An Essential Guide to HPLC Fittings for Your Laboratory

An Introduction to HPLC Fittings

HPLC fittings play a vital role in chromatography systems, connecting tubing, adapters, and components to ensure leak-free, stable operation. Secure connections are critical for maintaining system pressure, minimizing dead volume, and achieving accurate, reproducible results. In this guide, we’ll review the most common fittings used in HPLC, explain their differences, and highlight how to choose the right ones for your system.

"Creating good connections with fittings is extremely important for successful chromatography."

In most analytical systems, a fitting consists of two main parts: a nut and a ferrule. The nut provides compression force, while the ferrule creates the seal between tubing and connection ports. When selecting fittings, consider factors such as thread type, geometry, tubing size, material, and pressure rating. For an in-depth discussion of fitting types, check out our previous article: What Types of Fittings Are Used in HPLC?

Fittings for Low-Pressure Sections

Although HPLC stands for high-pressure liquid chromatography, not all parts of the system operate at high pressures. The low-pressure areas include:

• The tubing between solvent reservoirs and the pump inlet
• The waste lines following the HPLC column

In these sections, fittings are typically ¼-28 flat-bottom and used with 1/8” OD tubing. Polymeric fittings (such as PEEK) are commonly preferred here because they’re easier to handle, require no tools, and provide excellent chemical resistance for solvent compatibility.

Fittings for High-Pressure Sections

High-pressure areas are generally located between the pump outlet and the analytical column. These connections must withstand the full system pressure—often exceeding 6,000 psi in UHPLC systems. The most common high-pressure fittings are 10-32 coned fittings used with 1/16” OD tubing.

For typical HPLC pressures, polymeric fittings may suffice. However, for UHPLC or other ultra-high-pressure applications, metal nuts and ferrules (usually stainless steel) are strongly recommended to ensure safe, leak-free connections under demanding conditions.

Typical HPLC System Overview

Below is a simplified diagram of an HPLC system, showing where low- and high-pressure fittings are typically used. The low-pressure fittings are used near the solvent reservoirs and waste lines, while the high-pressure fittings are used between the pump and column.

Other Common Fitting Types

In addition to ¼-28 and 10-32 fittings, other fitting types are frequently used throughout chromatography setups:

• Barbed fittings: Ideal for waste lines and non-pressurized tubing connections.
• Luer fittings: Commonly used for connecting syringes to tubing or for quick, low-pressure connections.
• Large-bore fittings: Used in specialized applications requiring higher flow rates or larger tubing diameters.

Chrom Tech offers a complete selection of fittings for both low- and high-pressure connections, ensuring compatibility with virtually any HPLC configuration.

Other Chromatography Consumables to Keep on Hand

Maintaining consistent performance in your HPLC system requires more than just the right fittings. Chrom Tech recommends keeping essential consumables in stock to minimize downtime and ensure smooth operation:

• Chromatography vials and closures
• Sample preparation consumables such as syringe filters and SPE cartridges
• Tubing and fittings
• HPLC columns
• Syringes and sample loops
• Instrument-specific replacement parts
• HPLC solvents and reagents

As a trusted chromatography supplier, Chrom Tech provides the fittings, consumables, and replacement parts you need to keep your lab running efficiently. Reach out to our technical support team for help identifying the correct fittings or replacement components for your specific system.