Jeffrey S. Rohrer

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Cell culture and fermentation broth media are used in the manufacture of biotherapeutics and many other biological materials. Characterizing the amino acid composition in cell culture and fermentation broth media is important because deficiencies in these nutrients can reduce desired yields or alter final product quality. Anion-exchange (AE) chromatography(More)
One of the principal goals of glycoprotein research is to correlate glycan structure and function. Such correlation is necessary in order for one to understand the mechanisms whereby glycoprotein structure elaborates the functions of myriad proteins. The accurate comparison of glycoforms and quantification of glycosites are essential steps in this(More)
Neomycin B is one of a class of aminoglycoside antibiotics that lack a good chromophore, and is therefore difficult to determine using reversed-phase HPLC with absorbance detection. This is especially true for determining the quantity of each impurity. We show that neomycin sulfate and its major impurities, including neamine (neomycin A), can be separated(More)
Tobramycin is one of a class of aminoglycoside antibiotics that lack a good chromophore, and is therefore difficult to determine using reversed-phase HPLC with absorbance detection. This is especially true for determining the quantity of each impurity. We show that tobramycin and its major impurities, including kanamycin B and neamine (neomycin A), can be(More)
The deposition of Fe(II) into ferritin using 18O2 as the oxidant was investigated. Only 3-4% of the oxygen atoms in the FeOOH core of ferritin were derived from the oxidant. This was true whether large (1200-1900 Fe/molecule) or small (220-240 Fe/molecule) amounts of iron were added to apoferritin or when iron was added to ferritin already containing 1000(More)
Commercial-scale fermentation for tobramycin manufacture is carried out with Streptomyces tenebrarius. Impurity profiling during various phases of pharmaceutical production is important for evaluating the effectiveness of a processing step and meeting regulatory requirements. High-performance anion-exchange (HPAE) chromatography with integrated pulsed(More)
We developed and validated an ion chromatography method to assay iodide in serum sampled from rats and rabbits that had been exposed to iodomethane. Iodomethane is of interest because it is a volatile liquid pre-plant soil crop protection fumigant that has been proposed as a non-ozone-depleting alternative to methyl bromide. Serum was prepared from whole(More)
Single-laboratory validation (SLV) data from a method for the determination of choline in infant formula and adult nutritionals by ion chromatography (IC) and suppressed conductivity were generated and presented to the Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Expert Review Panel (ERP) at the AOAC Annual Meeting held in Las Vegas,(More)