Determination of Chlorogenic Acid in Coffee Products According to DIN 10767

Importance of the topic

Coffee is one of the most consumed beverages worldwide and its quality is strongly influenced by phenolic compounds such as chlorogenic acids. These compounds affect flavor, antioxidant capacity and may cause digestive discomfort in sensitive individuals. Accurate quantification of chlorogenic acid content is essential for product standardization, authenticity testing and health‐related research.

Objectives and overview

This application note illustrates a validated HPLC method for determining chlorogenic acid in roasted coffee according to DIN 10767. The study assesses method linearity, sensitivity, precision and accuracy using an Agilent 1260 Infinity LC system. Performance comparisons are made between conventional C18 and reduced‐diameter “solvent saver” columns as well as core‐shell columns of varying dimensions to optimize solvent consumption and sample throughput.

Methodology and instrumentation

Sample preparation involved Soxhlet extraction of 2 g roasted coffee with 150 mL methanol/water (50/50 v/v), filtration through a 0.45 µm regenerated cellulose syringe filter and dilution to volume.

• Instrument: Agilent 1260 Infinity LC system with binary pump, autosampler with thermostat, thermostatted column compartment and diode array detector (324 nm).
• Software: Agilent OpenLAB CDS ChemStation for LC.
• Columns:
• ZORBAX Eclipse Plus C18, 4.6 × 150 mm, 5 µm
• Poroshell 120 EC-C18, 3.0 × 150 mm, 2.7 µm
• Poroshell 120 EC-C18, 3.0 × 50 mm, 2.7 µm
• Mobile phase: A = water + 1 % phosphoric acid; B = acetonitrile; gradient from 10 % to 40 % B over 40 min.
• Flow rates ranged from 1.0 mL/min (4.6 mm id) down to 0.43 mL/min (3.0 mm id), with injection volumes from 1.4 to 10 µL.

Main results and discussion

A calibration curve for 3-O-caffeoylquinic acid (3-CQA) exhibited excellent linearity (R2 > 0.99998) over 0.156–20 mg/L. Limits of detection and quantification on the conventional column were 0.03 mg/L (S/N = 3) and 0.09 mg/L (S/N = 10), respectively. Precision at 10 mg/L (n = 10) yielded retention‐time RSD = 0.07 % and area RSD = 0.15 %. Carryover was negligible in blank injections following high‐level standards.

Using a 3.0 × 150 mm solvent saver column reduced solvent use by 57 % and improved sensitivity (LOD = 0.015 mg/L, LOQ = 0.05 mg/L) without compromising precision (r.t. RSD = 0.22 %, area RSD = 0.21 %). Analysis of a real roasted coffee sample gave 1.19 g/100 g n-chlorogenic acid and a total of 2.61 g/100 g all isomers.

Shorter core-shell columns (3.0 × 50 mm) and elevated flow rates enhanced throughput. Gradient times reduced by two-thirds achieved full separation in 13 min, doubling flow to 0.86 mL/min shortened runs to 6.5 min, and 1.72 mL/min allowed 3.25 min cycles.

Benefits and practical applications

The method offers robust accuracy, high reproducibility and flexible throughput options. Solvent saver and short columns lower solvent costs and increase sample capacity. It can be integrated into routine quality control labs for coffee authenticity, roasting process monitoring and nutritional labeling.

Future trends and applications

Future work may explore ultrahigh‐performance LC to further reduce analysis time, coupling with mass spectrometry for structural confirmation, online extraction techniques for automation and expanded profiling of related polyphenols. Data integration into LIMS and real‐time process monitoring are expected to streamline coffee QC workflows.

Conclusion

This application note confirms that the Agilent 1260 Infinity LC system meets DIN 10767 requirements for chlorogenic acid determination in roasted coffee. Comparable or improved sensitivity and precision were achieved with solvent saver and core‐shell columns. Adjustments in column dimensions and flow rates enable tailored solvent consumption and throughput for diverse laboratory needs.

Reference

1. European Food Safety Authority. Scientific Opinion on coffee health claims including chlorogenic acids. EFSA Journal 9(4):2057 (2011).
2. DIN 10767. Coffee and coffee products – Determination of chlorogenic acids by HPLC (1992).
3. DIN ISO 20481. Coffee and coffee products – Determination of caffeine content by HPLC (ISO 20481:2008) (2011).
4. DIN 10779. Coffee and coffee products – Determination of 16-O-methyl cafestol content in roasted coffee by HPLC (2011).
5. Agilent Application Note, publication number 5991-2853EN.
6. DIN EN 14132. Foodstuffs – Determination of ochratoxin A in barley, roasted coffee – HPLC with immunoaffinity clean-up (EN 14132:2009) (2009).
7. Agilent Application Note, publication number 5991-2854EN.
8. Herrmann K. Fortschritte der Chemie organischer Naturstoffe Bd. 35, Springer Verlag, 73–132 (1978).