High-performance Solid Phase Microextraction Research Articles

High-performance solid-phase microextraction based on a nanocomposite sorbent of MOF/COF hybrid for ultra-trace analysis of trifluralin in food samples using the ion mobility spectrometer

Two well-known porous hybrid materials, a metal-organic framework (MOF) based on manganese and a melamine-rich covalent organic framework (COF) were combined, resulting in a highly effective nanocomposite sorbent of Mn-terephthalic acid (TA) /COF. After investigating the properties of the synthesized adsorbent, it was finally used as a new fiber for solid-phase microextraction. The method, named high-performance solid-phase microextraction (HPSPME), was utilized for the extraction and ultra-trace analysis of trifluralin in agricultural waters, fruit, and vegetable samples by using corona discharge ionization-ion mobility spectrometer (CD-IMS). To increase the extraction efficiency, experimental parameters including, temperature and time of extraction and desorption, solution pH, and stirring rate were optimized. Considering the optimized conditions, the enrichment factor of 2002, the limit of detection (LOD) 0.08 ng mL−1 (S/N=3), and linear dynamic range (LDR) 0.25–10.00 ng mL−1 with a coefficient of determination (R2=0.9987) were obtained. Relative standard deviations (RSDs, n = 3) of <9.7, <3.5, and <8.9 % were obtained, respectively, for reproducibility of the prepared fibers, intra- and inter-day. The relative recovery values for the real samples were 84–124 %. The proposed method’s accuracy for the sample impregnated with trifluralin was also evaluated by the EPA standard method.

Efficient solid phase microextraction of organic pollutants based on graphene oxide/chitosan aerogel

The design and synthesis of novel high-performance solid phase microextraction (SPME) coatings towards organic pollutants with diverse chemical properties is still a challenge in sample preparation. Herein, a stable chitosan cross-linked graphene oxide (GOCS) aerogel was reported as a novel coating for solid phase microextraction. The interpenetrated meso- and macropores ensured the large surface area and high accessibility of the functional groups across the aerogel, resulting in high extraction performance towards target hydrophobic pollutants. The extraction capacities of the GOCS-coated SPME fiber towards analytes (e.g. polycyclic aromatic hydrocarbons, organophosphorus pesticides, organochlorine pesticides, pyrethroids, and polychlorinated biphenyls) were about 0.5–13 times as high as those obtained by the commercial fibers (30 μm polydimethylsiloxane (PDMS), 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB)), which was attributed to the hydrophobic, π-π, halogen bond and hydrogen bond interactions between the coating and the analytes. Under the optimized extraction conditions, superior analytical performances for PAHs were achieved with a wide linearity (0.5–1000 ng L−1), high enhancement factors (311–3740), and the low limits of detection (0.03–1.28 ng L−1). Finally, the GOCS-coated SPME fiber was successfully applied to the determination of PAHs in real water samples with good recoveries (91.6%–110%).

Multiple-helix cobalt(II)-based metal-organic nanotubes on stainless steel fibers for solid-phase microextraction of chlorophenol and nitrophenols from water samples

The high performance solid-phase microextraction (SPME) of polar phenols from aqueous matrices is a challenge due to the strong interaction between water molecules and polar phenols. The authors describe the fabrication of stainless steel fibers coated with multiple helix 3D metal-organic nanotubes via physical adhesion, and their application to the SPME of 2-chlorophenol, 2-nitrophenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol and 2,4,6-trichlorophenol from water samples. GC/MS was used for sample quantification and detection. Box-Behnken design was adopted to optimize the experimental conditions through response surface methodology. The fibers display good thermal stability (~400 °C), high enrichment factors (418–1874), excellent repeatability (4.31%–8.37%), wide linear range (0.5–1000 ng⋅L−1) and low limits of detection (0.07–0.18 ng⋅L−1) for the phenols. This method was successfully applied to the analysis of phenols in environmental water samples.

Volatile Characterization of Major Apricot Cultivars of Southern Xinjiang Region of China

The characterization of aroma of the 14 main apricot (Prunus armeniaca L.) cultivars in Xinjiang was evaluated using high-performance solid-phase microextraction (HP-SPME) with gas chromatography-mass spectroscopy (GC-MS). A total of 208 volatiles that include 80 esters, 25 aldehydes, 15 terpenes, 21 ketones, 39 alcohols, 27 olefins, and 1 acid were identified from these cultivars. The compounds propyl acetate, 3-methyl-1-butanol acetate, (Z)-3-hexen-1-ol acetate, d-limonene, β-linalool, hexanal, hexyl acetate, butyl acetate, β-myrcene, ethyl butanoate, and β-cis-ocimene were the major compounds responsible for aroma in these cultivars. GC-MS results showed that Kuchexiaobaixing, Guoxiyuluke, and seven other cultivars were characterized by a high level of esters and were considered to be fruity apricot aroma. ‘Luotuohuang’ and ‘Heiyexing’ accumulate high levels of terpenes and exhibited an outstanding floral aroma. Higher levels of alcohols and aldehydes were observed in ‘Danxing’, ‘Sumaiti’, and ‘Kumaiti’. The latter are considered green aroma cultivars. These three types of cultivars with different aroma characteristics can be significantly differentiated by using the principal component analysis (PCA) method. The contributions of volatiles to the apricot aroma were assessed by using the partial least squares regression (PLSR) model. Esters, terpenes, and C6 components were shown to be responsible for the fruity, floral, and green character of fresh apricots, respectively.