scholarly journals Methods development for the determination of methyl mercury in sediment samples using gas chromatography with atomic fluorescence detection

2013 ◽  
Vol 16 (2) ◽  
pp. 53-60
Author(s):  
An Quoc Trieu ◽  
Huy Phuong Tran ◽  
Dong Van Nguyen
Keyword(s):  
Gas Chromatography ◽  
Detection Limit ◽  
Fluorescence Detection ◽  
Potassium Oxalate ◽  
Fluorescence Detector ◽  
Atomic Fluorescence ◽  
Sediment Samples ◽  
Methods Development ◽  
Instrumental System

An analytical method for methylmercury (MeHg) using gas chromatography with atomic fluorescence detection is studied. The instrumental system is made based on a old gas chromatograph interfaced with an atomic fluorescence detector which is specific to Hg, currently available in our lab. Operating parameters for the GC-AFS system are optimised and analytical performances of the system are verified by quality control chart for stability. MeHg in sediment is leached and extracted to dichloromethane (DCM) in the presence of nitric acid, potassium chloride and copper sulfate. DCM in the extract is purged and MeHg is back extracted to aqueous phase followed by ethylation with sodium tetraethylborate in acetate buffer pH 5.3 containing potassium oxalate. The ethylated MeHg is then extracted to hexane and injected to GC-AFS for quantitation. The instrumental detection limit and method detection limit are 0.5 pg MeHg and 0.029 ppb MeHg (as Hg), respectively. The method can be applied for the determination of MeHg in soil, sludge and sediment samples.

Alcohol Determination by HPLC with Postcolumn Derivatization Based on the Thiosulfate-catalyzed Reaction of Alcohols and Cerium(IV) and Fluorescence Detection of Cerium(III)

2020 ◽  
Vol 16 ◽  
Author(s):  
Ikko Mikami ◽  
Eri Shibayama ◽  
Kengo Takagi
Keyword(s):  
Detection Limit ◽  
Fluorescence Detection ◽  
Reaction Rate ◽  
Detection Method ◽  
Fluorescence Detector ◽  
Reaction Solution ◽  
Optimum Detection ◽  
Postcolumn Derivatization ◽  
Sensitive Method

Background: Determination of a reducing substance based on the reaction between Ce(IV) and a reducing substance and fluorescence detection of Ce(III) generated has been reported as a selective and sensitive method. However, this method could not be applied to the determination of alcohol due to the low reaction rate of alcohol and Ce(IV). Objective: We found that thiosulfate catalytically enhanced reaction of alcohols (such as, methanol, ethanol, and propanol) and Ce(IV). Utilizing this effect, we developed a new method for the determination of alcohols. Results: In the presence of thiosulfate, an increase in fluorescence intensity was detected by injecting alcohol at concentrations of several millimolar, whereas it was not observed even at the concentration of 10% v/v (2 M for ethanol) in the absence of thiosulfate. The optimum detection conditions were determined to be 4.0 mM Ce(IV) sulfate and 0.50 mM thiosulfate, and the detection limit (S/N = 3) of ethanol under these conditions was 1 mM. In the calibration curves, changes in the slope were observed when the alcohol concentrations were approximately 10–25 mM. Using a thiosulfate solution containing ethanol as the reaction solution, a calibration curve without any change in slope was obtained, although the concentration of ethanol at the detection limit increased. The alcohols in the liquor and fuel were successfully analyzed using the proposed detection method as a postcolumn reaction. Conclusion: This new alcohol detection method using a versatile fluorescence detector can be applied to the postcolumn reaction of HPLC omitting need of time-consuming pretreatment processes.

Determination of Inorganic Selenium Species in Marine Waters by Hydride Generation - AFS

2004 ◽  
Vol 57 (10) ◽  
pp. 937 ◽  
Author(s):  
Bronwyn D. Wake ◽  
Edward C. V. Butler ◽  
Alison M. Featherstone ◽  
Patti Virtue ◽  
Bernard Averty ◽  
...  
Keyword(s):  
Detection Limit ◽  
Fluorescence Detection ◽  
Hydride Generation ◽  
Reduction Step ◽  
Marine Waters ◽  
Atomic Fluorescence ◽  
Inorganic Selenium ◽  
Cryogenic Trapping ◽  
Better Than

A method based on hydride generation with cryogenic trapping and atomic fluorescence detection was developed that is capable of determining both inorganic Se species (SeIV and SeVI) while at sea. Evaluation of the system for optimal performance was made for each stage of the analysis and detection sequence, as well as for the SeVI reduction step. A detection limit of 0.4 ng L−1 Se in a 10 mL sample was achieved using this method. Precision was better than 3.5% for 25, 100, and 1000 ng L−1 SeIV standard solutions. Accuracy was determined by recovery studies using natural samples and a certified reference seawater (NASS-5).

