Comparative Study of Spectroscopic & Chromatographic Methods for Caffeine Determination in Commercial Tea

Tan, Hui Sean (2026) Comparative Study of Spectroscopic & Chromatographic Methods for Caffeine Determination in Commercial Tea. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Caffeine is a widely consumed bioactive compound found in commercial tea and serves as an important quality and regulatory parameter in food analysis. Due to the complex nature of tea matrices, accurate determination of caffeine requires analytical methods that are both sensitive and selective. This study presents a comparative evaluation of UV-Vis spectrophotometry and High Performance Liquid Chromatography (HPLC) for the determination of caffeine content in selected commercial tea samples. Caffeine standard solutions were prepared and analysed using both UV-Vis spectrophotometry and HPLC to construct calibration curves. Method validation was performed by assessing key parameters including linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The validated methods were then applied to three commercial tea brands: AHMAD, BOH and LOTUS’s. The results showed excellent linearity for both methods, with R² values of 0.999 for UV-Vis and 1.000 for HPLC. HPLC shows higher sensitivity, with lower LOD and LOQ compared to UV-Vis. Accuracy as percentage recovery ranged from 95.3% to 103.4% for UV-Vis and 98.1% to 101.7% for HPLC. Precision results indicated that HPLC provided more consistent measurements with RSD values between 0.81% and 3.76% while UV-Vis showed RSD values between 1.22% and 6.53%. Analysis of commercial tea samples revealed that UV-Vis spectrophotometry consistently produced higher caffeine concentrations compared to HPLC. This discrepancy is attributed to matrix interference from co-extracted compounds which absorb in the ultraviolet region and affect UV-Vis measurements. In contrast, HPLC provided more reliable results due to effective chromatographic separation prior to detection. Overall, the findings demonstrate that HPLC is a more accurate and reliable method for caffeine determination in complex tea matrices, while UV-Vis spectrophotometry remains suitable for rapid screening applications where high throughput is prioritised over absolute accuracy.