Aroma plays an important role in fruit quality and varies among different fruit cultivars. In this study, a sensitive and accurate method based on headspace solid-phase microextraction (HS-SPME) coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) was developed to comprehensively compare aroma components of five pear cultivars. In total, 241 volatile compounds were identified and the predominant volatile compounds were esters (101 compounds), followed by alcohols (20 compounds) and aldehydes (28 compounds). The longyuanyangli has the highest relative concentration (838.12 ng/g), while the Packham has the lowest (208.45 ng/g). This study provides a practical method for pear aroma analysis using SPME and GC×GC-TOFMS.

To comprehensively understand the volatile compounds and assess the aroma profiles of different types of Pyrus ussuriensis Maxim. Anli, Dongmili, Huagai, Jianbali, Jingbaili, Jinxiangshui, and Nanguoli were detected via headspace solid phase microextraction (HS-SPME) coupled with two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS). The aroma composition, total aroma content, proportion and number of different aroma types, and the relative quantities of each compound were analyzed and evaluated. The results showed that 174 volatile aroma compounds were detected in various cultivars, mainly including esters, alcohols, aldehydes, and alkenes: Jinxiangshui had the highest total aroma content at 2825.59 ng/g; and Nanguoli had the highest number of aroma species detected at 108. The aroma composition and content varied among pear varieties, and the pears could be divided into three groups based on principal component analysis. Twenty-four kinds of aroma scents were detected; among them, fruit and aliphatic were the main fragrance types. The proportions of aroma types also varied among different varieties, visually and quantitatively displaying changes of the whole aroma of the different varieties of pears brought by the changes in aroma composition. This study contributes to further research on volatile compound analysis, and provides useful data for the improvement of fruit sensory quality and breeding work.

A fast, sensitive, and reliable method for the determination of fipronil and its metabolites (fipronil-sulfone, fipronil sulfide, and fipronil-desulfynil) in eggs was developed by a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment method and ultra-performance liquid chromatography-quadrupole-linear ion trap mass spectrometry (UPLC-QqLIT-MS/MS). The proposed multistage mass spectrometry (MS³) method provides sufficient sensitivity and excellent reproducibility. The four analytes were separated by a Waters ACQUITY UPLC^® BEH C18 column and detected by AB Sciex QTRAP^® 5500. The mean recoveries for the four analytes ranged from 90.7% to 105% with relative standard deviations (RSDs) of 0.7% to 4.9%. The calibration curve showed a good linearity within the concentration range of 0.05 to 20 ng/mL. The correlation coefficients (R²) were higher than 0.999. The limits of detection (LODs) obtained from the experimental results for fipronil, fipronil-sulfone, fipronil-sulfide, and fipronil-desulfinyl were 0.06, 0.02, 0.05, and 0.04 µg/kg, respectively. The MS³ method was successfully applied to detect fipronil and its metabolites in 60 egg samples purchased from Chinese supermarkets, and wholesale markets.