
Reagents:
Cadmium granules Ammonium chloride-EDTA solution Copper sulfate solution, 2% Color reagent Hydrochloric acid, 6M Stock nitrate solution Wash solution (reagent water) Sulfuric Acid, concentrated Stock nitrite solution PLEASE COMPLETE CHECKLIST IN INDELIBLE INK Please mark Y, N or NA in the column labeled LAB to indicate the common lab practice and in the column labeled SOP to indicate whether it is addressed in the SOP.
GENERAL LAB
SOP EXPLANATION
1
Is the SOP reviewed at least every 2 years? What is the most recent review/revision date of the SOP? [15A NCAC 2H .0805 (a) (7)] Date:

Quality assurance, quality control, and Standard Operating Procedure documentation shall indicate the effective date of the document and be reviewed every two years and updated if changes in procedures are made. Verify proper method reference. During review notate deviations from the approved method and SOP.
2
Are all review/revision dates and procedural edits tracked and documented? [15A NCAC 2H .0805 (a) (7)]
Each laboratory shall have a formal process to track and document review dates and any revisions made in all quality assurance, quality control and SOP documents.
3 Is there North Carolina data available for review? If not, review PT data
PRESERVATION and STORAGE LAB
SOP EXPLANATION
4 Is the sample preserved with H2SO4 to pH <2 S.U. within 15 minutes of collection? [40 CFR Part 136.3, Table II and footnote 2]
5 Is sample transported and stored at ≤ 6°C without freezing? [40 CFR Part 136.3, Table II and footnote 2]
6 Is the sample analyzed within 28 days of collection? [40 CFR Part 136.3, Table II]
7 Are date and time of sample collection documented? [15A NCAC 2H .0805 (a) (7) (F) (vi)]
8 Is the date of sample analysis documented? [15A NCAC 2H .0805 (a) (7) (F) (vii)]
PROCEDURE – Reduction Column Preparation LAB
SOP EXPLANATION
9 Is the reduction column purchased already packed? If yes, skip to next section for Meter Calibration
10 Are the cadmium granules prepared as required by the method? [SM
4500 NO3- E- 2016 (3) (b)] Wash 25 g new or used 20- to 100-mesh Cd granules with 6N HCl and rinse with water.
Nitrate + Nitrite: SM 4500 NO3- F-2016 Page 2
Revised 1/20/2022

Swirl Cd with 100 mL 2% CuSO4 solution for 5 min or until blue color partially fades.
Decant and repeat with fresh CuSO4 until a brown colloidal precipitate begins to develop. Gently flush with ammonium chloride-EDTA solution to remove all precipitated Cu.
11 Is the column prepared as required by the method? [SM 4500 NO3-
E- 2016 (4) (a)]
Insert a glass wool plug into bottom of reduction column and fill with water. Add
sufficient Cu–Cd granules to produce a column 18.5 cm long. Maintain water level above Cu–Cd granules to prevent entrapment of air. Wash column with 200 mL dilute NH4Cl-EDTA solution. Activate column by passing through it, at 7 to 10 mL/min, several 100 mL portions of a solution composed of one part 1.0 mg NO3- N/L standard and three parts NH4Cl-EDTA solution.
12 Is the column cleaned and stored per the method? [SM 4500 NO3- E-
2016 (3) (b) and (4) (b) (3)]
Pour 50 mL dilute NH4Cl-EDTA solution on to the top and let it pass through the system. Store activated Cd covered with dilute ammonium chloride–EDTA solution and never let it dry.
PROCEDURE – Meter Calibration LAB
SOP EXPLANATION
13
Is the meter calibrated with at least 5 non-zero standards? [SM 4500
NO3- E- 2016 (4) (c)] [15A NCAC 2H .0805 (a) (7) (H) (v)]
List standard concentrations:
The method requires 5 standards, so curves prepared daily must still analyze 5 standards.
14 If the curve is held, is it prepared every 12 months? [15A NCAC 2H .0805 (a) (7) (H) (v)]
PROCEDURE – Interferences LAB
SOP EXPLANATION
15 Is the sample filtered if turbid? [SM 4500 NO3- F-2016 (1) (b)]
Filter turbid sample through 0.45-µm membrane filter. Test filters for nitrate contamination. (i.e., filter the reagent blank if any samples must be filtered)
16
Are aliquots of samples that are treated for residual chlorine in the field brought to a neutral pH and verified to be chlorine free when
received in the lab? [SM 4500 NO3- F-2016 (1) (b)] [NC WW/GW
LCB Policy]

