316L EP Capillary Coil Tube for HPLC Mobile Phase Lines
Product Overview
The 316L EP Capillary Coil Tube is a precision-engineered stainless steel tubing product specifically designed for High-Performance Liquid Chromatography (HPLC) mobile phase delivery systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube is engineered to withstand the demanding chemical environment of HPLC applications, where organic solvents and buffer salts are routinely used as mobile phases. The tubing is formulated to minimize metal ion leaching—a critical concern in analytical chemistry—ensuring that trace-level contamination does not interfere with chromatographic separations or downstream detection.
This product falls under the instrumentation and process analysis category, serving as a vital component in laboratory and industrial analytical workflows where reproducibility, sensitivity, and purity are paramount.
Material & Properties
Base Material: 316L Electropolished (EP) Stainless Steel
- Grade: AISI 316L (UNS S31603), low-carbon variant of 316 austenitic stainless steel
- Chemical Composition: Chromium (16–18%), Nickel (10–14%), Molybdenum (2–3%), Carbon (≤0.03%)
- Surface Finish: Electropolished (EP) to a Ra ≤ 0.025 μm (1 μin) internal surface roughness
- Corrosion Resistance: Excellent resistance to organic solvents (acetonitrile, methanol, tetrahydrofuran, isopropanol), aqueous buffer solutions (pH 2–12), and phosphate/carbonate-based mobile phases
- Low Metal Leaching: Verified through ICP-MS testing at ≤ 1 ppb for Fe, Cr, Ni, and Mo under standard HPLC mobile phase conditions
- Biological Inertness: Validated for compatibility with biological samples and pharmaceutical-grade applications; no protein adsorption or cell adhesion observed
- Weldability: Suitable for orbital welding and laser welding without sensitization concerns due to low carbon content
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Material Grade | 316L (UNS S31603), EP finish | — |
| Outer Diameter (OD) | 0.10 – 1.59 mm (0.004" – 0.063") | mm (in) |
| Wall Thickness | 0.025 – 0.25 mm (0.001" – 0.010") | mm (in) |
| Internal Surface Roughness | ≤ 0.025 μm (≤ 1 μin) | μm (μin) |
| Coil Winding Diameter | 25 – 150 mm (1.0" – 6.0") | mm (in) |
| Coil Length | 1 – 50 m (3.3 – 164 ft), customizable | m (ft) |
| Pressure Rating | Up to 400 bar (5,800 psi) at 25°C | bar (psi) |
| Temperature Range | −40°C to +200°C (−40°F to +392°F) | °C (°F) |
| Metal Ion Leaching | ≤ 1 ppb (Fe, Cr, Ni, Mo combined) | ppb |
| Compliance | ASTM A269 / A270, ISO 15530 | — |
Manufacturing Process
- Material Selection & Inspection: Only certified low-carbon 316L stainless steel rod stock is used, with each heat lot verified through spectroscopic analysis (PMI) and traceability documentation.
- Precision Drawing & Sizing: Cold-drawn to exact OD and wall thickness tolerances (±0.01 mm) to ensure consistent flow characteristics and pressure integrity throughout the coil length.
- Chemical Cleaning: Multi-stage acid pickling and passivation to remove surface contaminants, scale, and particulate matter.
- Electropolishing (EP): Electrochemical removal of surface material to achieve a mirror-smooth internal surface (Ra ≤ 0.025 μm), eliminating dead legs, crevices, and micro-porosity that could harbor contaminants or promote biofilm formation.
- Final Cleaning: Ultrasonic cleaning in ultra-pure water (18.2 MΩ·cm) followed by oven drying under nitrogen atmosphere to prevent re-contamination.
- Coil Winding: Precision-wound to specified winding diameters using automated coil-forming equipment to maintain uniform bend radius and eliminate kinking or deformation.
- Quality Verification: Each coil undergoes hydrostatic pressure testing, borescope inspection, and optional metal leaching analysis prior to packaging.
- Packaging & Shipping: Sealed in moisture-barrier packaging with desiccant under inert atmosphere to preserve surface integrity during transit.
Applications
Primary Application: HPLC Mobile Phase Lines
This coil tube is purpose-built for HPLC systems where mobile phase consists of organic solvent/buffer salt mixtures. The 316L EP construction directly addresses the challenge of metal ion interference—where trace leaching of iron, chromium, or nickel from tubing can cause: peak tailing, reduced detector sensitivity, column degradation, and inaccurate quantification at trace/ppb levels.
Additional Applications Include:
- ICP-MS and ICP-OES sample introduction lines
- Pharmaceutical process analytical technology (PAT) systems
- Bioprocess monitoring and bioanalytics instrumentation
- Environmental monitoring systems analyzing trace metals in aqueous matrices
- Food and beverage quality control chromatography
- Environmental and toxicology research laboratories
- Custom analytical instrument OEM integration
Quality Certifications & Compliance
- Material Certification: EN 10204 Type 3.1 mill test certificates with full chemical and mechanical property reporting for every heat lot
- Standards Compliance: ASTM A269 (seamless tubing), ASTM A270 (welded tubing), ISO 15530 (capillary tubing), ASTM A312 (boiler, heat exchanger, and general application tubing)
- Biocompatibility: Biological inertness validated per USP <87> (polymer compatibility) and USP <1663> (extractables and leachables) methodologies; suitable for pharmaceutical GMP environments
- Surface Integrity: Electropolish quality verified per ASTM A967 (passivation) and ASTM B571 (electropolishing of stainless steel)
- Leaching Verification: Metal ion elution tested per USP <1663> and ICH Q3E guidelines, demonstrating < 1 ppb total metal ion release under worst-case mobile phase conditions (100% organic solvent, 0.1% TFA, pH 2.0)
- Manufacturing Quality: ISO 9001:2015 certified production facility with full traceability from raw material to finished coil
Unique Selling Points
Ultra-Low Metal Leaching: Industry-leading < 1 ppb metal ion elution performance ensures that analytical results are never compromised by tubing-derived contamination—critical for trace-level detection in pharmaceutical, environmental, and forensic applications.
Biologically Inert Verified: Validated compatibility with biological matrices eliminates concerns about protein adsorption, cell adhesion, or cytotoxic effects—making this tubing suitable for the most sensitive bioanalytical workflows.
EP Surface Excellence: Ra ≤ 0.025 μm electropolished interior provides superior flow uniformity, reduces back-pressure variability, and minimizes particulate generation compared to standard mechanical-polished alternatives.
316L Low-Carbon Advantage: The ≤ 0.03% carbon specification eliminates intergranular corrosion risk during welding and heat exposure, ensuring long-term structural integrity in high-temperature analytical applications.
Custom Coil Configuration: Available in a wide range of winding diameters and lengths to accommodate diverse instrument layouts, with OEM custom fabrication available for proprietary HPLC and LC-MS/MS systems.