Water injection systems centrifuges

Procedure Flavonoids are then further purified with 2 ml of methanolic HC1 (2 N), followed by centrifugation (2 min, 15 600 g), hydrolyzation of 150 il of suspension in an autoclave (15 min, 120 C). A reverse osmosis-Millipore UF Plus water purification system is used in high performance liquid chromatography (HPLC) with an autosampler. After injections of 5 pg of samples, the mobile phases flow at a rate of 1 ml/minute with isocratic elution in a column at 30 C. 

Sample preparation Plasma. 1 mL Plasma 50 p.L 100 pg/mL oxacillin in water -I- 20 pL 4% aqueous sodium dodecyl hydrogen sulfate solution, shake for 30 min, filter (Amicon MPS-1 micropartition system, YMT membrane) while centrifuging, a( ust the pH of the ultrafiltrate to 6.3-6.5 with pH 4 citrate buffer, inject a 500 pL aliquot onto column A with mobile phase A and elute to waste, after 10 min elute the contents of column A onto column B with mobile phase B, elute with mobile phase B, monitor the effluent from column B. Urine. 5-100 pL Urine -I- 50 pL 100 pg/mL oxacillin in water, make up to 500 pL with water, inject onto column A with mobile phase A and elute to waste, after 10 min elute the contents of column A onto column B with mobile phase B, elute with mobile phase B, monitor the effluent from column B. 

A low-pressure coolant system also is advantageous because replenishment of core coolant inventory can be accomplished with passive safety injection systems. With a high pressure system, safety injection must be accomplished with active components such as centrifugal pumps. Thus, failure of these active components must be accounted for when evaluating risk. With a low-pressure system, a tank of water that is elevated above the primary coolant system is capable of injecting coolant into the system. The probability of failure in such an injection system is significantly less than that of the typical active system. 

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Milbemectin consists of two active ingredients, M.A3 and M.A4. Milbemectin is extracted from plant materials and soils with methanol-water (7 3, v/v). After centrifugation, the extracts obtained are diluted to volume with the extraction solvent in a volumetric flask. Aliquots of the extracts are transferred on to a previously conditioned Cl8 solid-phase extraction (SPE) column. Milbemectin is eluted with methanol after washing the column with aqueous methanol. The eluate is evaporated to dryness and the residual milbemectin is converted to fluorescent anhydride derivatives after treatment with trifluoroacetic anhydride in 0.5 M triethylamine in benzene solution. The anhydride derivatives of M.A3 and M.A4 possess fluorescent sensitivity. The derivatized samples are dissolved in methanol and injected into a high-performance liquid chromatography (HPLC) system equipped with a fluorescence detector for quantitative determination. 

Blank, calibrator, control, and patient whole-blood samples (50 /iL) were transferred into 1.5 mL conical test tubes, mixed with 100 /xL of the IS, vortexed for 10 sec, and centrifuged at 13,000 g for 5 min. Twenty-five microliters of supernatant were injected onto a Cohesive Technologies Cyclone polymeric turbulent flow column (50 x 1 mm, 50 /flushed with a mixture of methanol and water (10 90 v/v) at a flow of 5 mL/min. Column switching from the TFC to HPLC systems was via a Cohesive Technologies system. The analytical column was a Phenomenex Phenyl-Hexyl-RP (50 x 2.1 mm, 5 /.mi). The mobile phase consisted of methanol and ammonium acetate buffer (97 3 v/v). The buffer was 10mM ammonium acetate containing 0.1% v/v acetic acid. The flow rate was 0.6 mL/min. 

Twenty-four-hour or spot urine should be collected in the presence of HC1. Add 10 ml of 20% (v/v) HC1 per liter of urine. Keep samples frozen at -20°C. Before injection into the HPLC system, dilute the urine (1) for oxalate 0.2 ml of centrifuged (3000 xg for 5 min) urine with 1.8 ml of 0.3 M boric acid (see below) (2) for glycolate and glycerate 0.2 ml of centrifuged (3000 xg for 5 min) urine with 1.8 ml of water. 

Reaction mixture 25 pi of freshly prepared 2 x reaction buffer, 15 pi of water, and 10 pi of filtered cell or tissue lysate (total volume of 50 pi). The reaction mixture is incubated for 30 min at 37°C in the dark, followed by adding 10 pi of oxidation solution. After oxidation for 30 min in the dark at room temperature, 10 pi of 1% ascorbic acid is added, mixed, and centrifuged for 20 min at 14,000 xg through a Micron 10,000 filter (Millipore, Ultracel YM-10). The filtrate is analyzed by HPLC (ideally only 20 pi of a 1 2 dilution with water are injected into the HPLC system). The starting lysate of 10 pi was diluted sevenfold. 

