🌿 Automatic photometric determination of chromium(VI), fluoride, total alkalinity, total hardness, calcium, magnesium, iron and iron(II), manganese and aluminium in ground, potable, surface water, waste water, eluates and boiler water (marine water after matrix matching) in a discrete analysis system — pre-set volumes of sample and reagents in a separate reaction cell for each determination, incubation, absorbance measurement usually in the 400–880 nm range; filtration of samples through 0.45 µm, calibration according to ISO 8466-1/-2, correction for inherent colour (Annex A), control solution at least once every 20 samples; procedures for parameters in Annexes B–J; result in µg/l or mg/l to three significant figures; ISO/TS 15923-2:2017

Environment ISO/TS 15923-2

Overview

WHAT THE STANDARD COVERS. We read the text in the iTeh sample of ISO/TS 15923-2:2017 (technical specification, English text): foreword, introduction, clauses 1–13 and normative Annex A (correction for inherent colour) — the sample ends on page 6. We do not read Annexes B–J with procedures for the individual parameters (B — chromium(VI), C — fluoride, D — total alkalinity, E — total hardness, F — calcium, G — magnesium, H — iron(II) and total iron, I — manganese, J — aluminium); we know their titles from the table of contents.

ACCORDING TO THE TEXT OF ISO/TS 15923-2:2017. The document was prepared by ISO/TC 147 "Water quality", Subcommittee SC 2 "Physical, chemical and biochemical methods". Introduction: many photometric determinations can be automated in a discrete analysis system — one instrument determines many parameters, with a different combination for each sample; small volumes require less sample and reagent; samples outside the range can be diluted automatically or measured in another range. Warning: tests must be carried out by suitably qualified staff. Scope (1): automatic determination of chromium(VI), fluoride, total alkalinity, total hardness, calcium, magnesium, iron, iron(II), manganese and aluminium with photometric detection in a discrete analysis system; field of application — ground, potable, surface, waste water, eluates and boiler water; also marine water with matrix matching of standard and control solutions; some parameters, notably iron, manganese and aluminium, and possibly chromium(VI), calcium and magnesium, may not be completely quantified if the sample contains particulates; samples can be digested in acid as long as the buffering capacity of the reaction mixture is not exceeded — such procedures are outside the document, which is best suited to the determination of dissolved metals after on-site filtration. References (2): ISO 3696, ISO 8466-1, ISO 8466-2; no terms and definitions (3). Principle (4): a discrete analysis system is an automated system for spectrophotometric and turbidimetric determinations; colour reactions take place in reaction cells (which may be cuvettes) in an incubator, a separate cell for each determination; pre-set volumes of sample and reagents are pipetted and mixed; after incubation the absorbance is measured at the wavelength applicable to the determination — passing the cuvettes through the photometer or transferring the solution to a photometer with a flow-through cell; the chemistry of each parameter — in the annexes. Interferences (5): particles may cause blockages and interfere with measurement — filtration through 0.45 µm is recommended (or settlement, centrifugation, dialysis); after filtration the fraction of a parameter adsorbed on particles is not measured; inherent colour and turbidity interfere — two colour correction procedures in Annex A; a reliable turbidity correction cannot be given, because the Beer–Lambert law does not apply to turbid solutions and many chromogenic reagents and coloured complexes adsorb on particles; parameter-specific interferences — in the annexes. Reagents (6): reagents for the parameters in Annexes B–J; analytical grade; thermally stable solid reagents are dried to constant weight at (105 ± 5) °C and stored in a desiccator; volumes may be adjusted to local requirements or the instrument; commercial preparations acceptable if storage instructions are followed; grade 1 water. Apparatus (7): discrete analysis system — sample injection device (automatic or manual), sample containers, reagent containers (refrigerated or not), incubator with temperature control, visible wavelength detector, e.g. spectrophotometer, usually 400–880 nm, control and data processing unit, recording device (e.g. PC with software); balance 0.0001 g, oven, desiccator, glassware, autopipettes 50–500 µl. Sampling and sample preparation (8): turbidity and particles interfere with detection — samples with particles are clarified by filtration through 0.45 µm (or settlement, centrifugation or dialysis), discarding the first few millilitres of filtrate; ISO 5667-3 gives guidance on preservation and storage, but the stability of some parameters depends on pH and composition — stability trials are carried out locally for each matrix type; acidification to pH 1–2 recommended in ISO 5667-3 for iron, manganese, aluminium, calcium and magnesium may be inappropriate where pH is critical (e.g. calcium and manganese) — the buffering capacity of the reaction mixture must not be exceeded; fluoride is stable for at least one month without pretreatment; chromium(VI) is best analysed as soon as possible — ISO 18412 recommends at most 4 days refrigerated, ISO 23913 at most 24 h at 2–5 °C; grade 1 water prepared like the sample serves as the blank; a control solution from a primary control standard at a level similar to the samples is run as a sample at appropriate intervals — at least once every 20 samples recommended. Calibration (9): a calibration function for each parameter at the first evaluation and at intervals (ISO 8466-1 or -2), with a series of standards from Annexes B–J and water as zero; validity checked regularly with a calibration standard, at least at the end of the batch, preferably in the upper third of the range; if full calibration is not done daily — an initial check with two standards in the lower and upper third of the range. Procedure (10): set-up and calibration according to the document and the manufacturer's instructions; consistent incubation temperature and time are essential for the stability of absorbance measurements; the blank is measured according to Annex A; a sample with absorbance above the top standard is diluted with water or the sample intake reduced so that it falls in the upper half of the range, and reanalysed; the procedure may be modified for other instruments, ranges, sensitivities or sample types. Calculation (11): mass concentration in µg/l or mg/l from the calibration line and corrected absorbances according to ISO 8466-1 or -2, with dilutions, usually by the software. Results (12): in µg/l or mg/l, to a maximum of three significant figures (example: 11.12 µg/l → 11.1 / 11 / 10 µg/l). Test report (13): reference to ISO/TS 15923-2:2017, sample identification, date of analysis, results, deviations and circumstances. Annex A (normative): correction for inherent colour is necessary; sample blanking — measurement after dispensing the sample and any reagents that change colour (e.g. through pH), before the chromogenic reagent, adjusted for the volume ratio and subtracted; standards measured in the same way; or a compensating solution — the same volumes without the colour-forming compound (water instead of the chromogenic reagent or a reagent without it); accurate turbidity correction is not possible by these methods; systems can be programmed for automatic correction.

