scholarly journals Interlaboratory Comparison of Pesticide Recovery from Water Using Solid-Phase Extraction Disks and Gas Chromatography

2002 ◽  
Vol 85 (6) ◽  
pp. 1324-1330 ◽  
Author(s):  
Wondi Mersie ◽  
Chris Clegg ◽  
R Don Wauchope ◽  
Jose A Dumas ◽  
Ross B Leidy ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Surface Water ◽  
Solid Phase Extraction ◽  
Physicochemical Properties ◽  
Water Samples ◽  
Interlaboratory Comparison ◽  
Solid Phase ◽  
Deionized Water ◽  
Interlaboratory Study ◽  
Phase Extraction

Abstract An interlaboratory study was conducted to assess the suitability of C18 solid-phase extraction disks to retain and ship different pesticides from water samples. Surface and deionized water samples were fortified with various pesticides and extracted using C18 disks. Pesticides were eluted from disks and analyzed in-house, or disks were sent to another laboratory where they were eluted and analyzed. Along with the disks, a standard pesticide solution in methanol was also shipped to be used for fortification, extraction, and analysis. The highest recovery from deionized or surface water using shipped disks was obtained for cyanazine (>97%), followed by metalaxyl (>96%), and atrazine (>92%). Although <40% of the bifenthrin, chlorpyrifos, and chlorothalonil fortified in surface water was recovered from shipped disks, recoveries from deionized water were >70%. From in-house eluted disks, bifenthrin and chlorpyrifos were recovered at 118 and 105%, whereas chlorothalonil showed 71% recovery, indicating that poor recovery from surface water was due to loss during shipping rather than low retention by the C18 disks. There was no consistent relationship between recovery from C18 disk and physicochemical properties for the pesticides included in this study. For most of the 13 pesticides tested, there were no differences in recovery between in-house extracted disks and shipped disks, indicating the suitability of disks to concentrate and transport pesticides extracted from water samples.

scholarly journals Cost-Effective Detection of Perfluoroalkyl Carboxylic Acids with Gas Chromatography: Optimization of Derivatization Approaches and Method Validation

2019 ◽  
Vol 17 (1) ◽  
pp. 100 ◽  
Author(s):  
Zhen Li ◽  
Hongwei Sun
Keyword(s):  
Gas Chromatography ◽  
Surface Water ◽  
Solid Phase Extraction ◽  
Carboxylic Acids ◽  
Water Samples ◽  
Solid Phase ◽  
Cost Effective ◽  
Phase Extraction ◽  
Surface Water Samples

The reliable quantification of perfluoroalkyl carboxylic acids (PFCAs) in environmental samples like surface water by using gas chromatography (GC) remains challenging because the polar PFCAs call for derivatization before injection and problems involving the integration of sample pretreatment and derivatization procedures. Here we proposed a cost-effective method for the GC based determination of C4–C12 PFCAs in surface water samples by integrating solid phase extraction and PFCAs anilide derivatization. First, we assessed the performance of different PFCAs derivatization methods, namely esterification and amidation. Esterification was unable to derivatize C4–C6 PFCAs. On the contrary, amidation procedures by using 2,4-difluoroaniline (DFA) and N,N′-dicyclohexylcarbodiimide (DCC) could successfully transform all the PFCA analogs to produce anilide derivatives, which could be easily detected by GC. Then the reaction conditions in the amidation approach were further optimized by using orthogonal design experiments. After optimizing the instrumental parameters of GC, the limits of detection (LOD) of this derivatization method were determined to be 1.14–6.32 μg L−1. Finally, in order to establish an intact method for the quantification of PFCAs in surface water samples, solid phase extraction (SPE) was used for extraction and cleanup, which was further integrated with the subsequent amidation process. The SPE-amidation-GC method was validated for application, with good accuracy and precision reflected by the PFCAs recoveries and derivatization of triplicates. The method reported here could provide a promising and cost-effective alternative for the simultaneous determination of C4–C12 PFCAs in environmental water samples.

scholarly journals Stability of Pesticides on Solid-Phase Extraction Disks After Incubation at Various Temperatures and for Various Time Intervals: Interlaboratory Study

