Determination of herbicides in soil samples by gas chromatography: optimization by the simplex method

Santos-Delgado, M.J.

doi:10.1016/s0039-9140(00)00498-7

Cited by 46 publications

(27 citation statements)

References 10 publications

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“…In ( Construct the third support and excavate to the bottom of the foundation pit sought, and they can be solved by the simplex optimization method [38][39][40]. Specifically, a group of initial values used to develop the initial simplex according to certain rules is provided first.…”

Section: Displacement Back Analysis Of the Value Of Mmentioning

confidence: 99%

Horizontal Bearing Test and Optimization of m Value for Precast Piles in Alluvium Stratum of the Yellow River

Lyu

Chen

Zhao

et al. 2018

Mathematical Problems in Engineering

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For a pile foundation design, the value of proportional coefficient m to define the soil horizontal resist force is a significant parameter. However, different geological conditions and experimental environment have led to different m values. In this paper, an in situ test is firstly carried out on the horizontal bearing capacity of large-size precast square-piles. The piles deformation is then derived by using the optimization method from the measured data. Secondly a back analysis model is established to calculate the m value by using the simplex method, which reveals the evolution rule of the value of proportional coefficient m. Results show that the horizontal bearing characteristics of precast piles depend on the interaction force of piles and soils. The action mechanism of the soils around the piles is gradually developed with the increase in the concrete content. The horizontal critical load and the Eigenvalue of horizontal bearing capacity increased by 16.7% and 20%, respectively. It is also seen that the higher the content of the cement-soil around the piles and the longer the pile length, the bigger the m value obtained. The variation of the proportional coefficient m with the horizontal displacement of pile top is defined by three stages: rapid decaying stage, slow decaying stage, and balanced stage, respectively. The inverse analysis method on the proposed m value can accurately reflect the actual working state of piles and soils. In the depth of 3∼18m in the west of Ji'nan, the range of m value is recommended as 4∼6.58 MN⋅m −4 . When Δ takes 12mm, the values of m are consistent with the result from the back analysis. In summary, the obtained m value can be effectively used to guide the design of enclosure structure in the super deep foundation pit in the Yellow River alluvial stratum.

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Section: Displacement Back Analysis Of the Value Of Mmentioning

confidence: 99%

Horizontal Bearing Test and Optimization of m Value for Precast Piles in Alluvium Stratum of the Yellow River

Lyu

Chen

Zhao

et al. 2018

Mathematical Problems in Engineering

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“…The conventional extraction and derivatization procedure was carried out according to the methylation procedure by Santos-Delgado [10].…”

Section: Experimental Conditions 241 Extraction and Derivatizationmentioning

confidence: 99%

“…Due to the polarity of carboxylic acids, a polar extraction solvent such as sulphuric acid and methanol can be used. This is the advantage of this derivatization system, because it can be used simultaneously for extraction and derivatization [10].…”

Section: Introductionmentioning

confidence: 99%

Extraction and derivatization of polar herbicides for GC‐MS analyses

Ranz¹,

Maier²,

Motter³

et al. 2008

J of Separation Science

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A sample preparation procedure including a simultaneous microwave-assisted (MA) extraction and derivatization for the determination of chlorophenoxy acids in soil samples is presented. For a selective and sensitive measurement, an analytical technique such as GC coupled with MS needs to be adopted. For GC analyses, chlorophenoxy acids have to be converted into more volatile and thermally stable derivatives. Derivatization by means of microwave radiation offers new alternatives in terms of shorter derivatization time and reduces susceptibility for the formation of artefacts. Extraction and derivatization into methyl esters (ME) were performed with sulphuric acid and methanol. Due to the novelty of the simultaneous extraction and derivatization assisted by means of microwave radiation, a careful investigation and optimization of influential reaction parameters was necessary. It could be shown that the combination of sulphuric acid and methanol provides a fast sample preparation including an efficient clean up procedure. The data obtained by the described method are in good agreement with those published for the reference material. Finally, compared to conventional heating and also to the standard procedure of the EPA, the sample preparation time could be considerably shortened.

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“…The analysis method used for the detection of 2,4-D is generally GC (Santos-Delgado et al, 2000;Yu and Wells, 2007), GC/MS (Thorstensen et al, 2000;Rodriguez et al, 2005;Quintana et al, 2007), or sometimes capillary electrophoresis (CE; Miura et al, 1999;Baggiani et al, 2001;Farran and Ruiz, 2004). GC and some CE analyses have been shown to have adequate selectivity and sensitivity (Voos et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Development and validation of an analytical method for determination of endocrine disruptor, 2,4‐D, in paddy field water

Park

Choi

El‐Aty

et al. 2010

Biomedical Chromatography

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The acidic herbicides are an important class of chemical compounds that are used to control a variety of weeds that threaten many crops. Owing to their low microbial activity levels, the acidic herbicides exhibit a residual activity remaining for periods of up to several months in soils and water. The principal objective of this study was to develop an analytical method based on liquid-liquid and solid-phase extraction followed by HPLC, for the determination of 2,4-D in paddy field water. The residues were verified via tandem mass spectrometry (MS/MS) in negative-ion electrospray ionization (ESI) mode. Linearity was good over a concentration range of 1-100 µg/L with a correlation coefficient (r(2) ) of 0.999. The mean recovery rates of triplicate results ranged from 85.2 to 90.85%. The limits of detection and quantitation were 0.4 and 1.0 µg/L, respectively. The method proposed herein was applied to field samples acquired from Hampyung and Sunchang counties, Republic of Korea. The analyte was detected at a concentration range of 6.8-12.8 and 3.55-24.0 µg/L, respectively.

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Determination of herbicides in soil samples by gas chromatography: optimization by the simplex method

Cited by 46 publications

References 10 publications

Horizontal Bearing Test and Optimization of m Value for Precast Piles in Alluvium Stratum of the Yellow River

Horizontal Bearing Test and Optimization of m Value for Precast Piles in Alluvium Stratum of the Yellow River

Extraction and derivatization of polar herbicides for GC‐MS analyses

Development and validation of an analytical method for determination of endocrine disruptor, 2,4‐D, in paddy field water

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