Determination of pKa using the half-volume method: A laboratory experiment

1977 ◽  
Vol 54 (11) ◽  
pp. 711 ◽  
Author(s):  
S. Jane Stephens ◽  
Michael J. Jonich
Keyword(s):  
Laboratory Experiment ◽  
Volume Method

scholarly journals A Toolbox for the Determination of Nitroaromatic Explosives in Marine Water, Sediment, and Biota Samples on Femtogram Levels by GC-MS/MS

Toxics ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 60
Author(s):  
Tobias Hartwig Bünning ◽  
Jennifer Susanne Strehse ◽  
Ann Christin Hollmann ◽  
Tom Bötticher ◽  
Edmund Maser
Keyword(s):  
Sample Preparation ◽  
Freeze Drying ◽  
Solid Phase ◽  
Phase Extraction ◽  
Direct Extraction ◽  
Time Saving ◽  
Marine Samples ◽  
Volume Method ◽  
Biota Samples

To determine the amount of the explosives 1,3-dinitrobenzene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, and its metabolites in marine samples, a toolbox of methods was developed to enhance sample preparation and analysis of various types of marine samples, such as water, sediment, and different kinds of biota. To achieve this, established methods were adapted, improved, and combined. As a result, if explosive concentrations in sediment or mussel samples are greater than 10 ng per g, direct extraction allows for time-saving sample preparation; if concentrations are below 10 ng per g, techniques such as freeze-drying, ultrasonic, and solid-phase extraction can help to detect even picogram amounts. Two different GC-MS/MS methods were developed to enable the detection of these explosives in femtogram per microliter. With a splitless injector, limits of detection (LODs) between 77 and 333 fg/µL could be achieved in only 6.25 min. With the 5 µL programmable temperature vaporization—large volume method (PTV-LVI), LODs between 8 and 47 fg/µL could be achieved in less than 7 min. The detection limits achieved by these methods are among the lowest published to date. Their reliability has been tested and confirmed by measuring large and diverse sample sets.

Determination of Nitrate and Nitrite in Water by Capillary Electrophoresis: An Undergraduate Laboratory Experiment

1998 ◽  
Vol 75 (12) ◽  
pp. 1588 ◽  
Author(s):  
David S. Hage ◽  
Anuja Chattopadhyay ◽  
Carrie A. C. Wolfe ◽  
Julie Grundman ◽  
Paul Kelter
Keyword(s):  
Capillary Electrophoresis ◽  
Laboratory Experiment ◽  
Undergraduate Laboratory ◽  
Nitrate And Nitrite

Inverse determination of thermal conductivity in lumber based on genetic algorithms

Holzforschung ◽  
2016 ◽  
Vol 70 (3) ◽  
pp. 235-241 ◽  
Author(s):  
Jingyao Zhao ◽  
Zongying Fu ◽  
Xiaoran Jia ◽  
Yingchun Cai
Keyword(s):  
Thermal Conductivity ◽  
Genetic Algorithms ◽  
Heat Conduction ◽  
Heat Conduction Equation ◽  
Convective Heat Transfer Coefficient ◽  
Conduction Equation ◽  
New Equation ◽  
Volume Method ◽  
Good Agreement

Abstract A 3D numerical solution of the heat conduction equation is proposed based on the finite volume method to describe the heating of wood, where the thermal conductivity (ThC) is variable, and the convective heat transfer coefficient is constant. ThC parameters were found through an optimization process based on genetic algorithms. The objective function between measured and simulated curves is determined, and parameters with greatest correspondence between measured and estimated values were obtained. As a result, a new equation for ThC is proposed, which depends on moisture and temperature. The proposed coefficient is validated by experiments, and a good agreement was found between experimental heating curves and those obtained by simulation by means of the new heat conduction equation.

Mathematical Model of Multi-Layer Wall with Phase Change Material and its Use in Optimal Design

2013 ◽  
Vol 649 ◽  
pp. 295-298
Author(s):  
Lubomir Klimes ◽  
Pavel Charvát ◽  
Josef Stetina
Keyword(s):  
Mathematical Model ◽  
Optimal Design ◽  
Phase Change ◽  
Phase Change Material ◽  
Control Volume ◽  
Operational Conditions ◽  
Volume Method ◽  
The Mathematical Model ◽  
Change Material

The paper deals with the mathematical model of the multi-layer wall containing the phase change material (PCM). The model utilizes the effective heat capacity method for modeling the latent heat of phase change and the control volume method is used for the discretization of the model. The utilization of the model is then demonstrated on the problem of the optimal design of the multi-layer wall with the PCM. The TMY2 data for the city of Brno were used in simulations as operational conditions. The main attention is aimed at the determination of the optimal thickness of the PCM layer for the multi-layer wall design with various thicknesses of the masonry.

Sign in / Sign up

Export Citation Format

Share Document