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.

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.

A simplified QuEChERS method coupled with a small injection volume was developed for the simultaneous determination of 28 pesticides in 6 matrices (apples, cucumbers, tomatoes, luffa, cabbages, and eggplants) using LC-MS/MS. In the sample procedure, acetonitrile with 0.1% (v/v) formic acid was used to extract and no depurative powder was used. Three fortified levels (10, 50, and 100 μg kg⁻¹) were determined and the recoveries of 168 analyte/matrix combinations were in the range of 60–120% except for cyromazin, pendimethalin, and fenpropathrin. Half of the 168 LOQs were below 0.1 μg kg⁻¹, and 29 LOQs were above 1 μg kg⁻¹. Moreover, four relationships between signal suppression and injection volume were observed ranging from 0.5 μL to 15 μL. For many analyte/matrix combinations, the matrix effects could be reduced to less than 20% if the injection volume was less than a critical value (named critical volume). The critical volume depending on the initial extent of matrix effects was explored and the conclusion was: for weak or medium MEs, usually ≤2 μL injection volume was needed and for several weak MEs, injection volume ≤ 5 μL can reduce the matrix effect to a negligible level.