Performance Evaluation of the Agilent InfinityLab Pro iQ Series

Significance of the topic

Rapid, sensitive and robust analytical methods for small-molecule pharmaceuticals are essential across drug discovery, medicinal chemistry, QA/QC and manufacturing control. Analytical platforms that combine high chromatographic resolution with reliable mass-detection and simple operation reduce turnaround times, improve trace-level impurity and cleaning-validation workflows, and enable walk-up usage in multiuser laboratories.

Objectives and study overview

This application note evaluated the Agilent InfinityLab Pro iQ Series (single‑quadrupole MS coupled to UHPLC) for simultaneous separation and quantification of eight representative small‑molecule drugs (amoxicillin, aspirin, buspirone, captopril, chloramphenicol, erythromycin, ibuprofen, omeprazole). Key goals were to demonstrate chromatographic speed, sensitivity (limits of quantification), linear dynamic range, reproducibility, and the impact of ionization source selection (ESI versus Agilent Jet Stream, AJS) for routine pharmaceutical analysis.

Methodology and instrumentation

Sample preparation and standards:

• Individual 1 mg/mL stock solutions prepared in methanol (amoxicillin and omeprazole in DMSO due to solubility limits).
• Combined working stock at 10 µg/mL in 1:1 water:methanol, diluted into 9:1 water:methanol to produce calibration and test ranges from 0.02 to 1,000 ng/mL.

Chromatography and detection (summary):

• Column: Agilent ZORBAX Eclipse Plus C18 RRHD, 2.1 × 100 mm, 1.8 µm.
• LC system: Agilent 1290 Infinity II with OpenLab CDS.
• Flow rate: 0.6 mL/min; column temperature: 40 °C; injection volume: 10 µL; UV detection at 254 nm used as complementary detection.
• Gradient: rapid reversed‑phase program delivering full separation within ~9 minutes (initial %B 5%, ramp to 60% by 6 min and to 95% by 8 min, short re-equilibration to 5% B).
• Mobile phase additives screened: 0.5 mM ammonium fluoride, 5 mM ammonium formate + 0.1% formic acid, and 0.1% formic acid. Optimal additives varied by analyte (e.g., captopril: 5 mM ammonium formate + 0.1% FA; erythromycin: 0.1% FA; most others: 0.5 mM ammonium fluoride).

Mass spectrometry (summary):

• MS: Agilent InfinityLab Pro iQ Plus (G6170A) single quadrupole, operated in both scan (m/z 100–800) and Selected Ion Monitoring (SIM) modes for quantitation.
• Ionization: evaluated conventional electrospray ionization (ESI) and Agilent Jet Stream (AJS) sources; polarity chosen per analyte (negative for chloramphenicol and ibuprofen; positive for the rest).
• Sensitivity optimized by selecting the most intense ion per compound (e.g., [M+H]+, [M-H]–, adduct/fragment ions used where appropriate).

Instrumentation used

• Agilent 1290 Infinity II LC system (modules G7120A pump, G7129B autosampler with heated compartment, G7117B DAD).
• Agilent InfinityLab Pro iQ Plus single‑quadrupole MS (G6170A) with ESI and Agilent Jet Stream options.
• ZORBAX Eclipse Plus C18 RRHD, 2.1 × 100 mm, 1.8 µm (p/n 959758-902).
• Software: Agilent OpenLab CDS (version 2.8 Update08 FP2).

Main results and discussion

Chromatography and detection:

• All eight analytes were resolved within approximately nine minutes. Two compounds (captopril and erythromycin) were essentially UV-inactive at 254 nm and required MS detection for reliable monitoring.

Linearity and sensitivity:

• Linear calibration ranges covered up to four orders of magnitude for some analytes; R² values exceeded 0.995 for all compounds. Aspirin required a quadratic fit across the full tested range, suggesting a narrower strictly linear window at the highest concentrations.
• Limits of quantification (LOQ) spanned from 0.02 ng/mL (buspirone) up to 5 ng/mL (captopril); representative LOQs: buspirone 0.02 ng/mL (S/N ≈ 40), chloramphenicol 0.1 ng/mL, erythromycin 0.1 ng/mL, omeprazole 0.1 ng/mL, amoxicillin 1 ng/mL, ibuprofen 1 ng/mL, aspirin 0.5 ng/mL.

Reproducibility:

• Repeatability was strong: relative standard deviations (n = 4) were ≤3% across tested concentrations (0.5 and 1 ng/mL for applicable compounds), demonstrating robust quantitative precision for trace-level assays.

Impact of ion source (ESI vs AJS):

• Switching from conventional ESI to Agilent Jet Stream gave a two‑ to five‑fold increase in signal intensity across the analyte panel at 10 ng/mL, indicating substantial sensitivity gains with AJS for low‑level quantitation.

Benefits and practical applications of the method

• Fast throughput: sub‑10‑minute separations enable high sample throughput suited to screening and routine QA/QC tasks.
• Trace-level performance: LOQs down to 0.02 ng/mL and broad linear ranges support cleaning validation and trace impurity/contaminant monitoring.
• Walk-up suitability: combination of robust UHPLC and a user‑friendly single‑quadrupole MS is appropriate for multiuser laboratories and medicinal chemistry environments where ease of use is important.
• Method versatility: screening of mobile phase additives and SIM acquisition allow adaptation to diverse chemistries and ionization behaviors.

Future trends and potential applications

• Further integration with high‑resolution MS would extend structural confirmation for impurities while retaining the demonstrated UHPLC speed.
• Automated method scouting and AI‑assisted optimization could shorten development time when transferring the workflow to other analyte classes or matrices.
• Greener chromatography (reduced organic solvent use) and miniaturized flow paths may reduce cost per analysis while maintaining sensitivity.
• Expanded use of enhanced ion‑source technologies (e.g., AJS variants, alternative desolvation schemes) and improved data‑processing pipelines will push LOQs lower and simplify trace‑level reporting.

Conclusion

The Agilent InfinityLab Pro iQ Series combined with a rapid reversed‑phase UHPLC method achieved fast baseline separations of eight structurally diverse pharmaceuticals in roughly nine minutes, with excellent sensitivity (LOQ down to 0.02 ng/mL), wide linear ranges (R² > 0.995 for most compounds), and reproducible quantitation (RSD ≤ 3%). The Agilent Jet Stream source substantially increased signal versus conventional ESI, enhancing trace-level detection. These attributes make the platform well suited for walk‑up analytical labs, medicinal chemistry screening, QA/QC, and cleaning-validation/trace impurity workflows.

Reference

• Guricza L., Batoon P., Performance Evaluation of the Agilent InfinityLab Pro iQ Series: Assessment of key performance metrics in the simultaneous separation of eight drug substances. Agilent Technologies Application Note, 2026.