Development and Validation of a Solid Phase Extraction and LC-MS Method for the Determination of Caulophine in Rat Plasma and Tissue: Application to Study Its Pharmacokinetics

A rapid and sensitive liquid chromatography-mass spectrometric (LC-MS) method was developed for investigating the pharmacokinetics of caulophine in rats. Biological samples were isolated by solid phase extraction (SPE) and analyzed by the LC-MS. A Shimadzu C18 VP-ODS column (150 mm × 2.0 mm ID, 5 µm) was used as the analytical column, with methanol-water-formic acid (33:67:0.1) as the mobile phase and a flow rate of 0.2 mL/min. Within-day and between-day precision was 1.40–3.49% and 1.29–6.91%. Average recoveries for all matrices were greater than 85.0%. The main pharmacokinetic parameters were T_max = (0.84 ± 0.31) h, C_max = (0.22 ± 0.08) µg/mL, AUC = (0.87 ± 0.16) h · µg/mL.     

Determination of Mycophenolic Acid (MPA) and Its Acyl and Phenol Glucuronide Metabolits Simultaneously in Human Plasma by a Simplified HPLC Method

Abstract

A simple HPLC method with ultraviolet detection for simultaneous determination of Mycophenolic acid (MPA), its phenol glucuronide metabolite (MPAG) and acyl‐MPAG (AcMPAG) in human plasma was established. The plasma samples were prepared with protein‐preciptaing reagent, and the supernatant was eluted on Zorbax column (250 mm×4.6 mm i.d, 5 µm) with 20 mmol/l NaH₂PO₄ buffer (pH 3.0, adjusted with 20% phosphoric acid) and methanol (45:55, v/v) at 304 nm. The column temperature was 45°C, and the flow rate was 1.2 ml/min. The assay was linear within the range of 0.2–50 µg/L for MPA (r=0.9997), 2.8–531 µg/L for MPAG (r=0.9999), and 0.3–24 µg/L for AcMPAG (r=0.9994). Mean absolute recovery of MPA and its metabolites and internal standard was >80%. The average recoveries of MPA, MPAG, and AcMPAG were 94.0–101.4, 98.4–101.9, and 96.1–104.2%, respectively. The RSD of within‐day and between‐day were all lower than 15%. The method described is sensitive, reproducible, and will be useful in TDM or pharmacokinetic studies of MPA.     

Rapid determination and comparative pharmacokinetics of tetrahydropalmatine in spontaneously hypertensive rats and normotensive rats

A rapid high‐performance liquid chromatographic method was developed and validated for determination of tetrahydropalmatine (THP), an active component of Rhizoma Corydalis, in rat plasma. The samples were prepared using protein precipitation and separated on an Agilent XDB‐C₁₈ column (150 × 4.6 mm, 5 µm) with the mobile phase consisting of methanol–0.1% phosphate acid solution, adjusted with triethylamine to pH 5.5 (65:35). Good linearity was found within 0.10–10.00 µg/mL of THP in rat plasma sample. The intra‐ and inter‐day precision values were less than 10%. The developed method was successfully applied to assess the pharmacokinetics of THP in spontaneously hypertensive rats (SHR) and normotensive rats. After oral administration of a single dose of THP (60 mg/kg), the maximum plasma concentrations were 6.15 ± 2.1 and 7.54 ± 2.9 µg/mL for normotensive rats and SHR, respectively. The mean values of AUC_0–∞ of THP in SHR were 81.44 ± 45.0 µg h/mL, significantly higher (p < 0.05) than in normotensive rats (44.06 ± 19.6 µg h/mL). The t_1/2 and MRT in SHR were much longer than that in healthy Sprague–Dawley rats, indicating slow elimination of THP in SHR. The results indicated that there are some differences in pharmacokinetics of THP in SHR and Sprague–Dawley rats and it is very important to investigate the pharmacokinetic properties of drugs in pathological conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Chemical constituents of essential oil of endemic Rhanterium suaveolens Desf. growing in Algerian Sahara with antibiofilm,antioxidant and anticholinesterase activities

