Direct analysis of volatile components from intact jujube by carbon fiber ionization mass spectrometry

Shihao Sun,Lei Wu,Jianxun Zhang,Yue Su,Hui Xi,Peng Li,Guixin Peng,Yihan Zhang

doi:10.1186/s13065-019-0641-4

Abstract

In situ analysis of odor is an important approach to connect odor with chemical composition. However, it is difficult to conduct a rapid direct analysis of the odor sample because of low analyte concentration and sampling. To achieve the direct analysis, a carbon fiber ionization mass spectrometry (CFI-MS) method has been developed and applied to measure volatile components releasing from intact jujube. To build the CFI source, a 2.0-cm long carbon fiber bundle was integrated on the pin of a commercial corona discharge needle by mean of a 1.3-cm long stainless hollow tube. Odor sample driven by N2 gas can be directly introduced to the carbon fiber bundle to complete the ionization of analytes. Acetic acid, ethyl acetate, ethyl caproate, octyl acetate, and damascone present in jujube were selected to evaluate the performance of the CFI-MS method on quantitative analysis of the gaseous sample. Good lineary was obtained (R2 ≥ 0.9946) between 5.0 and 500.0 ng/L with limits of detection (LOD) ranging from 0.5 to 1.5 ng/L. Recoveries of five volatile compounds for the spiked jujube samples were between 94.36 and 106.74% with relative standard deviations (RSDs) less than 7.27% (n = 5). Jujube of different varieties can be distinguished by principal components analysis based on the analytical results of volatile compounds. The developed method demonstrated obvious advantages such as simplicity, high throughput, good sensitivity and wide range of applicability, which will be an alternative way for in situ analysis of the odor sample.

Highlights

Jujube fruits (Ziziphusjujuba Mill.), which belong to the Rhamnaceae family, are indigenous to China for over 4000 years [1]
HS-SPME/GC–MS and E-nose are widely used for characterization volatile profile from different samples
Initial experiments were performed to demonstrate the feasibility of the carbon fiber ionization mass spectrometry (CFI-MS) by analyzing the jujube sample and the standard gaseous sample consist of acetic acid, ethyl acetate, ethyl caproate, octyl acetate and β-damascone

Summary

Introduction

Jujube fruits (Ziziphusjujuba Mill.), which belong to the Rhamnaceae family, are indigenous to China for over 4000 years [1]. Jujube fruits have high nutritional and nutraceutical values and present unique flavor which makes them very popular. The flavor of jujube is affected by a large number of factors, such as variety, growth stage, climate, storage and processing methods. Variety is one of the most important factors that affect the aroma of jujubes. Odor is caused by volatile molecule acting on nasal receptors. According to the previous study, alcohols, acids, aldoketones, and esters were the main aroma compounds in different varieties jujubes [3]. Volatile components are usually employed to distinguish the odor characteristics of different samples. HS-SPME/GC–MS and E-nose are widely used for characterization volatile profile from different samples. Limits of GC–MS such as multistep analytical procedures, poor sensitivity and time-consuming should be taken into account. Direct mass spectrometry techniques have drawn people’s attention to measure chemical constituents

Methods

Results

Conclusion