Carrier flow rates

Duarte and colleagues used a factorial design to optimize a flow injection analysis method for determining penicillin potentiometricallyd Three factors were studied—reactor length, carrier flow rate, and sample volume, with the high and low values summarized in the following table. 

As mentioned in Section 11.8.4, the parameters that are most important for a qualitative analysis using most GC detectors are retention time, tR adjusted retention time, t R and selectivity, a. Their definitions were graphically presented in Figures 11.16 and 11.17. Under a given set of conditions (the nature of the stationary phase, the column temperature, the carrier flow rate, the column length and diameter, and the instrument dead volume), the retention time is a particular value for each component. It changes... 

Clark described another gas chromatographic method, which used a 2 m x 4 mm glass column with 2.5% SE-30 on 100 mesh Chromosorb G 80 [4]. An oven temperature of about 118°C and a nitrogen carrier flow rate of 45 mL/min. were used. 

Molar carrier flow rate in each line Qn2 is calculated from Equation 3, knowing the volumetric normalized flow rates Qvn2 normalized (Llr1 at 273.15 K, latm) of carrier gas used for saturation, usually obtained by mass flow meters ... 

The electron capture detector (ECD) is also a concentration-dependent detector, and like the TCD will give a higher response for a given compound at lower carrier flowrates. Carrier flow-rate must be carefully controlled. Usually a 95% argon - 5% methane mixture is used for carrier gas. Presence of oxygen or water in the carrier gas results in loss of sensitivity and a compression of the linear range. 

Injector and detector temperatures were maintained at 150 and 200°C, respectively. Nitrogen carrier flow rates were measured with a Gasmet flow meter and were maintained between 22 and 24 ml min-1. Gas holdup times were measured with 20 1 injections of methane. 

Oven Temp. Carrier Flow Rate Detection ... 

Figure 3. Variance of Nt tracer profile vs. He carrier flow rate. Key O, with bed , in absence of bed and---------, difference between curves through O and .

Figure 4. Confidence Indices (upper number) and retention times in sec (lower number) for 9 cannabinoids. Reported as K for 1 ng samples. (Column = 180 cm X 0.2 cm ID borosilicate glass packed with 1.5% OV-17 on 100/120 mesh HP Chromosorb G column temperature = 275°C nitrogen carrier flow rate = 30...

Acetylcholineesterase and choline oxidase Enzyme immobilized over tetra-thiafulvalene tetracyanoquinodi-methane crystals packed into a cavity at the tip of a carbon-fiber electrode. The immobilization matrix consisted of dialdehyde starch/glutaraldehyde, and the sensor was covered with an outer Nafion membrane. The ampero-metric performance of the sensor was studied with the use of FIA system. An applied potential of +100 mV versus SCE (Pt-wire auxiliary electrode) and a carrier flow rate of 1 mL/min. The Ch and ACh biosensors exhibited linear response upto 100 pM and 50 pM, respectively. Response times were 8.2 s. [97]... 

FIGURE 4 (A) Adsorption isotherms of bovine and horse heart cytochrome c each at two different salt concentrations (90 and 125 m/W). Column 50 X 5 mm i.d. strong cation exchanger (8 (im) flow rate 0.2 mL/min. (Kundu et al.49) (B) Displacement separation of cytochrome c s from bovine and horse heart using BAEE as the displacer. Column 105 X 5 mm i.d. strong cation exchanger (8 /im) mobile phase 50 m/VI sodium phosphate buffer, pH 6.0 feed 1.6 mL of 0.52 m M each of bovine and horse heart cytochrome c in carrier displacer concentration 40 mAI N-a-benzoyl arginine ethyl ester (BAEE) in the carrier flow rate 0.2 mL / min fraction size 200 mL. 

FIGURE 5 Displacement chromatography of proteins on IMAC using imidazole as the displacer. Column SO X 5 mm i.d. Cu2+ charged metal chelate Sepharose (10 /urn) mobile phase I M NaCI, 25 mM phosphate buffer, pH 7.0 feed l.8mL of 0.89 mM ribonuclease A and 0.69 mM myoglobin in the carrier displacer 10 mM imidazole in the carrier flow rate 0.1 mL/min fraction size 100 /cL fractions. (Vunnum et a/.58)... 

However, even sophisticated calibration procedures cannot account for wall effects of the sample which might be absent for the calibration standard. The term wall effects summarizes all kinds of forces, both attractive and repulsive, which can become significant as the colloidal particles are usually forced to be in direct contact with the accumulation wall. Therefore, any information from such experiments can become error prone, so it is recommended to reduce the field or to alter the carrier flow rate in order to switch from the steric to the hyperlayer mode. 