Determination of the Malachite Green in Sediment by High Performance Liquid Chromatography with Fluorescence Detection

2013 ◽  
Vol 781-784 ◽  
pp. 942-946 ◽  
Author(s):  
Jian Chao Deng ◽  
Xian Qing Yang ◽  
Lai Hao Li ◽  
Jian Wei Cen ◽  
Shu Xian Hao ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Malachite Green ◽  
Fluorescence Detection ◽  
High Performance ◽  
Solid Phase ◽  
Fluorescence Detector ◽  
Sediment Samples ◽  
Relative Standard

A new method of determination of malachite green (MG) in sediment has been developed by high performance liquid chromatography with fluorescence detection (HPLC-FLD). It is based on use of a deoxidation reaction which converts malachite green (MG) into LMG in the process of extraction. The sediment samples were extracted with a solution of formic acid and acetonitrile. Clean up and isolation was performed on MCX solid phase extraction (SPE) column. Chromatographic separation was achieved by using C18column with an isocratic mobile phase consisting of acetonitrile and ammonium acetate buffer (0.05 M, pH 4.5) (80:20, v/v). High performance liquid chromatography with fluorescence detector (λex=265 nm and λem=360 nm) was used for the determination of LMG. The recovery values of MG in sediment samples fortified with MG were determined by measuring the amount of MG in the samples, after carrying out deoxidation reaction with potassium borohydride, which converts the MG into LMG. Under the optimized conditions, the average recoveries of MG from sediment at three levels (1.0, 10 and 50 μg/kg) were 85.0% (range from 80.8 to 87.6%). Relative standard deviations (RSD) of recoveries at all fortification levels were less than for 9.57% for MG. The method detection limit obtained for MG was 0.5 μg/kg.

Determination of monomethylmercury in low- and high-polluted sediments by microwave extraction and gas chromatography with atomic fluorescence detection

2008 ◽  
Vol 608 (1) ◽  
pp. 30-37 ◽  
Author(s):  
J.J. Berzas Nevado ◽  
R.C. Rodríguez Martín-Doimeadios ◽  
F.J. Guzmán Bernardo ◽  
M. Jiménez Moreno
Keyword(s):  
Gas Chromatography ◽  
Fluorescence Detection ◽  
Microwave Extraction ◽  
Atomic Fluorescence ◽  
Polluted Sediments

Determination of Picogram Levels of Methylmercury by Aqueous Phase Ethylation, Followed by Cryogenic Gas Chromatography with Cold Vapour Atomic Fluorescence Detection

1989 ◽  
Vol 46 (7) ◽  
pp. 1131-1140 ◽  
Author(s):  
Nicolas Bloom
Keyword(s):  
Gas Chromatography ◽  
Fluorescence Detection ◽  
Precise Determination ◽  
Atomic Fluorescence ◽  
Extraction Step ◽  
Bottom Waters ◽  
Cold Vapour ◽  
Simple Extraction ◽  
Lake Waters

A technique is presented, which allows the rapid and precise determination of methylmercury in aqueous samples. The sample is first reacted with sodium tetraethylborate, to convert the nonvolatile monomethyl mercury to gaseous methylethylmercury. The volatile adduct is then purged from solution, and recollected on a graphitic carbon column at room temperature. The methylethylmercury is then thermally desorbed from the column, and analyzed by cryogenic gas chromatography with cold vapour atomic fluorescence detection. The method allows the simultaneous determination of labile Hg(II) species, through the formation of diethylmercury, and of dimethylmercury, which is not ethylated. The methylmercury detection limit is about 0.6 pg Hg, or 0.003 ng∙L−1 for a 200-mL sample. The technique has been successfully applied directly to a wide variety of freshwater samples and alkaline tissue digestates. Seawater is analyzed following a simple extraction step to separate the methylmercury from the interfering chloride matrix. Analyses of natural surface waters have shown methylmercury levels typically in the range of 0.02–0.10 ng∙L−1, with values as high as 0.64 ng∙L−1 in a polluted urban lake. Waters collected from the anoxic bottom waters of a stratified remote lake have shown methylmercury levels as high as 4 ng∙L−1 as Hg.

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