Twenty compounds were detected in the essential oil of Rhanterium suaveolens representing 98.01% of the total oil content. Perillaldehyde (45.79%), caryophyllene oxide (24.82%) and β-cadinol (5.61%) were identified as the main constituents. In β-carotene–linoleic acid assay, both the oil and the methanol extract exhibited good lipid peroxidation inhibition activity, with IC₅₀ values of 17.97 ± 5.40 and 11.55 ± 3.39 μg/mL, respectively. In DPPH and CUPRAC assays, however, the methanol extract exhibited a good antioxidant activity. The highest antibiofilm activity has been found 50.30% against Staphylococcus epidermidis (MU 30) at 20 μg/mL for essential oil and 58.34% against Micrococcus luteus (NRRL B-4375) at 25 mg/mL concentration for methanol extract. The in vitro anticholinesterase activity of methanol extract showed a moderate acetylcholinesterase inhibitory (IC₅₀ = 168.76 ± 0.62 μg/mL) and good butyrylcholinesterase inhibitory (IC₅₀ = 54.79 ± 1.89 μg/mL) activities. The essential oil was inactive against both enzymes.     

Chemical composition and in vitro antibacterial and antiproliferative activities of the essential oil from the leaves of Psidium myrtoides O. Berg (Myrtaceae)

In this study, the chemical composition and antibacterial and antiproliferative potential of the essential oil obtained from fresh leaves of Psidium myrtoides (PM-EO) against oral pathogens and human tumour cell lines were investigated for the first time. GC-FID and GC-MS analyses showed that trans-β-caryophyllene (30.9%), α-humulene (15.9%), α-copaene (7.8%), caryophyllene oxide (7.3%) and α-bisabolol (5.3%) are the major constituents of PM-EO. The antibacterial activity of PM-EO against a panel of oral pathogens was investigated in terms of their minimal inhibitory concentrations (MIC) using the broth microdilution method. PM-EO displayed moderate activity against Streptococcus mitis (MIC = 100 μg/mL), S. sanguinis (MIC = 100 μg/mL), S. sobrinus (MIC = 250 μg/mL), and S. salivarius (MIC = 250 μg/mL), and strong activity against S. mutans (MIC = 62.5 μg/mL). The antiproliferative activity in normal (GM07492A, lung fibroblasts) and tumour cell lines (MCF-7, HeLa, and M059 J) was performed using the XTT assay. PM-EO showed 50% inhibition of normal cell growth at 359.8 ± 6.3 μg/mL. Antiproliferative activity was observed against human tumour cell lines, with IC₅₀ values significantly lower than that obtained for the normal cell line, demonstrating IC₅₀ values for MCF-7 cells (254.5 ± 1.6 μg/mL), HeLa cells (324.2 ± 41.4 μg/mL) and M059 J cells (289.3 ± 10.9 μg/mL). Therefore, the cytotoxicity of PM-EO had little influence on the antibacterial effect, since it showed antibacterial activity at lower concentrations. Our results suggest that PM-EO is a promising source of new antibacterial and antitumour agents.     

A reliable method of liquid chromatography for the quantification of acetaminophen and identification of its toxic metabolite N-acetyl-p-benzoquinoneimine for application in pediatric studies

The aim of the present study was to develop a simple, selective and reliable method to quantify acetaminophen and its toxic metabolite N‐acetyl‐p‐benzoquinoneimine (NAPQI) for pediatric studies using 100 µL plasma samples, by reverse‐phase HPLC and UV detection. The assay was performed using a C₁₈ column and an isocratic elution with water–methanol–formic acid (70:30:0.15; v/v/v) as mobile phase. Linearity of the method was assayed in the range of 1–30 µg/mL for acetaminophen and 10–200 µg/mL for NAPQI, with a correlation coefficient r = 0.999 for both compounds, and inter‐ and intra‐day coefficients of variation of less than 13%. Several commonly co‐administered drugs were analyzed for selectivity and no interference with the determinations was observed. The detection and quantification limits for acetaminophen and NAPQI were 0.1 and 1 µg/mL, and 0.1 and 10 µg/mL respectively. The present method can be used to monitor acetaminophen levels using 100 µL plasma samples, which may be helpful when very small samples need to be analyzed, as in pharmacokinetics determination or drug monitoring in plasma in children. This assay is also able to detect the NAPQI for drug monitoring in patients diagnosed with acetaminophen intoxication. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of Total Arsenic in Wastewater and Sewage Sludge Samples by Using Hydride-Generation Atomic Fluorescence Spectrometry Under the Optimized Analytical Conditions

