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A new method for simultaneous analysis of semi-volatile organic compounds in outdoor/indoor air of large office buildings


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Abstract

Exposure to various groups of SVOCs, particularly in the indoor air, is of increasing concern worldwide. These groups include PAHs, PCBs, phthalate esters, organochlorines, and many others, which are classified among the priority organic pollutants. A new method was developed and optimized for simultaneous whole air sampling using recent canister/helium diffusion technology followed by online cryogenic trapping, concentration of the SVOCs, and direct on-column injection into the GC/MS. The method was optimized using 25 SVOCs (seven of PAHs, eight of PCBs, four of phthalates, three OCs, and three of others) and tested in the analysis of 294 air samples, which were collected from the outdoor and the indoor at eight large office buildings on 21 different dates from January 2011 to August 2011. The method detection limits ranged from 0.05 ppbv for 2,4-dinitrobenzene to 2.6 ppbv for chrysene. Phthalates were the most abundant among other SVOCs, whereas fluorine and dichlorobiphenyl were the most abundant among the PAHs and PCBs, respectively. The I/O ratios of most SVOCs were < 1, indicating that the outdoor air was the main source of indoor pollutants. The method demonstrated: (1) accurate and efficient for various SVOCs determination, which allowed assessment of the factors affecting their levels in the sampling locations, and (2) the capability of reliable use of recent technology which eliminates the disadvantages of using sorbents and solvents by the current methods.

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Use of Sorbent-Based Vacuum Extraction for Determination of Volatile Phenols in Beer


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Abstract

A novel method based on vacuum-assisted sorbent extraction (VASE) used with gas chromatography-mass spectrometry (GCMS) for isolation of volatile phenols was described. The method is based on extraction of analytes into sorbent traps (sorbent pen) filled with Tenax in a vacuum system—vials with traps from which air was evaluated. The method was applied for extraction of volatile phenols from aqueous matrix and smoked beer was used as a food example. Methyl-, dimethyl-, and trimethylphenols, along with 4-ethylphenol, 4-methylguaiacol, 4-ethylguaiacol, 4-propylguaiacol, and eugenol, were used in method development. Optimal extraction parameters were elaborated. For the analysis of volatile phenols in beer matrix, the method was characterized with satisfactory linearity (r2 ≥ 0.99) in a range of 0.005–0.5 mg/L. Limits of detection (LODs) for analyzed compounds ranged from 0.0006 to 0.018 mg/L and repeatability for majority of compounds was < 5% for a single trap extraction. The detected volatile phenols in beer samples ranged from 0.003 to 0.672 mg/L.­­­

 

Solvent Free Extraction Technique for Determination of Semi-Volatile Organic Compounds in Water Samples by EPA Method 8270


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Overview

The need for accurate monitoring of SVOCs in water samples using methods such as US EPA Method 8270 continues to grow in importance as the comprehension of their adverse effects on human health evolves. Improvements in analytical technology for accurate determination down to sub-PPB levels is critical to obtain the most comprehensive monitoring possible. Current techniques for extraction of base/neutral/acid SVOCs include solvent extraction and separatory funnel extraction, however these methods require many steps and environmentally unfriendly solvents. Additionally, there are many analytical challenges due to matrix interferences, contamination, and the broad range of chemical properties.

 

7650-L20 GC Gas Autosampler


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The Entech 7650-L20 is the only system handling automated injection of Tedlar bags and other gas phase samples using a single inlet robotic autosampler. The 7650-L20 can automate the analysis of up to 16 Tedlar bags, or 24 to 80 Bottle-Vac samplers or MiniCans depending on the size of the canister or Bottles. Canisters and gas sampling Bottle-Vacs can be heated prior to analysis to extend the molecular weight range of recoverable compounds, allowing a reliable way of measuring heavy volatiles or semi-volatiles. The dual loop system simultaneously injects an Internal standard along with the sample or calibration standard to support internal standard calibration methods. A 100% Silonite coated ceramic pathway ensures recovery of difficult compounds, creating the most comprehensive technique available for the quantitative measurement of organic compounds in gas phase samples. The 7650-L20 can automate the injection of gas samples to virtually all GCs by using the model specific communication cables available from Entech.

Improving Canister Sampling Accuracy and Reliability Using Helium Diffusion Sampling into Silonite Coated Stainless Steel Canisters


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A new, simplified approach for filling air sampling canisters during monitoring of Environmental pollutants in air is described. The new approach uses helium diffusion to drive the sampling process in a way that has several advantages over vacuum sampling. Canisters are filled with helium after cleaning, using a valve and inlet fitting combination that allows the proper time integrated sample to be collected simply by removing the valve and allowing helium to leak out through a calibrated orifice. Orifice sizes are available for performing a range of integration times from 3 hours to 1 month, without the need for an external flow controller. Elimination of the flow controller from the flow path reduces sample loss, prevents contamination from previous sampling events, greatly increases simplicity and reliability of the sampling process, and increases the molecular weight range recoverable to include Semi-Volatile compounds. Utilizing HDS™ can also reduce the potential for contamination during field and lab leak checking. Data is presented detailing the advantages of HDS™, including comparisons with vacuum sampling canisters to show precision and sampling consistency.

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