Overview
ISO 17190-1:2020 specifies a laboratory test method for determination of pH of granular polyacrylate superabsorbent powders used in urine-absorbing aids for incontinence. The standard defines the principle, required reagents and apparatus, conditioning and sampling procedures, step-by-step measurement instructions, reporting elements and method precision. It is intended for consistent pH measurement of polymer powders that swell in saline and form a gel.
Key topics and requirements
- Scope and principle: pH is measured in the supernatant saline solution after adding a defined mass of superabsorbent polymer; measurement is made with a glass pH-responsive electrode and pH meter.
- Reagents and solutions: Grade 3 water (ISO 3696), 0.9 % sodium chloride solution adjusted to pH 6.0 ± 0.05, 0.1 mol/L NaOH and HCl for adjustment, and standard buffer solutions (pH 4.00 and 7.00) for calibration.
- Apparatus: analytical balances, pH meter with suitable electrode, magnetic stirrer and a recommended cross-centred stir bar to minimize gel tearing, 250 ml beaker (tall form preferred), graduated cylinders and volumetric flask.
- Sampling & conditioning: samples must be in closed containers and equilibrated to laboratory conditions (preferred 23 ± 2 °C, 45 ± 15 % RH per ISO 187); homogenize by rotating container and remove lumps >1 mm.
- Procedure highlights:
- Calibrate electrode with at least two buffers (e.g., pH 4 and 7).
- Add 100 ml saline to beaker, stir gently, disperse 0.49–0.51 g sample, stir 10 minutes without vortex.
- Allow gel to settle (~10 min), measure pH of supernatant avoiding contact with gel.
- Record value when two successive readings agree within ±10 %; report pH to the nearest 0.1 unit.
- Safety note: limit routine exposure to respirable polyacrylate dust (MAK guideline ~0.05 mg·m−3).
- Precision: validated over pH range ~5.84–6.22. Repeatability (r) and reproducibility (R) reported (~0.18–0.20 pH units).
Applications and users
ISO 17190-1:2020 is directly applicable to:
- Quality control and analytical testing laboratories measuring pH of superabsorbent polymers used in diapers, incontinence pads and sanitary products.
- Manufacturers and suppliers of urine-absorbing aids performing incoming material checks and batch release.
- R&D teams characterizing polymer performance and compatibility with body fluids.
- Regulatory and certification bodies assessing product safety and material specifications.
Practical benefits include harmonized pH measurement, reproducible test results across labs, and standardized reporting to support product quality and regulatory compliance.
Related standards
- ISO 17190 series (other parts related to superabsorbent material characterization)
- ISO 3696 - Water for analytical laboratory use
- ISO 187 - Standard atmosphere for conditioning and testing
- ISO 10523 - pH measurement and buffer preparation
- NWSP 200.0 (related method referenced in bibliography)
Keywords: ISO 17190-1:2020, polyacrylate superabsorbent powders, pH test method, urine-absorbing aids, incontinence, pH determination, saline solution, electrode calibration, repeatability, reproducibility.