In this work, an improved hydride-generation atomic fluorescence spectrometry (HG-AFS) method for the determination of total arsenic (As) in wastewater and sewage sludge samples was applied. The samples were digested completely with mixtures of HNO₃ and HClO₄. Analytical conditions were studied and optimized through uniform experimental design U*₁₀(10⁸) combined with a single factor test. A mathematical model was established, and a quadratic polynomial stepwise regression analysis by using the DPS software was employed to obtain the factors that impact the fluorescence intensity. This technique is then combined with a single factor test. The optimized experimental conditions were obtained as follows: PMT voltage was 305 V, lamp current was 70 mA, KBH₄ concentration was 2.0% (m/v), carrier liquid (HCl) concentration was 5% (v/v), carrier gas (Ar) flow rate was 300 mL min^?1, and reaction acidity was 10% (v/v) HCl. The pre-reduction of all forms of As to As(III) was performed by using a mixed solution of 1% thiourea and 1% ascorbic acid. The content of total As was determined under the optimized experimental conditions. The detection limits for total As in wastewater and sewage sludge were 0.09 µg L^?1 and 0.01 mg kg^?1, respectively. The linear ranges were 0.24–100 µg L^?1, and the recovery was 91.0–102.0%. The relative standard deviation (RSD, n = 5) for eleven replicate measurements of the certified reference materials containing 60.6 ± 4.2 µg L^?1 As (certified sample of water) and 10.7 ± 0.8 mg kg^?1 As (certified sample of soil) were 3.1% and 1.6%, respectively. The proposed method was validated by the analysis of certified reference materials and was successfully applied to the determination of total As in real samples of wastewater and sewage sludge with satisfactory results.     

Liquid Chromatographic Analysis of Cephalexin in Human Plasma by Fluorescence Detection of the 9-Fluorenylmethyl Chloroformate Derivative

Abstract

A simple and sensitive precolumn derivatization method for the determination of cephalexin in human plasma has been developed. Cephalexin was derived with 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer (5 mM, pH 8.5) for 15 min at 25°C. Optimal conditions for the derivatization were described. The derivative was chromatographed on an XDB-C₁₈ column with water–acetonitrile (10:90, v/v) as mobile phase at a flow rate of 1.0 mL/min. The fluorescence excitation and emission wavelengths were 268 nm and 314 nm, respectively. The standard curve in spiked plasma was linear over the range of 0.0234–58.5 µg/mL; the detection limit (signal-to-noise ratio = 3; injection volume, 10 µL) was about 0.014 µg/mL. The performance of analysis was studied, and the validated method showed excellent performance in terms of selectivity, sensitivity, precision, and accuracy.     

Development of a liquid chromatography assay for the determination of opicapone and BIA 9–1079 in rat matrices

Opicapone is a novel potent, reversible and purely peripheral third generation catechol‐O‐methyltransferase inhibitor, currently under clinical trials as an adjunct to levodopa therapy for Parkinson's disease. To support additional nonclinical pharmacokinetic studies, a novel high‐performance liquid chromatographic method coupled to a diode array detector (HPLC‐DAD) to quantify opicapone and its active metabolite (BIA 9–1079) in rat plasma and tissues (liver and kidney) is herein reported. The analytes were extracted from rat samples through a deproteinization followed by liquid‐liquid extraction. Chromatographic separation was achieved in less than 10 min on a reversed‐phase C₁₈ column, applying a gradient elution program with 0.05 M monosodium phosphate solution (pH 2.45 ± 0.05) and acetonitrile. Calibration curves were linear (r² ≥ 0.994) within the ranges of 0.04‐6.0 µg/mL for both analytes in plasma, 0.04‐4.0 µg/mL for opicapone in liver and kidney homogenates, and 0.07‐4.0 µg/mL and 0.06‐4.0 µg/mL for BIA 9–1079 in liver and kidney homogenates, respectively. The overall intra‐ and inter‐day accuracy ranged from ?12.68% to 7.70% and the imprecision values did not exceed 11.95%. This new HPLC‐DAD assay was also successfully applied to quantify opicapone and BIA 9–1079 in a preliminary pharmacokinetic study. Copyright © 2015 John Wiley & Sons, Ltd.     

