Abstract: This study aimed to develop a reliable method for determining the content of ethyl p-methoxycinnamate in hawthorn. The compound was analyzed using gas chromatography (GC). A SE-30 column was used with a column temperature of 200°C. The results showed a strong linear relationship (r = 0.9995), an average recovery rate of 97.8%, and a relative standard deviation (RSD) of 1.1% (n=5). The proposed method is simple, accurate, and suitable for quality control of hawthorn as a medicinal material.
Keywords: Gas chromatography; Hawthorn; Ethyl p-methoxycinnamate
Hawthorn, scientifically known as Kaempferia galanga L., is a plant from the Zingiberaceae family. Its dried rhizomes are commonly cultivated in regions such as Taiwan, Guangdong, Guangxi, and Yunnan. It has been traditionally used for its warming, digestive, and pain-relieving properties. In the 2000 edition of pharmacopoeias, the volatile oil content must be no less than 4.5% (ml/g), with ethyl p-methoxycinnamate being the main component. This paper presents a gas chromatographic method for quantifying ethyl p-methoxycinnamate in hawthorn samples, which can serve as an effective quality evaluation parameter.
1. Instruments and Reagents
1.1 Instrumentation: A Puri GC7800 gas chromatograph and an ultrasonic cleaner were used for the analysis.
1.2 Reagents: The reference substance of ethyl p-methoxycinnamate was obtained from the China National Institute for Food and Drug Control, with batch number 0835.9601. It was purified by recrystallization and confirmed to have a purity of over 98%. All other reagents were of analytical grade.
1.3 Sample Preparation: Commercially available hawthorn samples were used. The roots were identified by our laboratory and then ground and sieved through a 40-mesh sieve.
2. Methods and Results
2.1 Chromatographic Conditions: A glass column (2.1 m × 0.3 cm) coated with 10% SE-30 was employed. The column temperature was set at 200°C, while the injection and detector temperatures were both 250°C. The carrier gas flow rate was 80 kPa, hydrogen flow rate 100 kPa, and air flow rate 50 kPa. The sensitivity was set at 10â»Â¹.
2.2 Extraction Optimization: Ethyl acetate and methanol were tested as solvents. Ultrasonic extraction for 30 minutes yielded the highest extraction efficiency. The results indicated complete extraction within this time frame.
2.3 Linearity Test: Reference solutions of ethyl p-methoxycinnamate were prepared at concentrations of 0.5, 1.0, 2.0, 5.0, and 10.0 mg/mL. Each solution was injected into the GC, and peak areas were recorded. A linear regression equation was established: Y = 316412.8X - 43265.8, with r = 0.9995. The linearity was good in the range of 1–20 μg.
2.4 Precision and Stability: Five repeated injections of the same sample showed an RSD of 0.8% based on peak area. Stability tests over 24 hours revealed an RSD of 1.0%, indicating good sample stability.
2.5 Reproducibility: Five samples of the same type were tested, yielding contents of 39.3, 39.6, 40.9, 40.2, and 40.3 mg/g. The average was 40.1 mg/g, with an RSD of 1.6%.
2.6 Recovery Test: Known amounts of reference substance were added to 0.5 g of hawthorn samples, and the recovery was calculated to be 97.8%, with an RSD of 1.1% (n = 5).
2.7 Sample Analysis: Approximately 1 g of hawthorn was mixed with 10 mL of methanol, weighed, and sonicated for 30 minutes. After adjusting for weight loss, the solution was filtered and used as the test sample. Both the reference solution (4.0 mg/mL) and the test solution were injected, and the results are presented in the table.
3. Discussion
The quality of hawthorn is typically judged by its strong aromatic scent and pungent taste. The volatile oil content ranges between 3% and 4%, with ethyl p-methoxycinnamate as the primary component. Accurate determination of this compound helps ensure the quality of medicinal materials and supports the improvement of hawthorn’s quality standards.
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