SIST EN ISO 5810:1998

SIST EN ISO 5810:1998 is a Slovenski standard from SIST for determining chloride content in starches and derived products by potentiometric titration. It specifies how to prepare the sample, carry out the silver nitrate titration, calculate the result as sodium chloride, and report the test. The method is used by laboratories and quality-control staff working with starch materials.

What does SIST EN ISO 5810:1998 specify?

SIST EN ISO 5810:1998 specifies a potentiometric method for chloride determination in starches and derived products. The method applies to a solution or suspension of the sample and is not used for cationic starches or amyloids soluble when cold, because those materials do not behave well in the stirring and titration conditions.

The standard is organized into clauses on scope, principle, reagents, apparatus, procedure, expression of results, and test report. In practice, that gives the user a complete laboratory method from sample preparation to reporting.

What are the key requirements of SIST EN ISO 5810:1998?

SIST EN ISO 5810:1998 measures chloride by titrating the sample with standard volumetric silver nitrate solution and following the end-point potentiometrically. The result is expressed as sodium chloride by mass, which is useful when chloride is being checked against a product specification.

Sample preparation and test portion

Clause 5 requires the sample to be mixed thoroughly so it is homogeneous before testing. The mass of the test portion is then chosen according to the expected chloride content, so the analyst uses a larger mass for low chloride levels and a smaller mass when chloride is higher. In practice, this helps keep the titration within a usable range.

Solution or suspension preparation

SIST EN ISO 5810:1998 distinguishes between soluble and insoluble products. Soluble products are stirred until dissolved and cooled if needed before titration, while insoluble products are made into a homogeneous suspension and stirred further for 15 minutes. That matters because the method must give a stable, representative liquid phase for the electrode measurement.

Reagents and apparatus

Clause 3 requires reagents of recognized analytical quality and distilled water, or water of equivalent purity. Clause 4 calls for ordinary laboratory equipment plus a potentiometer or pH-meter calibrated in millivolts, a silver/silver chloride electrode, a reference electrode, a variable speed stirrer, beakers, pipettes and burettes. ISO 648 and ISO 385/2 are named for the pipettes and burettes, so the glassware has to meet those accuracy requirements.

Titration procedure

During the determination, the silver/silver chloride electrode is connected to the positive pole and the reference electrode to the negative pole. Nitric acid is added, then the sample is titrated with silver nitrate, using 1 mL additions and smaller additions near the end-point. The operator traces the potentiometric curve and takes the inflection point as the end-point, which gives a practical way to read the chloride consumption.

Calculation and performance checks

Clause 6 gives the calculation as a percentage by mass of sodium chloride and notes that the 0.02 mol/l silver nitrate solution is preferable for very low chloride contents. The same clause also sets repeatability and reproducibility limits, so a laboratory can check whether two results are close enough for routine work and inter-laboratory comparison.

Test report

Clause 7 requires the report to state the method used, the result and how it is expressed. It also requires any optional or non-specified operating conditions and any circumstances that could have affected the result, plus the details needed to identify the sample.

What terms does SIST EN ISO 5810:1998 define?

• Potentiometric titration - A titration in which the end-point is found from the electrode potential instead of a color change.
• Silver/silver chloride electrode - The indicator electrode used to follow chloride during the titration.
• Reference electrode - The stable comparison electrode paired with the indicator electrode.
• Test portion - The weighed amount of sample taken for one determination.
• Test solution or suspension - The prepared sample in liquid form for soluble products, or as a suspension for insoluble products.
• End-point - The inflection point of the potentiometric curve, used as the titration finish.
• Repeatability - How close two results are when the same sample is tested in the same laboratory under closely related conditions.
• Reproducibility - How close two results are when the same sample is tested in different laboratories.

Who uses SIST EN ISO 5810:1998?

SIST EN ISO 5810:1998 is used by laboratories that test starches and derived products for chloride content. Typical users include quality-control laboratories, product release teams, incoming goods inspectors, and analytical laboratories serving starch producers and food or ingredient manufacturers. Buyers and suppliers use it to define and check a chloride specification in a common laboratory method.

What changed in SIST EN ISO 5810:1998 from the previous edition?

SIST EN ISO 5810:1998 is stated to be identical to EN ISO 5810:1994.

Which standards are used with SIST EN ISO 5810:1998?

• ISO 648 - Defines the requirements for the one-mark pipettes used in the method.
• ISO 385/2 - Defines the requirements for the burettes used to deliver the silver nitrate titrant.

What does the SIST EN ISO 5810:1998 document contain?

The document contains a titration-based analytical method, a reagent list, apparatus requirements, a sample-preparation procedure, and the steps for carrying out the chloride determination. It includes a mass-selection table for the test portion, so the analyst can match sample size to expected chloride level. It also provides the calculation formula, the repeatability and reproducibility criteria, and the required test-report items.

For laboratory work, the most practical parts are the electrode set-up, the titration sequence, and the way the end-point is read from the potentiometric curve. The document is therefore suited to routine chemical analysis, method standardization, and reporting of chloride results for starch products.