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Comprehensive Analysis of Waters Alliance 2695 High-Performance Liquid Chromatography System

The Waters Alliance 2695 High-Performance Liquid Chromatography (HPLC) system is a benchmark product in the field of HPLC technology. Since its launch in 1996, it has undergone multiple technological upgrades and improvements, becoming a widely used analytical tool in pharmaceuticals, chemicals, food safety, environmental monitoring, and life sciences research. This system integrates advanced solvent management, sample management, and column temperature control technologies, delivering exceptional analytical performance, reliability, and ease of operation. Below is a detailed introduction to this HPLC system from four aspects: system composition, technical features, performance parameters, and application areas.

System Composition and Modular Design

The Alliance 2695 is the core separation unit of Waters' HPLC and LC-MS systems, consisting of three main modules: the solvent delivery system, sample management system, and column oven. The solvent delivery system employs a quaternary gradient pump design, capable of handling 1-4 mobile phases simultaneously. With an integrated vacuum degasser and precise low-pressure mixing technology, it ensures high accuracy and reproducibility in solvent proportioning. The sample management system features a 120-position autosampler tray that supports standard 2mL sample vials and offers an optional temperature control module (4°C–40°C), making it particularly suitable for analyzing thermally sensitive samples.

The system adopts a modular design philosophy, allowing users to customize it with various functional components. For example, the column oven comes in two versions: a heating-only model (ambient +5°C to 65°C) and a heating/cooling model (4°C to 65°C), effectively reducing retention time drift and peak shape variations caused by temperature fluctuations. Additionally, the system supports optional modules such as post-column derivatization, multi-position switching valves (enabling automatic switching between 3-6 columns), and GPC/SEC components, significantly expanding its application scope.

Core Technical Features and Advantages

The Alliance 2695 system incorporates multiple patented Waters technologies, ensuring its leading position in the HPLC field. The dual-piston serial pump design, combined with digitally controlled linear drive technology, delivers pulse-free solvent flow without requiring a pulse damper. The flow rate precision is as high as <0.075% RSD, with an accuracy of ±1% or ±10μL/min. The system features a unique "fixed dwell volume" design (less than 650μL), which remains unaffected by backpressure changes, ensuring accurate and reproducible gradient elution.

In terms of sample management, the system is highly automated and intelligent. Injection volumes can be precisely controlled within a range of 0.1–100μL (standard) or 0.1–2000μL (optional), with an injection precision of <0.5% RSD and carryover below 0.0025%. The system also supports programmable needle wash routines and adjustable needle heights, accommodating samples of varying viscosities and different vial specifications. An integrated seal wash system automatically cleans the pump piston seal, significantly extending seal life when using buffer salt mobile phases.

Outstanding Performance Parameters

The Alliance 2695 system excels in various performance metrics. It offers a wide flow rate range (0.010–10.000 mL/min, in 0.001 mL/min increments) and a maximum operating pressure of 34.5 MPa (5000 psi), meeting diverse needs from routine analysis to semi-preparative applications. The gradient system provides 11 gradient curve options (including linear, step, concave, and convex), with gradient accuracy of ±0.5% and precision <0.15% RSD.

In terms of detector compatibility, the system can be coupled with Waters' full range of detectors, including photodiode array (PDA), UV/Vis, fluorescence (FLR), refractive index (RI), evaporative light scattering (ELS), and various mass spectrometers. Notably, when paired with the ACQUITY QDa mass detector, it enables easy acquisition of mass spectral data during routine HPLC analysis, enhancing compound identification capabilities.

Broad Application Areas

Thanks to its stable and reliable performance, the Alliance 2695 system plays a crucial role in multiple fields. In the pharmaceutical industry, it is FDA-approved and listed in pharmacopeias, widely used for drug quality control, dissolution testing, and stability studies. In food safety, the system can detect pesticide residues, additives, and illegal substances. In environmental monitoring, it analyzes trace organic pollutants in water.

In life sciences research, the system is suitable for separating and analyzing biomolecules such as proteins, peptides, nucleic acids, and carbohydrates. Additionally, with the optional GPC/SEC module, it can be used for polymer molecular weight distribution analysis. The system's seamless integration with Waters Empower or MassLynx software enables full automation from instrument control and data acquisition to result analysis, making it ideal for compliance in GLP/GMP environments.

Conclusion

The Waters Alliance 2695 HPLC system represents the maturity and reliability of HPLC technology. Its integrated design, superior manufacturing quality, and continuous technological advancements have kept it at the forefront of the industry for over two decades. The system's excellent reproducibility, ease of operation, and broad applicability make it a trusted tool in analytical laboratories. With the introduction of new technologies such as CORTECS 2.7μm columns, the Alliance 2695 system further narrows the performance gap between HPLC and UPLC, providing users with a more flexible and efficient analytical solution.