Separation and enrichment of active components in Toddalia asiatica (L.) Lam.by carboxylated chitosan-modified magnetic metal-organic frameworks.

Metal organic frameworks (MOFs) for magnetic solid-phase extraction of pyrazole/pyrrole pesticides in environmental water samples followed by HPLC-DAD determination

A high‐performance liquid chromatography–diode array detection (HPLC‐DAD) method was developed and validated for the determination of efavirenz in human blood plasma samples from patients taking the antiretroviral drug. Results were compared with those previously obtained using gas chromatography/mass spectrometry (GC/MS) on the same sample extracts using dispersive liquid‐liquid microextraction. Validation of the HPLC‐DAD method yielded the United States Food and Drug Administration guidelines acceptable values. However, when validated, the accuracy using the HPLC‐DAD method was poor in contrast to GC/MS at the lower limit of quantification (LLOQ) level. The linearity of the HPLC‐DAD method was good with a coefficient of determination (R 2 ) of 0.9922. The linear range of the calibration curve was 0.05–0.5 µg/mL. The LLOQ was 0.03 µg/mL at which spike level the accuracy was 8.9% ( n = 3) and the precision was 8.3% ( n = 3). Statistical analysis of the data showed that there were no systematic errors introduced in the HPLC‐DAD method but that there was a matrix effect that suppressed the signals and led to random error and subsequently impacted the accuracy of the results.

In this study, simultaneous quantification of allantoin, uric acid, xanthine, and hypoxanthine in cow milk by solid phase extraction (SPE) and high performance liquid chromatography-diode array detection (HPLC-DAD) method was perform. Five different SPE cartridges were tested in order to evaluate the isolation of purine derivatives (PD) from cow milk. Chromatography was carried out on ODS-2 Hypersil column and 0.05 M (NH<sub>4</sub>)<sub>2</sub>HPO<sub>4</sub> buffer solution (pH = 7.76) as mobile phase. The HPLC-DAD validated method showed a linearity with regression coefficients higher than 0.999 and the limits of detection and quantification with values in the range 0.09–0.74 µg mL<sup>–1</sup> and 0.27–2.24 µg mL<sup>–1</sup>, respectively. The method showed good precision with a relative standard deviation (RSD) below 4.48%, while the accuracy ranged from 95.34 to 104.47% for all analytes. The best recovery degree of PD by SPE were obtained on Strata SCX cartridge for xanthine (87.79%) and hypoxanthine (89.02%); on Strata NH<sub>2</sub> for allantoin (35.09%) and on Strata C8 for uric acid (101.08%). Finally, the HPLC-DAD method with SPE on SCX cartridges was applied to quantify the PD in a batch of thirty cow milk samples.

A systematic high-performance liquid chromatography-diode array detection (HPLC-DAD) method was developed for the rapid, accurate, and simultaneous quantification of eight marker compounds, paeoniflorin, 6-gingerol, decursin, glycyrrhizin, cinnamic acid, hesperidin, poncirin and magnolol, in Ojeok-san, a traditional Korean herbal medicine. These compounds were separated in less than 50 min using a Dionex C(18) column with a gradient elution system of water and methanol at a flow rate of 1 ml/min. All calibration curve of standard components showed excellent linearity (R(2) > 0.9922). Limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.01 to 0.11 μg/ml and 0.03 to 0.34 μg/ml, respectively. The relative standard deviations (RSDs) of data of the intra- and inter-day experiments were less than 2.15 and 2.60%, respectively. The accuracy of recovery test ranged from 94.27 to 107.68% with RSD values 0.15-3.61%. The results of validation showed that the HPLC method was stable and very accurate for the quantification of eight marker components in Ojeok-san.

β-Cyclodextrin modified magnetic microspheres were synthesized and used as an effective adsorbent for the solid-phase extraction of three phenols from water samples. Scanning electron microscopy and Fourier transform infrared spectrometry were used to characterize the adsorbents. The major parameters affecting the extraction and desorption efficiencies, such as adsorbent dosage, extraction time, pH, ionic strength, and eluent type were systematically optimized. Under these conditions, three phenols in water samples were extracted and determined by high performance liquid chromatography (HPLC) with diode array detection (DAD). Limits of detection (LODs) of 0.04–0.34 ng mL−1 and limits of quantification (LOQs) from 0.13 to 1.14 ng mL−1 were achieved with good repeatability (relative standard deviation <7.5%). The developed method was applied for the determination of 2,4-dichlorophenol, 2,4-dinitrophenol and bisphenol A in spiked Yangtze River water, and the recoveries were from 81.0% to 94.9%. The results demonstrated that the combination of magnetic solid-phase extraction (MSPE) with HPLC-DAD is suitable for the determination of trace phenolics in environmental water.

