scholarly journals A comparison of sodium sulfite, ammonium chloride, and ascorbic acid for quenching chlorine prior to disinfection byproduct analysis

2021 ◽  
Author(s):  
Nathan Moore ◽  
Shelir Ebrahimi ◽  
Yanping Zhu ◽  
Chengjin Wang ◽  
Ron Hofmann ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Ascorbic Acid ◽  
Ammonium Chloride ◽  
Sodium Sulfite ◽  
Haloacetic Acids ◽  
Electron Capture Detection ◽  
Water Sampling ◽  
Disinfection Byproduct ◽  
Emerging Dbps ◽  
Control Samples

Abstract This study compared 3 commonly used quenching agents for dechlorinating samples prior to disinfection byproduct (DBP) analysis under typical drinking water sampling conditions for a representative suite of chlorination byproducts. Ascorbic acid and sodium sulfite quenched the residual free chlorine to below detection within 5 seconds. Ammonium chloride did not quench the chlorine to below detection with up to a 70% molar excess, which agrees with published ammonium chloride-chlorine chemistry. With respect to the DBPs, ascorbic acid worked well for the trihalomethanes and haloacetic acids, except for dibromoiodomethane, which exhibited 2.6–28% error when using ascorbic acid compared to non-quenched control samples. Sodium sulfite also worked well for the trihalomethanes (and performed similarly to ascorbic acid for dibromoiodomethane) and was the best performing quenching agent for MX and the inorganic DBPs, but contributed to the decay of several emerging DBPs, including several halonitromethanes and haloacetamides. Ammonium chloride led to considerable errors for many DBPs, including 27–31% errors in chloroform concentrations after 24 hours of storage. This work shows that ascorbic acid is suitable for many of the organic DBPs analyzed by gas chromatography-electron capture detection and that sodium sulfite may be used for simultaneous chlorite, chlorate, and bromate analysis.

Gas Chromatographic Determination of the Plant Growth Regulator Flurprimidol in Soil and Soil-Grass Samples

1986 ◽  
Vol 69 (4) ◽  
pp. 572-575
Author(s):  
Sheldon D West ◽  
Bonnie S Rutherford
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Detection Limit ◽  
Plant Growth ◽  
Plant Growth Regulator ◽  
Chromatographic Determination ◽  
Gas Chromatography Mass Spectrometry ◽  
Electron Capture Detection ◽  
Control Samples

Abstract A method is described for the determination of flurprimidol residues in soil and soil-grass samples. Flurprimidol is extracted from the sample by refluxing with methanol-water. An aliquot is partitioned into hexane and purified by alumina B Sep-Pak column chromatography. The compound is detected and measured by gas chromatography with electron capture detection. Residue identity is confirmed by gas chromatography-mass spectrometry with detection at m/z 269.0. The detection limit is 0.01 ppm, and recoveries for control samples fortified with flurprimidol at 0.01-2.0 ppm averaged 80% for soil and 78% for soil-grass samples.

Residue Analysis of Organophosphorus and Organochlorine Pesticides in Fatty Matrices by Gas Chromatography Coupled with Electron-Capture Detection

2006 ◽  
Vol 61 (5-6) ◽  
pp. 341-346 ◽  
Author(s):  
Jae-Woo Park ◽  
A. M. Abd El-Aty ◽  
Myoung-Heon Lee ◽  
Sung-Ok Song ◽  
Jae-Han Shim
Keyword(s):  
Gas Chromatography ◽  
Electron Capture ◽  
Simple Procedure ◽  
Linear Regression Analysis ◽  
Residue Analysis ◽  
Electron Capture Detection ◽  
Relative Standard ◽  
Wide Range ◽  
Repeatability And Reproducibility

A multiresidue method for the simultaneous determination of 22 organochlorine (OCs) and organophosphorus (Ops) pesticides (including isomers and metabolites), representing a wide range of physicochemical properties, was developed in fatty matrices extracted from meat. Pesticides were extracted from samples with acetonitrile/n-hexane (v :v, 1:1). The analytical screening was performed by gas chromatography coupled with electron-capture detection (ECD). The identification of compounds was based on their retention time and on comparison of the primary and secondary ions. The optimized method was validated by determining accuracy (recovery percentages), precision (repeatability and reproducibility), and sensitivity (detection and quantitation limits) from analyses of samples fortified at 38 to 300 ng/g levels. Correlation coefficients for the 22 extracted pesticide standard curves (linear regression analysis, n = 3) ranged from 0.998 to 1.000. Recovery studies from 2 g samples fortified at 3 levels demonstrated that the GC-ECD method provides 64.4-96.0% recovery for all pesticides except 2,4′-DDE (44.6-50.4%), 4,4′-DDE (51.1-57.5%) and 2,4′-DDT (50.0-51.2%). Both repeatability and reproducibility relative standard deviation values were < 20% for all residues. Detection limits ranged from 0.31 to 1.27 ng/g and quantification limits were between 1.04 and 4.25 ng/g. The proposed analytical method may be used as a simple procedure in routine determinations of OCs and Ops in meat. It can also be applied to the determination of pesticide multi-residues in other animal products such as butter and milk.

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