This document details a method for analyzing flavonoids in complex plant extracts, specifically using orange juice as a sample matrix. The technique combines Capillary Electrophoresis (CE) for separation with Electrospray Mass Spectrometry (ESI-MS) for specific identification of analytes like hesperidine and naringin. This approach offers high sensitivity and specificity for monitoring product quality in food and flavor applications.
The experimental setup utilizes an Agilent Capillary Electrophoresis system equipped with DAD detection and controlled via Agilent ChemStation software. The method employs 50 um id capillaries with a UV detection window, a 50 mM borate buffer at pH 9.3, and positive ion detection modes to identify specific m/z values for the target compounds.
| Capillary ID | 50 um |
|---|---|
| Capillary Length | 75 cm |
| Buffer Concentration | 50 mM |
| Buffer pH | 9.3 |
| Sheath Flow Rate | 4 uL/min |
| HPLC Pump Flow | 400 pL/min |
| Split Ratio | 1:100 |
| Sheath Liquid Composition | 1% formic acid in 50 % methanol |
| Hesperetin m/z | 325 |
| Naringin m/z | 581 |
| Voltage | 30 kV |
| Temperature | 25°C |
| Nebulizing Gas Pressure | 20 psi |
| Drying Gas Flow | 6.0 L/min |
| Injection Pressure | 1500 mbar sec |
The analysis focused on hesperidine (a flavone glucoside) and naringin (a rhamnoglucoside flavanone).
Hesperetin was found at an m/z value of 325, corresponding to the Na adduct mass.
Naringin was detected as the protonated adduct at an m/z value of 581.
The correlation coefficient for the naringin detection linearity was 0.99884.