🧪 Ammonium nitrogen in water and wastewater — flow analysis CFA/FIA

Physicochemistry PN-EN ISO 11732

Overview

WHAT THIS STANDARD DESCRIBES. The scope from the PKN catalogue card, in full: "Określono metodę oznaczania azotu amonowego w różnych rodzajach wód (np. w wodach podziemnych, powierzchniowych, wodzie do spożycia i ściekach) za pomocą analizy przepływowej, w zakresie stężeń masowych w próbce nierozcieńczonej od 0,1 mg/l do 10 mg/l. Podano do wyboru technikę analizy przepływowej wstrzykowej (FIA) lub analizy przepływowej ciągłej (CFA)" [A method is specified for the determination of ammonium nitrogen in various types of water (e.g. groundwater, surface water, drinking water and wastewater) by flow analysis, in the mass concentration range in the undiluted sample from 0.1 mg/l to 10 mg/l. Flow injection analysis (FIA) or continuous flow analysis (CFA) is given as the technique to choose]. The standard was published on 29 June 2007, has 24 pages and is maintained by KT 121 Water Quality — Chemical Testing — Inorganic Substances, ICS 13.060.50. In the "Implements" field the card gives EN ISO 11732:2005 and ISO 11732:2005, and in the "Replaces" field — PN-EN ISO 11732:2005 in the English-language version, i.e. the same European document made available earlier in English. The 2007 edition is therefore the Polish text of the same standard, not a new version of the method.

WHY THIS ENTRY WAS CREATED. The standards described on this site are usually selected according to how many laboratories cite them. Such a selection will not find a standard that a regulation indicates but laboratories rarely use. This standard was selected the other way round: from the list of reference methodologies in Annex No. 12 to the regulation of the Minister of Maritime Economy and Inland Navigation of 12 July 2019 (Journal of Laws 2019 item 1311), promulgated on 15 July 2019.

FOUR METHODOLOGIES FOR ONE PARAMETER. For ammonium nitrogen (item 6 of the annex) the regulation does not indicate one method, but lists four, each with a different technique: molecular absorption spectrophotometry (photocolorimetry) — PN-ISO 7150-1; the volumetric (titrimetric) method — PN-ISO 5664; flow analysis (CFA and FIA) with spectrometric detection — PN-EN ISO 11732; ion chromatography — PN-EN ISO 14911. Explanatory note 1 to the annex adds that the reference method is selected from among the standardised methodologies, and that the determination range specified in the standard should correspond to the range of concentrations in the wastewater under test.

WHAT THIS CHOICE LOOKS LIKE IN ACCREDITATION SCOPES. We give two measures, because they answer different questions. The first counts all notations of the number of a given standard in the reference-document field, regardless of the name of the test (neither a digit nor a letter may stand before the number, and no digit after it): PN-ISO 7150-1 — 176 laboratories and 278 entries, PN-ISO 5664 — 104 and 155, PN-EN ISO 14911 — 30 and 52, PN-EN ISO 11732 — 15 and 36. The second takes only entries whose test name begins with the words "Stężenie azotu amonowego" [ammonium nitrogen concentration]: PN-ISO 7150-1 — 118 laboratories and 154 entries, PN-ISO 5664 — 98 and 124, PN-EN ISO 11732 — 13 and 20, PN-EN ISO 14911 — 2 and 2. The first measure says how often the standard occurs in the scopes at all; the second — what those who name the test exactly so use to determine ammonium nitrogen. For PN-EN ISO 14911 the difference is relatively the largest — 30 laboratories against 2. Among the entries with this standard whose test name refers to nitrogen or ammonium, names other than "Stężenie azotu amonowego" predominate — e.g. "Stężenie jonu amonowego" [ammonium ion concentration] or "Stężenie kationów" [cation concentration] with a list of ions. Reading of 23.09.2026 on the copy of the database of accreditation scopes.