NC WW/GW LCB Policy: Each chemically preserved sample must be checked for effectiveness and the results documented. Dechlorinating agents used at the time of sampling must be documented to have been effective (either by the sample collector or the receiving laboratory) by verifying a chlorine residual <0.5 mg/L at a neutral pH. If measuring chlorine concentration in an acidified sample, pour off a small portion of the sample and neutralize the pH prior to
testing. Use sufficiently strong base to not dilute the sample. Discard that portion after testing.
PROCEDURE – Sample Analysis LAB
SOP EXPLANATION
17 Is the sample pH adjusted to 5-9 S.U.? [SM 4500 NO3- F-2016 (4)]
QUALITY ASSURANCE LAB
SOP EXPLANATION
18
Has a Method Detection Limit (MDL) been established? [SM 4500
NO3- A-2016 (3)] [40 CFR 136 Appendix B]

The initial MDL determination must consist of minimum of 7 spikes and 7 method blanks. They must be divided among 3
Nitrate + Nitrite: SM 4500 NO3- F-2016 Page 3
Revised 1/20/2022

State MDL value here: State determination date here:
separate prep batches on 3 separate days.
19 Are at least two spikes at the same concentration as the initial MDL study analyzed in separate batches each quarter that samples are analyzed? [40 CFR 136 Appendix B]
Must have at least two per quarter, however if additional standard at that concentration are analyzed, they must be included in the ongoing recalculation of the MDL.
20 Is the MDL evaluated at least every 13 months and updated if required? [40 CFR 136 Appendix B]
21
Has each new analyst completed an Initial Demonstration of
Capability (IDC) before analyzing any samples? [SM 4500 NO3- A-
2016 (3)] [SM 4020 B-2014 (3)] Attach a copy of each analyst’s IDC to this checklist.

At a minimum, include 1 reagent blank and at least 4 LFBs at a concentration between 1
and 4 times the MRL (or other level specified in the method). Run the IDC after analyzing all required calibration To establish laboratory-generated accuracy and precision limits, calculate the upper and lower control limits from the mean and standard deviation of percent recovery for ≥20 data points: Upper control limit = Mean + 3(Standard deviation) Lower control limit = Mean − 3(Standard deviation)
22 Is the correlation coefficient of the calibration curve ≥0.995? [SM
4500 NO3- A-2016 (3)]
Using a calculator, electronic spreadsheet, or instrument software, calculate the slope, intercept, and correlation coefficient (r) or coefficient of determination ( r2) of the calibration curve. The r value must be at least 0.995 (r2 = 0.99).
23 Are the standard values back-calculated with each calibration? [SM
4500 NO3- A-2016 (3)] [15A NCAC 2H .0805 (a) (7) (H)] Back-calculate the apparent concentrations of the standards.
24
What are the acceptance criteria for the back-calculated standards?
[SM 4020 B-2014 (1)] [SM 4500 NO3- A-2016 (3)] [15A NCAC
2H .0805 (a) (7) (A)] Acceptance criteria:

