7725 - Syringe Loading Inj, w/MBB, SS

The IDEX Rheodyne Model 7725 is a six-port manual sample injector engineered for precise sample introduction in analytical HPLC workflows. Designed with a built-in needle port in the front of the valve, the 7725 allows direct loop loading for dependable manual injections with strong repeatability and efficient sample handling.

The Model 7725 is the stainless steel analytical-scale version in the Rheodyne 7725 series. It is designed for laboratories that need robust pressure capability, reliable switching, and proven manual injection performance across routine chromatography methods. A 20 µL sample loop is supplied as standard, making the valve well suited for common analytical HPLC applications.

One of the defining features of the 7725 is its Make-Before-Break (MBB) valve architecture. As the handle rotates from LOAD to INJECT, the valve maintains uninterrupted mobile phase flow during switching. This continuous-flow design helps support stable operation while the sample moves through the loop and onto the column.

The valve is rated to 5000 psi and up to 80°C, providing the durability needed for demanding analytical separations. Wetted materials include 316 stainless steel, alumina ceramic, and an inert polymer, helping the injector deliver chemical resistance, dependable sealing, and long-term performance in chromatography systems.

Key Features

• Six-port manual injector for analytical HPLC workflows
• Front-mounted built-in needle port for direct sample loading
• Stainless steel construction for high-pressure applications
• Make-Before-Break flow design for uninterrupted switching
• Maximum pressure rating of 5000 psi
• Maximum operating temperature of 80°C
• Standard 20 µL sample loop included

Injection Flexibility

The Model 7725 supports both complete loop filling and partial loop filling. Complete loop filling delivers the highest precision because the injected volume is determined by the loop. Partial loop filling is useful when sample quantity is limited and the syringe determines the injected volume. This flexibility makes the 7725 suitable for both routine laboratory use and limited-volume analytical work.

The manual also notes that a 2 µL internal sample loop is available for the 7725, allowing users to configure the valve for smaller-volume injections when method requirements call for lower sample volume and tighter sample handling.

Supplied with the Valve

The Model 7725 is supplied with fitting sets for all ports along with the accessories needed for installation and routine use. Included items consist of hex keys, needle port cleaner, mounting screws, vent tubes, and a 20 µL sample loop.

Maintenance and Serviceability

The 7725 is designed for straightforward maintenance. The primary wear components are the rotor seal and stator face assembly, both of which can be replaced as part of routine service. For long-term upkeep, IDEX Rheodyne offers a dedicated 7725-999 RheBuild™ Kit containing the parts, tools, and instructions needed to maintain valve performance.

Ideal Applications

The Model 7725 is an excellent fit for laboratories needing a manual stainless steel HPLC injector with high-pressure capability, repeatable sample introduction, and continuous-flow switching performance. It is especially useful in analytical chromatography methods where reliability, durability, and precise loop-based injection are critical.