Determination of prohibited lead and cadmium traces in hair dyes and henna samples using ultrasound assisted-deep eutectic solvent-based liquid phase microextraction followed by microsampling-flame atomic absorption spectrometry.

In this study ultrasound assisted-deep eutectic solvent-based liquid phase microextraction followed by microsampling-flame atomic absorption spectrometry was developed to determine prohibited lead and cadmium traces in hair dye and henna samples. For this purpose, deep eutectic solvent, prepared from choline chloride and phenol, was used as an extraction solvent, dithizone was used as a complexing agent, and THF was used as an aprotic solvent. All parameters that affect extraction efficiency, such as pH, the DES volume and composition, the extraction time, the amount of dithizone, were optimized. Under the optimal conditions, for Pb(ii) and Cd(ii), enhancement factors of 92 and 57, LODs of 2.5 µg L-1 and 0.75 µg L-1, LOQs of 7.8 µg L-1 and 2.5 µg L-1, linear working ranges of 10-250 µg L-1 and 2.5-50 µg L-1, were obtained, respectively. Relative standard deviation (n = 10) was calculated to be 2.7 for 100 µg L-1 of Pb(ii) and 2.1 for 25 µg L-1 of Cd(ii). The matrix effect was investigated by comparing the solvent-based calibration curve with the matrix-matched calibration curve. The determination of lead and cadmium in hair dye and henna samples without being affected by the sample matrix was successfully performed. The lead content was between 1.3 and 6.5 µg g-1, and the cadmium content was between 0.028 and 0.54 µg g-1 for the selected hair dye and henna samples.

Arsenic removal in a sulfidogenic fixed-bed column bioreactor.

In the present study, the bioremoval of arsenic from synthetic acidic wastewater containing arsenate (As(5+)) (0.5-20mg/L), ferrous iron (Fe(2+)) (100-200mg/L) and sulfate (2,000 mg/L) was investigated in an ethanol fed (780-1,560 mg/L chemical oxygen demand (COD)) anaerobic up-flow fixed bed column bioreactor at constant hydraulic retention time (HRT) of 9.6h. Arsenic removal efficiency was low and averaged 8% in case iron was not supplemented to the synthetic wastewater. Neutral to slightly alkaline pH and high sulfide concentration in the bioreactor retarded the precipitation of arsenic. Addition of 100mg/L Fe(2+) increased arsenic removal efficiency to 63%. Further increase of influent Fe(2+) concentration to 200mg/L improved arsenic removal to 85%. Decrease of influent COD concentration to its half, 780 mg/L, resulted in further increase of As removal to 96% when Fe(2+) and As(5+) concentrations remained at 200mg/L and 20mg/L, respectively. As a result of the sulfidogenic activity in the bioreactor the effluent pH and alkalinity concentration averaged 7.4 ± 0.2 and 1,736 ± 239 mg CaCO3/L respectively. Electron flow from ethanol to sulfate averaged 72 ± 10%. X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the nature of the precipitate generated by sulfate reducing bacteria (SRB) activity. Precipitation of arsenic in the form of As2S3 (orpiment) and co-precipitation with ferrous sulfide (FeS), pyrite (FeS2) or arsenopyrite (FeAsS) were the main arsenic removal mechanisms.

Indoor aerosol determination with respect to a soiling phenomenon in private residences.

Indoor aerosol exposure has become of major interest since health hazards arising from fine and ultrafine dust particles have become more evident. The study presented here is dedicated to fine and ultrafine dust characterization and determination in more than 150 private residences with special respect to a phenomenon of enhanced soiling. In the scientific community committed to ecological housing and building it is referred to as "black magic dust" though the staining is often film-like in nature. This phenomenon has been observed for 20 years in residences in Europe and North America and there is strong evidence that it is correlated to emission of semivolatile organic compounds (SVOCs) from refurbishing materials. In this study we show that fine dust particle concentrations are elevated in such homes and that there is characteristic particle morphology for "black magic dust" staining. From the results we suggest that elevated particle concentration and particle size are significant to induce a condensation process which causes the observed blackening. Reduced air exchanges due to new insulation standards may also contribute to its occurrence.

Ligandless-solidified floating organic drop microextraction method for the preconcentration of trace amount of cadmium in water samples.

In this article, a new ligandless solidified floating organic drop microextraction (LL-SFODME) method has been developed for preconcentration of trace amount of cadmium as a prior step to its determination by flow injection-flame atomic absorption spectrometry (FI-FAAS). The methodology is based on the SFODME of cadmium with 1-dodecanol in the absence of chelating agent. Several factors affecting the microextraction efficiency, such as, pH, sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate and temperature were investigated and optimized. Under optimized experimental conditions an enhancement factor of 205 was obtained for 100mL of sample solution. The calibration graph was linear in the range of 1.0-25.0 ng mL(-1), the limit of detection (3s) was 0.21 ng mL(-1) and the limit of quantification (10s) was 0.62 ng mL(-1). The relative standard deviation (RSD) for 10 replicate measurements of 10 ng mL(-1) cadmium was 4.7%. The developed method was successfully applied to the extraction and determination of cadmium in standard and several water samples and satisfactory results were obtained.