Model, chromatographic

In modeling liquid chromatographic processes, frequently the following assumptions are justified  

Consequently, standard models describing chromatographic columns consist typically of one-dimensional mass balances. The pressure drop can be calculated by Equation 2.25. 

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A Hewlett Packard gas chromatograph, model 5890A, equipped with a flame ionization detector and a Hewlett Packard integrator, model 3396 series 2, were used. 

It is the main aim of semiempirical chromatographic models to couple the empirical parameters of retention with the established thermodynamic quantities generally used in physical chemistry. The validity of a model for chromatographic practice can hardly be overestimated, because it often and successfully helps to overcome the old trial-and-error approach to running the analyses, especially when incorporated in the separation selectivity oriented optimization strategy. 

Gas chromatograph. Model 3400 (Varian, San Jose, CA, USA) equipped with split/ splitless injector and a niAogen-phosphorus detector (GC/NPD) or equivalent Heater, HPLC column... 

Gas chromatograph. Model 6890 (Agilent Technology) equipped with split/splitless injector and a mass spectrometer. Model 5973, or equivalent Tissumizer, Model SDT 1810 SI with S25N probe (Tekmar, Cincinnati, OFl, USA) or equivalent... 

High-performance liquid chromatograph Model LC-6A equipped with RF-535 fluorescence detector (Shimadzu Co., Japan)... 

King PH, McCarty PL. 1968. A chromatographic model for predicting pesticide migration in soils. 

Spectra-Physics, Autolab Div., San Jose, CA Liquid Chromatograph, Model SP8100 XR Technical Bulletin D/S-01, 12/84. 

Typical reaction procedure is as follows biphenyl (25 mmol), propene (50 mmol), HM (1 g), and trans-decalln (20 cm ) were heated in an autoclave at 200°-300°C for 4 h. Products were analyzed by a Hewlett-Packard Gas-chromatograph Model 5890 equipped with a 25 m capillary column of Ultra-1. 

Sehnert SS, Risby TH. 1988. Chromatographic modeling of the release of particle-adsorbed molecules into synthetic alveolar surfactant. Environ Health Perspect 78 185-195. 

The results can be divided in several parts. The first part concerns the determination of suitable models which describe the R as function of the solvent composition, temperature and relative humidity. This part can be subdivided in the selection of a suitable Box-Cox transformation, determination of the suitable models and a discussion of the performance of the models found versus the more chromatographic models such as models (5) and (6). The second part of the results concerns the search for an optimum separation. This can be subdivided in a part concerning an optimum at a fixed setting of temperature and relative humidity and a part concerning the search for an optimum separation which is robust against changes in temperature and relative humidity. 

Figure 6.2a shows the HPLC chromatogram using the NH2 column (Friedman et al, 2003c). HPLC chromatography was carried out with the aid of a Hitachi liquid chromatograph model... 

The assay was carried out using a Varian gas chromatograph (model 5000 LC) under the following experimental condition. The oven injector and flame ionization detector temperatures were 125°C and 225°C respectively. A Porapak column was used, the eluent was N2 at a flow rate of 30 ml/min and the injected volume 2 pi. Various concentrations of purified methylene chloride in purified methanol were injected (both solvents were distilled to discard any impurity which might interfere with the sensitive assay). Calibration curves were linear in the range 50-500 ppm (the limit of detection was 10 ppm). Methylene chloride detection in the microspheres was performed by dissolving various amounts (20-200 mg) of microspheres in 220 ml of purified methanol prior to the injection. 

An authentic sample from Aldrich Chemical Company, Inc., had m.p. 45-50°. The product is analyzed by gas chromatography at 80° on F M Research chromatograph model 1810 with 3% OV-17 column, which indicates the contamination of the product by 4-ferf-butylcyclohexanol (<2%) and 4-fert-butylcyclohexyl-methyl methylthiomethyl ether (<2%).3 The submitters reported a yield of 6.0 g. (96%) of purity greater than 96%. 

The description of the model up to this point is analogous to a description of a chromatographic model which incorporates the concept of the theoretical plate ( 5). ... 

Poole, S. K., and C. F. Poole, Chromatographic models for sorption of neutral organic compounds by soil from water and air , J. Chromatogr. A, 845, 381-400 (1999). 

The analysis starts when a small quantity of sample in liquid or gaseous state is injected. The dual role of the injector is to vaporise the analytes and to mix them uniformly in the mobile phase. Once the sample is vaporised in the mobile phase, it is swept into the column, which is usually a tube coiled into a very small section with a length that can vary from 1 to over 100 m. The column containing the stationary phase is situated in a variable temperature oven. At the end of the column, the mobile phase passes through a detector before it exits to the atmosphere. Some gas chromatograph models have their own power supply, permitting them to be used in the field (see Fig. 2.16). 

Product Characterization by GPC. A Waters gel permeation chromatograph, model 200, was used in this work. The instrument was operated at room temperature, and tetrahydrofuran was used as the elution solvent. Samples were analyzed on a four-column system column permeabilities were 2.5 X 105, 1.5 X 104, 103, and 102 A (Waters designation). Oligomer samples (0.5% by weight in tetrahydrofuran) were injected for 120 seconds. A solvent flow rate of 1 ml/minute was used. 

Equipment. A commercial 300 ml magnedrive autoclave (Autoclave Engineers) reactor was used for all reaction studies and has been previously described (3-6). Varian gas chromatographs (Model 920 and 1800) were used for analysis of gas samples and products from the hydrotreating reactions. 

Py-GC experiments were performed using a modified SGE pyrolysis inlet, interfaced either with a Chrompack gas chromatograph (model 437S) equipped with a flame ionization detector and a double flame photometric detector or with a Delsi gas chromatograph (model DI300) interfaced with a Delsi mass spectrometer (model R10 10). The control of the Chrompack GC and the data acquisition were done with a PCI-Chrompack program and a PC computer. 

King, P.H., McCarthy, P.L. (1968) A chromatographic model for predicting pesticide migration in soils. Soil Sci. Soc. Am. Proc. 106, 248-261. 

An important advantage of the Simplex method is that it does not rely on any chromatographic model and does not require any chromatographic insight. This implies that a Simplex optimization program can be applied to LSC as well as to RPLC without any modifications [506]. This is not true for many other methods as will be discussed in section 5.5.1. 

The analysis of the extracts was made in a Perkin Elmer Gas Chromatograph model 8700 with an detector NPD. The analysis conditions were 423 K for 1 minute followed by ramp of 15.0 K/min until 523 K and another ramp with 30.0 K/min until 553 K. Injector and detector were setted at 533 K and 543 K, respectively. It was used a capillar column BP5 (cross-linked 5 % biphenyl, 95 % dimethylssiloxane) with 50 m long and 0.25 pm of diameter from SGE. Carrier gas used was He at 2 ml 7 min. 

Oxygen Uptake. A Carle gas chromatograph model GC 8700 containing an O2-N2 detection column was used to measure oxygen uptake. Samples of gas were withdrawn from the test chambers with a 10-juL syringe inserted through the silicone disc. Initial trials indicated that operator error is insignificant and that reliable reproducible results can be obtained so that 0.25 is a more than adequate error allowance. 

The equilibrium isotherms for adsorption of peptide were measured by the batch method. Equilibrium was fully reached in 4 days. The solution for the peptide was analyzed with a Shimadzu Liquid Chromatograph Model LClOATvp and a Shimadzu Fluorescence HPLC Monitor Model FLD-1. The pH of the equilibrium solution was analyzed with a Horiba pH meter Model F-23. 

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