2006 ◽  
Vol 89 (4) ◽  
pp. 903-912 ◽  
Author(s):  
Jean M Cobb ◽  
John D Mattice ◽  
Scott A Senseman ◽  
Jose A Dumas ◽  
Wondi Mersie ◽  
...  
Keyword(s):  
Solid Phase Extraction ◽  
Water Samples ◽  
Solid Phase ◽  
Deionized Water ◽  
Interlaboratory Study ◽  
Time Interval ◽  
Phase Extraction ◽  
Time Intervals ◽  
The Stability

Abstract An interlaboratory study was conducted at 8 locations to assess the stability of pesticides on solid-phase extraction (SPE) disks after incubation at various temperatures and for various time intervals. Deionized water fortified with selected pesticides was extracted by using 2 types of SPE filtration disks (Empore C18 and Speedisk® C18XF), and after extraction, the disks were incubated at 3 temperatures (25, 40, and 55C) and for 2 time intervals (4 and 14 days). Deionized water was fortified with atrazine, carbofuran, and chlorpyrifos by all participating laboratories. In addition, some of the laboratories included 2 of the following pesticides: metolachlor, metribuzin, simazine, chlorothalonil, and malathion. Concurrently, fortified water samples were extracted with the incubated samples by using each disk type at 4 and 14 days. Pesticides had equivalent or greater stability on ≤1 of the C18 disk types, compared with storage in water. The lowest recoveries of carbofuran (6%) and chlorpyrifos (7%) were obtained at 55C after storage for 14 days in incubated water. At 55C after 14 days, the lowest recovery for atrazine was 65% obtained by using Empore disks. Pesticide-specific losses occurred on the C18 disks in this study, underlining the importance of temperature and time interval when water is extracted at remote field locations and the SPE disks containing the extracted pesticides are transported or shipped to a laboratory for elution and analysis.

scholarly journals Development of Surface Molecularly Imprinted Polymers as Dispersive Solid Phase Extraction Coupled with HPLC Method for the Removal and Detection of Griseofulvin in Surface Water

2019 ◽  
Vol 17 (1) ◽  
pp. 134 ◽  
Author(s):  
Kamran Bashir ◽  
Zhimin Luo ◽  
Guoning Chen ◽  
Hua Shu ◽  
Xia Cui ◽  
...  
Keyword(s):  
Surface Water ◽  
Solid Phase Extraction ◽  
Molecularly Imprinted Polymers ◽  
Water Samples ◽  
Solid Phase ◽  
Phase Extraction ◽  
Dispersive Solid Phase Extraction ◽  
Molecularly Imprinted ◽  
Imprinted Polymers ◽  
Surface Water Samples

Griseofulvin (GSF) is clinically employed to treat fungal infections in humans and animals. GSF was detected in surface waters as a pharmaceutical pollutant. GSF detection as an anthropogenic pollutant is considered as a possible source of drug resistance and risk factor in ecosystem. To address this concern, a new extraction and enrichment method was developed. GSF-surface molecularly imprinted polymers (GSF-SMIPs) were prepared and applied as solid phase extraction (SPE) sorbent. A dispersive solid phase extraction (DSPE) method was designed and combined with HPLC for the analysis of GSF in surface water samples. The performance of GSF-SMIPs was assessed for its potential to remove GSF from water samples. The factors affecting the removal efficiency such as sample pH and ionic strength were investigated and optimized. The DSPE conditions such as the amount of GSF-SMIPs, the extraction time, the type and volume of desorption solvents were also optimized. The established method is linear over the range of 0.1–100 µg/mL. The limits of detection and quantification were 0.01 and 0.03 µg/mL respectively. Good recoveries (91.6–98.8%) were achieved after DSPE. The intra-day and inter-day relative standard deviations were 0.8 and 4.3% respectively. The SMIPs demonstrated good removal efficiency (91.6%) as compared to powder activated carbon (67.7%). Moreover, the SMIPs can be reused 10 times for water samples. This is an additional advantage over single-use activated carbon and other commercial sorbents. This study provides a specific and sensitive method for the selective extraction and detection of GSF in surface water samples.

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