Search results for "Quantitative determination"

Analysis of psychoactive substances in water by information dependent acquisition on a hybrid quadrupole time-of-flight mass spectrometer.

2016

Emerging drugs of abuse, belonging to many different chemical classes, are attracting users with promises of “legal” highs and easy access via internet. Prevalence of their consumption and abuse through wastewater-based epidemiology can only be realized if a suitable analytical screening procedure exists to detect and quantify them in water. Solid-phase extraction and ultra-high performance liquid chromatography quadrupole time-of-flight-mass spectrometry (UHPLC–QqTOF–MS/MS) was applied for rapid suspect screening as well as for the quantitative determination of 42 illicit drugs and metabolites in water. Using this platform, we were able to identify amphetamines, tryptamines, piperazines, p…

Clinical parameters and aMMP-8-concentrations in gingival crevicular fluid in pregnancy gingivitis.

2013

BACKGROUND During pregnancy hormonal changes may increase the risk for developing gingivitis. The aim of this study was to evaluate the signs of gingival inflammation and the enzyme activity of matrix metalloproteinase-8 (aMMP-8) in the gingival crevicular fluid of pregnant women. METHODS After approval by the ethics commission, a total of 40 volunteers participated in the study; group 1 (n = 20, age: 32 +/- 4 years) with pregnant women, and group 2 (n = 20, age: 30 +/- 10 years) with age-matched non-pregnant women as controls. After obtaining anamnestic data, the dental examination included assessment of oral hygiene, gingival inflammation, probing pocket depth, and recession. Gingival cre…

Quantitative Determination of Calcium Hydroxide by using Near Infrared Spectroscopy

2018

Calcium hydroxide (CH) is a by-product from hydration reaction of cement along with calcium silicate hydrate (C-S-H) gel. It helps to protect the steel reinforcements in concrete structures from corrosion process due to carbonation. The presence of calcium hydroxide provides a basic environment (pH˃10) that induces the formation of passive oxide film and keeps steel structures from corrosion. The detection and quantification of calcium hydroxide in concrete structures are important to understand the nature and state of the steel structures in concretes. In this research work, the variation of calcium hydroxide to calcium silicate ratios in cement were measured by using near-infrared spectro…

Die quantitative Bestimmung der p-Oxyphenylbrenztraubens�ure im Harn

1950

Es wird ein Verfahren zur quantitativen Bestimmung der p-Oxyphenylbrenztraubensaure im Harn beschrieben, das auf der Reduktion der p-Oxyphenylbrenztraubensaure zur p-Oxyphenylmilchsaure beruht. Die Methode gestattet den spezifischen Nachweis der im Harn ausgeschiedenen p-Oxyphenylbrenztraubensaure und ist geeignet, die Leberfunktionsprobe nachFelix undTeske wesentlich zu vereinfachen.

Indirect Quantitative Determination of Organolithium Compounds by Gas Chromatography

1976

Extraktionschromatographische trennung der freien uroporphyrinisomere i und iii und deren simultane quantitative bestimmung

1968

Abstract Separation and simultaneous quantitative determination of the free uroporphyrin isomers I and III by means of extraction chromatography Separation and quantitative determination of the uroporphyrin isomers I and III in the acid from can be performed simultaneously in the partition system tri-n-butylphosphate/I N hydrochloric acid using columns with a large number of theoretical plates (N) = 300-450). The eluent is passed through a flow cuvette and the transmission is recorded continuously. The transmission peaks of the isomers are digitized and transformed into extinction values. By integrating the extinction peaks, the amount of the uroporphyrins can be evaluated from the correspo…

Hard cap espresso extraction-stir bar preconcentration of polychlorinated biphenyls in soil and sediments.

2017

Abstract A Nespresso © hard cap espresso machine has been employed for the quantitative extraction of polychlorinated biphenyls (PCBs) from sediments and soils. Sample extraction was performed from five grams of sample in less than 40 s, with 200 mL ethanol 40% (v/v) in water and PCBs were concentrated using stir bar sorptive extraction (SBSE) and determined by thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS-MS). Eleven PCB congeners (28, 52, 77, 80, 81, 101, 118, 138, 153,169, and 180) were determined in soils and sediments with limits of quantification in the 0.03–0.08 ng g −1 range. Extraction efficiency was established by the analysis of soil samples spiked with…

Comparative assessment of three extraction procedures for determination of emerging Fusarium mycotoxins in pasta by LC–MS/MS

2013

Abstract A new rapid, sensitive, reproducible and reliable method was developed for the quantitative determination of enniatins A, A1, B and B1, beauvericin and fusaproliferin in dry and fresh pasta by liquid chromatography-triple quadrupole-tandem mass spectrometry. A comparative study of different rapid and economical extraction procedures was performed for the extraction of these mycotoxins in pasta. For this purpose, three different approaches were studied during the extraction step (Ultra-Turrax, ultrasonic bath and microwave). Optimal extraction conditions were reached using Ultra-Turrax with acetonitrile for 3 min without purification step. The chromatographic separation of the six m…

Tetra- and pentachlorodibenzothiophenes are formed in waste combustion

1991

Abstract Two different waste combustion samples have been analyzed for tetra- and pentachlorodibenzothiophenes. HRGC/HRMS with a resolution of 20 000 was used for identification. By resolution of 10 000 chlorinated dibenzo-p-dioxins and some unknown compounds gave GC/SIM peaks at the exact masses of the chlorinated dibenzothiophenes. These peaks were no more present by resolution 20 000. Several tetra- and pentachlorodibenzothiophenes were found in both samples. In the other one of the samples the concentrations were seemingly high although exact quantitative determination could not be done.

Silymarin compounds: Chemistry, innovative extraction techniques and synthesis

2020

Abstract Silymarin complex consisting of four flavonolignans (silychristin, silydianin, silibinin and taxifolin) has been used from ancient times in both traditional European and Asian medicine for liver disorders treatment. Moreover, over the last years, the anticancer activity of these compounds against various types of cancer cells (e.g., breast, skin, colon, cervix, ovary, prostate, lung and hepatocellular cancers, among others) has been demonstrated. Therefore, at this stage of development, food and pharmaceutical interest have shown an increased interested in the recovery of these molecules. Conventional solvent extraction has been traditionally used to recover silymarin complex from …