Samples (0.8 ml) are diluted with 0.2 ml 1ST solution and 0.1 ml 30% HC1, kept on ice for 15 min, centrifuged at 14,000 rpm (16,100xg) and filtered (Acrodisc LC 13, Millipore) into brown HPLC autosampler tubes. Aliquots (20 pi) of standards and samples are injected into the HPLC system. Samples with high concentrations of porphyrins should be diluted with distilled water 1 10, initially. 

The reaction is stopped by the addition of 1 ml ice-cold 10% trichloroacetic acid and the tubes are kept in ice water for 15 min. They are then centrifuged for 5 min at 14,000 rpm (16,1OOxg) in a bench-top centrifuge. One milliliter of supernatant is aspirated with a 1-ml syringe and filtered into brown HPLC autosampler tubes. Twenty-microliter aliquots of standards and samples are injected into the HPLC system. Spectrofluorimetric determination may be used instead of HPLC. 

This approach was used for the determination of OTC, TC, and CTC in milk samples. The centrifuged raw milk was mixed with succinate buffer (pH 4.0) to precipitate proteins. The clear supernatant was loaded directly on an MCAC column (1.5-ml Chelating Sepharose Fast-Flow) activated by passage of both water and 10 mM copper(II) sulphate solution. The blue-colored column was washed with both water and MeOH, and TCs were eluted with McIlvaine/EDTA/NaCl buffer. The extract was injected directly into the chromatographic system (25). 

Arce et al. [39] developed a flow injection analysis (F1A) system (Fig. 5.3) for online filtration of water samples prior to CE analysis. They also constructed a pump-driven unit for extraction and filtration of soil samples combined with CE in an online mode (automated sample transfer between pre-CE sample preparation step and the CE) [40]. The method was precise and four times faster than conventional methods of sample preparation with an off-line unit. Blood samples are centrifuged immediately to remove red blood cells and the serum is stored as discussed above. Sometimes, urine samples also contain precipitates which are removed by centrifuge. 

Purified COX-2 (0.79 nmol) is treated with 1.0 mol equivalent of inhibitor and the mixture is incubated for 60 min at room temperature. The remaining activity at this time is 4% that of a vehicle-treated control. The sample is then divided in two and the protein denaturated by treatment with four volumes of ethyl acetate/methanol/1 M citric acid (30 4 1). After extraction and centrifugation (10000 g for 5 min), the organic layer is removed and the extraction repeated. The two organic layers are combined and dried under N2. The extract is dissolved in 10 pi of HPLC solvent mixture consisting of water/acetonitrile/acetic acid (50 41 0.1) and 50 pi are injected onto a Novapak C-18 column (3.9 x 150 mm) and developed at 1 ml/min. The inhibitor is detected by absorption at 260 nm and eluted with a retention time of 6.6 min in this system. Control experiments for inhibitor recovery are performed with incubation of the inhibitor in the absence of enzyme and processing of the samples in an identical fashion before quantitation by HPLC. 

The enzymatic reaction mixture contained 0.1 M Tris-HCl buffer (pH 8.0), 10 mM MgQ2, and 0.1 M KC1 at 37°C. The final volume ranged between 500 and 100 jllL. The reaction was initiated by cAMP to give a final concentration of 0.15 to 0.2 mil/. The reaction was terminated by heating the tubes in a boiling water bath for 3 minutes. Samples were clarified by centrifugation or filtration before injecting into the HPLC system. 

The assay contained in a volume of 1 mL 20 mM potassium phosphate buffer (pH 5.75), 0.08 mM ZnCl2,0.06 mM KG, 0.02 mM isopyridoxal (internal standard), 1.2 mM ATP, 0.1 mM pyridoxine, and liver extract as the source of enzyme. To assay the yeast enzyme, ZnQ2 was replaced by 0.1 mM MgG2 and KC1 was omitted. The reaction was started by adding enzyme, and incubations were continued in the dark at 37°C for 90 minutes. The reaction was stopped by heating the test tubes in a boiling water bath for 3 minutes. After centrifugation, an aliquot of the supernate was injected into the HPLC system. The reaction was linear for at least 90 minutes when the rate of pyridoxine phosphate formation was not more than 13 nmol/h. 

Air saturation systems—The advance in dissolving air into water has come primarily from injecting air into pumps capable of handling water with entrained air. The operating pnmps work at higher pressure than standard centrifugal pumps, which increases both air satnra-tion and volumetric efficiency. 

---