Selective extraction and detection of ß-agonists in swine urine for monitoring illegal use in livestock breeding.

The illegal use of ß-agonists often endangers animal-derived food safety. In this study, a selective detection method for ß-agonists in swine urine was established via the combination of polymeric ionic liquid-molecularly imprinted graphene oxide-miniaturized pipette tip solid-phase extraction and high-performance liquid chromatography. It is worth noting that this method relied mainly on the designed adsorbent, which presented a rich adsorption mechanism, fast mass transfer rate, and high selectivity, and was successfully utilized in the selective extraction of ß-agonists from swine urine samples. The proposed method has low LOD (0.20-0.56 ng/mL), high recovery (94.9-107.9%), and high reusability (4 times, 91.9-108.8%), which indicates its high potential as a selective, sensitive, accurate, and nonfatal method for monitoring the illegal use of ß-agonists in the livestock breeding stage.

Boronic acid-modified polyhedral oligomeric silsesquioxanes on polydopamine-coated magnetized graphene oxide for selective and high-capacity extraction of the catecholamines epinephrine, dopamine and isoprenaline.

Amino-functionalized polyhedral oligomeric silsesquioxanes (POSS-8NH2) were covalently bound to the surface of polydopamine-coated magnetized graphene oxide. It was then reacted with 4-formylphenylboronic acid to prepare a "cubic boronic acid"-bonded magnetic graphene oxide adsorbent. The new adsorbent exhibits better selectivity and much higher adsorption capacity for ortho-phenols over adsorbents where small boronic ligands are directly bound to the surface of the material. It is shown to enable selective and faster enrichment of the catecholamines epinephrine (EP), dopamine (DA) and isoprenaline (IP) with high selectivity over many potential interferents that can occur in urine. The analytes were then quantified by HPLC with fluorometric detection. Under optimal conditions, response is linear (R2 ≥ 0.9907), limits of detection are low (0.54-2.3 ng·mL-1), and reproducibility is acceptable (inter- and intra-day assay RSDs of≤10.9%). The method was successfully applied to the determination of endogenous EP and DA and exogenous IP in urine samples. Graphical abstractSchematic of boronic acid (BA)-modified polyhedral oligomeric silsesquioxanes (POSS) on polydopamine-coated magnetized graphene oxide (magGO). The material (magGO@POSS-BA) has good selectivity and higher adsorption capacity to ortho-phenols and can be applied to enrich the catecholamines in urine.

Hydrogen bonding recognition and colorimetric detection of isoprenaline using 2-amino-5-mercapto-1,3,4-thiadiazol functionalized gold nanoparticles.

In this paper, we describe a rapid, low-cost and highly sensitive colorimetric method for the detection of isoprenaline, based on 2-amino-5-mercapto-1,3,4-thiadiazol (AMTD) functionalized gold nanoparticles (AMTD-AuNPs) as a sensing element. Hydrogen bonding interaction between isoprenaline and AMTD resulted in the aggregation of AuNPs and a consequent color change of AuNPs from red to blue. The concentration of isoprenaline could be detected with the naked eye or a UV-visible spectrometer. Results showed that the absorbance ratio (A650/A524) was linear with isoprenaline concentrations in the range of 0.2 to 2.6µM (R=0.997). The detection limit of this method was 0.08µM. The proposed method is simple, without using complicated instruments and adding salts for enhancing sensitivity. This probe could be successfully applied to the determination of isoprenaline in human serum samples and urine samples after deproteinization.

Molecularly imprinted phloroglucinol-formaldehyde-melamine resin prepared in a deep eutectic solvent for selective recognition of clorprenaline and bambuterol in urine.

