On‐line characterization of a hybridoma cell culture process
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Abstract The on‐line determination of the physiological state of a cell culture process requires reliable on‐line measurements of various parameters and calculations of specific rates from these measurements. The cell concentration of a hybridoma culture was estimated on‐line by measuring optical density (OD) with a laser turbidity probe. The oxygen uptake rate (OUR) was determined by monitoring dynamically dissolved oxygen concentration profiles and closing oxygen balances in the culture. The base addition for neutralizing lactate produced by cells was also monitored on‐line via a balance. Using OD and OUR measurements, the specific growth and specific oxygen consumption rates were determined on‐line. By combining predetermined stoichiometric relationships among oxygen and glucose consumption and lactate production, the specific glucose consumption and lactate production rates were also calculated on‐line. Using these on‐line measurements and calculations, the hybridoma culture process was characterized on‐line by identifying the physiological states. They will also facilitate the implementation of nutrient feeding strategies for fed‐batch and perfusion cultures. © 1994 John Wiley & Sons, Inc.Keywords:
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A rapid method for the isolation and high-performance liquid chromatographic (HPLC) determination of sulfamethazine (SMZ) in pork tissues (kidney, liver, and muscle) without using organic solvents is developed. The isolation is performed by homogenization with an acid solution using an ultrasonic-homogenizer, followed by centrifugation. The HPLC analyses are performed using a reversed-phase C(4) column (150- x 4.6-mm i.d.), a mobile phase of 0.02 mol/L citric acid solution, and a photodiode array detector. The resulting HPLC chromatograms are free from interferences for determination and identification. The proposed technique is shown to be linear (r > 0.99) over the concentration range 0.1-2.0 microg/g for all pork tissues. Average recoveries of SMZ (spiked 0.1-2.0 microg/g) range from 87.6% to 90.2%, with inter- and intra-assay variabilities of less than 4%. The total time required for the analysis of one sample and limit of quantitation is less than 20 min and 0.09 microg/g, respectively.
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A simple method based on micellar liquid chromatography (MLC) was developed to enable the simultaneous determination of norharmane, harmane, harmol, harmalol, harmine, and harmaline in phytotherapic samples of Passiflora incarnata L., Passiflora alata Dryander and urine with virtually no sample preparation. Chromatographic separation was performed under 30 min using a C18 HPLC column and isocratic elution with an aqueous micellar mobile phase (phosphate buffer pH 8.0 containing 220 mmol L−1 of sodium dodecyl sulfate and 0.5% of triethylamine) containing only 3% (v/v) of acetonitrile. Fluorescence detection allowed limits of quantification below 4.5 ng g−1. Recoveries in controlled samples were close to 100% and the sample analysis enabled the quantification of harmol as the principal β-carboline found in the phytotherapic samples, whereas another three were detected. In urine samples, the determination of harmol was made after 8 hours of drug ingestion. Both repeatability and intermediary precision, for all alkaloids, were between 0.1 and 5%.
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A simple, rapid method for the determination of the benzodiazepines, diazepam and chlordiazepoxide, and their metabolites by high performance liquid chromatography (HPLC) has been developed. The procedure is applicable to the assay of other similar drugs in biological fluids. The method utilizes BondElut™ extraction columns to facilitate the extraction. BondElut columns selectively adsorb the benzodiazepines and metabolites from serum at a pH of 9.0. The compounds are eluted with 300μl of methanol which makes sample concentration rapid, if even necessary. Analysis is performed using isocratic reversed-phase chromatography, and quantitation is carried out by ultraviolet (UV) detection. Using this procedure, it is possible to determine drug and metabolite levels to as low as 25 ng/ml in 0.5 ml of serum.
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