Search results for "Central composite design"

Supercritical carbon dioxide extraction of seed oil from yellow horn (Xanthoceras sorbifolia Bunge.) and its anti-oxidant activity

2010

Supercritical fluid carbon dioxide (SF-CO(2)) extraction (SFE) of seed oil from yellow horn and its anti-oxidant activity were investigated. The effects of CO(2) flow rate and particle size were firstly optimized, and a central composite design (CCD) combined with response surface methodology was used to study the effects of extraction pressure, temperature and time on the extraction yields. A maximal extraction yield of 61.28% was achieved under optimal conditions of extraction pressure 30 MPa at 45.68 degrees C, 2.08 h and CO(2) flow rate 12 kg/h with 0.5mm particle size. By analyzing the chemical composition of the seed oil, we found that the content of unsaturated fatty acids was approx…

Multivariate optimization of the hollow fibre liquid phase microextraction of muscimol in human urine samples.

2016

Abstract A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determination was developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples. Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen, tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. A multivariate design of experiments was used in which a half fractional factorial approach was applied to screen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate, extraction time and salt content) for their extent of vitality i…

Combined effect of solvent content, temperature and pH on the chromatographic behaviour of ionisable compounds.

2008

The organic solvent content and the pH in the mobile phase are the usual main factors in reversed-phase liquid chromatographic separations, owing to their strong effects on retention and/or selectivity. Temperature is often neglected. However, even in cases where the impact of this factor on selectivity is minor, the reduction in analysis time is still an interesting reason to consider it. In addition, ionisable compounds may exhibit selectivity changes, owing to the interaction of organic solvent and/or temperature with pH. The separation of ionisable compounds (nine diuretics: bendroflumethiazide, benzthiazide, bumetanide, chlorthalidone, furosemide, piretanide, probenecid, trichloromethi…

Modeling hexanal production in oxido-reducing conditions by the yeast Yarrowia lipolytica

2009

International audience; Hexanal produced by cells of a recombinant Yarrowia lipolytica yeast expressing the hydroperoxide lyase (HPL) from green bell pepper fruit was studied under oxido-reducing conditions using the reducing dithiotreitol and oxidizing potassium ferricyanide compounds. The combined effect of pH, linoleic acid 13-hydroperoxides concentration, temperature and oxido-reducing molecules on the hexanal production was studied. Significant positive effects for the hexanal production were found using high concentrations of hydroperoxides (100 mM, 30 g/L). Adding reducing molecules enhanced significantly hexanal production while the oxidizing molecules had an inhibitory effect. Comb…

Enzyme pretreatment and negative pressure cavitation extraction of genistein and apigenin from the roots of pigeon pea [Cajanus cajan (L.) Millsp.] a…

2012

Abstract An enzyme pretreatment and negative-pressure cavitation extraction (E-NPCE) method was investigated for extraction genistein and apigenin from pigeon pea roots. The important parameters involved in E-NPCE process were optimized by single-factor experiments and then critical parameters were investigated by a 2 3 full factorial central composite design (CCD) to optimize extract conditions. Under optimal conditions, the yields of genistein and apigenin were 0.628 mg/g and 0.359 mg/g, which represented an increase of 44.70% and 53.05%, respectively, compared to standard NPCE. Furthermore, from DPPH scavenging activity test the extract of E-NPCE showed better antioxidant activity than t…

Systematic investigation of the adsorption and inhibition properties of a new clickable 1,2,3‐triazole compound for mild steel in 1 M HCl medium

2021

Multivariate optimization of the hollow fibre liquid phasemicroextraction of muscimol in human urine samples

2016

A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determinationwas developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples.Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen,tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. Amultivariate design of experiments was used in which a half fractional factorial approach was applied toscreen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate,extraction time and salt content) for their extent of vitality in carrier media…