STATUS (as of 03.10.2026). The PKN search engine (query "15923-2", 03.10.2026) returns "No search results" — the document has no Polish counterpart in the PKN catalogue, and laboratories cite ISO/TS 15923-2:2017 directly. We did not read the status of ISO/TS 15923-2:2017 in the iTeh catalogue (since 03.10.2026 the catalogue pages require a browser with scripts).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read 03.10.2026). The number 15923-2 appears in 7 records at 3 laboratories: AB 313 (3), AB 1525 (2), AB 1651 (2). In the current PCA documents (read 03.10.2026; AB 313 issue no. 43 of 08.07.2026, AB 1525 issue no. 19 of 05.08.2026, AB 1651 issue no. 10 of 09.09.2026) the number appears in 6 lines at the same 3 laboratories (at AB 313 alkalinity and hydrogen carbonates share one reference); in each document the number of page markers equals the number of PDF pages, without duplicates; searching all PCA documents downloaded from the BIP on 03.10.2026 found no laboratories outside the database copy. Forms: "ISO/TS 15923-2:2017-10" (AB 313), "ISO/TS 15923-2:2017 Annex F" and "Annex G" (AB 1525), "ISO-TS 15923-2:2017" and "ISO 15923-2:2017" (AB 1651). None of these items is suspended. The "Laboratories" tab under the queries "ISO/TS 15923-2", "ISO-TS 15923-2" and "ISO 15923-2" shows all 3 laboratories in total (under the first query also one Czech laboratory) — checked by tab queries on the labcoda.pl production server on 03.10.2026.

