Determination of nabilone in bulk powders and capsules by high-performance liquid chromatography/tandem mass spectrometry.
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Capsules↗
Biomedical subjects
R Curini
Publications and source records attributed to R Curini.
Development of a method based on accelerated solvent extraction and liquid chromatography/mass spectrometry for determination of arylphenoxypropionic herbicides in soil.
A sensitive and specific analytical procedure for determining arylphenoxypropionic herbicides in soil samples, using Ionspray ionization (ISI) liquid chromatography/mass spectrometry (LC/MS), is presented. Arylphenoxypropionic acids are a new class of herbicides used for selective removal of most grass species from any non-grass crop, commercialized as herbicide esters. Previous studies have shown that the esters undergo fast hydrolysis in the presence of vegetable tissues and soil bacteria, yelding the corresponding free acid. The feasibility of rapidly extracting arylphenoxypropionic herbicides from soil by accelerated solvent extraction (ASE) techniques was evaluated. Four different soil samples were fortified with target compounds at levels of 5 and 20 ng/g by following a procedure able to mimic weathered soils. Herbicides were extracted by a methanol/water (80:20 v/v) solution (0.12 M) of NaCl at 90 degrees C. After clean-up using graphitized carbon black (GCB) as absorbent, the extract was analyzed by HPLC/ISI-MS. The effect of concentration of acid in the mobile phase on the response of ISI-MS was investigated. The effects of varying the orifice plate voltage on the production of diagnostic fragment ions, and on the response of the MS detector, were also investigated. The ISI-MS response was linearly related to the amounts of analytes injected between 1 and 200 ng. The limit of detection (signal-to-noise ratio = 3) of the method for the pesticides in soil samples was estimated to be less than 1 ng/g.
Acids↗
Method development for measuring trace levels of penicillins in aqueous environmental samples.
A method based on liquid chromatography/mass spectrometry with an electrospray ion source and a single quadrupole instrument (LC/ES-MS) has been developed for determining trace levels of eight widely used penicillins in aqueous environmental samples. Analyte extraction was performed from 4 L tap water, 2 L groundwater, 1 L river water, 0.2 L treated sewage and 0.1 L raw sewage, by using a Carbograph 4 cartridge. During removal of the solvent, penicillins were purposely allowed to convert into their penicilloyl methyl esters. This 'in situ' derivatization step resulted in a dramatic enhancement of the response of the ES-MS system for non-amphoteric penicillins. Analyte recoveries were better than 80% irrespective of the type of aqueous sample, with the exception of amoxicillin (76%) and ampicillin (77%) in tap water. At the level of 50 ng/L of each analyte in ground water, the within-day precision was in the range 6-10%. Calibration curves were linear for injected amounts up to 800 ng, with R(2) in the range 0.9952-0.9995. When injecting large equivalent volumes of the aqueous samples, the electrospray matrix effect altered in-source collision-induced dissociation (CID) spectra of the analytes by severely weakening signals for fragment ions, as compared to spectra of reference standards. Remedies to obviate this anomalous unwelcome effect are suggested. On the basis of a signal-to-noise ratio of 10, limits of quantification were estimated to range between 2 (cloxacillin) and 24 ng/L (amoxicillin) in river water.
Chromatography, Liquid↗
Solid-phase extraction followed by liquid chromatography-mass spectrometry for trace determination of beta-lactam antibiotics in bovine milk.
A confirmatory assay able to unambiguously identify and quantify 10 approved-for-use beta-lactam antibiotics in milk below stipulated U.S. and EU tolerance levels is presented. beta-Lactams are extracted from 10 mL of intact milk by a Carbograph 4 cartridge. After solvent removal, residue reconstitution, and filtration, a completely transparent and uncolored extract is injected into a liquid chromatography -mass spectrometry (LC-MS) instrument equipped with an electrospray (ES) ion source and a single quadrupole. During the chromatographic run, the ES/MS system is operated first in the positive-ion mode (PI) and then in the negative-ion (NI) mode. This is done to circumvent matrix interferences resulting in remarkable signal weakening of the last-eluted analytes, when detecting them as [M+H]+ adduct ions. MS data acquisition is performed by a time-scheduled three-ion selected ion monitoring program. At the 5 ng/mL level, recoveries of the beta-lactams are between 70 (nafcillin) and 108% (cephalin), with relative standard deviations ranging between 5 (oxacillin) and 11% (amoxicillin and ceftiofur). The response of the ES/MS detector is linearly related to injected amounts up to 500 ng, irrespective of the chemical characteristics of the beta-lactams and the acquisition mode selected (PI or NI modes). Limits of quantification, based on a minimal value of the signal-to-noise ratio of 10, were estimated to be within 0.4 (cephalin) and 3 ng/mL (dicloxacillin). Analyses of milk samples taken after intramammary application of amoxicillin showed that 1.2 ng/mL of this penicillin was still present 6 days after treatment. At this concentration level, the identification power of the method is not weakened, as signals of the three product ions of amoxicillin are still well distinguishable from the background noise.