4020B: If any recalculated values are not within the method’s acceptance criteria - up to twice the MRL, ±50%; between 3 and 5 times the MRL, ±20%; or greater than 5 times the MRL ±10%- unless otherwise specified in the individual methods, identify the source of any outlier(s) and correct before sample quantitation.
4500 NO3- A: For standards more than 10
times the MDL, the measured values must be 90% to 110% of the true values.
25
Is a second-source calibration-verification standard (CVS) analyzed immediately after the calibration?
[SM 4500 NO3- E-2016 (3)] [15A NCAC 2H .0805 (a) (7) (H) (ii)]

Prepare a calibration-verification standard (CVS) from a stock solution separate from that used to prepare the calibration
standards. The CVS’s NO3--N concentration
should be 30% to 70% of the highest calibration standard; however, some QA/QC programs may require different concentrations. Run the CVS immediately after calibration; the result must be 90% to 110% of the expected value.
Rule: Laboratories shall analyze one known second source standard to verify the accuracy of standard preparation if an initial calibration is performed and in accordance with the referenced method requirements thereafter.
26
Is the acceptance criterion for the second-source CVS recovery
within ±10% of the true value? [SM 4500 NO3- A-2016 (3)]
True value:
See above
Nitrate + Nitrite: SM 4500 NO3- F-2016 Page 4
Revised 1/20/2022

Acceptance criterion:
27 Is a standard at the lowest reporting concentration analyzed or back calculated each day samples are analyzed? [15A NCAC 2H .0805 (a) (7) (H)]
If the reporting limit is the same as one of the calibration standards, this will be covered by the curve back-calculation requirement.
28
What is the acceptance criterion for the lowest reporting
concentration standard? [SM 4020 B-2014 (1)] [SM 4500 NO3- A-
2016 (3)] [15A NCAC 2H .0805 (a) (7) (A)] Acceptance criterion:

4500 NO3- A: For standards more than 10
times the MDL, the measured values must be 90% to 110% of the true values. 4020B: If less than 10 times the MDL: For standards up to twice MRL, ±50%; between 3 and 5 times MRL, ±20%; greater than 5 times MRL ±10% of the true values.
29 Is a Laboratory Fortified Blank (LFB) analyzed with each sample set or on a 5% basis, whichever is more frequent? [SM 4020 B- 2014 (6)]
30 Is the LFB filtered if any samples require filtration? [SM 4020 B-2014 (6)] Process the LFB through all sample preparation and analysis steps.
31 Is Sodium thiosulfate added to the LFB if any samples must be treated for residual chlorine? [SM 4020 B-2014 (6)]
32 What is the acceptance criterion for the LFB? [SM 4020 B- 2014 (6)] Acceptance criterion:
Evaluate the LFB for percent recovery of the added analytes by comparing results to method-specified limits, control charts, or other approved criteria. If there are a mix of both filtered and unfiltered samples, you must have both a filtered and unfiltered LFB.
33 Is a method blank analyzed with each sample set (batch) or on a 5% basis, whichever is more frequent? [SM 4020 B- 2014 (5)]
34 Is the method blank filtered if any samples require filtration? [SM
4020 B-2011 (5)] If there is a mix of filtered and unfiltered samples, you must have both a filtered and unfiltered method blank.
35 Is Sodium thiosulfate added to the method blank if any samples must be treated for residual chlorine? [SM 4020 B-2014 (5)]
36 Is the acceptance criterion for the method blank ≤½ reporting limit? [15A NCAC 2H .0805 (a) (7) (H) (i)]
37
Is a midpoint continuing calibration verification (CCV) analyzed prior to sample analysis, after every 10th sample, and at the end of each
sample group? [15A NCAC 2H .0805 (a) (7) (H)] [SM 4500 NO3- A-
2016 (3)] True Value:

38
Is the acceptance criterion for the CCV recovery within ±10% of the
true value? [SM 4500 NO3- A-2016 (3)]

If the measured NO3- - N concentration in
the CCV is not 90 to 110% of the expected value, recalibrate and rerun all samples read since the last good CCV reading.
39
Is a calibration blank analyzed prior to sample analysis, after every 10th sample, and at the end of each sample group? [15A NCAC
2H .0805 (a) (7) (H)] [SM 4500 NO3- A-2016 (3)]

