Lifetime Testing of Agilent RoHS Compliant Ion Injectors on Multiple Agilent LC/MS Triple Quadrupole Instruments to Test Their Robustness towards Heavy Matrix and a Novel Cleaning Technique

Importance of the Topic

The ion injector is a critical interface in LC/MS systems, guiding ions from atmospheric pressure to the vacuum region. Heavy sample matrices such as bovine urine can deposit contaminants on ion optics, causing signal suppression, autotune failures and maintenance alerts. Ensuring robust, compliant ion injectors supports reliable quantitation in routine analysis, while meeting environmental restrictions on hazardous materials under RoHS regulations.

Objectives and Study Overview

This study evaluated the lifetime performance of Agilent RoHS-compliant ion injectors on two triple quadrupole LC/MS instruments under heavy matrix stress. Over 13,000–15,000 injections of dilute bovine urine were performed to test injector robustness and the effectiveness of a new Citranox-based cleaning protocol combined with routine autotuning.

Methodology and Instrumentation

Sample Preparation and Analysis Workflow:

• Bovine urine diluted 1:1 with acetonitrile/water (50:50) and centrifuged at 4,500×g for 10 min.
• UHPLC guard column: Zorbax Extend-C18, 2.1 mm, 80 Å.
• Isocratic flow: 0.8 mL/min of acetonitrile/water (50:50) with 0.1 % formic acid.
• Injection volumes: 2 µL on G6475A system; 10 µL on Ultivo system.
• Detector gain settings: 4 for G6475A; 3 for Ultivo.
• Checktunes performed at every 1,000 injections; autotune invoked if out of tolerance.

Cleaning Protocol:

• Ion injector tips protected in pipette tips, sonicated 15 min in 2 % Citranox solution.
• Rinsed and sonicated three times in LC/MS-grade water, then sonicated 15 min in methanol.

Used Instrumentation

Instrument 1 (G6475A LC/TQ):

• Multisampler G7167B
• Binary Pump G7120A
• G6475A LC/TQ with Ion Injector G3911-30000

Instrument 2 (Ultivo LC/TQ):

• Vialsampler G7129C
• Binary Pump G1312B
• Ultivo LC/TQ with Ion Injector G3911-30001

Main Results and Discussion

Tune Ion Abundances:

• G6475A: Ion injector cleaning alone restored negative-mode abundances but required autotuning to recover positive-mode signals; a repair at 5,000 injections improved recovery further.
• Ultivo: Cleaning significantly boosted abundances in both polarities; post-cleaning autotuning led to gradual reduction in electronic voltages, suggesting improved detector health.

Mass Calibration and Peak Width:

• G6475A remained within ±0.14 Da for m/z assignment and peak width after cleaning, with autotuning tightening deltas close to zero.
• Ultivo showed occasional out-of-tolerance events when autotune was skipped; autotuning post-cleaning maintained mass and FWHM tolerances (±0.1 Da m/z, ±0.14 Da width).
• Visual inspection of the source inlet before and after the experiment confirmed significant soiling on both systems.

Benefits and Practical Applications

The new RoHS-compliant injectors demonstrated high robustness to heavy biological matrices, enabling extended operation (more than 13,000 injections) with minimal downtime. The Citranox-based cleaning protocol with routine autotuning preserves performance, reduces maintenance frequency and supports sensitive quantitative workflows in pharmaceutical, environmental and food analysis laboratories.

Future Trends and Opportunities

• Systematic studies on solvent and surfactant alternatives to optimize cleaning efficacy.
• Automation of cleaning and tuning cycles guided by real-time performance metrics.
• Extension of lifetime testing to other analyte classes and more complex sample matrices.
• Integration with instrument control software for predictive maintenance and reduced downtime.

Conclusion

Lifetime testing confirms that Agilent RoHS-compliant ion injectors withstand heavy-matrix stress when combined with a Citranox cleaning workflow and regular autotuning. This approach ensures stable signal recovery, maintains mass accuracy and peak shape, and supports environmentally compliant mass spectrometry operations.