Animals↗
Solid-phase extraction followed by high-performance liquid chromatography-ionspray interface-mass spectrometry for monitoring of herbicides in environmental water.
In this work we developed a sensitive and specific multiresidue method, based on reversed-phase liquid chromatography-mass spectrometry, with an ionspray interface (LC-ISI-MS), for determining 52 of most representative compounds of herbicides in water samples. The procedure used involved passing 0.5 l of surface water, 2 l of ground water and 4 l of drinking water samples, respectively, through a 0.5 g graphitized carbon black (GCB) extraction cartridge. Base-neutral and acid herbicides were differential eluted from GCB cartridge and follow analyzed by HPLC-ISI-MS apparatus. A conventional 4.6-mm-ID reversed-phase LC C18 column, operating with a mobile phase flow-rate of 1 ml/min, was used to chromatograph the analytes. A flow of 100 microl/min of the column effluent was diverted to the ISI source. The study demonstrates the sensitivity of the technique, with detection limit under 10 ng/l in drinking water samples. Performance data for the method such as recovery and precision are also reported.
Chromatography, High Pressure Liquid↗
Determination of herbicides in water using HPLC-MS techniques.
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Chromatography, High Pressure Liquid↗
Solvent effect in vitro of Anticolana Valley water on renal stones: analytical-instrumental study.
The presence of humic and fulvic acids in the Anticolana Valley (Fiuggi) water has been established. On the basis of this evidence we investigated the capacity of Anticolana Valley (Fiuggi) water to dissolve renal calculi in vitro. Crystals of calcium oxalate monohydrate to simulate a kidney stone were prepared. Human renal stones of calcium oxalate monohydrate were obtained by courtesy of the Division of Urology of 'La Sapienza' University (Rome), the Division of Urology of the University of Havana (Cuba) and the ASTIF of Fiuggi. The study was performed using the Anticolana Valley (Fiuggi) water, distilled water and tap water (ACEA, Rome), in a specially designed Perspex apparatus. Each calculus was subjected to a water flow of 2 liters/24 h. The capacity of the Anticolana Valley (Fiuggi) water to dissolve human and synthetic calculi was found to be much higher than that of distilled water which in turn was significantly more effective than tap (ACEA) water.
Calcium Oxalate↗
Short-term effects of secretagogues on the mouse parotid and sublingual gland tissular water.
The effects of isoproterenol and pilocarpine on the tissular water of mouse parotid and sublingual glands were studied by thermogravimetry (TG) coupled with Fourier transform infrared spectroscopy (FTIR). Results demonstrated that the short-term effects partly resemble the long-term action of these substances on the above-mentioned organs. Due to the different stages examined, it is difficult to speculate on the comparison between previous and the present findings. The original data resulting from the present research corresponded to the dimorphism expressed in the thermoanalytical profile of the parotid glands treated with secretagogues.
Adrenergic beta-Agonists↗
Spongy state (status spongiosus) and inhibition of Na,K-ATPase: a pathogenetic theory.
Spongiform encephalopathies are characterized above all by spongiosis. This neuropathological characteristic is morphologically mimed by in vivo inhibition of cerebral brain Na,K-ATPase by means of subdural administration of ouabain. In this paper we underline the possibility that the 'spongiotic state' in other diseases might also be caused by the inhibition of this enzyme, thus hypothesizing that it is the enzyme itself that is targeted by the infective agent. The infective agent could, we believe, be shown to be linked to the enzyme if it were separated from the infected brain.
Animals↗
Quantitative and qualitative fluctuation of water in the mouse submandibular gland under secretagogue effect.