In this research a new magnetic material called M88 was fully synthetized and characterized for the extraction of pharmaceutical and personal care products in water samples. In addition, a portable prototype of magnetic solidphase extraction (MSPE) device was developed for the onsite preconcentration. The MSPE coupling with high performance liquid chromatography-Diode array detector (HPLC-DAD) method was developed and validated for simultaneous analysis of 11 PPCPs (mefenamic acid, chloroamphenicol, ketoprofen, clofibric acid, indometacin, acetylsalicylic acid, bisphenol A, phenylphenol, gemfibrozil, triclosan, and ibuprofen) in environmental water samples. Experimental parameters affecting the extraction efficiencies, such as the amount of M88, desorption solvent, extraction time, and solution pH and sample volume were investigated. Under the optimal conditions, the limits of detection (LODs, S/N = 3) for the selected PPCPs were found to be in the range of 0.7–9.4 ng/L, with good linear correlation coefficients. It is also shown that the extraction efficiency of M88 was comparable to that of the commercial Oasis HLB and was evidently higher than that of the C18 cartridge. The optimised method was further verified by performing spiking experiments in water samples from Taihu Lake, with good recovery and reproducibility for all the compounds.

A novel and Rapid Resolution Reversed-Phase High-Performance Liquid Chromatography-Diode Array Detector method has been developed and validated for the simultaneous determination of sildenafil, vardenafil, and tadalafil in pharmaceutical preparations and counterfeit drugs. An Agilent Zorbax SB C8 column (50 × 4.6 mm i.d., 1.8 μm particle size) was used. The mobile phase consisted of a mixture of 0.030 M of ammonium formate (adjusted to pH 3.0 with formic acid) and acetonitrile in the ratio 70:30. Ultraviolet (UV) detection was performed at 230 nm. Total run time was 7 min; these three drugs were eluted at the retention times of 1.654, 2.032, and 5.067 min for vardenafil, sildenafil, and tadalafil, respectively. The method was validated for accuracy, precision, linearity, specificity, and sensitivity. From the validation study, it was found that the method is specific, rapid, accurate, precise, and reproducible. Calibration curves were linear over the concentration ranges of 0.2–200 μg ml−1 for sildenafil, vardenafil, and tadalafil. The limits of detection (LOD) values were 1.0, 1.1, and 1.0 ng and the limit of quantification (LOQ) values were 2.0, 2.1, and 2.0 ng for sildenafil, vardenafil, and tadalafil, respectively. The method is rapid both for routine quantitative analysis of sildenafil, vardenafil, and tadalafil in pharmaceutical preparations and screening their suspected counterfeit drugs.

Analysis of saponins in raw and steamed Panax notoginseng using high-performance liquid chromatography with diode array detection

Fabrication of N,N-dimethyldodecylamine functionalized magnetic adsorbent for efficient enrichment of flavonoids

The main objective of this study was to establish a method for determining the content of orientin, calceolarioside B, kaempferol-3-O-rutinoside in Stauntonia Brachyanthera, and to compare the quality differences of Stauntonia Brachyanthera in different regions. The determination was performed on a Diamonsil®C18 column (4.6 mm × 250 mm, 5 μm) with acetonitrile-0.2% formic acid water as mobile phase, gradient elution, detection wavelength at 340nm, and column at room temperature. Orientin, calceolarioside B, kaempferol-3-O-rutinoside have a good linear relationship with peak area integration values. The regression equation is y = 1700.9x + 2.1473 (R² = 0.9997), y = 1131.5x + 5.8228 (R² = 0.9992), y = 1602x + 2.1948 (R² = 0.9993). The average dosing recovery rates were 98.6% (RSD = 1.76%), 102.6% (RSD = 1.88%), 99.6% (RSD = 1.25%). The High Performance Liquid Chromatography-Diode Array Detection (HPLC-DAD) method is suitable for the rapid determination of three components in the leaves of the Stauntonia Brachyanthera. The three components were different in the leaves of Stauntonia Brachyanthera from different regions, and the comprehensive analysis of Hongjiang has the highest content, which may be related to the picking period, soil quality, climate and other conditions.

