🌿 Ammonia in workplace air — indophenol method (sodium hypochlorite, phenol, sodium nitroprusside), visible-light spectrophotometry; limit of quantification according to the standard 4 mg/m³; MAC (NDS) 14 mg/m³, STEL (NDSCh) 28 mg/m³; PN-Z-04009-03:1990 (withdrawn 17-10-2011)

Environment PN-Z-04009-03

Overview

WHAT THE STANDARD COVERS. Scope from the PKN card, in full: "The method consists in the reaction of ammonia with sodium hypochlorite and phenol in the presence of sodium nitroprusside, which produces blue-coloured indophenol. The ammonia content is determined spectrophotometrically. The limit of quantification of the method is 4 mg in 1 cubic m of air. The method cannot be used when formaldehyde and hydrogen cyanide are simultaneously present in the air in amounts above 14 mg/cubic m and in the presence of aromatic amines" (our translation; no full stop at the end on the card). The card does not give the sampling method, the absorbing solution, the wavelength or the air volume. We did not have the text of the standard (3 pages); the CIOP method index for 2000–2017 lists no article on ammonia (searched on 05.10.2026).

NDS VALUES (list in the annex to the regulation of 26 March 2026, Journal of Laws 2026 item 447). Item 23: "Ammonia [7664-41-7]" — NDS 14 mg/m³, NDSCh 28 mg/m³, no "skin" notation and no note on the fraction; the substance is not covered by the transitional provisions of § 2. The limit of quantification according to the card, 4 mg/m³, is about 29 % of the NDS.

STATUS (card as of 05.10.2026). The card of PN-Z-04009-03:1990 (Polish version) has the heading "Withdrawn" without naming a replacing standard: publication 03-02-1990, withdrawal date 17-10-2011, 3 pages, price group B, Health, Environment and Medicine Sector, KT 159 Chemical and Dust Hazards in the Working Environment, ICS 13.040.30. PKN search (05.10.2026): under "PN-Z-04009" — 14 items of the series "Tests for nitrogen and its compounds"; only parts -11:2008 (nitrogen monoxide and nitrogen dioxide at workplaces) and -12:2008 (dinitrogen oxide at workplaces) are current, the others — including this part and the parts on ammonia in ambient air (-02:1984, -02:1991, -2:1999) — are labelled "Withdrawn". Among the first 50 results for "amoniaku", the standards on ammonia in air are — besides the PN-Z-04009 series — the withdrawn PN-Z-04041:1955 and PN-Z-04041:1971 and the current PN-EN 17346:2020-11, which concerns ambient air (diffusive samplers), not workplaces; the term "azanu" gives no results. The withdrawn PN-Z-04041:1971 (Nessler reagent method) is described in a separate entry of this database.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read on 05.10.2026). Number 04009-03 appears in 2 records at 2 laboratories; in the current PCA documents (read on 03.10.2026; issues of 04.09.2025 and 04.02.2026) — in 2 rows at the same laboratories; a search of all PCA documents downloaded from the BIP found no laboratories outside the database copy (many documents contain other parts of this series — -11 and -12 on nitrogen oxides); no entry is suspended and no pages are repeated in any document. Notations: "PN-Z-04009-3:1990" (part number without the zero) — AB 935; "PN-90/Z-04009.03" — AB 964. The "Laboratories" tab searches for records beginning with the term entered: "PN-Z-04009-3" and "PN-90/Z-04009.03" show 1 laboratory each, 2 in total — the same in the copy and on the labcoda.pl production server (tab queries on 05.10.2026).

WHAT THE LABORATORIES TEST (database copy and PCA documents). Subject: working environment — air; AB 935 — air samples. Quantity: concentration (content) of ammonia. Ranges: AB 935 — 0.5–40 mg/m³ (0.001–0.02 mg per sample); AB 964 — 1.33–66.7 mg/m³. Technique: spectrophotometric method — both laboratories.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — interferences: according to the card the method is not used when formaldehyde and hydrogen cyanide occur together in the air above 14 mg/m³, or in the presence of aromatic amines; a report from such a workplace should show that these conditions did not occur. Second — lower limit: the card gives a limit of quantification of 4 mg/m³, while AB 935 starts at 0.5 and AB 964 at 1.33 mg/m³, which requires conditions different from those on the card. Third — withdrawn standard with no successor: the PKN search returns no current Polish standard for ammonia at workplaces; the current PN-EN 17346 concerns ambient air and does not replace this method. Fourth — part number: AB 935 writes "04009-3", and the term "PN-Z-04009-03" (with the zero) will not show this laboratory; parts -11 and -12 of this series are nitrogen oxides, not ammonia.

WHAT WE DO NOT GIVE. We did not have the text of the standard — we do not give the absorbing solution, the volume or flow rate of the air sample, the reagent concentrations, the colour development time, the wavelength, the calibration or the calculations.

Method principle

Ammonia from workplace air reacts with sodium hypochlorite and phenol in the presence of sodium nitroprusside; blue indophenol is formed and measured spectrophotometrically (PKN card); limit of quantification according to the card — 4 mg/m³. The method is not used when formaldehyde and hydrogen cyanide are present together above 14 mg/m³ or when aromatic amines are present. The result in mg/m³ is compared with the NDS of 14 mg/m³ and the NDSCh of 28 mg/m³ (Journal of Laws 2026 item 447).

Applications

• Workplace air — ammonia — in the current scopes of 2 laboratories despite the withdrawal of the standard
• Assessment of occupational exposure against the NDS of 14 mg/m³ and the NDSCh of 28 mg/m³ (Journal of Laws 2026 item 447, item 23 of the list) — except at workplaces with formaldehyde and hydrogen cyanide above 14 mg/m³ and with aromatic amines

Key parameters

Standard

Standard number

PN-Z-04009-03:1990

Title (PL)

Ochrona czystości powietrza — Badania zawartości azotu i jego związków — Oznaczanie amoniaku na stanowiskach pracy metodą spektrofotometryczną w świetle widzialnym, indofenolową

Title (EN)

Air purity protection — Tests for nitrogen and its compounds — Determination of ammonia at workplaces by visible-light spectrophotometry, indophenol method

Step-by-step procedure

1. Suitability check

   Checking that formaldehyde and hydrogen cyanide above 14 mg/m³ and aromatic amines are not present together in the air (PKN card).

2. Sampling

   WE DO NOT GIVE details — the card does not describe them.

3. Reaction and measurement

   Reaction with sodium hypochlorite and phenol in the presence of sodium nitroprusside, spectrophotometric measurement of the blue indophenol (PKN card); WE DO NOT GIVE the conditions.

4. Result and assessment

   Concentration of ammonia in mg/m³; comparison with the NDS of 14 mg/m³ and the NDSCh of 28 mg/m³ (Journal of Laws 2026 item 447).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Ammonia, phenol, sodium hypochlorite and sodium nitroprusside — safety rules of the chemical laboratory
• TECHNICAL NOTE: the method is not used when formaldehyde and hydrogen cyanide are present together above 14 mg/m³ or with aromatic amines (PKN card); standard withdrawn with no successor

Frequently asked questions