316L EP-Grade Capillary Coil Tube for HPLC Mobile Phase Delivery Systems
Product Overview
The 316L EP-Grade Capillary Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered stainless steel tubing solution purpose-built for High Performance Liquid Chromatography (HPLC) mobile phase delivery systems. Designed to withstand the rigorous demands of analytical laboratories and process analysis environments, this coil tube delivers exceptional chemical inertness, minimal metal ion elution, and superior flow consistency when transporting aggressive mobile phase mixtures comprising organic solvents and aqueous buffer salts.
In HPLC applications, even trace-level metal contamination can compromise chromatographic resolution, distort detection signals, and introduce systematic errors in quantitative analysis. This product addresses these critical pain points through advanced metallurgical processing and electropolishing technology, ensuring that the tubing remains biologically and chemically inert throughout its service life.
Material & Properties
Grade 316L Austenitic Stainless Steel is selected as the base material due to its superior corrosion resistance, particularly in chloride-containing environments. The addition of molybdenum (2.0–2.5%) provides enhanced pitting and crevice corrosion resistance, while the ultra-low carbon content (≤0.03%) eliminates intergranular corrosion susceptibility during welding and heat exposure.
- Ultra-Low Metal Elution: The electropolished (EP) surface finish reduces surface roughness to a Ra ≤ 0.1 μm, significantly minimizing the leaching of chromium, nickel, and molybdenum ions into the mobile phase stream.
- Biologically Inert Verification: The tubing has undergone biological compatibility testing to confirm that it does not release cytotoxic or genotoxic substances, making it suitable for pharmaceutical and biomedical analytical workflows.
- Chemical Resistance: Demonstrated compatibility with methanol, acetonitrile, tetrahydrofuran (THF), formic acid, acetic acid, ammonium formate, ammonium acetate, and phosphate buffer solutions at concentrations typical in reversed-phase and normal-phase chromatography.
- Magnetic Permeability: Non-magnetic or near-non-magnetic properties ensure no interference with detector electronics or flow sensors in the analytical instrument.
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | AISI 316L (UNS S31603) |
| Surface Finish | Electropolished (EP), Ra ≤ 0.1 μm |
| Outer Diameter Range | 0.10 mm – 3.00 mm (customizable) |
| Wall Thickness Range | 0.025 mm – 0.50 mm (customizable) |
| Coil Diameter | 50 mm – 500 mm (customizable) |
| Maximum Working Pressure | Up to 800 bar (4000 psi) |
| Operating Temperature Range | −40 °C to +250 °C |
| Inner Surface Roughness | Ra ≤ 0.1 μm (EP); Ra ≤ 0.25 μm (standard) |
| Metal Ion Elution Level | Below ICP-MS detection limit (< 1 ppb) |
| Form | Coiled capillary tubing (pre-wound coil) |
| Custom Lengths | Available upon request |
Manufacturing Process
Wenzhou Jixing Metal Materials Co., Ltd. employs a multi-stage manufacturing process to achieve the exacting specifications required for HPLC-grade tubing:
- Bar Stock Selection: High-purity 316L stainless steel bar stock is sourced from certified mills with documented chemical composition traceability, ensuring consistent microstructure and low impurity levels.
- Hot and Cold Drawing: The bar stock undergoes precision cold drawing through multi-stage dies to achieve the target outer diameter and wall thickness with tight dimensional tolerances (±0.01 mm).
- Heat Treatment (Solution Annealing): Tubes are solution-annealed at 1050–1100 °C followed by controlled water quenching to achieve a fully austenitic, stress-free microstructure with maximum corrosion resistance.
- Electropolishing (EP): The tubing interior and exterior surfaces are subjected to electropolishing using a phosphoric acid–sulfuric acid electrolyte system. This process removes the top 2–5 μm of metal, eliminates surface defects, and creates a smooth, passivated surface with a self-forming chromium oxide layer.
- Coiling: The finished tubing is precision-wound onto a coil former at controlled tension to produce uniform coil diameters without introducing residual stress or deformation.
- Final Cleaning & Passivation: Tubes undergo ultrasonic cleaning and nitric acid passivation to remove any residual particulate matter and restore the passive oxide film to maximum integrity.
Applications
- HPLC Mobile Phase Tubing: Primary application for delivering mobile phase mixtures (organic solvents + buffer salts) from solvent reservoirs to the pump and column in liquid chromatography systems.
- UPLC/UHPLC Systems: Suitable for ultra-high-pressure liquid chromatography systems operating at pressures up to 15,000 psi, where tubing integrity is critical.
- Process Analytical Technology (PAT): Used in pharmaceutical process analysis for real-time monitoring of reaction intermediates and final product quality attributes.
- Biopharmaceutical Analysis: Ideal for bio-incompatible-free analytical workflows where metal ion contamination must be absolutely minimized.
- Food & Beverage Quality Control: Application in residual pesticide, mycotoxin, and contaminant analysis where ultra-trace detection limits are required.
- Environmental Monitoring: Suitable for water quality analysis and environmental sample preparation where low blank values are essential.
Quality Certifications & Compliance
- Material Certification: Each batch is accompanied by a Mill Test Certificate (MTC) documenting chemical composition, mechanical properties, and heat treatment records in accordance with EN 10204 Type 3.1.
- ISO 9001:2015: Manufactured under a certified Quality Management System ensuring consistent product quality and process control.
- ISO 13485: Compliant with medical device manufacturing quality requirements, relevant for pharmaceutical and biomedical analytical applications.
- Biological Inertness: Tested in accordance with USP <87> (Extractables and Leachables) and USP <661> (Biocompatibility Evaluation) protocols.
- Low Elution Verification: Metal ion elution tested via ICP-MS (Inductively Coupled Plasma Mass Spectrometry) to confirm levels below 1 ppb for all alloying elements.
- Custom Testing Available: Additional testing protocols can be performed upon customer request, including GMP-compliant cleanroom processing and validated cleaning procedures.
Unique Selling Points
1. Ultra-Low Metal Elution Guarantee: EP-finished 316L capillary tubing with verified metal ion elution below 1 ppb—ensuring zero interference with trace-level analytical measurements.
2. Biologically Inert Certified: Rigorously tested for biological compatibility, making this tubing a safe choice for pharmaceutical, clinical, and life science applications.
3. Precision Coil Form: Pre-wound coils eliminate on-site forming, reducing installation time, preventing kinking, and ensuring consistent flow path geometry.
4. Customizable Dimensions: Wide range of OD, wall thickness, and coil diameter options tailored to specific instrument configurations and flow requirements.
5. Full Traceability: Complete batch-level documentation from raw material through final inspection, supporting regulatory compliance in GMP environments.
Wenzhou Jixing Metal Materials Co., Ltd. is committed to delivering world-class precision stainless steel tubing solutions that meet the most demanding analytical requirements. For custom specifications, sample requests, or technical consultation, please contact our engineering team directly.