A new molecularly imprinted phloroglucinol-formaldehyde-melamine resin (MIPFMR) was synthesized in a deep eutectic solvent (DES) using phenylephrine as a dummy template. The MIPFMR was used as a solid phase extraction (SPE) sorbent for the selective isolation and recognition of clorprenaline (CLP) and bambuterol (BAM) in urine. Phloroglucinol and melamine were used as double functional monomers that introduced abundant hydrophilic groups (such as hydroxyl groups, imino groups, and ether linkages) into the MIPFMR, making it compatible with aqueous solvents. In addition, the formation of DES by combining the quaternary ammonium salt of choline chloride with ethylene glycol as a hydrogen bond donor was an environmentally safe alternative to toxic organic solvents such as chloroform and dimethylsulfoxide that are typically used in the preparation of most molecularly imprinted polymers (MIPs). Moreover, MIPFMR-based SPE of CLP and BAM in urine resulted in higher recoveries and purer extracts than those obtained by using other SPE materials (e.g., SCX, C18, HLB, and non-imprinted phloroglucinol-formaldehyde-melamine resin (NIPFMR)). The optimized MIPFMR-SPE-HPLC-UV method had good linearity (r2 ≥ 0.9996) ranging from 15.0 to 3000.0 ng mL-1 for CLP and BAM, and the recoveries at three spiked levels ranged from 91.7% to 100.1% with RSDs ≤7.6%. The novel MIPFMR-SPE-HPLC-UV method is simple, selective, and accurate, and can be used for the determination of CLP and BAM in urine samples.

[Detection and identification of major metabolites of clorprenaline in swine urine using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry].

This study was conducted to detect and identify the metabolites of clorprenaline in swine urine using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS), and the major metabolic pathways of clorprenaline were proposed. The swines were administered a single dose each of 10 mg/kg b. w. clorprenaline by oral gavage. The urine samples were collected before and after administration. After a simple preparation, the urine samples were analyzed using UPLC/Q-TOF MS. Combined with data processing techniques including extracted ion chromatography (EIC) and mass defect filtering (MDF), two phase I and seven phase II metabolites were detected in the urine samples collected 0-24 h after administration. The structures of detected metabolites were elucidated by comparing their characteristic product ions with those of the parent clorprenaline. Based on the identified metabolites, the metabolic pathways of clorprenaline included hydroxylation, glucuronidation and sulphate conjugates. Among those detected metabolites, hydroxylated-clorprenaline and its conjugates were responsible for over 60% of the total MS responses, much greater than those of clorprenaline, and were proposed as the primary metabolites in swine urine. This study can provide scientific basis for determining appropriate marker residues of clorprenaline, and facilitate to effectively control clorprenaline residues in animals.

Lateral-flow assay for rapid quantitative detection of clorprenaline residue in swine urine.

Clorprenaline (CLP), a ß2-adrenergic agonist, was first found in veterinary drugs for cold treatment in China in 2013. It is a potential new lean meat-boosting feed additive because it can promote animal muscular mass growth and decrease fat accumulation. A competitive colloidal gold-based lateral flow immunoassay system with a portable strip reader was successfully developed for rapid quantitative detection of CLP residue in swine urine. The detection system was optimized so that the detection can be completed within 9 min with a limit of detection of 0.15 µg · liter(-1). The assay exhibited good linear range from 3.0 to 20.0 µg · liter(-1), with reliable correlation of 0.9970 and with no obvious cross-reaction with five other ß2-agonist compounds. Twenty spiked swine urine samples were tested by lateral flow immunoassay and liquid chromatography-tandem mass spectrometry to confirm the accuracy of the system. Results show good correlation between the two methods. This method is rapid, sensitive, specific, and convenient. It can be applied in the field for on-site detection of CLP in urine samples.

Ionic liquids modified dummy molecularly imprinted microspheres as solid phase extraction materials for the determination of clenbuterol and clorprenaline in urine.

New ionic liquid modified dummy molecularly imprinted microspheres (DMIMs) were synthesized by aqueous suspension polymerization using phenylephrine as dummy template and 1-allyl-3-ethylimidazolium bromide as co-functional monomer. The obtained DMIMs were characterized by Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM), and empolyed as the special sorbent of solid-phase extraction for isolation of clenbuterol (CLB) and clorprenaline (CLP) from urine sample. The results indicated that the ionic liquid modified polymers were monodispersed microspheres and had high selectivity and adsorbability to CLB and CLP, and the matrix interferences could be efficiently eliminated from the samples. Meanwhile, the effect of template leakage of DMIMs on quantitative analysis was avoided. Compared with other commercial sorbents (HLB, PCX, C18 and SCX), the DMIMs exhibited higher affinity and purification ability to CLP and CLB. Under the optimized conditions, good linearity was observed in a range of 0.90-400µgL(-1) (r(2)=0.9999) with LOD of 0.19 and 0.070µgL(-1) for CLP and CLB, respectively. The recoveries at three spiked levels were ranged from 93.3% to 106% with RSD≤5.6% (n=3).

Determination of isoproterenol and uric acid by voltammetric method using carbon nanotubes paste electrode and p-chloranil.

