Overview

Tubing dimensions play an important role in HPLC system performance. The selected tubing ID can influence:

• System backpressure
• Extra-column volume
• Peak dispersion
• Gradient performance
• Method sensitivity
• Overall chromatographic efficiency

Because HPLC systems are used for a wide variety of applications, tubing selection is often based on method requirements rather than a single industry standard.

Common Tubing Outer Diameters

High-Pressure Side of the HPLC System

For most analytical HPLC systems, the standard tubing size is:  1/16 inch OD

This tubing is commonly used between:

• Pump and injector
• Injector and column
• Column and detector
• Other high-pressure fluidic connections

Its compact size supports high-pressure operation and minimizes extra-column volume.

Low-Pressure Side of the HPLC System

On the solvent delivery side of the instrument, either of the following sizes may be used:

• 1/16 inch OD
• 1/8 inch OD

The choice depends on:

• Instrument design
• Bottle configuration
• Solvent line routing
• Laboratory preference

Both sizes are widely used for solvent uptake and mobile phase delivery.

Common Tubing Internal Diameters

Several tubing IDs are commonly used in chromatography systems:

• 0.005 inch
• 0.007 inch
• 0.010 inch
• 0.020 inch

Each size offers different flow characteristics and system-volume considerations.

Most Common Tubing ID for Analytical HPLC

For modern analytical HPLC systems using:

• 4.6 mm ID columns
• 3.0 mm ID columns

the most commonly used tubing size is:  0.007 inch ID

This size often provides a practical balance between:

• Pressure requirements
• System volume
• Chromatographic efficiency
• Ease of use

As a result, 0.007 inch ID tubing has become a popular choice for many routine analytical applications.

Factors to Consider When Selecting Tubing ID

Column Internal Diameter

Smaller chromatography columns typically benefit from lower-volume tubing to minimize extra-column dispersion.  Larger columns may tolerate larger tubing IDs without significant performance loss.

Flow Rate

Methods operating at lower flow rates often benefit from smaller tubing IDs.  Higher flow-rate applications may utilize larger IDs when system volume is less critical.

Detector and Pump Configuration

The tubing should be appropriate for the flow characteristics and volume requirements of the instrument.  System design can influence the optimal tubing selection.

Method Performance Goals

Tubing selection should support the objectives of the method, including:

• Maximum efficiency
• Lowest dispersion
• Highest sensitivity
• Reduced system volume

General Selection Guidelines

Smaller Internal Diameters

Advantages may include:

• Reduced extra-column volume
• Lower peak dispersion
• Improved efficiency

Commonly used for:

• LC-MS methods
• Narrow-bore columns
• High-efficiency separations

Larger Internal Diameters

Advantages may include:

• Lower flow resistance
• Greater fluid capacity
• Easier handling

Commonly used for:

• Higher flow applications
• Solvent delivery lines
• Certain preparative workflows

Key Takeaways

• There is no universal standard tubing ID for HPLC systems.
• The most appropriate tubing depends on the method and instrument configuration.
• 1/16 inch OD tubing is commonly used on the high-pressure side of HPLC systems.
• 1/16 inch OD and 1/8 inch OD tubing are commonly used on the low-pressure side.
• Common tubing IDs include 0.005, 0.007, 0.010, and 0.020 inch.
• 0.007 inch ID tubing is frequently used with 4.6 mm and 3.0 mm analytical HPLC columns.
• Tubing selection should support the performance goals of the chromatographic method.

Additional Resources

For tubing specifications, internal diameter options, fluidic connection components, product images, and ordering information, view:  HPLC Tubing Specifications, Internal Diameter Selection Guide, Fluidic Connection Components, and Ordering Information