Determination of brominated diphenyl ethers (from mono- to hexa- congeners) in indoor dust by pressurised liquid extraction with in-cell clean-up and gas chromatography–mass spectrometry

Use of microextraction by packed sorbents following selective pressurised liquid extraction for the determination of brominated diphenyl ethers in sewage sludge by gas chromatography-mass spectrometry

In this work, a method based on selective pressurised liquid extraction followed by microextraction by packed sorbents (MEPS) for the determination of brominated diphenyl ethers (BDEs) in sewage sludge is presented. The factors affecting the MEPS procedure were optimised. Acetone:water (25:75) sPLE extracts were drawn-ejected 10 times through C18 cartridges at 5 μL s(-1). The cartridge was dried five times with 250 μL of air and the BDEs were eluted at 25 μL s(-1) with 100 μL of n-hexane that were directly injected at 13 μL s(-1) in the GC-MSMS system. Under these conditions, there were no carry-over effects. The method was characterised in terms of limits of detection, repeatability, intermediate precision and accuracy. The use of MEPS for the determination of BDEs in sewage sludge means an improvement of the limits of detection due to the preconcentration and clean-up performed before the injection of the whole elute in the PTV injector. The GC-MSMS LODs (25 pg mL(-1)) were improved with MEPS to less than 3 pg mL(-1). RSD less than 7% and recovery values from 92% to 102% were shown. Finally, the method was applied to the sPLE extract analyses of sewage sludge from several wastewater treatment plants in La Rioja. To our knowledge, this is the first time that the MEPS technique has been applied to the analysis of BDEs, and the first time that it has been used for the analysis of extracts from a solid sample.

Distribution of polybrominated diphenyl ethers and dust particle size fractions adherent to skin in indoor dust, Pretoria, South Africa

In order to determine human exposure to the indoor toxicant, selection of dust fraction and understanding dust particle size distribution in settled indoor dust are very important. This study examined the influence of dust particle size on the concentration of polybrominated diphenyl ethers (PBDEs) congeners, assessed the distribution of dust particle size and characterized the main indoor emission sources of PBDEs. Accordingly, the concentrations of PBDE congeners determined in different indoor dust fractions were found to be relatively higher in the order of dust particle size: 45-106 μm>(<45 μm)>106-150 μm. The finding shows arbitrary selection of dust fractions for exposure determination may result in wrong conclusions. Statistically significant moderate correlation between the concentration of Σ9PBDEs and organic matter content calculated with respect to the total dust mass was also observed (r=0.55, p=0.001). On average, of total dust particle size <250 μm, 93.4 % (m/m%) of dust fractions was associated with less than 150 μm. Furthermore, of skin adherent dust fractions considered (<150 μm), 86 % (v/v%) is in the range of particle size 9.25-104.7 μm. Electronic materials treated with PBDEs were found the main emission sources of PBDE congeners in indoor environment. Based on concentrations of PBDEs determined and mass of indoor dust observed, 150 μm metallic sieve is adequate for human exposure risk assessment. However, research in this area is very limited and more research is required to generalize the fact.

Focused ultrasound solid-liquid extraction and gas chromatography tandem mass spectrometry determination of brominated flame retardants in indoor dust

This study presents a focused ultrasound solid-liquid extraction (FUSLE) and gas chromatography tandem mass spectrometry method for the determination of brominated diphenyl ethers (BDEs), from mono- to hexa-congeners, in indoor dust. This approach provided a simple, fast, and economical method. After the solvent extraction selection, the FUSLE conditions were studied using a central composite design. Finally, the number of extraction cycles was studied. The selected conditions were 8 mL of 3:1 n-hexane-acetone mixture as extraction solvent, at a power of 65% for 20 s. The proposed method allowed accurate determination of BDEs, with recovery values around 100% and detection limits between 0.05 and 0.8 ng g(-1). It also has advantages over other existing methods in terms of simplicity, analysis time, and solvent consumption. The analysis of several indoor dust samples showed high concentration values of BDEs 47, 99, 100, 153, and 154 in some of the samples, moreover, BDEs 47 and 99 were found in all samples.

In-Cell Clean-Up Pressurised Liquid Extraction Method to Determine Pesticides in Mushroom Compost by Gas Chromatography-Tandem Mass Spectrometry

A fast, simple, and easily automated method for the determination of two insecticides, diazinon and deltamethrin, and two fungicides, iprodione and prochloraz, in mushroom cultivation compost samples, based on selective pressurised liquid extraction (SPLE) and gas chromatography coupled to tandem mass spectrometry, is presented. The proposed method integrates extraction and clean-up processes in one single step, by adding a clean-up sorbent into the extraction cell. SPLE variables were thoroughly studied by experimental design. First, different clean-up sorbents and extraction solvents were screened at two temperature levels using a multifactor design; resulting Florisil and 1 : 1 acetone-dichloromethane the best combination. Then, temperature, extraction time, and sample-sorbent mass ratio were optimized by a central composite design. Best recoveries were obtained with a 0.4 sample-sorbent ratio, at 105°C and a 2 min extraction time. The SPLE method was characterized in terms of recovery (with values ranging from 81 to 103%), repeatability and intermediate precision (showing relative standard deviations less than 12% in most cases), and sensitivity (providing detection limits between 0.1 and 6 ng mL–1). However, in spite of the clean-up process a matrix effect was observed and therefore standard addition calibration was recommended.

Determination of nicotine and N-nitrosamines in house dust by pressurized liquid extraction and comprehensive gas chromatography--nitrogen chemiluminiscence detection

A novel, highly selective method for the determination of nicotine, N-nitrosamines and tobacco-specific nitrosamines (TSNAs) in indoor dust samples is presented in this study. Samples were extracted by in-cell clean-up pressurized liquid extraction (PLE) that allows high extraction efficiency with moderate consumption of organic solvents. The extracts were analyzed by comprehensive gas chromatography and detected with a nitrogen chemiluminiscence detector (GC×GC-NCD) that provided enhanced selectivity and sensitivity for organic nitrogen containing compounds. Method validation showed good linearity, repeatability and reproducibility (%RSD<8%). Recovery was higher than 80% for most target compounds and limits of detection lower than 16 ng g(-1). The method was used for the determination of the nitrosamine target compounds in house dust samples from both smoking and non-smoking households. All the analytes were found in the samples, nicotine being the most abundant compound in smokers' dust and one of the most abundant in non-smokers' dust. To our knowledge this is the first time that volatile N-nitrosamines and TSNAs have been determined in indoor dust samples. The results demonstrate the presence of these highly carcinogenic compounds in house dust, with inherent human exposure through inhalation and/or involuntary ingestion of house dust.