Development and validation of a high‐performance liquid chromatographic method for the determination of stemoninine in rat plasma after administration of Stemona tuberosa extracts

For the first time, an HPLC method was developed and validated for the determination of stemoninine in plasma after oral and intravenous administration of the extract of the roots of Stemona tuberosa to rats. Plasma samples were analyzed on a Waters reversed‐phase C₁₈ column using a gradient mobile‐phase of eluent A (water containing 0.1% formic acid and 0.2% triethylamine, pH 3.68) and eluent B (acetonitrile–water, 50:50, v/v). The flow rate was 1.0 mL/min and the detector wavelength was 210 nm. The Waters Oasis solid‐phase extraction cartridge was applied for the preparation of plasma samples with high recovery. A good linear relationship was obtained in the concentration range of 1.55–124 µg/mL (r = 0.9995). The limits of quantification and detection were 1.55 and 0.42 µg/mL, respectively. The average recoveries ranged from 91.11 to 96.43% in plasma at stemoninine concentrations of 3.10, 62.0 and 99.2 µg/mL. Intra‐ and inter‐batch coefficient of variations were 3.27–5.37% and 2.49–3.92%, respectively. This method was successfully applied to pharmacokinetic studies after oral and intravenous administration of Stemona tuberosa extract in rats. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of aromatic amines in environmental water samples using solid-phase extraction modified with sodium dodecyl sulphate and micellar liquid chromatography

Extraction and determination of seven aromatic amines in environmental water samples were performed with solid-phase extraction (SPE) and micellar liquid chromatography (MLC) using experimental design. Extraction of aromatic amines was carried out with a C₁₈ cartridge modified with sodium dodecyl sulphate (SDS). The washing solution and elution solvent for extraction of aromatic amines were aqueous solution containing 5% (v/v) acetonitrile and 5% (v/v) acetone and 3 mL methanol, respectively. The chemometrics approach was applied for the separation optimisation of these compounds using MLC. Different mobile phase compositions were used for modelling based on retention times to obtain the best separation using central composite design. The optimum mobile phase composition for separation and determination of analytes in water samples was 69 mM SDS, 9% v/v 1-propanol and pH = 6.4. Recoveries were between 84.8–93.5% with relative standard deviation (RSD) less than 5.8% (n = 5). Limits of detection and linear range were 1–4.5 and 3.1–125.0 µg/L, respectively. The proposed method was applied to determine the aromatic amines in real samples (river and well waters). Amount of 4-nitroaniline and 3-nitroaniline in river water sample were 2.15 and 1.91 µg/L, respectively.     

A simple and sensitive HPLC-UV method for the determination of ponicidin in rat plasma and its application in a pharmacokinetic study

A simple, rapid, selective and sensitive HPLC‐UV method has been developed and validated for the determination of ponicidin in rat plasma. The analyte was extracted from rat plasma by liquid–liquid extraction with ethyl acetate as the extraction solvent. The LC separation was performed on a Zorbax Eclipse XDB C₁₈ analytical column (150 × 4.6 mm i.d., 5 µm) with an isocratic mobile phase consisting of methanol–water–phosphoric acid (45:55:0.01, v/v/v) at a flow rate of 1.0 mL/min. There was a good linearity over the range of 0.1–25 µg/mL (r = 0.9995) with a weighted (1/C²) least square method. The lower limit of quantification was proved to be 0.1 µg/mL. The accuracy was within ±10.0% in terms of relative error and the intra‐ and inter‐day precisions were less than 9.1% in terms of relative standard deviation. After validation, the method was successfully applied to characterize the pharmacokinetics of ponicidin in rats. Copyright © 2010 John Wiley & Sons, Ltd.     

