Search results for "cellar"
showing 10 items of 230 documents
Screening of some banned aromatic amines in textile products from Indian bandhani and gamthi fabric and in human sweat using micellar liquid chromato…
2021
Certain dyes in textile products, which are capable of reductively splitting into carcinogenic aromatic amines, are strictly controlled in many countries. A simple, rapid, sensitive and green chromatographic method has been developed and validated for the simultaneous determination of 4-aminophenol (4-AMP), p-phenylenediamine (p-PPD) and benzidine (BNZ), banned aromatic amines in dyeing clothes and human sweat. The separation was achieved using a micellar mobile phase of 0.1 M SDS, 4% 1- butanol (v/v) buffered to pH 7 with sodium dihydrogen phosphate, flowing under isocratic mode at 1 mL/min through a C18 column. Photodiode array detector was set at 210 nm. Using the above chromatographic c…
Micellar liquid chromatography in doping control.
2010
The issue of doping control in sport involves the development of reliable analytical procedures and efficient strategies to process a large number of samples in a short period of time. Reversed-phase LC techniques with aqueous–organic mobile phases and MS or diode-array detection yield satisfactory results for the identification of prohibited substances in sport. However, time-consuming sample pretreatment steps are required, which reduces sample throughput. Micellar LC (MLC) that uses hybrid mobile phases of surfactant above its critical micellar concentration and organic solvent has been revealed as an interesting alternative. The surfactant sodium dodecyl sulfate solubilizes the protein…
Chromatographic monitoring of diuretics in urine samples using a sodium dodecyl sulphate—propanol micellar eluent
1994
Abstract The effect of a varying pH, in the range 3−7, on the retention of several diuretics eluted with a sodium dodecyl sulphate (SDS) micellar mobile phase and with UV detection was studied. Significant changes in the capacity factors ( K′ of the diuretics bumetanide, ethacrynic acid, furosemide, probenecid and xipamide were observed. The protonation constants of these compounds were calculated from the k′ data. A study was also performed to select the optimum composition of the mobile phase (pH, concentration of SDS and nature and concentration of alcohol) for the separation of the above diuretics and the diuretics amiloride, bendroflumethiazide, chlorthalidone, hydrochlorothiazide, spi…
Chromatographic determination of diuretics in urine samples using hybrid micellar mobile phases with fluorimetric detection
1998
Abstract A rapid and simple chromatographic procedure, that uses hybrid micellar mobile phases of sodium dodecyl sulphate (SDS), propanol and phosphate buffer at pH 3, and fluorimetric detection ( λ exc =270 nm, λ em =430 nm), is reported for the determination of mixtures of seven diuretics of diverse efficacy (amiloride, bendroflumethiazide, bumetanide, furosemide, hydroflumethiazide, piretanide and triamterene), in urine samples. The application of a sequential optimization procedure for the resolution of the mixtures of the diuretics was problematic. However, their separation was achieved through the use of an interpretive optimization procedure based on the accurate description of the r…
CALIBRAZIONE DI MODELLI USLE-DERIVATI MEDIANTE I MASSIMI ANNUALI DELLA PERDITA DI SUOLO PER EVENTO
2016
Numerosi risultati sperimentali hanno evidenziato che la perdita di suolo pluriennale di una parcella è influenzata apprezzabilmente dall’erosione che si verifica in un numero complessivamente limitato di eventi particolarmente gravosi. Conseguentemente, un intervento di conservazione del suolo calibrato sull’erosione media annua può risultare poco efficace in occasione degli eventi meteorici più significativi dal punto di vista dell’erosione complessiva. La disponibilità di modelli di previsione dell’erosione idrica parcellare in grado di fornire stime accurate dei valori più elevati della perdita di suolo alla scansione del singolo evento erosivo riveste pertanto interesse pratico, potend…
DEDUZIONE DEL FATTORE L DELLA USLE-MM NELLE PARCELLE SPERIMENTALI DI SPARACIA, IN SICILIA
2010
Nell’indagine è stato messo a punto un modello alternativo per la stima della perdita di suolo parcellare che riproduce anche la relazione tra Ae e dedotta sperimentalmente. L’approccio utilizzato è quello della USLE-MM, che presuppone l’introduzione, nel set di variabili indipendenti, del coefficiente di deflusso parcellare. Nel modello proposto, il fattore topografico L stabilisce un legame crescente tra Ae e ma la perdita di suolo dovuta a un fissato evento di pioggia può anche diminuire al crescere della lunghezza allorquando, come verificato sperimentalmente, all’incremento di risulta associata una diminuzione del deflusso. La verifica del modello proposto con set di dati indipen…
Synthesis of spherical porous silicas in the micron and submicron size range: challenges and opportunities for miniaturized high-resolution chromatog…
2000
Classical silica technology has reached its limit with respect to an ultimate minimum particle size of about 2 microm in diameter. Here, a novel process is presented which allows one to synthesize porous silica beads and control their particle diameter in situ, within the range of 0.2-2.0 microm. As a result, no sizing is required and losses of silica are avoided. Furthermore, the process enables one to control in situ the pore structural parameters and the surface chemistry of the silica beads. Even though surface funtionalized silicas made according to this process can principally be applied in fast HPLC the column pressure drop will be high even for short columns. In addition, the column…
Un modello realistico per visualizzazioni dinamiche in didattica della chimica
2020
In questo lavoro sono presentate due applicazioni per la visualizzazione dei processi di aggregazione e di solubilizzazione di particelle interagenti e prive di struttura. Le applicazioni consentono di dimostrare qualitativamente e quantitativamente, per mezzo dell'osservazione dell'evoluzione temporale del rapporto superficie/volume e della frazione di particelle aggregate, che, da un lato, il processo di crescita di nanoaggregati è accompagnato da una diminuzione del rapporto superficie/volume, dall'altro, che interazioni soluto-solvente favorevoli e temperature elevate producono soluzioni omogenee. Si propone che, insieme ad opportuni esempi macroscopici, visualizzazioni mediante le pres…
Retention–property relationships of anticonvulsant drugs by biopartitioning micellar chromatography
2001
Epilepsy may be considered as a group of disorders with only one thing in common: the fact that recurrent anomalous electrochemical phenomena appear in the central nervous system. Different classes of drugs are included under the generic term of anticonvulsant drugs. All of them work by decreasing discharge propagation in different ways. Biopartitioning micellar chromatography (BMC) is a mode of reversed-phase liquid chromatography, which can be used as an in vitro system to model the biopartitioning process of drugs when there are no active processes. In this paper, relationships between the BMC retention data of anticonvulsant drugs, their pharmacokinetics (oral absorption, protein bindin…
Control of spontaneous spiral formation in a zwitterionic micellar medium
2011
The transition from planar fronts, trigger waves or solitary pulses to spirals in excitable media, has attracted increasing interest in the past few decades, mainly because of its relevance for biological and medical applications. In this paper we describe a new and convenient method for spiral generation starting from symmetric wavefronts. By using the micelle-forming zwitterionic surfactant N-tetradecyl- N,N-dimethylamine oxide in a Belousov–Zhabotinsky solution, it is possible to control to a large extent the domains where spirals can be spontaneously generated. The mechanism responsible for the wavefront break up lies in the interaction of the propagating waves with the unexcitable regi…