Determination of sevoflurane and its metabolite hexafluoroisopropanol by direct injection of human plasma into gas chromatography–tandem mass spectrometry

The developed method for trace analysis of volatile components in plasma allows direct injection of up to 150 samples to the GC–MS/MS system without injector cleaning. This method requires no modification of plasma and the working environment does not interfere with the determination of these analytes. The method allows simultaneous quantification of non-polar sevoflurane and its polar metabolite hexafluoroisopropanol (free, unconjugated form). It is characterized by high repeatability and sensitivity with the detection limit of 0.009 mg L^?1 for sevoflurane and 0.018 mg L^?1 for hexafluoroisopropanol and the linear range 0.050–150 mg L^?1. The method was used to determine the concentration of sevoflurane and hexafluoroisopropanol in plasma samples of 7 patients undergoing general anesthesia with sevoflurane. The average concentration of sevoflurane and free hexafluoroisopropanol was 57.2 mg L^?1 and 0.39 mg L^?1, respectively. The method can be applied for clinical monitoring, as well as for analytical toxicology.     

A calorimetric study of plant–plant and plant–soil interactions of extracts from Ixorhea tschudiana

The effect of the CHCl₃ and MeOH extracts from aerial parts from the Northwestern Argentina endemic species Ixorhea tschudiana Fenzl. on germination of the dicot tomato and the monoct onion and on soil microbial activity was studied by calorimetric and calorespirometric experiments. The CHCl₃ extract inhibited seedling growth of tomato which increased with increasing concentrations. Seeds imbibed with 250 mg dm^?3 extract germinated 24 h later than control and those imbibed with 100 and 500 mg dm^?3 extract. This was reflected in the calculated low specific seedling growth rate (p_SGΔH_B) as determined from calorespirometric experiments. On the other hand, seedlings obtained in 500 mg dm^?3 extract showed shorter and thicker hairy roots than control with significantly higher p_SGΔH_B. Probably, the extract induces inhibition of water uptake by seedling roots. Germination was reduced 50% in onion seeds imbibed with 500 mg dm^?3 CHCl₃ extract which apparently is due to higher rate of imbibition during the first stages as determined for calorimetry. On the other hand, 83 and 250 mg kg^?1 of the MeOH and CHCl₃ extract seem to selectively inhibit the growth of certain microorganisms and to enhance the activity of soil actinomycetes. Two actinobacteria were isolated from soil treated with these concentrations of both extracts: Kocuria sp. and Kocuria rosea; this latter species is known as a keratinolytic agent and seems to degrade complex carbon compounds of the soil and those incorporated by the MeOH extract. Both Kocuria specie seem to be beneficial for the soil converting substrate into biomass and thus I. tschudiana could be used as a soil phytoremediator.     

Chemical composition and biological potential of seed oil and leaf extracts of Henophyton deserti Coss. & Durieu

Henophyton deserti was characterized in respect to its chemical composition, antioxidant potential and antimicrobial activity. Fourteen compounds were identified by LC/MS, GC/MS, and GC in leaf and seed extracts. Total flavonoids ranged between 45.66 and 181.2 mg QE g^?1 and 2.03 and 38.95 mg QE g^?1 dry weight (dw) in leaf and seed polar extracts, respectively. Rutin, Kaempferol 3-rutinoside, Diosmetin 7-O-Glucoside, and Acacetin 7-O-Glucoside flavonoids were tentatively identified in this plant. The profile of seed fatty acids revealed oleic acid (C18:1, 27%), linoleic acid (C18:2, 12%) and linolenic acid (C18:3, 17%). The highest antioxidant activities of 85.2% and 67.5% were obtained with methanol and ethyl acetate leaf extracts. All H. deserti extracts were active against at least one of the tested bacteria, leaf ethyl acetate extract showed the lowest MIC of 0.156 mg ml^?1. Only seed ethyl acetate extract showed antifungal activity with a MIC of 2.5 mg ml^?1.     