Screening and evaluation of α-glucosidase inhibitors from indigenous medicinal plants in Dak Lak Province,Vietnam

α-Glucosidase inhibitors have received much attention due to their important use in treating diabetes mellitus. Although some synthetic α-glucosidase inhibitors have been available for a long time, they often cause various unexpected side effects. Thus, the present study was aimed at finding a safe, natural source of α-glucosidase inhibitors. Twenty-six samples of 22 medicinal plants were collected in the Dak Lak province of Vietnam and evaluated for α-glucosidase inhibitory activity. Trunk bark extract from Euonymus laxiflorus Champ (ELC extract) was selected as the best α-glucosidase inhibitor with the smallest IC₅₀ = 0.36 mg/mL against rat-derived α-glucosidase. This extract had a stronger inhibitory activity against α-glucosidase from Saccharomyces cerevisiae (IC₅₀ = 1.32 µg/mL) and Bacillus stearothermophilus (IC₅₀ = 5.15 µg/mL). The potential inhibition against some other enzymes were tested, and the results showed that the ELC extract did not inhibit fungal cellulase but strongly inhibited porcine α-amylase (IC₅₀ = 6.7 µg/mL). The ELC extract also inhibited the proteases papain and bromelain, with IC₅₀ = 339 µg/mL and IC₅₀ = 226 µg/mL, respectively. The thermal and pH stabilities of the ELC extract were also investigated.     

Rapid and Highly Sensitive HPLC and TLC Methods for Quantitation of Amlodipine Besilate and Valsartan in Bulk Powder and in Pharmaceutical Dosage Forms and in Human Plasma

Two simple, sensitive, and specific high-performance liquid chromatography and thin-layer chromatography methods were developed for the simultaneous estimation of Amlodipine besilate (AM) and Valsartan (VL). Separation by HPLC was achieved using a xTerra C18 column and methanol /acetonitrile /water/ 0.05% triethylamine in a ratio 40:20:30:10 by volume as mobile phase, pH was adjusted to 3 ± 0.1 with o-phosphoric acid. The flow rate was 1.2 mL min^?1. The linearity range was 0.2 to 2 µg mL^?1 for amlodipine besilate and 0.4 to 4 µg mL^?1 for Valsartan with a mean percentage recovery of 99.59 ± 0.523% and 100.61 ± 0.400% for amlodipine besilate and valsartan, respectively. The TLC method used silica gel 60 F₂₅₄ plates; the optimized mobile phase was ethyl acetate/ methanol / ammonium hydroxide (55:45:5 by volume). Quantitatively, the spots were scanned densitometrically at 237 nm. The range was 0.5–4.0 µg spot^?1 for amlodipine besilate and 2.0–12.0 µg spot^?1 for valsartan. The mean percentages recovery was 99.80 ± 0.451% and 100.61 ± 0.363% for amlodipine besilate and valsartan, respectively. The HPLC method was found to be simple, selective, precise, and reproducible for the estimation of both drugs from spiked human plasma.     

Design,synthesis of new novel quinoxalin-2(1H)-one derivatives incorporating hydrazone,hydrazine, and pyrazole moieties as antimicrobial potential with in-silico ADME and molecular docking simulation

