Simplex optimization of analytical chemical methods

Morgan, Stephen L.; Deming, Stanley N.

doi:10.1021/ac60345a035

Cited by 333 publications

(68 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The simplex method was invented in the early 1960's (Spendley, et al, 1962), and it has been used to solve a variety of problems ranging from shimming the gradient and curvature setting in NMR instruments to optimizing the solvent composition in HPLC by the "seven solvent" system (Ernst, 1963;Morgan and Demming, 1974;Ritter et al, 1975;Lam et al, 1976;Jurs and Isenhour, 1975). As the results presented below indicate, simplex can also be used to obtain rate constants and other important data from transient absorption decay curves by a completely unbiased analysis of the experimental data.…”

Section: The Simplex Methodsmentioning

confidence: 99%

The Advanced Chemistry Basins Project

Goddard¹,

Meulbroek²,

Tang³

et al. 2004

View full text Add to dashboard Cite

In the next decades, oil exploration by majors and independents will increasingly be in remote, inaccessible areas, or in areas where there has been extensive shallow exploration but deeper exploration potential may remain; areas where the collection of data is expensive, difficult, or even impossible, and where the most efficient use of existing data can drive the economics of the target. The ability to read hydrocarbon chemistry in terms of subsurface migration processes by relating it to the evolution of the basin and fluid migration is perhaps the single technological capability that could most improve our ability to explore effectively because it would allow us to use a vast store of existing or easily collected chemical data to determine the major migration pathways in a basin and to determine if there is deep exploration potential. To this end a the DOE funded a joint effort between California Institute of Technology, Cornell University, and GeoGroup Inc. to assemble a representative set of maturity and maturation kinetic models and develop an advanced basin model able to predict the chemistry of hydrocarbons in a basin from this input data. The four year project is now completed and has produced set of public domain maturity indicator and maturation kinetic data set, an oil chemistry and flash calculation tool operable under Excel, and a user friendly, graphically intuitive basin model that uses this data and flash tool, operates on a PC, and simulates hydrocarbon generation and migration and the chemical changes that can occur during migration (such as phase separation and gas washing).The DOE Advanced Chemistry Basin Model includes a number of new methods that represent advances over current technology. The model is built around the concept of handling arbitrarily detailed chemical composition of fluids in a robust finite-element 2-D grid. There are three themes on which the model focuses: chemical kinetic and equilibrium reaction parameters, chemical phase equilibrium, and physical flow through porous media. The chemical kinetic scheme includes thermal indicators including vitrinite, sterane ratios, hopane ratios, and diamonoids; and a user-modifyable reaction network for primary and secondary maturation. Also provided is a database of typespecific kerogen maturation schemes. The phase equilibrium scheme includes modules for primary and secondary migration, multi-phase equilibrium (flash) calculations, and viscosity predictions. Abstract

show abstract

Section: The Simplex Methodsmentioning

confidence: 99%

The Advanced Chemistry Basins Project

Goddard¹,

Meulbroek²,

Tang³

et al. 2004

View full text Add to dashboard Cite

show abstract

“…The FIA variables (injection volume, flow rate of the carrier, oxidant and sample) were optimized by using a multivariate strategy, the modified simplex method (MSM). [33][34][35] Two consecutive simplex procedures were performed, the interval for each variable in the second being restricted to the zone that gave the best results in the first. Then, some of the higher vertices were selected for a new and large comparative (n = 45) study to choose the output resulting in the best compromise sensitivity (peak height), sample throughput (peakbase width) and reproducibility.…”

Section: Procedures Preparation Of Pesticide Stock Solutionsmentioning

confidence: 99%

Chemiluminescent Determination of the Pesticide Bromoxynil by On-line Photodegradation in a Flow-Injection System

et al. 2006

View full text Add to dashboard Cite

IntroductionBromoxynil (3,5-dibromo-4-hydroxybenzonitrile) is a nitrile herbicide 1 that is used for the post-emergent control of annual broad-leaf weeds, especially in cereal, corn, sorghum, flax, onions, mint and non-cropland. This pesticide acts to inhibit photosynthesis in the target plants. The molecular structure is shown in Fig. 1.Most of the reported analytical methods for the determination of Bromoxynil are chromatographic, often in tandem with mass spectrometry, with UV detection, or even a combination of both.2 There are methods for the determination in atmospheric samples (gas and particles), 3 crops, 4 water, 5-11 from biological origins, 12 wines with a solid-phase extraction (SPE), 13 soils, [14][15][16] foodstuffs 17,18 or plants. 15 Electrochemical detection has been combined with HPLC for the determination of Bromoxynil and Ioxynil in barley. 19Two capillary electrophoresis methods 20,21 provided with solid-phase extraction have been proposed for Bromoxynil determination in the analysis of water samples.Although separative methods are by far the most commonly used; some attempts for direct determination have been published. Abubaker et al. 22 proposed peroxyoxalate chemiluminescence for the determination of phenol herbicides in soil. An ester is formed by a reaction with anhydride triethylamine and oxalyl chloride in tetrahydrofuran (THF). After eliminating of the supernatant liquid phase under a vacuum, a re-dissolution in THF containing 9,10-diphenylanthracene was implemented and the injection of H2O2 into a standard quartz spectrophotometer cell yielded light emission, which was measured at two different time intervals of 1 and 3 s. However, the linear range was observed for quite high concentrations, over the range of 10 -100 mg l -1 .Phosphorescence has been also used. 23 The spectra (264 and 420 nm for excitation and emission, respectively) were recorded in ether-isopentane-ethanol (5:5:2) at 77 K. A linear behavior was found in the range from 0.2 (quantitation limit) to 7.5 mg l -1 of Bromoxynil. Finally, a Photosystem II-based biosensor have been proposed by Koblizek et al. 24 This present paper contributes to the non-separation methods for the Bromoxynil determination. The selected detector was a luminometer; due to direct chemiluminescence, it provides a strong oxidant and has proved to be a highly sensitive method that is applicable over a wide range of concentrations and with very low detection limits. 25,26 To obtain the emitter product, online irradiation with UV light was used, as a clean reactive for derivatization. The UV irradiation proved to be an easy and clean way of derivatization to obtain fluorometric 27-29 or chemiluminescent structures. 30-32 A discussion of possible photoproducts is included. In order to automate the method, a flow injection analysis (FIA) manifold was developed. A new, robust and simple method is proposed for the chemiluminescent determination of the pesticide Bromoxynil. The empirical procedure is performed with the aid of a flow-injection manifol...

show abstract

“…All other FIA variables (volume, length, flow rate) were optimized by using a multivariate strategy: the modified simplex method (MSM). [35][36][37] The pH and buffer presence were the first variables to be reoptimized. An assembly was prepared with a mono-channel configuration with pure water circulating at 6.3 ml min -1 as the carrier-stream, in which the sample volume was inserted.…”

Section: Influence Of Other Chemical Parameters: Solvent Polarity Prmentioning

confidence: 99%