Micellar liquid chromatography determination of some biogenic amines with electrochemical detection

Use of Micellar Liquid Chromatography to Determine Mebendazole in Dairy Products and Breeding Waste from Bovine Animals

Mebendazole is an anthelmintic drug used in cattle production. However, residues may occur in produced food and in excretions, jeopardizing population health. A method based on micellar liquid chromatography (MLC) was developed to determine mebendazole in dairy products (milk, cheese, butter, and curd) and nitrogenous waste (urine and dung) from bovine animals. Sample treatment was expedited to simple dilution or solid-to-liquid extraction, followed by filtration and direct injection of the obtained solution. The analyte was resolved from matrix compounds in less than 8 min, using a C18 column and a mobile phase made up of 0.15 M sodium dodecyl sulfate (SDS)–6% 1-pentanol phosphate buffered at pH 7, and running at 1 mL/min under isocratic mode. Detection was performed by absorbance at 292 nm. The procedure was validated according to the guidelines of the EU Commission Decision 2002/657/EC in terms of: specificity, method calibration range (from the limit of quantification to 25–50 ppm), sensitivity (limit of detection 0.1–0.2 ppm; limit of quantification, 0.3–0.6 ppm), trueness (92.5–102.3%), precision (<7.5%, expressed at RSD), robustness, and stability. The method is reliable, sensitive, easy-to-handle, eco-friendly, safe, inexpensive, and provides a high sample-throughput. Therefore, it is useful for routine analysis as a screening or quantification method in a laboratory for drug-residue control.

Determination of paroxetine in blood and urine using micellar liquid chromatography with electrochemical detection

Paroxetine is a potent selective serotonin reuptake inhibitor used for the treatment of depression and related mood disorders. A micellar liquid chromatographic method was developed for the determination of paroxetine in serum and urine. Detection of paroxetine was carried out using a C18 column and a mobile phase of 0.15 M sodium dodecyl sulfate, 6% 1-pentanol at pH 3 (buffer salt 0.01 M NaH2PO4) running under isocratic mode at 1.0 mL/min and electrochemical detection at 0.8 V. The analyte was eluted without interferences in <15 min. The proposed methodology was validated under the guidelines of the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use in matrix in terms of specificity, linearity (r(2) > 0.9999; 0.5-5 μg/mL range), accuracy (88-97.5%, recovery), repeatability (RSD < 0.54%), intermediate precision (RSD < 0.54%), limit of detection and quantification (0.001 and 0.005 μg/mL, respectively) and robustness (RSD < 3.63%). Developed method was successfully applied to real blood and urine samples as well as in spiked serum and urine samples. The developed method was specific, rapid, precise, reliable, accurate, inexpensive and then suitable for routine analysis of paroxetine in monitorized samples.

Analysis of Some Biogenic Amines by Micellar Liquid Chromatography

Micellar liquid chromatography (MLC) with the use of high performance liquid chromatography (HPLC) was used to determine some physicochemical parameters of six biogenic amines: adrenaline, dopamine, octopamine, histamine, 2-phenylethylamine, and tyramine. In this paper, an influence of surfactant’s concentration and pH of the micellar mobile phase on the retention of the tested substances was examined. To determine the influence of surfactant’s concentration on the retention of the tested amines, buffered solutions (at pH 7.4) of ionic surfactant—sodium dodecyl sulfate SDS (at different concentrations) with acetonitrile as an organic modifier (0.8/0.2 v/v) were used as the micellar mobile phases. To determine the influence of pH of the micellar mobile phase on the retention, mobile phases contained buffered solutions (at different pH values) of sodium dodecyl sulfate SDS (at 0.1 M) with acetonitrile (0.8/0.2 v/v). The inverse of value of retention factor () versus concentration of micelles () relationships were examined. Other physicochemical parameters of solutes such as an association constant analyte—micelle ()—and partition coefficient of analyte between stationary phase and water (hydrophobicity descriptor) () were determined by the use of Foley’s equation.

Development of an LC-MS/MS method for the analysis of serotonin and related compounds in urine and the identification of a potential biomarker for attention deficit hyperactivity/hyperkinetic disorder

