Search results for "quantitative analysis"

Simultaneous determination of 4-nitroanisole, 4-nitrophenol, and 4-nitrocatechol by phase-sensitive ac polarography.

1977

Abstract Phase‐sensitive ac polarography was applied to the simultaneous quantitative determination of 4‐nitroanisole, 4‐nitrophenol and 4‐nitrocatechol in alkaline solutions. Certain experimental precautions are necessary to determine each compound in the presence of the other two. Thus, 4‐nitrocatechol is determined indirectly by forming a yellow ratio chelate with cupric ions, whereas 4‐nitroanisole is determined directly by the reduction waves of the nitro group. For the determination of 4‐nitrophenol, the interference by the simultaneously present 4‐nitrocatechol must be eliminated by masking it by the addition of magnesium ions. The method described permits a qualitative and quantitat…

Ascorbic Acid Stability in Ground Asparagus Samples and in Oxalic Acid Extracts

1995

To establish the storage conditions for asparagus preparation before ascorbic acid determination, samples were ground, the mass was divided into three aliquots that were, respectively, stored at 4°C, – 18°C, or extracted with 1% oxalic acid. The extract was further split into aliquots and stored at 25°, 4°, –18° and -75°C. Ascorbic acid content was measured at different times of storage by a polarographic method. The rate of degradation increased with storage temperature; the degradation rate was higher in ground samples than in extracts; no significant changes in ascorbic acid content were observed in extracts stored for 7 days at -18° or for 90 days at -75°C.

FIA-spectrophotometric determination of N-substituted phenothiazine derivatives by oxidation with a solid-phase reactor of manganese dioxide incorpor…

1995

Abstract The determination of several N -substituted phenothiazine derivatives was carried out by the reaction of the drug with managanese dioxide entrapped in a polymeric material in a packed-bed reactor; the oxidized drug was monitored at λ max . The calibration graph is linear over the range 5–50 μg/ml of phenothiazine derivatives with a relative standard deviation of 0.5–1% (at 10 μg/ml) and sample throughput of 40–48 h −1 . The influence of foreign compounds was studied and the method was applied to the determination of six different phenothiazine derivatives in pharmaceutical formulations.

FIA-AAS determination of salicylic acid by a solid-phase reactor of copper carbonate incorporated in polyester resin beads.

1994

Abstract The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0–75 μg ml −1 of salicylic acid, with a relative standard deviation of less than 1.5% and a sample throughout of 257 h −1 . The influence of foreign compounds was studied and the method was applied to the determination of salicylic acid content in two different pharmaceutical formulations.

1984

Physicochemical stability of cabazitaxel containing premix solution and diluted infusion solutions

2015

Objectives This study was conducted to investigate the extended physicochemical stability of cabazitaxel containing premix solution and diluted infusion solutions in either 0.9% sodium chloride (NaCl) or 5% glucose (G5) vehicle solution. Methods A stability indicating, reverse phase, high performance liquid chromatography assay with ultraviolet detection was developed and validated. Premix solutions of cabazitaxel were prepared in the original vials. Infusion solutions were prepared in prefilled polypropylene/polyethylene (PP/PE) infusion bags (0.9% NaCl, G5) to achieve the recommended minimum and maximum cabazitaxel concentrations (0.1 mg/mL, 0.26 mg/mL). Test solutions were stored refrige…

Clean-up and confirmation procedures for gas chromatographic determination of pesticide residues in contaminated waters. Part I

1993

The effects of sulphuric acid, potassium hydroxide and chromic acid on eleven organochlorine and ten organophosphorus pesticides were investigated. The treatments destroy some pesticides totally or partially, leave others unaltered and have a clean-up effect. These reactions can be used to confirm the presence of an identified pesticide. The clean-up extracts in the environmental samples facilitate the identification of the organochlorine and organophosphorus pesticides and their quantitative analysis. The results obtained for contaminated surface waters show the usefulness of these methods for multi-residue capillary gas chromatography without the need for other additional separative chrom…

Integrated quantitative proteomic and transcriptomic analysis of lung tumor and control tissue: a lung cancer showcase

2015

Proteomics analysis of paired cancer and control tissue can be applied to investigate pathological processes in tumors. Advancements in data-independent acquisition mass spectrometry allow for highly reproducible quantitative analysis of complex proteomic patterns. Optimized sample preparation workflows enable integrative multi-omics studies from the same tissue specimens. We performed ion mobility enhanced, data-independent acquisition MS to characterize the proteome of 21 lung tumor tissues including adenocarcinoma and squamous cell carcinoma (SCC) as compared to control lung tissues of the same patient each. Transcriptomic data were generated for the same specimens. The quantitative prot…

Column switching and high-performance liquid chromatography in the analysis of amitriptyline, nortriptyline and hydroxylated metabolites in human pla…

1992

A column-switching system for the direct injection of plasma or serum samples, followed by isocratic high-performance liquid chromatography and ultraviolet detection, is described for the simultaneous quantitation of the tricyclic antidepressant amitriptyline, its demethylated metabolite nortriptyline and the E- and Z-isomers of 10-hydroxyamitriptyline and 10-hydroxynortriptyline. The method included adsorption of amitriptyline and metabolites on a reversed-phase C8 clean-up column (10 microns; 20 mm x 4.6 mm I.D.), washing of unwanted material to waste and, after on-line column-switching, separation on a cyanopropyl analytical column (5 microns; 250 mm x 4.6 mm I.D.). The compounds of inte…

Quantitative analysis of airway obstruction in lymphangioleiomyomatosis

2020

Lymphangioleiomyomatosis (LAM) is a rare, cystic lung disease with progressive pulmonary function loss caused by progressively proliferating LAM cells. The degree of airway obstruction has not been well investigated within the pathogenesis of LAM. Using a combination of ex vivo computed tomography (CT), microCT and histology, the site and nature of airway obstruction in LAM explant lungs was compared with matched control lungs (n=5 each). The total number of airways per generation, total airway counts, terminal bronchioles number and surface density were compared in LAM versus control. Ex vivo CT analysis demonstrated a reduced number of airways from generation 7 on (p<0.0001) in LAM compar…