The next step is column selection. Many factors contribute to the chromatographic results that are obtained on a given sample. Some of these are related to the instrument, and others are operational parameters. The column is in both ways important. The column as part of the chromatographic hardware is a design parameter which should be selected according to the needs of individual laboratories. Operational parameters, including column temperature and carrier flow rate, both of which may exercise profound influences on column behavior must be selected by the operator, considering the application as well as the characteristics of the column. 

The concentration c of adsorbate in the carrier gas is expressed in terms of the detector response and the carrier flow rate by substituting Equation 8 into Equation 6 ... 

Figure 12.7 Individual band profiles in the displacement chromatogram of inosine, deoxp-nosine, adenosine, and deoxyadenosine. Column 250 x 4.6 mm +150 x 4.6 mm packed with 5 im Supelcosil LC-18 carrier 10 mM acetate buffer, pH 5.0 displacer 27.5 mM benzyl-tributylammonium chloride in the carrier flow rate 0.1 mL/min fraction volume 100 jiL temperature 22°C feed 10 mg of each component in 2.0 mL in carrier. Reproduced with permission from Cs. Horvath, J. Frenz and Z. El Rossi, J. Chromatogr., 255 (1983) 273 (Fig. 3).

Figure 12.23 Influence of the sample size and the displacer concentration on the displacement of -lactoglobuhns A and B. Column TSK DEAE 5-PW, 75x7.5 mm carrier 25 mM phosphate, pH 7.0 displacer 10 mg/mL of chondroitm sulfate in the carrier flow rate 0.1 mL/min temperature 22°C fraction volume 200 jiL sample volume 4 mL. (a) Feed 100 mg LAC. (b) Same as in (a), except feed, 78 mg LAC. (c) Same as in Figure 12.22a, except displacer concentration 20 mg/mL and sample size 62 mg LAC. (d) Same as in (a), except displacer concentration 3 mg/mL and sample size 70 mg LAC. Reproduced with permission from A.W. Liao, Z. El Rossi, D.M. LeMaster and Cs. Horvath, Chromatographia, 24 (1987) 881 (Figs. 2 and 3).

Y.-H. Li, H.-C. Ma, Two trends of sample dispersion variation with carrier flow rate in a single flow-injection manifold, Talanta 42 (1995) 2033. 

In the measurements of the adsorption equilibrium and intracrystalline diffusion data, the injection sample loop was first filled with a sample solution (water as solvent) of a known sorbate concentration by a syringe. The sample was then injected into the column after a stable base line in the recorder had been obtained. For each adsorbate at a given temperature, about 4 to 6 samples of different adsorbate concentration (CG from about 0.015 to 0.06 g/ml) and at different carrier flow rate (Q from 0.5 to 2.0 ml/min) were injected to give the corresponding response peaks at the outlet of the column. The response peaks were recorded and then directly read from the recording chart and input to a DEC-20 computer for further analysis. Figure 2 shows some recorded response peaks from the silicalite LC column for ethanol, n-propanol and n-butanol. 

The second experimental parameter examined was the rate of gas supply to the specimen. Varying the argon carrier flow rate from 156 to 1000 cm min- - had no marked effect upon the oxidation behaviour of the deposit in water vapour at either 815°C (with Pjjjo = 362 mm Hg) or 1050°C (with Pi O 38 and 362 mm Hg) (Figure 1). In the majority of the later experiments the argon flow rate was maintained at 500 cm min- -. 

The first four steps are the background, and the fifth is the signal. Materials that can be ionized by 11.6 ev are detectable. Moderate variations in carrier flow rate and temperature have negligible effects on the detector base current. The LDR is about 5 x 10 ... 

Both the differential and ratiometric responses of the sensor can be tuned by changing certain sensor parameters. The sensor provides independent temperature control for each polymer zone, enabling tuning of the differential time response between polymer zones. In addition, the magnitude of the sensor response is temperature sensitive, so by varying the temperature of the polymer zones the ratiometric responses can be optimized for a given analyte or analytes. The carrier flow rate can also be adjusted to fine-tune the selectivity of the sensor. 

So the selection of chromatographic conditions (colunm, temperature, carrier flow rate) will be influenced by the compound volatility, molecular weight, and polarity. 

The optimal feed concentration of the pervaporation unit depends on carrier flow rate, reflux ratio and number of theoretical trays of the extractive distillation. Retentate concentration and cut rate of the pervaporation stage follow from the requested product quality xlt + x31 <0.008. For the design of the pervaporation stage, the worst case has been assumed that only benzene and no furfural (3) will pervaporate. The major factor for the cost reduction is the much lower energy consumption of the hybrid process of 1.18 t/h heating steam against 1.7 t/h for the conventional process. 

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