Removal of Heavy Metals by a Membrane Bioreactor Combined with Activated Carbon

Royal Society; Ad-Bio: Advanced Biological Wastewater Treatment Processes; Natural Environment Research Council (NERC): Newton Advanced Fellowship - 2015/R2

Determination of As, Cd, and Pb in tap water and bottled water samples by using optimized GFAAS system with Pd-Mg and Ni as matrix modifiers

Arsenic, lead and cadmium were determined in tap and bottled water samples consumed in the west part of Turkey at trace levels. Graphite Furnace Atomic Absorption Spectrometry (GFAAS) was used in all detections. All of the system parameters for each element were optimized to increase sensitivity. Pd-Mg mixture was selected as the best matrix modifier for As while the highest signals were obtained for Pb and Cd in the case of Ni used as matrix modifier. Detection limits for As, Cd, and Pb were found to be 2.0, 0.036 and 0.25 ng/mL, respectively. 78 tap water and 17 different brands of bottled water samples were analyzed for their As, Cd and Pb contents under the optimized conditions. In all water samples, concentration of cadmium was found to be lower than detection limits. Lead concentration in the samples analyzed varied between N.D. and 12.66 +/- 0.68 ng/mL. The highest concentration of arsenic was determined as 11.54 +/- 2.79 ng/mL. Accuracy of the methods was verified by using a certified reference material namely Trace Element in Water, 1643e. Results found for As, Cd, and Pb in reference materials were in satisfactory agreement with the certified values

hplc-icp-ms and hplc-es-ms kullanılarak türleme çalışmaları.

Knowledge about selenium content of foods containing selenium species is very important in terms of both nutrition and toxicity. Bioavailability of selenium species for human body is different from each other. Hence, speciation of selenium is more important than total selenium determination. In the selenium speciation study, chicken breast samples, selenium supplement tablets and egg samples were analyzed for their selenium contents. In chicken breast study, chickens were randomly categorized into three groups including the control group (25 chickens), inorganic selenium fed group (25 chickens) and organic selenium fed group (25 chickens). After the optimization of all the analytical parameters used throughout the study, selenomethionine, selenocystine, Se(IV) and Se(VI) were determined using Cation Exchange-HPLC-ICP-MS system. In selenium supplement tablet study, anion and cation exchange chromatographies were used to determine selenium species. Arsenic is known as toxic element, and toxicity of inorganic arsenic species, As(III) and As(V), is much higher than organic arsenic species like arsenobetaine and arsenosugars. Hence, speciation of arsenic species in any matrix related with human health is very important. In the arsenic speciation study, Cation Exchange-HPLC-ICP-MS and Cation Exchange-HPLC-ES-MS systems were used to determine arsenobetaine content of DORM-2, DORM-3 and DOLT-4 as CRMs. All of the parameters in extraction, separation and detection steps were optimized. Standard addition method was applied to samples to eliminate or minimize the matrix interference. Thiols play an important role in metabolism and cellular homeostasis. Hence, determination of thiol compounds in biological matrices has been of interest by scientists. In the thiol study, Reverse Phase-HPLC-ICP-MS and Reverse Phase-HPLC-ES-MS systems were used for the separation and detection of thiols. For the thiol determination, thiols containing –S-S- bond were reduced using dithiothreitol (DTT). Reduction efficiencies for species of interest were found to be around 100%. Reduced and free thiols were derivatized before introduction on the column by p-hydroxymercuribenzoate (PHMB) and then separated from each other by using a C8 column. In the real sample measurement, yeast samples were analyzed using HPLC-ES-MS system.Ph.D. - Doctoral Progra

Determination of Cadmium in Tap, Sea and Waste Water Samples by Vortex-Assisted Dispersive Liquid-Liquid-Solidified Floating Organic Drop Microextraction and Slotted Quartz Tube FAAS After Complexation with a Imidazole Based Ligand

This study presents a combination of dispersive liquid-liquid-solidified floating organic drop microextraction (DLLSFODM) and slotted quartz tube (SQT) with conventional flame atomic absorption spectrometry (FAAS) to improve the sensitivity for cadmium determination. A ligand namely 2-(4-methylphenyl)-1H-imidazo-[4,5-f]-[1,10]-phenanthroline which has not been used in trace analyte determination was used to form a cadmium complex. Stepwise optimization of parameters affecting complex formation (pH, ligand, and buffer solution) and extraction (extraction and dispersive solvents, salt effect and mixing) was done to maximize cadmium absorbance. The slotted quartz tube was fitted onto the flame burner and optimized to increase residence time of atoms in the flame. Instrumental parameters such as sample and fuel flow rate were also optimized to further enhance the absorbance signal for cadmium. Using optimal parameters and values, the limits of detection and quantification were determined to be 0.81 and 2.69 μg L−1, respectively. Low percent relative standard deviations (< 6.0%) indicated good precision for both extraction and instrumental measurements. Recovery tests were used to determine the accuracy of the method and the recovery results obtained were between 88 and 113%. [Figure not available: see fulltext.]. © 2018, Springer International Publishing AG, part of Springer Nature

Simultaneous determination of iprodione, procymidone, and chlorflurenol in lake water and wastewater matrices by GC-MS after multivariate optimization of binary dispersive liquid-liquid microextraction

This study reports the optimization of a binary dispersive liquid-liquid microextraction method for the determination of iprodione, procymidone, and chlorflurenol by gas chromatography mass spectrometry. The study was aimed at using two extraction solvents to increase the extraction efficiency of all analytes. The binary solvents recorded results higher than the mono-solvents. After examining the effects of main experimental parameters and their interactions by analysis of variance, 200 µL of binary mixture (dichloromethane and 1,2-dichloroethane), 2.5 mL of ethanol, and 15 s vortex were obtained as optimum parameters. The detection and quantification limits calculated for the analytes were found to be between 0.30–1.6 and 1.0–5.3 ng/mL, respectively. Enhancement in detection power calculated as a ratio of the binary extraction detection limit to the detection limit of direct GC-MS analysis was 105-, 214-, and 233-fold for chlorflurenol, iprodione, and procymidone, respectively. In order to check the accuracy of the developed method, recovery study was performed. Water sampled from a lake and two wastewater samples from treatment facilities were spiked at two concentrations, and the percent recovery calculated for the samples ranged between 87 and 116%. These results confirmed the suitability of the method to real samples for accurate determination of the analytes at trace levels. © 2018, Springer Nature Switzerland AG