Tracing historical changes, degradation, and original sources of airborne polycyclic aromatic hydrocarbons (PAHs) in Jilin Province, China, by Abies holophylla and Pinus tabuliformis needle leaves

Due to their wide distribution and availability, plant leaves can be considered interesting candidates as biomonitoring substrates for the evaluation of atmospheric pollution. In addition, some species can also retain historical information, for example, related to environmental pollution, due to their leaf class age. In this study, the content of polycyclic aromatic hydrocarbons (PAHs) in Abies holophylla and Pinus tabuliformis needle samples in the function of their class age has been investigated to obtain information regarding the degradation constant for each PAH under investigation (α values ranging from 0.173 to 1.870) and to evaluate the possibility to correlate the presence of PAHs in needles with some important pollution environmental factors. Considering air pollutant variables registered in Jilin Province, interesting correlations (at 95% confidence level) have been found between coal consumption per year and anthracene contents in needles, while fluorene, phenanthrene, and anthracene results correlated with coal consumption. Furthermore, it has been demonstrated that the total PAH concentration in needles, for both species, increased with their age (from 804 to 3604 ng g^-1 dry weight), showing a general tendency to accumulate these substances through years. PAH degradation rates increased instead with molecular complexity. This study could be considered a first trial to obtain historical environmental information by pine needles biomonitoring.

One-step integrated sample pretreatment technique by gas-liquid microextraction (GLME) to determine multi-class pesticide residues in plant-derived foods

Gas-liquid microextraction technique (GLME) has been integrated with dispersive solid phase extraction to establish a one-step sample pretreatment approach for rapid analysis of multi-class pesticides in different plant-derived foods. A 50 μL of organic solvent plus 40 mg of PSA were required throughout the 5-minute pretreatment procedure. Good trueness (recoveries of 67.2 - 105.4%) and precision (RSD ≤ 18.9%) were demonstrated by the one-step GLME method, with MLOQs ranged from 0.001 to 0.011 mg kg^-1. As high as 93.6% pesticides experienced low matrix effect through this method, and the overall matrix effects (ME%) were generally better or comparable to QuEChERS. This method successfully quantified 2-phenylphenol, quintozene, bifenthrin and permethrin in the range of 0.001 - 0.008 mg kg^-1 in real food samples. The multiresidue analysis feature of GLME has been validated, which displays further potential for on-site determination of organic pollutants in order to safeguard food safety and human health.

In-a-syringe surfactant-assisted dispersive liquid-liquid microextraction of polycyclic aromatic hydrocarbons in supramolecular solvent from tea infusion

In this work, an automated surfactant-assisted dispersive liquid-liquid microextraction approach based on in-a-syringe concept was developed for the first time. The procedure assumed mixing aqueous sample phase and hydrophilic emulsion containing hexanoic acid and sodium hexanoate in a syringe of flow system. Sodium hexanoate acted as an emulsifier in dispersive liquid-liquid microextraction process and it was required for the formation of supramolecular solvent phase. After spontaneous separation of phases in the syringe, the upper supramolecular solvent phase containing target analytes was withdrawn and analyzed. The procedure was applied to the determination of 13 polycyclic aromatic hydrocarbons in tea infusion by high performance liquid chromatography with fluorescence detection. It was shown that the supramolecular solvent provided effective extraction of polycyclic aromatic hydrocarbons and fast phase separation in the syringe without centrifugation. The enrichment factors were in the range of 38-46. The automated microextraction procedure lasted 4 min including syringe cleaning. Under optimal experimental conditions the linear detection ranges were found to be 0.05-50.00 μg L^-1 with limits of detection calculated from a blank test, based on 3σ, 0.02-0.04 μg L^-1. Recovery values in the range of 85-105% were achieved for tea infusion with a reproducibility expressed as RSD less than 4.1%.

A fast and selective gas liquid microextraction of semiochemicals for quantitative analysis in plants

A trapping-based gas liquid microextraction (GLME) method coupled with gas chromatography-mass spectrometry (GC-MS) was utilized to qualitatively and quantitatively characterize semiochemicals in plants. The main GLME extraction efficiency associated parameters (heating temperature and extraction time) were optimized. The results obtained from GLME process were compared with those of steam distillation and ultrasonic extraction, and the recovery, peak number and reproducibility were evaluated by using Thuja koraiensis Nakai as a representative plant. Furthermore, the quantitative performances of the GLME in terms of sample amount, recoveries of spiked standards and correlation were systematically evaluated using standard addition method, which gave a good quantitative ability for all the compounds with squares of correlation coefficient (r²) of higher than 0.99. Finally, the contents of α-pinene, camphene, linalool, α-terpinenol, β-caryophyllene, α-caryophyllene, and totarol in Thuja koraiensis Nakai samples were quantified, and their concentrations (SD, n = 3) were; 0.65 (0.06), 0.62 (0.05), 4.12 (0.15), 0.99 (0.08), 1.11 (0.07), 0.63 (0.04), and 21.91 (0.25) μg g^-1, respectively. It was demonstrated that GLME is a powerful sample preparation technique for quantitative and qualitative analysis of plant semiochemicals.