An electrochemical method is described for the voltammetric determination of isoproterenol in the presence of uric acid using p-chloranil-carbon nanotubes paste electrode. Cyclic voltammetric, chronoamperometric, and electrochemical impedance spectroscopic methods have used to investigate the suitability of p-chloranil as a mediator for the electrocatalytic oxidation of isoproterenol at pH=10.5. Using differential pulse voltammetry, isoproterenol (ISPT) and uric acid (UA) in a mixture can be measured simultaneously and individually with a potential difference of 360 mV. The electrocatalytic currents increase linearly with ISPT and UA concentrations over the concentration ranges of 0.015-100 µmol L(-1) ISPT and 3.0-310 µmol L(-1) UA. The detection limits for ISPT and UA were equal to 0.009 and 2.3 µmol L(-1), respectively. The diffusion coefficient and the kinetic parameters such as electron transfer coefficient and heterogeneous rate constant were determined for ISPT, using the electrochemical approaches. The proposed method was successfully applied to the determination of isoproterenol in both ampoule and urine samples.

Sensitive determination of norepinephrine, synephrine, and isoproterenol by capillary electrophoresis with indirect electrochemiluminescence detection.

A new and sensitive method for the determination of norepinephrine (NE), synephrine, and isoproterenol was developed by CE separation and indirect electrochemiluminescence detection (ECL) based on their quenching effects on the tris(2,2'-bipyridyl)-ruthenium(II)/tripropylamine (TPA) system. The conditions for CE separation and ECL detection were investigated in detail. Under the optimum conditions, the three analytes were well separated within 9 min. The LODs (S/N = 3) in standard solution are 2.6 x 10(-8) mol/L for NE, 6.6 x 10(-9) mol/L for synephrine and 8.4 x 10(-8) mol/L for isoproterenol, respectively. The precisions of intraday and interday are less than 4.4 and 6.1%, respectively. The LOQs (S/N = 10) in real human urine samples are 2.6 x 10(-7) mol/L for NE, 8.8 x 10(-8 ) mol/L for synephrine, and 8.8 x 10(-7) mol/L for isoproterenol, respectively. The applicability of the proposed method was illustrated in the determination of 20 human urine samples from diabetic patients and healthy persons. The results obtained indicated that the level of NE in patients (mean value 0.41 micromol/L) was higher than that in healthy persons (mean value 0.24 micromol/L).

Determination of catecholamines by CE with direct chemiluminescence detection.

A rapid and sensitive method to detect three catecholamines, isoprenaline, epinephrine, and dopamine, by CE coupled with direct luminol-potassium periodate chemiluminescence (CL) detection is described. The conditions for CE separation and CL reaction were systematically optimized. Under the optimum conditions, the baseline separation of three catecholamines was achieved within 6.5 min. The LODs obtained in standard solution were 5.3 x 10(-8 )mol/L for isoprenaline, 4.7 x 10(-8 )mol/L for epinephrine, and 1.5 x 10(-7 )mol/L for dopamine. The RSD of the migration time and peak area were less than 1.8 and 3.6% (n = 5), respectively. The present method was applied to the determination of the dopamine in urine samples of cigarette smokers and nonsmokers. The results obtained indicate that there is a close relationship between the content of dopamine in human urine and the amount of cigarettes smoked daily; the level of dopamine in smokers is higher than in nonsmokers.

Determination of salbutamol enantiomers in human urine using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin in nonaqueous capillary electrophoresis.

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the resolution and the determination of salbutamol enantiomers in urine samples using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin (HDAS-beta-CD). After optimization of the electrophoretic parameters, namely the background electrolyte (BGE) composition and the HDAS-beta-CD concentration, salbutamol enantiomers were completely resolved using a BGE made up of 10 mM ammonium formate and 15 mM HDAS-beta-CD in methanol acidified with 0.75 M formic acid. Isoprenaline was selected as internal standard. Solid-phase extraction (SPE) was used for sample cleanup prior to the CE separation. Different sorbents involving polar, nonpolar interactions or dual retention mechanisms were evaluated and extraction cartridges containing both nonpolar and strong cation-exchange functionalities were finally selected. Salbutamol enantiomers recoveries from urine samples were determined. The method was then successfully validated using a new approach based on accuracy profiles over a concentration range from 375 to 7500 ng/mL for each enantiomer.

Determination of urine catecholamines by capillary electrophoresis with dual-electrode amperometric detection.

