ISCO column

Another advantage of the micro-LC approach is that the required sample size is minimal, so the sample can be drawn from a 1-1 laboratory scale reactor without influencing the reactor composition. The ISCO pLC-500 microflow syringe pump has proven to be reliable and reproducible in evaluations in our laboratory. Capillary liquid columns have been fabricated on planar devices such as silicon to form a miniaturized separation device.19... 

It is worth noting that the commercial (ISCO, Inc.) monolithic column utilized in these evaluations is very stable. Over a period of about 7 months, approxi-... 

Fig. 20. Test of stability of weak cation exchange monolithic column (ISCO). Conditions column, 50 X4.6 mm i.d., mobile phase gradient of sodium chloride in 0.01 mol/1 sodium phosphate buffer (pH 7.6) from 0.1 to 0.5 mol/1 in 4.5 min and to 1 mol/1 in 6.5 min, overall gradient time 11 min, flow rate 10 ml/min. Peaks Ribonuclease (1), cytochrome c (2), lysozyme (3). The two separations shown in this figure were achieved 503 runs apart...

General Experimental Procedures MPLC fractionation was performed using an Isco CombiFlash, and HPLC isolation was performed using Shimadzu pumps and detector and YMC-Pack ODS-AQ C18 column. 

In-situ chemical derivatizations were performed by adding 0.5 to 2 mL of the derivatization reagent, trimethylphenyl ammonium hydroxide (TMPA) in methanol (Eastman Kodak Company, Rochester, NY) directly to the sample cell of an ISCO model SFX extraction unit. The sample and reagent were pressurized with C02 (typically 400 to 500 atm), and heated to an appropriate temperature (typically 80°C). The derivatization was performed in the static SFE mode for 5 to 15 minutes, then the derivatized analytes were recovered by dynamic SFE using a typical flow rate of 0.6 to 1.0 mL/min (measured as liquid C02 at the pump). No other sample preparation of the derivatized extracts was performed prior to GC analysis. All GC analyses were performed using Hewlett-Packard 5890 GCs with appropriate detectors and HP-5 columns (25 m X 250 pm i.d., 0.17 pm film thickness). 

Analysis of Tween 80 was performed using a Hewlett Packard 1100 series HPLC equipped with a Sedex 55 Evaporative Light Scattering Detector (ELSD). The mobile phase consisted of 80% acetonitrile and 20% water. Duplicate injections (5 pL) of each sample were evaluated by HPLC. Potassium iodide, used for the 1-D column and 2-D box tracer studies, was analyzed with a continuous flow Isco V4 variable UV wavelength absorbance detector equipped with an EZChrom Chromatography data acquisition system. 

An adjustable glass column of 9mm ID, packed with 5g of Fractosil 200 was connected to a Spectra Physics pump connected to solvent reservoirs with a six way rotary switch. The sample was injected onto the column with a rotary loop sampler. The effluent from the column was collected with an Isco fraction collector set so that 10 ml of eluate was collected for each... 

The column eluate was monitored with an Isco dual beam UV-vis detector operating at 310 nm and 546 nm. Ten-milliliter fractions were collected with an Isco fraction collector triggered by a siphon counter, and after completion of a run, adjacent 10-mL fractions were combined into five cuts. 

Samples were run on a Supelco LC-18-DB HPLC column, 2.1 mm X 25 cm. The buffers were A= 0.1% TFA in Milli-Q water, B= 0.09% TFA in 70% acetonitrile and the gradient was 0% B, 5min. 0 - 10% B, lOmin. 10 -50% B, 60 min. 50 - 100% B, 25 min. 100% B, lOmin. Fractions were collected in 1.5 nd polypropylene tubes, which were precleaned with 0.1% TFA in 50% acetonitrile, using an Isco Foxy fraction collector with peak separator. The fraction collector was enclosed in a Plexiglas chamber which was under positive nitrogen pressure to minimize airborne contamination of fractions. Fractions were capped and stored at -20 C. Immediately before loading on the sequencer, TFA (ABI) was added to fractions (25% final) to minimize peptide losses due to adsorption to the tube or pipet tip (18). 

Swift Isco (USA) Monolithic columns Styrene, methacrylate lEX, RP... 

All the samples were analysed by a HPLC comprising a pump, a 250 mm x 4.6 mm ID Supelcosil LC-SAX (5 micron) column, and a ISCO V4 Variable Wavelength UV/VIS detector which is capable of measuring the absorbance of light ranging from 190 to 750 nm. The mobile phase was 65% acetonitrile with 35% water (for hydrophilic dyes) and 80% methanol with 20% water (for hydrophobic dyes). In addition, a spectrophotometer Spectronic(R) Genesys was also used to scan the spectra of the tested samples at 3 nm intervals. 

Fig. 3. Diagram of ISCO Model 314 pumping system, a = pump, b = washout valve, c = pressure gauge, d = three-way re-fill valve, e = solvent reservoir, f = to column...

The methods employed for the miscible displacement studies were similar to those used in previous experiments (Hu and Brusseau, 1998). We connected a high-performance liquid chromatography (HPLC) pump (Model 301 from Alltech Associates Inc., Deerfield, IL) to the column, and placed a three-way valve in-line to facilitate switching between treatment solutions. Several iodine species (iodide, iodate, and 4-iodoaniline) were used to study transport behavior. We also examined the transport of tritium and bromide, commonly used conservative tracers, so that we could compare their transport behavior with iodine species. For transport experiments of 4-iodoaniline, which is used as a representative refractory organic iodine species, the solution was allowed contact only with glass or stainless steel, to avoid potential interaction of organoiodine with plastics in the column system. Column effluents were collected with an automated fraction collector (Retriever 500, ISCO Inc., Lincoln, NE) for chemical analysis, as described below. 

Figure 2. Elution profiles of compounds from Sephadex LH-20 column using tetrahydrofuran (THF) as eluant. The lines for each compound indicate the volume of THF in which the compounds eluted. Elution of compounds was monitored with an ISCO model UA-5 absorbance monitor at 280 nm.

Figure 3 A schematic of a typical high pressure apparatus A high purity CO2 tank B charcoal, oxysorb catalyst, drying columns C ISCO pump D check valve E pressure gauge F relief valve G sapp e window H thermocouple. Other vdves on high pressure cell are omitted for clarity.

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