HOW MANY LABORATORIES HAVE THIS STANDARD AND IN WHAT FORM. All notations of the number 11732: 36 entries at 15 laboratories, in five forms. The form "PN-EN ISO 11732:2007" — 32 entries at 13 laboratories; the other four notations occur once each: "EN ISO 11732:2007" without the PN element, "PN-EN ISO 11732:2007 pkt 4 M", "PN-EN ISO 11732:2007 z wyłączeniem punktu 3" [z wyłączeniem punktu = excluding clause] and a field with three standards at once — "PN-EN 12457-2:2006 PN-EN 12457-4:2006 PN-EN ISO 11732:2007". Object of testing: for 29 entries water or wastewater (in various notations, most often "Woda, ścieki" [water, wastewater] — 14 times), for 7 — solid matrices: waste, soil, sewage sludge, fertilisers, building materials. The card of the standard speaks only of waters; for each of these seven entries another standard stands next to it in the reference-document field — PN-EN 12457-4:2006 (together with PN-EN 12457-2:2006 or alone), PN-EN 14671:2007, PN-EN ISO 21268-2:2020-01 or PN-R-04028:1997.

WHAT THE "LABORATORIES" TAB SHOWS. The tab searches for notations BEGINNING with "PN-EN ISO 11732" and shows 34 entries at 15 laboratories. Two entries drop out because their notation begins with something else: "EN ISO 11732:2007" has no PN element, and in the field with three standards this one stands in third place. The number of laboratories does not change — both notations belong to laboratories that also have a notation beginning with this designation.

THE RANGE IN AN ACCREDITATION SCOPE IS SOMETIMES WIDER THAN ON THE CARD. The card gives 0.1–10 mg/l for the undiluted sample. Laboratory AB 213 declares a range of (0.20 – 100) mg/l for this standard, and for one entry (0.100 – 100) mg/l. The number from the accreditation scope and the number from the standard's card therefore need not be the same quantity: the first may include dilution of the sample, the second — according to the card — concerns the undiluted sample.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN makes it available for a fee (24 pages). The card says that the technique is flow-based (FIA or CFA to choose from), and the title — that the detection is spectrometric. We therefore do not give the reaction on which the detection is based, the reagents, the flow conditions, the calibration or the sample preparation.

Method principle

According to the card and the title of the standard: ammonium nitrogen is determined by flow analysis, in one of two techniques to choose from — flow injection analysis (FIA) or continuous flow analysis (CFA) — with spectrometric detection, in the mass concentration range from 0.1 mg/l to 10 mg/l in the undiluted sample. This is where what we know from the sources ends. WE DO NOT GIVE the reaction on which the detection is based, the composition of the reagents, the flow conditions or the sample preparation — we did not have the text of the standard.

Applications

• Groundwater and surface water — scope of the standard according to the card
• Water intended for human consumption — scope of the standard according to the card
• Wastewater — scope of the standard according to the card; when testing for the purposes of Journal of Laws 2019 item 1311, one of the four methodologies listed for ammonium nitrogen (Annex No. 12, item 6)

Key parameters

Standard

Standard number

PN-EN ISO 11732:2007

Title (PL)

Jakość wody — Oznaczanie azotu amonowego — Metoda analizy przepływowej (CFA i FIA) z detekcją spektrometryczną

Title (EN)

Water quality — Determination of ammonium nitrogen — Method by flow analysis (CFA and FIA) and spectrometric detection

Step-by-step procedure

1. Checking the concentration range

   The card gives a range of 0.1–10 mg/l for the undiluted sample. If the laboratory dilutes samples, the range in its accreditation scope may be wider — and then it is not the same quantity as the range on the card.

2. Choice of technique: FIA or CFA

   The standard offers both techniques to choose from (card). Record the chosen technique in the test procedure and in the report.

3. Determination

   WE DO NOT GIVE the course of the determination — calibration, flow conditions, checks: we did not have the text of the standard.

4. Entry in the report when testing wastewater

   The regulation lists four methodologies for ammonium nitrogen. Indicating the standard according to which the determination was performed allows the recipient to check that it was one of them.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• We do not describe the hazards associated with the reagents — we do not know their list, because we did not have the text of the standard; the safety data sheets of the reagents used in the laboratory apply

Frequently asked questions