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Sample handling of complex samples such as plant materials is a challenge because of the presence of organic matrix compounds that may interfere with the selective extraction. The approach presented here involves the use of a membrane to physically separate the selective sorbent from the original sample. Thus, matrix components can be prevented from reaching the sorbent and the operation can be performed before the concentration step, thereby saving time. Examples of this approach will illustrate its effectiveness., Sample handling of complex samples such as plant materials, sludge, and sediments remains a challenge because of the multitude of organic matrix components that are present. Most of these interfering [...]

Membrane techniques have been used in many analytical applications and processes such as the selective removal and concentration of cations in solution, selective separation of gases and organic compounds in [...]

The form and bioavailable fractions of the metal ion are important factors that must be known in exposure risk assessment of any ecosystem. Supported liquid membrane extraction is capable of [...]

A coupled-column system, consisting of a combination of a molecularly imprinted polymer (MIP) and a [C.sub.18]-silica column, was used for selective triazine detection in the HPLC mode. Complex aqueous samples, spiked with triazines, were selectively extracted by the MIP followed by subsequent identification by analytical reversed-phase chromatography. The MIP showed good performance for selectively discriminating triazines from humic acid, whereas urine and apple extract had some tendency to be retained by the MIP. Enrichment was observed in all cases, and triazine-enrichment factors of up to 100 could be recorded, with good extraction efficiency (74-77%). The results indicate that the high selectivity of MIPs can be favorably used for selective sample enrichment in conjunction with reversed-phase HPLC.

In this work, molecularly imprinted polymer (MIP) was synthesized by a bulk polymerization method, characterized and parameters were optimized for adsorption of albendazole, ciprofloxacin, norfloxacin and venlafaxine in aqueous environment. The optimized MIP extraction parameters were adsorbent (MIP) mass 50 mg, sample pH of 9 and adsorption time of 20 min and 1 mL mixture of formic acid in water and methanol elution solvent. The adsorption experimental data fitted with the Freundlich isotherm model which indicates that the binding occurred on the heterogeneous sites and pseudo-second-order kinetic model best fitted which implied adsorption through chemisorption. The polymer selectivity was found to be in the order of albendazole > venlafaxine > norfloxacin > ciprofloxacin. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop and validate a high performance liquid chromatography (HPLC) method for the determination of thirteen selected pharmaceutical compounds (metformin, amoxicillin, chloroquine, theophylline, trimethoprim, caffeine, norfloxacin, ciprofloxacin, acetylsalicylic acid, doxycycline hyclate, metronidazole, albendazole and cloxacillin) in bulk and tablet dosage form. Chromatographic separation using a Kromasil C18 column, gradient elution with aqueous formic acid (0.1%), methanol and acetonitrile, a UV absorption wavelength of 250 nm and a mobile phase flow rate of 1 mL/min over a 22 min run time was optimized for complete separation of the selected target compounds. The method was validated and results for: linearity, precision, sensitivity, accuracy, specificity, suitability and method robustness were obtained and met the ICH guidelines. Calibration curve correlation coefficients ranged from 0.9985-0.9998 and the percentage relative standard deviations for repeated analysis was below 5%, indicating acceptable method precision. The limits of detection (LODs) and quantification (LOQs) ranged from 0.020-0.27 µg/L and 0.080-0.91 µg/L, respectively. The accuracy study yielded recoveries in the ranges 86.0-102% for pure compounds and 90.9-106% for compounds in tablet dosage form. The method is robust for small or deliberate changes to the chromatographic parameters and found to be appropriate for analysis of tablets for the determination of the thirteen pharmaceuticals. [ABSTRACT FROM AUTHOR]

Mineral commodities in Earth's crust, such as platinum, palladium, and gold have to be sustained especially since their ore deposits have been dramatically declining, due to intensive mining, motivated by high demand. The mining of these commodities results in large amounts of wastewater containing traces of precious elements. The current study presents on the recovery of Pt(IV) from aqueous solutions using spent brewer's yeast‐functionalized zeolite (SBYFZ). Batch and column experiments were conducted at different conditions. Two‐ and three‐parameter isotherm and kinetic models were fitted using adsorption data. Pt(IV) was significantly (p <.05) recovered from aqueous solutions within 300 min of contact time, using 10 g/L adsorbent dosage and 2 mg/L at pH 2. The platinum uptake was reduced by 5% when incorporated with adsorption competing ions. Other platinum group elements were successfully removed from aqueous solutions along with Pt(IV). Column studies indicated that breakthrough times were proportional to increasing bed height, highly acidic pH, and low influent concentration. The recovery of Pt(IV) was through mass transfer as concluded from column adsorption models. These results indicated that SBYFZ was excellent for the significant recovery of Pt(IV) from aqueous solutions. Thus, SBYFZ can be used in wastewaters with optimum conditions. [ABSTRACT FROM AUTHOR]