A series of 6-(morpholinosulfonyl)quinoxalin-2(1H)-one based hydrazone, hydrazine, and pyrazole moieties were designed, synthesized, and evaluated for their in vitro antimicrobial activity. All the synthesized quinoxaline derivatives were characterized by IR, NMR (¹H /¹³C), and EI MS. The results displayed good to moderate antimicrobial potential against six bacterial, and two fungal standard strains. Among the tested derivatives, six quinoxalin-2(1H)-one derivatives 4a, 7, 8a, 11b, 13, and 16 exhibited a significant antibacterial activity with MIC values (0.97–62.5 µg/mL), and MBC values (1.94–88.8 µg/mL) compared with Tetracycline (MICs = 15.62–62.5 µg/mL, and MBCs = 18.74–93.75 µg/mL), and Amphotericin B (MICs = 12.49–88.8 µg/mL, and MFC = 34.62–65.62 µg/mL). In addition, according to CLSI standards, the most active quinoxalin-2(1H)-one derivatives demonstrated bactericidal and fungicidal behavior. Moreover, the most active quinoxaline derivatives showed a considerable antibacterial activity with bactericidal potential against multi-drug resistance bacteria (MDRB) strains with MIC values ranged between (1.95–15.62 µg/mL), and MBC values (3.31–31.25 µg/mL) near to standard Norfloxacin (MIC = 0.78–3.13 µg/mL, and MBC = 1.4–5.32 µg/mL. Further, in vitro S. aureus DNA gyrase inhibition activity were evaluated for the promising derivatives and displayed potency with IC₅₀ values (10.93 ± 1.81–26.18 ± 1.22 µM) compared with Ciprofloxacin (26.31 ± 1.64 µM). Interestingly, these derivatives revealed as good immunomodulatory agents by a percentage ranging between 82.8 ± 0.37 and 142.4 ± 0.98 %. Finally, some in silico ADME, toxicity prediction, and molecular docking simulation were performed and showed a promising safety profile with good binding mode.     

Monitoring of Polychlorinated Biphenyls in Surface Water Using Liquid Extraction,GC/MS,and GC/ECD

Abstract

A rapid and reliable analytical method, at trace level concentration was developed and validated for monitoring polychlorinated biphenyls (PCBs) in Jordanian surface water. The method combines the advantage of liquid extraction together with gas chromatography‐mass spectrometry (GC/MS) and gas chromatography‐electron capture detector (GC/ECD). The performance of the method was evaluated by analyzing certified reference material (CRM) of the analytes and applied on real water samples collected from different sites in Jordan. A mixture of 60∶40 dichloromethan‐petroleum ether was chosen as a convenient binary solvent for liquid–liquid extraction. The GC conditions for GC/MS were optimized using He as a carrier gas, temperature programming, and chlorpropham as an internal standard (IS).

The conditions for GC/ECD were performed using N₂ gas and a temperature program from 160 to 280°C with different increasing rates. The method of GC/MS in the selective ion mode (SIM) gave linear relationships for all PCBs tested between 0.60–6.0 µg/l with R ²=0.9934 (n=7×18). Recoveries from spiked water samples ranged between 87.6 and 91.4%. The mean accuracy and precision obtained were 4.9% and 2.16%, respectively. The mean of detection limit was 0.14±0.04 µg/l. In GC/ECD, linear relationships for all PCBs examined over the range of 0.3–2.4 µg/l was verified as characterized by a linear regression equation and correlation coefficient, R ²=0.9915 (n=12). The average precision and accuracy were 4.86% and 5.21%, respectively. Analyses results clarified that none of the examined Jordanian water samples contained any of the searched for PCBs within the detection limit achieved.     

Porcine pancreatic α-amylase inhibitors from <Emphasis Type="Italic">Euonymus laxiflorus</Emphasis> Champ.

Twenty-six samples of indigenous medicinal plants were collected in Dak Lak Province of Vietnam and evaluated for α-amylase inhibitory activity. Of these samples, trunk bark extract from Euonymus laxiflorus Champ. (ELC extract) showed the greatest α-amylase inhibitory activity with the smallest 50 % inhibitory concentration (IC₅₀) of 6.6 ± 0.6 µg/mL against porcine pancreatic α-amylase. This extract possessed strong inhibitory activity against human saliva α-amylase and slightly lower activity against Bacillus subtilis α-amylase, with IC₅₀ values of 4.2 ± 0.2 and 27.8 ± 1.8 µg/mL, respectively. ELC extract was found to be strongly thermostable, retaining 72–100 % relative activity even after heating at 100 °C for 5 min to 2 h. This extract was also stable at various pH values. These results suggest that ELC extract may be a good candidate for treatment of non-insulin-dependent diabetes mellitus (NIDDM) and obesity.     