40 Is the acceptance criterion for the calibration blank ≤ ½ reporting limit? [15A NCAC 2H .0805 (a) (7) (H) (i)]
41 Is a matrix spike (MS) and matrix spike duplicate (MSD) pair analyzed with each sample set (batch of 20 samples or less) or on a 5% basis, whichever is more frequent? [SM 4020 B- 2014 (7)]
42
How is the MS/MSD prepared? Answer:

See NC WW/GW LCB “Matrix Spiking Policy and Technical Assistance” document for volume and sample dilution requirements. SM states: Add a concentration that is at least 10 x MRL, less than or equal to the midpoint of the calibration curve, or method-specified level to the selected sample(s).
Nitrate + Nitrite: SM 4500 NO3- F-2016 Page 5
Revised 1/20/2022

The analyst should use the same concentration as for LFB (4020 B.6) to allow
analysts to separate the matrix’s effect from laboratory performance. Prepare LFM from the same reference source used for LFB. Make the addition such that sample background levels do not adversely affect recovery (preferably adjust LFM concentrations if the known sample is more than 5 times the background level). At a minimum, the spike must at least equal the background concentration, unless the method specifies otherwise. For example, if the sample contains the analyte of interest, then add approximately as much analyte to the LFM sample as the concentration found in the known sample.
43
What is the acceptance criterion for the accuracy of the MS/MSD (recovery)? [SM 4020 B-2014 (7)] Answer:

SM states: Evaluate LFM results for percent recovery; if they are not within control limits, then take corrective action to rectify the matrix effect, use another method, use the method of standard addition, or flag the data if reported. See method for specific LFM acceptance criteria until the laboratory develops statistically valid, laboratory-specific performance criteria. If the method does not provide limits, use the calculated preliminary limits from the IDC (4020 B.3). LFM control limits may be wider than for LFB or LCS, and batch acceptance generally is not contingent upon LFM results.
44
What is the acceptance criterion for the precision of the duplicates? (RPD) [15A NCAC 2H .0805 (a) (7) (A)] Answer:

45
Is at least one mid-level NO2- standard compared to a NO3- standard
at the same concentration to verify reduction column efficiency? [SM
4500 NO3- F-2014 (6)]

Run a mid-level NO3- -N standard followed
immediately by a NO2- -N standard of the
same concentration. Calculate reduction efficiency as follows:
Efficiency = (NO3- -N response ÷ NO2- -N
response) × 100.
46
What is the acceptance criterion for reduction efficiency? [SM 4500
NO3- F-2016 (6)]
Answer:
The efficiency must be 90% to 110%.
47 Are Cu-Cd granules reactivated if the reduction efficiency falls below
90%? [SM 4500 NO3- F-2016 (6)]
If not, stop and correct the problem by either
following the manufacturer’s instructions or passing 6 M HCl through the column followed by rinsing with dilute ammonium chloride-EDTA solution. Prepare or, if it cannot be reactivated, purchase a new column according to 4500-NO3 E.3 b and activate according to 4500-NO3 E.4 a.
48 Is the data qualified on the Discharge Monitoring Report (DMR) or client report if Quality Control (QC) requirements are not met? [15A NCAC 2H .0805 (a) (7) (B)]
If the sample cannot be reanalyzed, or if the quality control results continue to fall outside established limits or show an analytical problem, the results shall be qualified as such. If data qualifiers are used to qualify samples not meeting QC requirements, the data may not be useable for the intended purposes. It is the responsibility of the laboratory to provide the client or end-user of the data with sufficient information to determine the
Nitrate + Nitrite: SM 4500 NO3- F-2016 Page 6
Revised 1/20/2022

usability of the qualified data.

Additional Comments:
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________

Inspector: ______________________________________________________Date:_________________________________________