Evaluation of the Permanence of Flame Accelerating Material on Burned Material with GC-MS Analytical Techniques

The aim of the work is to evaluate the permanence, understood as a presence detected by the analyzes, after a burn, of the flame-accelerating material used to start a fire, even in largely burnt residues, in order to be able to recognize, even in the investigative context, whether the fire was caused by an accident or if it was facilitated by the emission (voluntary or non- voluntary) of a flame-accelerating substance. The analytical technique used to give answers to this is the use of the gas chromatograph-mass spectrometer (GC-MS), which allows to detect the presence of flame accelerators even in small quantities in the samples. A series of burnt material samples will be reproduced in a controlled environment, originally containing flame-accelerating materials and then compared to burnt samples without flame-accelerating agents. The results will be obtained through GC-MS analysis with the headspace (HS) and fiber (SPME) method, in order to evaluate, in greater detail, which of the two methods is the best performing to achieve the objective. As final result, the SPME fiber is very performing for the goal to be achieved, because it is able to detail the flame accelerating compounds found.

Plant Extract and Herbal Products as Potential Source of Sorbent for Analytical Purpose: An Experimental Study of Morphine and Codeine Determination Using HPLC and LC–MSMS

Solid-phase microextraction (SPME) is an analytical method for microextraction of analytes, in which the analytes bind to the sorbent on the surface of the SPME fiber. Many types of chemical agents are used as sorbent; however, many of these sorbents cause secondary contamination or are not cost-effective. Here, aqueous extract of Ferula gummosa was evaluated as potential source of sorbent for simultaneous microextraction of morphine and codeine. For this purpose, multiwalled carbon nanotubes were carboxylated with H2SO4/HNO3 (3:1) and then functionalized with aqueous extract of F. gummosa. Functionalization was confirmed by Fourier transform infrared and Raman spectroscopy measurements as well as scanning electron microscopy analysis. Porous polypropylene hollow fibers were filled with the functionalized carbon nanotubes (CNTs) and used for analyte extraction in urine sample at 40°C and pH 6 for 2 min. Reversed-phase high-performance liquid chromatography (RP-HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed that the fiber could preconcentrate 1 ng/mL of morphine and 0.75 ng/mL codeine in urine sample and was successfully used for 30 times with no significant loss in the extraction efficiency. Limit of detection (LOD) and limit of quantification (LOQ) for morphine were 1 and 3.3 ng/mL, respectively. LOD and LOQ for codeine were determined 0.75 and 2.47 ng/mL, respectively. Recovery of the fiber was 80% and 93% for morphine and codeine, respectively. SPME fiber using extract of F. gummosa plant was used for the detection of a small amount of morphine in urine sample. Therefore, plants can be considered as abundant and cheap sources of sorbent for various analytical purposes.

Carbon aerogel-based solid-phase microextraction coating for the analysis of organophosphorus pesticides

A carbon aerogel-coated SPME fiber is prepared, and the DI-SPME-GC-MS method is developed for the analysis of organophosphorus pesticides from environmental samples.

Identification of Aroma Compounds in Freeze-dried Strawberries and Raspberries by HS-SPME-GC-MS

The objective of this study was to determine a method for the identification of aroma volatile compounds in freeze-dried (FD) strawberries and raspberries for quality purposes. The aroma profile was examined using headspace solid-phase micro-extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). FD strawberries and raspberries were extracted at four different times (10,15, 20 and 30 min) and three different temperatures (40 °C, 60 °C and 80 °C) using a SPME fiber coated with 50/30 µm divinylbenzene/carboxen on polydimethylsiloxane (DVB/CAR-PDMS) to determine optimum recoveries for aroma volatile compounds. The DVB/CAR-PDMS SPME fiber showed the best extraction of aroma volatile compounds from strawberry and raspberry at 60°C for 15 min. Twenty-nine volatile compounds were identified from the strawberry samples and 20 from the raspberry samples, including terpenes, aldehydes, esters, acids and alcohols. Select aroma compounds in FD strawberries and raspberries were quantitated using SPME and GC-MS. It is important to determine the desirable aroma active compounds in freeze-dried strawberries and raspberries for quality uses since they are becoming popular commercially.

A simple strategy based on fibers coated with surfactant-functionalized multiwalled carbon nanotubes to improve the properties of solid-phase microextraction of phenols in aqueous solution

Methods and Experiments: In this study, a functionalized multiwalled carbon nanotube (MWCNT)-coated solid-phase microextraction (SPME) fiber was developed for concentrating analytes in aqueous samples. Sodium deoxycholate(NaDC) was used as a dispersing agent for non-covalent modification of MWCNTs. The coating showed porous structure and large adsorption capacity. To investigate the capability of this MWCNTs/NaDC SPME fiber, it was applied to the analysis of phenols in aqueous solution. After extraction, the analytes were desorbed in an acetonitrile–water solution and analyzed using high-performance liquid chromatography. Results: The MWCNTs/NaDC fiber exhibited good analytical performance, and fine preparation reproducibility was obtained with the relative standard deviations (RSDs) ranging from 4.9% to 10.2% (n = 6) in one batch, from 5.7% to 11.9% (n = 3) among different batches. Under the optimum extraction conditions, the detection limits were 0.15–0.30 ng/mL(S/N=3), the linear detection ranges were 1–100 ng/mL (R2≥0.9997) for these analytes, and good recoveries(80.3%–95.4%) were obtained for the spiked samples. Conclusion: This is a simple and accurate pretreatment method for the analysis of phenols in aqueous samples.