The short-term effects of two different secretagogues on the water contained in the mouse submandibular gland were studied using the thermal analysis as investigation method. Isoproterenol induced a retention while pilocarpine promoted a release of weakly and strongly bound water. In addition, submandibular glands of subjects administered with isoproterenol were characterized by a thermal behaviour different in males and females above all as concerns the time of reaction to the secretagogue; the reaction delay observed in females was correlated with the effects of this pharmacological substance on the convoluted granular tubules that are responsible for the sexual dimorphism in mice.
Animals↗
Thermal behaviour of the rabbit sublingual gland.
The purpose of this study was to show how some aspects of the biological matrix water can be investigated by thermoanalytical methods when using thermogravimetry and differential scanning calorimetry. Such methods allow to investigate the water in the rabbit sublingual gland and to quantitate it. The results supported the view that the water contained in this secretory organ show a large number of energetic interactions established on the basis of differential steps of water release by thermal disruption.
Animals↗
Thermogravimetry study on the water in secretory tissues of rabbit.
Isothermic and dynamic thermogravimetry was applied to rabbit parotid and submandibular glands to quantitate and characterize the water present inside them. Isothermic thermogravimetry demonstrated that at 95 degrees C a quota of water is still present in the samples. Dynamic thermogravimetry evidenced that temperatures higher than 200 degrees C are required for the release of the highest energy bound water from both glands. In addition during present research it was found that submandibular gland, an organ considered histologically homogenenous, reveals an heterogeneous distribution of water.
Animals↗
Differentiation of rat salivary glands by thermoanalytical analysis.
The water release from the sublingual, parotid and submandibular glands of male and female rats was analyzed by thermal analysis in order to detect the total water content and types. Different types of water, which are increasing from the sublingual to the parotid gland, were found and the relative distribution appeared to be a function of the bond energy of water to glandular components. In addition, evidence of a sexual dimorphism in the rat sublingual gland was demonstrated.
Animals↗
Characterization of mouse salivary glands by water content and type.
The thermoanalytical analysis was applied to samples of sublingual, submandibular and parotid glands from sexually mature mice of both sexes. Findings indicated that the three salivary glands show a behaviour of water release characteristic for each type of gland. Derivative thermogravimetry curves concerned with the sublingual and parotid glands belonging to male and female subjects exhibited overlapped results. As regards submandibular gland, instead, some differences emerged between subjects of different sex. Water content and types in sublingual, submandibular and parotid glands were discussed and related to the different morphological expression, histochemical reactivity and chemical composition of these organ tissues.
Animals↗
High-performance liquid chromatographic analysis of norfloxacin in human tissues and plasma with fluorescence detection.
A high-performance liquid chromatographic analysis with fluorimetric detection is described for the quantitative determination of norfloxacin in renal, prostatic tissues and in plasma. The analytical procedure in the tissue pretreatment, consists of purification of the obtained sample by a solid state extraction and quantitation by HPLC. The samples were chromatographed on a C(8) reversed-phase column. Analytical recoveries ranged from 95.2 to 97.6%. Within and between day precision were assessed by analysing serum containing 50 and 500 ng/ml norfloxacin. At each concentration, within day precision was < or = 3.6% (relative standard deviation, n = 10) and day-to-day precision was < or = 5.3% (n = 10). Limit of detection was ca 1 ng/ml.
Journal Article↗
High-performance liquid chromatographic determination of norfloxacin in human tissues and plasma with fluorescence detection.
A high-performance liquid chromatographic method with fluorimetric detection is described for the quantitative determination of norfloxacin in renal and prostatic tissues and in plasma. It consists of tissue pretreatment, purification by solid-state extraction and separation and quantification by high-performance liquid chromatography on a C8 reversed-phase column. Analytical recoveries ranged from 95.2 to 97.6%. Within-day and between-day precision were assessed by analysing serum containing 50 and 500 ng/ml norfloxacin. At each concentration, the within-day precision was less than or equal to 3.6% (coefficient of variation; n = 10) and the day-to-day precision was less than or equal to 5.3% (n = 10). The limit of detection was 1 ng/ml.
Chromatography, High Pressure Liquid↗
Total phosphorus determination in human bile. Comparison between two spectrometric methods.
The two most commonly used spectrometric methods for the determination of the phosphorus content of human bile are compared. The optimum experimental conditions are studied, and the analytical characteristics of the two methods, using both standard samples and human bile, are evaluated. The methods are compared on the basis of their sensitivity, precision and accuracy, and the correlation between the two techniques demonstrated using fifteen samples of human bile. Data obtained by both methods have been used to calculate lithogenic index values.
Journal Article↗