WHAT THE LABORATORIES TEST (PCA items). AB 313: water — alkalinity (0.40–100) mmol/l, hydrogen carbonate concentration (25–6000) mg/l, total hardness (20.0–2000) mg/l CaCO3, spectrophotometric method. AB 1525: water — calcium (10–500) mg/l (Annex F) and magnesium (10–500) mg/l (Annex G), spectrophotometric method. AB 1651: water intended for human consumption — fluoride (0.05–1.50) mg/l; waste water — chromium(VI) (0.010–1.00) mg/l; colorimetric method.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Filtration: after 0.45 µm filtration the fraction of a parameter adsorbed on particles is not measured, and with particles in the sample iron, manganese and aluminium (possibly also chromium(VI), calcium and magnesium) may be underestimated (1, 5) — it must be known whether the dissolved or total form is determined. Preservation: acidification to pH 1–2 may disturb pH-dependent determinations (e.g. calcium, manganese) by exceeding the buffering capacity (8). Chromium(VI): analysis as soon as possible — the sources give 4 days refrigerated (ISO 18412) or 24 h at 2–5 °C (ISO 23913) (8). Colour and turbidity: colour is corrected (Annex A), turbidity is not (5). Incubation: constant temperature and time determine the stability of absorbance (10). Control: control solution at least once every 20 samples, calibration check at least at the end of the batch (8, 9). Result: to a maximum of three significant figures (12). Hydrogen carbonates: the scope of the document names total alkalinity; AB 313 lists hydrogen carbonates beside alkalinity as a separate characteristic — the conversion is not in the part of the document read. Status: it is a technical specification without a Polish counterpart in the PKN catalogue; laboratories write the number in three ways, so the "Laboratories" tab spreads them over three queries.

WHAT WE DO NOT GIVE. We did not read the reagents, wavelengths, ranges and interferences for the individual parameters (Annexes B–J). We do not summarize the parts of ISO/TS 15923-2 on iron, manganese and aluminium, or ISO 18412 and ISO 23913, in this entry.

Method principle

For each determination the discrete analyser pipettes pre-set volumes of sample and reagents into a separate reaction cell, mixes and incubates them at constant temperature; the colour formed is a measure of the parameter's concentration. Absorbance is measured at the wavelength appropriate to the colour reaction (usually 400–880 nm), and the concentration is calculated from the calibration function after correction for the sample's inherent colour. The reaction chemistry for chromium(VI), fluoride, alkalinity, hardness, calcium, magnesium, iron, manganese and aluminium is given in separate annexes.

Applications

• Ground, potable and surface water, waste water, eluates and boiler water; marine water after matrix matching (1)
• Dissolved metals after on-site filtration — the application best suited to the document (1)
• Water, water intended for human consumption and waste water — alkalinity, hydrogen carbonates, hardness, calcium, magnesium, fluoride, chromium(VI) — 7 accreditation scope records of 3 laboratories in PCA

Key parameters

Standard

Standard number

ISO/TS 15923-2:2017

Title (PL)

Jakość wody — Oznaczanie wybranych parametrów za pomocą systemów analizy nieciągłej — Część 2: Chrom(VI), fluorki, zasadowość ogólna, twardość ogólna, wapń, magnez, żelazo, żelazo(II), mangan i glin z detekcją fotometryczną

Title (EN)

Water quality — Determination of selected parameters by discrete analysis systems — Part 2: Chromium(VI), fluoride, total alkalinity, total hardness, calcium, magnesium, iron, iron(II), manganese and aluminium with photometric detection

Step-by-step procedure

1. Sample preparation

   0.45 µm filtration, discarding the first millilitres; blank from water (8). ISO/TS 15923-2:2017 — no counterpart in the PKN catalogue (03.10.2026).

2. Calibration

   Series of standards with water as zero, regression according to ISO 8466-1/-2; check with two standards if not daily (9).

3. Analysis

   Pipetting sample and reagents, incubation at constant temperature and time, absorbance measurement (4, 10).

4. Correction and dilution

   Colour correction (Annex A); sample above the top standard — dilution into the upper half of the range (10).

5. Control and result

   Control solution ≥ once every 20 samples; result in µg/l or mg/l, to three significant figures (8, 11, 12).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Tests must be carried out by suitably qualified staff; the user establishes safety and health practices (warning)

Frequently asked questions