oSIST prEN 18388:2026

oSIST prEN 18388:2026 is the Slovenian version of prEN 18388, a draft European Standard from CEN/TC 260. It specifies a method for determining chloride content in inhibitors by ion chromatography with conductivity detection (IC-CD). Laboratories and product-control teams use it for inhibitors and inhibiting compounds, including mixtures of those materials.

What does oSIST prEN 18388:2026 specify?

oSIST prEN 18388:2026 specifies how to determine chloride in inhibitors using ion chromatography. The method applies to inhibitors and inhibiting compounds, including mixtures of inhibitors and inhibiting compounds.

The document is organized into scope, normative references, terms and definitions, principle, reagents, apparatus and equipment, sampling and sample preparation, chromatographic conditions, calibration, test solution preparation, quality control, calculation, environmental aspects, precision, and test report. Annex A gives the results of the inter-laboratory test used to assess precision.

Sampling itself is outside the method. The standard points users to EN 1482-1 for a recommended sampling approach and requires sample preparation to follow EN 1482-2.

What are the key requirements of oSIST prEN 18388:2026?

Measurement principle and reagents

oSIST prEN 18388:2026 measures chloride after the inhibitor sample is diluted in water, then analyzed by IC-CD. In practice, the analyst works with an aqueous test solution rather than the original material.

Clause 5 requires analytical-grade reagents with negligible chloride compared with the sample level. Water must be distilled or demineralized, chloride standard solution is used for calibration, and a chloride quality control sample is required. The eluent is chosen according to the instrument manufacturer, so the chromatographic system is set up to match the column and detector used in the laboratory.

Apparatus and chromatographic setup

The standard calls for an ion chromatography device with a conductivity detector, with an autosampler and column oven as optional equipment. A suppressed conductivity detector may be used to reduce noise and background. The supporting equipment includes a balance readable to 0.1 mg, a 0.45 µm syringe filter, a 100 ml graduated flask, pipettes, and a shaker.

Clause 7.2 gives recommended chromatographic conditions: a quaternary ammonium stationary phase, carbonate/bicarbonate mobile phase, manufacturer-guided flow and temperature, chemical or electrochemical suppression, and an injection volume of 5 µl to 100 µl. This means laboratories must document their chosen column and operating conditions so the method remains consistent and repeatable.

Calibration, sample preparation, and determination

Clause 7.3 requires a calibration series prepared from the chloride standard solution at several levels between 0.10 and 10.0 mg/ml. Clause 7.4 then sets the sample preparation: weigh 1 000 mg ± 100 mg of sample into a 100 ml flask, add water, shake for 5 to 10 minutes, fill to volume, and filter through the syringe filter.

The determination is performed twice, and the injected results must fall within the calibration range. If the sample is outside that range, an extra dilution step is recommended. In practice, this helps avoid reporting a result from an overloaded or under-range chromatogram.

Quality control, calculation, and precision

Clause 7.5 requires a quality control sample in each sample series, also determined twice. Clause 8 states that evaluation is based on the calibration curve over peak areas, and the curve may be used if the correlation coefficient is at least 0.999. The result is reported as chloride mass fraction in g/kg.

Clause 10 requires the quality control sample recovery to be between 95 % and 105 %; if not, recalibration is needed. Repeatability and reproducibility are checked against limits given in Table 3, with the supporting inter-laboratory study summarized in Annex A. Clause 11 then defines what must be included in the test report, including sample identification, the method reference, results, sampling information if known, finish date, repeatability-limit compliance, and any optional settings or incidents that could have affected the result.

What terms does oSIST prEN 18388:2026 define?

• IC-CD means ion chromatography with conductivity detection, the measurement technique used for chloride.
• Conductivity detector is the detector that measures the ionic signal after chromatographic separation.
• Quality control sample is the chloride check sample used to verify that a run is performing correctly.
• Repeatability is the closeness of results obtained in the same laboratory under the same conditions.
• Reproducibility is the closeness of results obtained in different laboratories under different conditions.
• HorRat is the study index reported in Annex A for comparing collaborative-study precision.

Who uses oSIST prEN 18388:2026?

oSIST prEN 18388:2026 is used by laboratories that test inhibitors and inhibiting compounds for chloride content. It is also relevant to manufacturers, quality managers, and buyers involved in fertilizer-related products, because the standard sits in ICS 65.080 and is tied to sample preparation, routine analysis, and test reporting.

It is especially useful for analysts who need a consistent IC-CD method, for QA teams checking batch consistency, and for organizations that need a documented test method for internal control or supplier verification.

Which standards are used with oSIST prEN 18388:2026?

• EN 1482-2 - gives the general sample preparation provisions required before analysis.
• EN 12944-1 - provides general vocabulary for fertilizers and liming materials.
• EN 12944-2 - provides vocabulary for terms relating to fertilizers.
• EN 1482-1 - is cited as the recommended sampling method for obtaining a representative sample.
• ISO 5725-3 - is used for the calculation approach behind repeatability and reproducibility in the precision study.

What does the oSIST prEN 18388:2026 document contain?

The document contains the method principle, reagent requirements, apparatus list, chromatographic conditions, calibration preparation, sample preparation steps, calculation guidance, environmental handling notes, precision requirements, and a test report checklist. Tables 1 to 3 cover the recommended IC conditions, calibration dilution steps, and precision limits.

Formula (1) gives the calculation for chloride mass fraction, and Annex A presents the inter-laboratory study used to support the precision statement. Annex A also includes statistical results for different inhibitor samples and the study terms used to summarize the data.