Rapid analysis of aldehydes by simultaneous microextraction and derivatization followed by GC-MS.

Ultrasound-assisted dispersive liquid-liquid microextraction (UDLLME) and simultaneous derivatization followed by GC-MS was developed for the analysis of four aldehydes including acetaldehyde (ACE), propionaldehyde (PRO), butyraldehyde (BUT) and valeraldehyde (VAL) in water samples. In the proposed method, the aldehydes were derivatized with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine (PFBHA) and extracted by UDLLME in aqueous solution simultaneously; finally, the derivatives were analyzed by GC-MS. The experimental parameters were investigated and the method validations were studied. The optimal conditions were: aqueous sample of 5 mL, PFBHA of 50 µL, 1.0 mL ethanol (disperser solvent) containing 20 µL chlorobenzene (extraction solvent), ultrasound time of 2 min and centrifuging time of 3 min at 6000 rpm. The proposed method provided satisfactory precision (RSD 1.8-10.2%), wide linear range (0.8-160 µg/L), good linearity (R(2) 0.9983-0.9993), good relative recovery (85-105%) and low limit of detection (0.16-0.23 µg/L). The proposed method was successfully applied for the analysis of aldehydes in water samples. The experimental results showed that the proposed method was a very simple, rapid, low-cost, sensitive and efficient analytical method for the determination of trace amount of aldehydes in water samples.

Rapid analysis of the essential oil components of dried Perilla frutescens (L.) by magnetic nanoparticle-assisted microwave distillation and simultaneous headspace solid-phase microextraction followed by gas chromatography-mass spectrometry.

In this work, two solvent-free sample preparation techniques of microwave distillation (MD) and headspace (HS) solid-phase microextraction (SPME) were combined, and developed for the determination of essential oil compounds in dry traditional Chinese medicine (TCM). Amine-functionalized magnetite nanoparticles (AMNs) were added and mixed with the dried Perilla frutescens (L.) sample, which was used as a microwave absorption solid medium for dry distillation of the TCM. Using the proposed method, isolation, extraction and concentration of TCM essential oil compounds can be carried out in a single step. The AMN-assisted MD-HS-SPME parameters including fiber coating, microwave power, irradiation time, and the amount of added AMN were studied. The optimal analytical conditions were: fiber coating of 100 µm PDMS/DVB, microwave power of 230 W, irradiation time of 2 min, as well as the addition of 0.1 g AMN to the TCM sample. The proposed method is applied to the determination of essential oil in Perilla frutescens (L.) and the RSD values is less than 9%. To demonstrate the method feasibility, the conventional HS-SPME method was also used for the analysis of essential oil in the TCM. Experimental results show that more compounds were isolated and identified by AMN-assisted MD-HS-SPME than those by HS-SPME. It was found that the proposed method is an alternative tool for the fast analysis of essential oils in dry TCMs.

(E)-Ethyl 3-(4-fluoro-anilino)-2-(4-methoxy-phen-yl)acrylate.

In the title compound, C(18)H(18)FNO(3), the dihedral angles between the two benzene rings and the plane through the acrylate group and the fluoro-phenyl ring are 61.58 (8) and 13.33 (9)°, respectively. Mol-ecules are linked into ribbons through C-H⋯O and N-H⋯O hydrogen bonds, and further linked by C-H⋯π inter-actions, forming a three-dimensional network.