Alliance Carryover Performance Part 2: Carryover Improvement Achieved Through Needle Wash Optimization for the 2018 Alliance HPLC System

Significance of the Topic

The minimization of sample carryover in HPLC workflows is critical for ensuring data integrity, reducing assay variability, and avoiding false positives in sequential injections. Optimizing needle wash procedures enhances laboratory throughput and reliability, particularly for challenging analytes prone to surface adhesion.

Aims and Study Overview

This application note evaluates how adjustments in needle wash mode and solvent composition on the 2018 Alliance HPLC System influence carryover for two test compounds, coumarin and quetiapine fumarate. The study compares standard, double, and extended wash cycles alongside different wash solvents to quantify carryover reduction.

Used Instrumentation

• 2018 Alliance e2695 Separations Module with 100 µL syringe and passive column preheater
• 2998 PDA Detector set at 275 nm (coumarin) and 230 nm (quetiapine fumarate)
• CORTECS C18 2.7 µm, 3 × 100 mm column for coumarin analysis
• XBridge BEH C8 5 µm, 4.6 × 250 mm column for quetiapine fumarate assay
• Empower 3 Chromatography Data Software

Methodology

Coumarin carryover was measured using a challenge solution saturating the detector and a 0.01 % standard, calculating carryover as the ratio of blank peak area to standard peak area times 0.01. Quetiapine fumarate carryover was assessed with challenge concentrations within the linear detector range and expressed as the blank peak area over standard peak area times 100. Each compound was injected in six replicates under varying wash modes and solvent compositions.

Main Results and Discussion

Switching wash modes from Normal to Double reduced carryover by 1.2× for coumarin and 1.5× for quetiapine fumarate. The Extended mode, which washes before and after injection, further improved results by 2.5× and 2.7× respectively. For quetiapine fumarate, replacing a 90:10 water:acetonitrile wash with a 70:30 methanol:water mixture decreased carryover by an additional factor of three, reflecting enhanced solubilization of the analyte on the needle surface.

Benefits and Practical Applications

Optimized needle wash protocols enable laboratories to:

• Maintain low-level quantitation accuracy by eliminating cross-sample contamination
• Improve assay reproducibility for compounds with strong surface affinity
• Enhance sample throughput by reducing the need for additional blanks

Future Trends and Potential Uses

Advancements may include automated selection of wash parameters based on analyte properties, integration of real-time carryover monitoring, and expansion of solvent libraries to cover a broader range of compound chemistries. Emerging machine-learning algorithms could further predict optimal wash conditions for new methods.

Conclusion

This study demonstrates that strategic optimization of needle wash modes and solvent composition on the 2018 Alliance HPLC System significantly reduces sample carryover for challenging analytes. Implementing Double or Extended wash cycles and tailoring wash solvents can deliver up to a 2.7× improvement in carryover reduction.

Reference

1. Jenkins T, Waite M. Low Sample Carryover with Key Performance Indicators on the Alliance HPLC System. Waters Technology Brief 2018;720004534EN.
2. United States Pharmacopeia. Quetiapine Fumarate USP 40–NF35 S1. USP–NF Online. 2017.
3. Dolan J. Autosampler Carryover. LCGC Europe. 2018;19(10):522–529.