有效萃取是分析复杂样品中苯氧羧酸类除草剂(PAs)残留的关键步骤。为此,该文利用“一锅法”水热技术快速、简便地制备了氨基碳纳米管功能化磁性纳米粒子(NH2-CNTs@M)并作为磁固相萃取(MSPE)的萃取介质,用于萃取谷物和蔬菜样品中痕量PAs。研究利用多种手段对NH2-CNTs@M的形貌、尺寸、磁性性质等进行了表征,结果表明Fe3O4的粒径、氨基化碳纳米管的直径以及NH2-CNTs@M的磁饱和值分别为30 nm、40 nm和44.2 emu/g。详细考察了制备条件和萃取参数对NH2-CNTs@M/MSPE萃取性能的影响,结果表明,NH2-CNTs@M/MSPE可通过π-π、疏水和氢键作用有效富集目标化合物,最佳萃取条件如下:吸附剂用量为30 mg,解吸溶剂为含2.0%(v/v)甲酸的乙腈溶液,吸附时间和解吸时间分别为8.0 min和3.0 min,基底pH值为6.0,不调节基底的离子强度。将NH2-CNTs@M/MSPE与高效液相色谱-二极管阵列检测技术(HPLC-DAD)联用,建立了谷物和蔬菜中PAs的灵敏检测方法。谷物和蔬菜基质中苯氧羧酸类除草剂的检出限(LOD, S/N=3)分别为0.32~1.6 μg/kg和0.53~1.6 μg/kg,定量限(LOQ, S/N=10)分别为0.94~4.8 μg/kg和1.6~4.8 μg/kg。在两种实际样品中不同浓度下的加标回收率分别为73.1%~112%和72.3%~113%。与现有方法相比,所建方法具有萃取速度快、灵敏度高和环境友好等特点。

The common practice of therapeutic drug monitoring (TDM) involves the quantification of drug plasma concentrations at a specific time in a dosing window. Although TDM for antibiotics is not considered mandatory, it may represent a valid tool for clinicians in order to limit antibiotic resistance and avoid therapeutic failures. The aim of our study was to develop and validate a high-performance liquid chromatography-diode array detection method for simultaneous quantification of 10 antibiotics in plasma. This method has a fast analytical procedure that uses the same chromatographic conditions to quantify ceftazidime, ceftriaxone, meropenem, ertapenem, ciprofloxacin, tigecycline, ampicillin, levofloxacin and piperacillin, plus the β-lactamase inhibitor tazobactam. Method validation was ensured by testing selectivity, accuracy, precision, limits of detection and quantification, recovery and stability. The calibration ranges, established accordingly to the expected plasma concentration in patients, showed a coefficient of determination >0.996 for all compounds. Within- and between-days precisions reported a coefficient of variation >15%. Similarly, the accuracy evaluation reported a relative standard deviation of <10% for each antibiotic. The recovery ranged between 97 and 103% for all compounds. This method could represent a useful tool for TDM of antibiotics.

Determination of chloramphenicol and tetracycline residues in milk samples by means of nanofiber coated magnetic particles prior to high-performance liquid chromatography-diode array detection

Quality determination of Crocus sativus L. flower by high-performance liquid chromatography

Toddalia asiatica (TA) is a classical traditional Chinese medicine used to treat rheumatoid arthritis and contusions. However, research regarding TA quality control is currently limited. We aimed to establish a strategy for identifying quality markers that can be used for the evaluation of the quality of TA. A rapid and efficient ultra-high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) method was developed for the quantitative determination of 19 compounds in TA from different regions. Then, the extraction process of TA was successively optimized by single-factor optimization and response surface methodology. Moreover, chemometrics was employed to confirm the correlation between quality and target compounds. Utilizing the UHPLC-MS/MS method, separation of the 19 bioactive compounds was achieved within 14 min. The method was validated in terms of linearity (r2 > 0.9982), precision (0.08%-3.70%), repeatability (0.50%-2.54%), stability (2.26%-5.46%), and recovery (95.8%-113%). The optimal extraction process (extraction solvent, 65% ethanol aqueous solution; solid-liquid ratio, 1:20; extraction time, 25 min) was determined with the total content of 19 bioactive compounds as indicator. Significant disparities were observed in the contents of target compounds across different batches of TA. Besides, all samples could be categorized into two distinct groups, and magnoflorine, (-)-lyoniresinol, nitidine chloride, norbraylin, skimmianine, and decarine were identified as quality markers. In the present study, we developed a strategy to improve the quality control of TA. In consideration of the pharmacodynamic activity and statistical differences, six compounds are proposed as quality markers for TA.