A simple and rapid high‐performance liquid chromatography method for determination of alendronate sodium in beagle dog plasma with application to preclinical pharmacokinetic study

A simple and rapid high performance liquid chromatographic (HPLC) method for quantifying alendronate in beagle dog plasma was developed, validated and applied to a pharmacokinetic study. The sample preparation involved coprecipitation with CaCl₂ and derivatization with o‐phthalaldehyde. Chromatographic separation was achieved on a Diamonsil? C₁₈ (250 × 4.6 mm, 5 µm) using acetonitrile–0.4% EDTA‐Na₂ (16:84, v/v) containing 0.034% of NaOH as mobile phase. The fluorimetric detector was operated at 339 nm (excitation) and 447 nm (emission). The linearity over the concentration range of 5.00–600 ng/mL for alendronate was obtained and the lower limit of quantification was 5.00 ng/mL. For each level of quality control samples, inter‐day and intra‐day precisions were less than 8.52 and 7.42% and accuracies were less than 9.07%. The assay was applied to the analysis of samples from a pharmacokinetic study. Following the oral administration of 70 mg alendronate sodium to beagle dogs, the maximum plasma concentration (C_max) and elimination half‐life were 152 ± 27.3 and 1.75 ± 0.267 h, respectively. The method was demonstrated to be highly feasible and reproducible for pharmacokinetic studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Monoclonal Antibody-Based Immunoassay for the Detection of Maduramicin in Chicken Tissues

Abstract

This paper reports on the preparation of a monoclonal antibody (Mab) against maduramicin (MD) and the development of a simple and sensitive ELISA for MD in chicken tissues. MD was conjugated to bovine serum albumin for immunogens and ovalbumin for coating antigens by mixed anhydride (MA) and active ester (AE) methods. Hybridoma cells were generated using spleen cells from a mouse immunized with MD-BSA conjugate. After screening with ELISA, the Mab with high anti-interference ability and high affinity was selected, and it exhibited negligible cross-reactivity with other usual-used polyether antibiotics. After optimization, the developed ELISA showed an IC₅₀ value of 2.12 ± 0.46 ng/ml (n = 20). Chicken muscle and liver samples were extracted with methanol-8% NaCl solution (4:1) and then directly diluted with PBS-10% methanol for analysis. The recoveries of MD from spiked chicken tissues at levels of 40–480 µg/kg ranged from 81.3% to 91.3% with variation coefficients of 5.2–12.1%, and the detection limits were 6.5 µg/kg in muscle and 9.2 µg/kg in liver, respectively (n = 20).     

Preconcentration of trace amounts of cobalt (II) ions in water and agricultural products samples using of 5-(4-dimethylaminobenzylidene) rhodanin modified SBA-15 sorbent prior to FAAS determination

In the present study, the ?5-(4-dimethylaminobenzylidene)rhodanin-modified SBA-15? was applied as stable solid sorbent for the separation and preconcentration of trace amounts of cobalt ions in aqueous solution. SBA-15 was modified by ?5-(4-dimethylaminobenzylidene)rhodanin reagent. The sorption of Co²⁺ ions was done onto modified sorbent in the pH range of 6.8–7.9 and desorption occurred in 5.0 mL of 3.0 mol L^?1 HNO₃. The results exhibit a linear dynamic range from 0.01 to 6.0 mg L^?1 for cobalt. Intra-day (repeatability) and inter-day (reproducibility) for 10 replicated determination of 0.06 mg L^?1 of cobalt was ±1.82% and ?±1.97%?. Detection limit was 4.2 µg L^?1 (3S_b, n = 5) and preconcentration factor was 80. The effects of the experimental parameters, including the sample pH, flow rates of sample and eluent solution, eluent type and interference ions were studied for the preconcentration of Co²⁺. The proposed method was applied for the determination of cobalt in standard samples, water samples and agricultural products.