Demonstrated in this study is that without pretreatment and preconcentration nanomolar-level catecholamines in human urine samples can be quantitatively determined with ease by utilizing capillary electrophoresis coupled with amperometric detection. The detector employs a parallel-opposed dual-electrode scheme assembled with an on-capillary electrode and a disk electrode and takes advantage of the redox cycling of analytes between the two working electrodes to improve the limit of detection. The matrix effect of urine samples significantly decreases the detection sensitivity from that obtained in standard solutions. Therefore, calibration curves derived from standard solutions cannot be used in quantitative determination of catecholamines. Methods of standard addition and internal standard have been studied. The results suggest that isoproterenol is a good internal standard to facilitate the measurements of dopamine, epinephrine, and norepinephrine in human urine samples.

Design and applications of a self-aligning liquid junction-electrospray interface for capillary electrophoresis-mass spectrometry.

A simple self-aligning liquid junction-electrospray interface for coupling a capillary electrophoresis (CE) system to an atmospheric pressure ionization (API) mass spectrometer (CE-MS) was developed. In contrast to previous liquid junction interfaces, the self-aligning liquid junction interface simplifies the precise alignment of the CE capillary and the sprayer needle and uses a positive make-up flow. Several capillary CE-MS applications were run using both the self-aligning liquid junction interface and the widely used sheath flow interface for comparison purposes. The electrospray stability of the self-aligning liquid junction interface is consistently better even when non-volatile electrolyte solutions are used. At first, some band broadening was obtained with the self-aligning liquid junction interface. Experiments with different CE buffer systems suggested that this band broadening was caused by the materials used in constructing the interface. By using a more inert material for the sprayer needle, the self-aligning liquid junction exhibits excellent electrophoretic resolution, comparable sensitivity, and higher signal-to-noise ratios when run under the same conditions as the sheath flow interface.

Determination of d-isoproterenol sulphate by high-performance liquid chromatography with amperometric detection.

The application of reversed-phase high-performance liquid chromatography (HPLC) to the determination of isoproterenol sulphate in human plasma and urine was investigated. Sulphoconjugation of the inactive isomer of isoproterenol was chosen as an experimental model to study individual variations in the rate of sulphation of phenols in man. This approach allowed the ingestion of relatively large amounts of drug and detection of the conjugated material after acid hydrolysis, using alumina clean-up and HPLC with amperometric detection. This method was found to be rapid, sensitive, precise and suited to pharmacokinetic studies in man.

Isoproterenol excretion and metabolism in the isolated perfused rat kidney.

[3H]isoproterenol excretion and metabolism were studied in the isolated perfused rat kidney using a one-pass, non-recirculating perfusion system with constant infusion rates of [3H]isoproterenol. The [3H]isoproterenol (U/P) to inulin (U/P) ratio was approximately 15 indicating extensive tubular secretion. A major renal metabolite, 3-O-methylisoproterenol, appeared in the urine and renal vein perfusate and also accumulated in the renal tissue. The fractional excretion of isoproterenol decreased with time while fractional excretion of p-aminohippurate remained stable. The observed decreasing urinary clearance and percent extraction of isoproterenol with time may be due to the progressive intrarenal accumulation of 3-O-methylisoproterenol.

[Urinary clearance of dl-isopropylnoradrenaline in the dog]. / Clairance urinaire de la dl-isopropylnoradrénaline chez le chien.

In dogs, the urinary clearance of IPNA-3H is very near GFR (ratio CIPNA-3H/GFR = 0,92). This ratio is not modified by cocaine. In our experimental conditions, we observe no tubulary secretion of IPNA-3H.

Is there an increase in monoamine-oxidase activity in depressive illness?

In a group of depressed patients who had either been treated with or considered suitable for monoamine oxidase (M.A.O.) inhibitor therapy, a highly significant decrease in conjugated tyramine output was observed after an oral tyramine load compared with normal controls. However, there was no difference in conjugated isoprenaline output between the two groups after isoprenaline ingestion, even though this amine is almost solely metabolised by what is likely to be the same conjugation mechanism. Whilst some explanation in terms of altered gut motility is conceivable, it seems more likely that the apparent deficit in tyramine conjugation in depression represents an increase in functional M.A.O. activity. Consequently, this enzyme would metabolise a greater proportion of available amine, causing a proportionately large decrease in the smaller conjugate pool.