Overview
ISO 3749:2022 specifies an analytical method for the quantitative determination of water‑soluble tungsten extractable from the inner surface of glass syringes. The procedure applies to Luer cone, staked‑needle and Luer‑lock syringe types and is intended to detect tungsten residues originating from tungsten pins used during syringe cone formation. The method uses ultrasonic extraction of filled syringes followed by instrumental analysis (ICP‑MS or ICP‑OES).
Key topics and technical requirements
- Scope: Quantitative determination of extractable tungsten (W) from glass syringe inner surfaces (ISO 3749:2022).
- Extraction method:
- Fill syringes to nominal volume with test water (ISO 3696 grade 2 or better).
- Perform ultrasonic extraction at (75 ± 5) °C for (60 ± 1) min, frequency 45 kHz, specific power ≥ 16 W/L.
- Two consecutive extractions are performed and combined for analysis.
- Sample preparation:
- Siliconization procedure for inner barrel when required (controlled silicone amount).
- Recommended lot size: not less than 60 syringes per lot to account for variability.
- Filling level determined with a reference syringe to ensure repeatability.
- Analytical measurement:
- Analyze extracts by ICP‑MS (masses 182, 183, 184 for W) or ICP‑OES (wavelengths such as 207.912 nm or 220.449 nm) in accordance with ISO 17294‑2 and ISO 11885.
- Use appropriate diluents (e.g., 5% HNO3 or 0.5% NH4OH), calibration standards and an internal standard (e.g., Tl, Re, Ir).
- Reagents and apparatus: Test water, suprapure nitric acid and ammonium hydroxide, tungsten stock standards, ultrasonic bath capable of the specified temperature/frequency/power, ICP instrumentation.
- Quality control: Includes calibration, matrix matching, internal standards and optional spiking (Annex A) to verify extraction efficiency.
Applications and who uses this standard
- Glass syringe manufacturers: process control and acceptance testing to monitor residual tungsten from manufacturing pins.
- Pharmaceutical and biopharma QC labs: assessment of extractable tungsten that can affect drug stability (e.g., protein aggregation).
- Contract testing and analytical laboratories: validated method for regulatory submissions or supplier qualification.
- Regulatory affairs and compliance teams: demonstrate conformity with established test methods for medical devices and drug container closure systems.
Related standards
- ISO 3696 - Water for analytical laboratory use (test water quality)
- ISO 11885 - ICP‑OES for determination of selected elements
- ISO 17294‑2 - ICP‑MS application for selected elements
Keywords: ISO 3749:2022, glass syringes, extractable tungsten, tungsten residues, ultrasonic extraction, ICP‑MS, ICP‑OES, Luer cone, staked needle, Luer lock, syringe testing, pharmaceutical quality control.
