Rapid Tea Analysis on Poroshell 120 SB-C18 with LC/MS

Significance of the Topic

The analysis of catechins and caffeine in tea is crucial for understanding the health benefits associated with polyphenolic compounds and for quality control in the food and beverage industry. Green tea is a rich source of antioxidants, and rapid, reliable quantification of its bioactive constituents supports research into nutritional efficacy, product standardization, and process optimization.

Objectives and Study Overview

This study aimed to adapt a published high‐performance liquid chromatography (HPLC) method for catechin analysis onto a superficially porous Poroshell 120 SB‐C18 column, achieving faster separations with lower backpressures and compatibility with mass spectrometry detection. Ten analytes (nine catechins and caffeine) were separated and quantified in bottled and brewed teas. A lifetime test evaluated column robustness using unfiltered green tea at high pressure.

Methodology and Instrumentation

Analyses were conducted on an Agilent 1200 Series Rapid Resolution LC coupled to a 6410 Triple Quadrupole MS in selected ion monitoring (SIM) mode. Key instrumentation and conditions included:

• Columns: Agilent Poroshell 120 SB‐C18 (2.1×50 mm, 2.7 µm) and larger formats for method scaling
• Mobile phase: 0.2% acetic acid in water (A) and acetonitrile (B), gradient 10–15–27% B over 0.71 min at 1.5 mL/min
• Mass spectrometry: electrospray source, –3500 V negative mode for catechins, +3500 V for caffeine, 350 °C drying gas
• Calibration: six‐point curves (0.5–10 ng on column) run in triplicate
• Sample preparation: bottled teas diluted 1:10; brewed teas injected undiluted

Main Results and Discussion

Method transfer from a 150×4.6 mm, 5 µm column to the 50×2.1 mm Poroshell column reduced run time from 15 min to under 1 min while preserving peak resolution. Screening of MS-compatible mobile phases identified acetic acid as optimal for signal intensity. All ten analytes exhibited linear calibration (R2>0.995). Quantification of commercial bottled teas revealed variations in catechin profiles linked to tea type and origin. Steeping studies on green and black tea bags showed maximum catechin extraction at 6–10 min with subsequent degradation, notably of epigallocatechin gallate. A lifetime experiment demonstrated stable performance over 1500 injections of undiluted green tea at 550 bar, highlighting the column’s resistance to fouling.

Method Benefits and Applications

The optimized Poroshell 120 SB‐C18 method offers:

• High‐throughput analysis with sub‐minute separations
• Reduced instrument backpressure enabling use of lower‐rated pumps
• Strong linearity and sensitivity for trace catechin/caffeine quantification
• Robustness to dirty, unfiltered samples for routine QA/QC
• Compatibility with LC/MS workflows in food and beverage laboratories

Future Trends and Applications

Advancements in column technology and high‐resolution mass spectrometry will further enhance speed and specificity in polyphenol profiling. Integration of on‐line sample cleanup, ultra‐high‐pressure LC, and data‐driven analytics (machine learning) may yield real‐time quality monitoring. Expansion of rapid methods to other natural products and nutraceuticals is expected.

Conclusion

This work successfully demonstrated the rapid transfer of a catechin analysis onto an Agilent Poroshell 120 SB‐C18 column with LC/MS detection. The method delivers sub‐minute separations, robust quantification, and sustained column life under challenging sample conditions, making it well suited for high‐throughput tea analysis and broader applications in food chemistry.

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