Serotonin is a major neurotransmitter and affects various functions both in the brain and in the rest of the body. It has been demonstrated that altered serotinergic function is implicated in various psychiatric disorders including depression and schizophrenia. Serotonin has also been implicated along with dopamine in attention deficit-hyperkinetic disorder (AD-HKD). This study provides a versatile validated method for the analysis of serotonin, hydroxyindole acetic acid and dopamine in urine using LC-MS/MS. This method was then used to quantify these analytes in a test group of 17 children diagnosed with severe AD-HKD. This group was compared to a matched control group to investigate the possibility that one of these compounds may be a potential biomarker for this condition. The developed method provided good linear calibration curves for the multiplex assay of analytes in urine (0.05-3.27 nmol/L; R(2) ≥ 0.9977). Acceptable inter-day repeatability was achieved for all analytes with RSD values (n = 9) ranging from 1.1% to 9.3% over a concentration range of 0.11-3.27 μmol/L in urine. Excellent limits of detection (LOD) and limits of quantitation (LOQ) were achieved with LODs of 8.8-18.2 nmol/L and the LOQs of 29.4-55.7 nmol/L for analytes in urine. Recoveries were in the ranges of 98-104%, 100-106% and 91-107% for serotonin, 5-HIAA and dopamine, respectively. An appropriate sample clean-up procedure for urine was developed to ensure efficient recovery and reproducibility on analysis. Evaluation of matrix effects was also carried out and the influence of ion suppression on analytical results reported. Confirmatory analysis was carried out on a linear trap quadrupole-Orbitrap mass spectrometer to obtain high mass accuracy data of the target analytes in the clinical samples.

Rapid and sensitive determination of nicotine in formulations and biological fluid using micellar liquid chromatography with electrochemical detection

Nicotine can be determined in pharmaceuticals and biological fluids by micellar liquid chromatography (MLC) using a C18 column, a mobile phase containing sodium dodecyl sulphate 0.15M-6% (v/v) pentanol-NaH(2)PO(4) 0.01 M (pH 6)-KCl 0.001 M, with electrochemical detection at 0.8 V. In the optimization step, the influence of the modifiers propanol, butanol and pentanol, and the voltage has been studied. With the proposed method the analysis time is below than 8 min, linearity better than 0.999, limits of detection and quantification (ng/ml) was 4 and 12 respectively, repeatability and intermediate precision below 1.8%, and all these parameters are adequate for the quantification of nicotine in chewing gum, dermal patches, tobacco and serum samples either by a pharmacologist, pathologist or toxicologist.

High performance liquid chromatography/tandem mass spectrometry determination of biogenic amines in typical Piedmont cheeses

The paper presents a new HPLC method, hyphenated with mass spectrometry detection, for the separation and determination of the biogenic amines that are most commonly present in cheese, namely cadaverine, histamine, spermidine, spermine, tyramine and tryptamine. The HPLC-MS/MS method is validated by comparison of the results with those obtained through a literature HPLC-UV determination, based on a pre-column dansyl chloride derivatisation step. The intercalibration is based on the statistical t-test for multiple samples that allows to compare simultaneously the results obtained with the two methods for more analytes and to decide, at a prefixed confidence level, if the two methods are inter-changeable. The new HPLC-MS/MS method, employed in selected reaction monitoring (SRM) mode, permits to achieve for standard solutions limit of detection (LOD) values ranging from 1.7 to 22.5 microg L(-1) and LOQ (limit of quantitation) values ranging from 5.6 to 68.2 microg L(-1). In order to apply the method in the analysis of cheeses, LOD and LOQ values have also been evaluated in "ricotta" cheese, in order to take as possible into account the matrix interference. In these conditions LODs range between 5.1 and 35.0 microg L(-1) and LOQs between 14.2 and 101.2 microg L(-1). The whole methodology, comprehensive of the homogenization-extraction process and HPLC-MS/MS analysis, has been applied in the analysis of three typical Piedmont (North-West Italy) cheeses, known as Toma Piemontese, Raschera and Castelmagno.

Determination of biogenic amines in chocolate by ion chromatographic separation and pulsed integrated amperometric detection with implemented wave-form at Au disposable electrode

A rapid and selective cation exchange chromatographic method coupled to integrated pulsed amperometric detection (PAD) has been developed to quantify biogenic amines in chocolate. The method is based on gradient elution of aqueous methanesulfonic acid with post column addition of strong base to obtain suitable conditions for amperometric detection. A potential waveform able to keep long time performance of the Au disposable electrode was set up. Total analysis time is less than 20min. Concentration levels of dopamine, serotonin, tyramine, histamine and 2-phenylethylamine were measured, after extraction with perchloric acid from 2g samples previously defatted twice with petroleum ether. The method was used to determine the analytes in chocolate real matrices and their quantification was made with standard addition method. Only dopamine, histamine and serotonin were found in the analysed real samples. Repeatabilities of their signals, computed on their amounts in the real samples, were 5% for all of them. Repeatabilities of tyramine and phenethylamine were relative to standard additions to real samples (close to 1mg/l in the extract) and were 7 and 3%, respectively. Detection limits were computed with the 3s of the baseline noise combined with the calibration plot regression parameters. They were satisfactorily low for all amines: 3mg/kg for dopamine, 2mg/kg for tyramine, 1mg/kg for histamine, 2mg/kg for serotonin, 3mg/kg for 2-phenylethylamine.