Cleaning Up Vegetable Samples Using a Modified “QuEChERS” Procedure for the Determination of 17 Plant Growth Regulator Residues by Ultra High Performance Liquid Chromatography–Triple Quadrupole Linear Ion Trap Mass Spectrometry

Three-phase hollow fiber liquid-phase microextraction combined with HPLC for determination of three trace acidic plant growth regulators in Anoectochilus roxburghii (Wall.) Lindl

The analysis of plant growth regulators presents a challenge due to their trace quantities and complex matrices. A novel, simple, and effective analytical method for the determination of three trace acidic plant growth regulators in Anoectochilus roxburghii (Wall.) Lindl was developed to address this issue. Three-phase hollow fiber liquid-phase microextraction combined with high-performance liquid chromatography was applied for the enrichment, purification, and determination of three acidic plant growth regulators, namely, indole-3-acetic-acid, indole-3-butyric-acid, and (+)-abscisic acid. The factors affecting extraction performance, including extractant species, pH of donor and acceptor phases, salt addition dosage, extraction time, temperature, and stirring rate, were investigated and optimized. Under optimum conditions, the proposed method provided good linearity (R² , 0.9994-0.9999), low limit of detection (0.038-0.12 ng/mL), and acceptable relative recoveries (56.7-117.6%). The enrichment factors were between 153 and 328. The developed method was successfully applied to the enrichment and determination of plant growth regulators in Anoectochilus roxburghii (Wall.) Lindl and exhibited increased purification capacity, higher sensitivity, and decreased organic solvent consumption compared with conventional sample preparation methods. This method may provide a testing platform for the monitoring of plant growth regulator residues, ensuring the safe and effective use of traditional Chinese medicine.

Validation of a QuEChERS-Based Gas Chromatography-Mass Spectrometry (GC-MS) Method for Analysis of Phthalate Esters in Grain Sorghum

A modified QuEChERS method coupled with gas chromatography-mass spectrometry (GC-MS) was developed for analysis of 14 phthalate esters (PAEs) in grain sorghum (GS). Chemical extraction was done with acetonitrile followed by dispersive-solid phase extraction technique with a mixture of sorbents including primary secondary amine and octadecyl silica. Under the optimized condition, the matrix-matched calibration curves for all PAEs showed good linear relationship in the concentration range between 5 and 500 μg/L with correlation coefficients (R² ) better than 0.99. Mean recoveries were between 82.0% and 120.2% at spiking levels of 0.06, 0.6, and 2.0 mg/kg with RSD of 0.3% to 7.8% (n = 5) for intra-day precision and 1.2% to 7.6% (n = 5) for inter-day precision. The LOD_GS and LOQ_GS for 14 PAEs were between 0.4 and 10.0 μg/kg and 0.5 and 20.0 μg/kg, respectively. Analysis of 32 commercial GS samples revealed that dimethyl-, diethyl-, diisobutyl-, dibutyl-, and di- (2-ethylhexyl) phthalate esters were detected in all of the analytes. In addition, content-color scale model was applied to visualize the concentration differences of PAEs in real GS samples. Principal component analysis of PAEs revealed that the GS samples did not have a distinctive cluster based on their geographic origins. The established method was proven to be simple, accurate, and effective for analysis of PAEs in GS, which might also be applied for analysis of PAEs in other matrices.

PRACTICAL APPLICATION

A modified QuEChERS-based GC-MS method was developed for the determination of phthalate esters (PAEs) in grain sorghum (GS). The ubiquitous presence of PAEs can migrate into GS. Therefore, evaluation of the total content of PAEs in GS is helpful to understand its impact of overall pollution level on other foods. This study has provided some basic information in terms of the content and contamination of PAEs in GS, which is helpful to establish relevant standards and risk assessment of GS for the government.