Filtering and degassing

Mobile phase Prepare a filtered and degassed mixture of methanol and 1-penta-nesulfonate sodium solution (60 40). Make adjustments if necessary (see system suitability under Chromatography <621 >). 

Soda pop samples must be filtered and degassed. Prepare samples by vacuum filtering through paper 0.45-/rm filters, and then fill small labeled vials. 

When finished, flush the system with a filtered and degassed neutral pH liquid, such as pure methanol or a methanol-water mixture. 

Inject 20 pL of each sample and observe the retention times. Then inject 20 pL of the mixture. Record all experiment parameters, e.g., flow rate, attenuation, pressure (if pressure gauge is installed), etc. Be sure to print hard copies of all chromatograms. When finished, flush the flow path for 10 min with filtered and degassed methanol. 

Install a reverse phase column and repeat. Do not change the parameters recorded in step 4. When finished, again flush the flow path with filtered and degassed methanol for 10 min. 

All buffers and solutions used for chromatography should be prepared with high-quality water, filtered, and degassed. Careful attention to this will result in decreased buffer backgrounds or spurious peaks owing to contaminants or air bubbles. Particles in the buffers can shorten the column life and plug the column or tubing. 

All reactions and manipulations should be performed under an atmosphere of dry nitrogen either in a dry box or using Schlenk tube techniques. Filtered and degassed solvents should be used for the chromatographic separations. 

Figure 8.3—Schematic of a standard capillary electrophoresis instrument. The electrolyte is an aqueous ionic solution that has been filtered and degassed. It can contain several additives. There are several processes that can be used to introduce the sample into the capillary (cf. 8.4). The use of voltages above 30 kV is rare because they require special insulation. The length of the capillary (L) and the effective distance of migration (/) must not be confused since the latter is shorter by 10 or 20 cm.

Isopropanol/NaOH solution 50% (v/v) isopropanol/0.4 M NaOH, 4°C 5 mM H2S04 (made fresh, sterilized with a 0.45-p.m filter, and degassed)... 

Solution A Prepare a filtered and degassed solution of 6 g of glycine in 1500 ml of water. Adjust with 50% sodium hydroxide solution to a pH of 9, and dilute with water to 2000 ml. 

Solution B Use a filtered and degassed mixture of acetonitrile and methanol (85 15). 

The analysis of aliphatic acids was performed using a P/ACE MDQ capillary electrophoresis instrument equipped with a 60 cm x 50 pm id fused silica capillary (Beckman Coulter, Fullerton, CA). The samples were filtered through a 0.45-gm cellulose acetate filter (Whatman, Maidstone, UK) prior to hydrodynamic injection at 15 psi for 4 s. The voltage was set to 20 kV at reversed polarity. The electrolyte, composed of 5.0 mM trimellitic acid, 50 mM tris(hydroxymethyl)-aminomethane, 1.0 mM tetradecyl-trimethylammoniumbromide, and 0.5 mM calcium chloride, had a pH of 9.8. Before use, it was filtered through a 0.2-gm cellulose nitrate filter and degassed withhelium. Detection was performedby indirect UV absorption at 220 nm. Succinic acid was used as internal standard. 

This compound is determined using HPLC analysis. A Diluent reagent is prepared as a 9 1 mixture of water and methanol. The Mobile Phase is prepared as a filtered and degassed solution by dissolving 5.6 g of monobasic potassium phosphate in 820 mL of water in a 1-liter volumetric flask, adjusting with phosphoric acid to a pH of 4.3, diluting with methanol to volume, and mixing. Adjustments in the composition may be made if required by the System Suitability requirements. 

Mobile Phase Prepare a filtered and degassed 87 13 v/v mixture of 0.025 M phosphoric acid (previously adjusted to a pH of 3.0 0.1 with triethylamine) and acetonitrile. 

According to the USP 26 and the Indonesian Pharmacopoeia, the assay for mefenamic acid is performed by a liquid chromatography method. A buffer solution is prepared as a 50 mM solution of monobasic ammonium phosphate, adjusted with 3 M ammonium hydroxide to a pH of 5.0. The system uses a filtered and degassed mixture of acetonitrile, buffer solution, and tetrahydrofuran (23 20 7) as the mobile phase. The liquid chromatograph is equipped with a 254 nm detector and a 4.6 mm x 25 cm column that contains packing LI. The flow rate is about 1 mL/min. The column efficiency is not less than 8200 theoretical plates, the tailing factor for the analyte peak is not more than 1.6, and the relative standard deviation for replicate injections is not more than 1.0% [1, 4]. 

Methanol and Acetonitrile (UV grade - Burdick Jackson Laboratories) and water purified with a Millipore Super Q system were filtered through an 0.5 micron filter and degassed prior to use. 

Mobile Phase Prepare a filtered and degassed 65 35 mixture of acetonitrile water. 

Mobile Phase Prepare 0.005 N sulfuric acid that has been suitably filtered and degassed. 

Mobile Phase Use a filtered and degassed 80 20 acetoni-trile water mixture at a flow rate of 2 mL/min. 

All mobile phases (whether organic or aqueous) must be of high purity (redistilled or HPLC grade), filtered and degassed prior to use. Such manipulations are necessary to circumvent operative problems such as clogging of HPLC filters (frits) or columns. These problems may arise from the introduction of... 

The mobile phase was composed of a buffer and acetonitrile in the ratio of 68 32, vol/vol. The pH of the mobile phase was adjusted to 7.5 with orthophosphoric acid. The buffer used in the mobile phase consisted of 10 mM disodium hydrogen phosphate and 10 mM SDS in double-distilled water. The mobile phase was premixed and filtered through a 0.45-pm nylon filter and degassed. 

Use HPLC or analytical grade buffers, freshly prepared, filtered and degassed before use. Filter or centrifuge the sample to remove particulate matter. Turbid samples should not be injected onto column. 

All buffers should be prepared with high quality water, filtered and degassed. 

A weighed tablet is powdered in a mortar and pestle. While it is being dissolved over a steam bath, the separating solvent is being filtered and degassed. The apparatus is brought to equilibrium, and a set of standards is run. The dissolved tablet then is examined, and the amount of each of the active components is determined. 

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