The solubility measurements of sodium dicarboxylate salts; sodium oxalate,malonate, succinate,glutarate, and adipate in water from T = (279.15 to 358.15) K

The solubility measurements of sodium dicarboxylate salts; sodium oxalate, malonate, succinate, glutarate, and adipate in water at temperatures from (278.15 to 358.15 K) were determined. The molar enthalpies of solution at T = 298.15 K were derived: Δ_solH_m (m = 2.11 mol · kg^?1) = 13.86 kJ · mol^?1 for sodium oxalate; Δ_solH_m (m = 3.99 mol · kg^?1) = 14.83 kJ · mol^?1 for sodium malonate; Δ_solH_m (m = 2.45 mol · kg^?1) = 14.83 kJ · mol^?1 for sodium succinate; Δ_solH_m (m = 4.53 mol · kg^?1) = 16.55 kJ · mol^?1 for sodium glutarate, and Δ_solH_m (m = 3.52 mol · kg^?1) = 15.70 kJ · mol^?1 for sodium adipate. The solubility value exhibits a prominent odd–even effect with respect to terms with odd number of sodium dicarboxylate carbon numbers showing much higher solubility. This odd–even effect may have implications for the relative abundance of these compounds in industrial applications and also in the atmospheric aerosols.     

Thermodynamic analysis of sorption isotherms of chromium(VI) anionic species on reed biomass

A new sorbent material for removing Cr(VI) anionic species from aqueous solutions has been investigated. Adsorption equilibrium and thermodynamics of Cr(VI) anionic species onto reed biomass were studied at different initial concentrations, sorbent concentrations, pH levels, temperatures, and ionic strength. Equilibrium isotherm was analyzed by Langmuir model. The experimental sorption data fit the model very well. The maximum sorption capacity of Cr(VI) onto reed biomass was found to be 33 mg · g^?1. It was noted that the Cr(VI) adsorption by reed biomass decreased with increase in pH. An increase in temperature resulted in a higher Cr(VI) loading per unit weight of the adsorbent. Removal of Cr(VI) by reed biomass seems to be mainly by chemisorption. The change in entropy (ΔS^°) and heat of adsorption (ΔH^°) for Cr(VI) adsorption on reed biomass were estimated as 2205 kJ · kg^?1 · K^?1 and 822 kJ · kg^?1, respectively. The values of isosteric heat of adsorption varied with the surface loading of Cr(VI).     

Apparent molar volumes and apparent molar heat capacities of aqueous tetrahydrofuran,dimethyl sulfoxide, 1,4-dioxane,and 1,2-dimethoxyethane at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

We determined apparent molar volumes V_? at 278.15 ? (T/K) ? 368.15 and apparent molar heat capacities C_p,? at 278.15 ? (T/K) ? 393.15 at p = 0.35 MPa for aqueous solutions of tetrahydrofuran at m from (0.016 to 2.5) mol · kg^?1, dimethyl sulfoxide at m from (0.02 to 3.0) mol · kg^?1, 1,4-dioxane at m from (0.015 to 2.0) mol · kg^?1, and 1,2-dimethoxyethane at m from (0.01 to 2.0) mol · kg^?1. Values of V_? were determined from densities measured with a vibrating-tube densimeter, and values of C_p,? were determined with a twin fixed-cell, differential, temperature-scanning calorimeter. Empirical functions of m and T for each compound were fitted to our V_? and C_p,? results.     

Chemometric interpretation of digital image colorimetry. Application for titanium determination in plastics

Basic color data (RGB) obtained from digital images were studied by Factorial Analysis. The results demonstrated that individual RGB data represent different contributions. On the other hand, the total intensity of colors is proposed like a fourth variable in digital colorimetry and can be interpreted as complementary information related to the conditions of image capture in digital cameras. The chemometric study evidences that the analytical information, for quantitative applications, is formed by two parts: deterministic, with valuable analytical interest, and undeterministic or unvaluable analytical information. These results were revealed after variable reduction and data compression, using Principal Component Analysis and Fourier Transform, respectively.The digital colorimetric study was applied to the reaction of Ti(IV) with hydrogen peroxide at 0.09 M sulfuric acid media. They produce a yellow–orange complex solution. And their RGB intensities could be linearly correlated with Ti(IV) concentration in the range of 2.0 to 30.0 mg l^? 1. In the best conditions, using the intensity of the blue color, a simple and fast method for Ti(IV) determination could be developed. Its detection limit was found to be (criterion 3 s) 0.6 mg l^? 1 and the rsd for 10.0 mg l^? 1 of Ti(V) was 4.8%.Calibration by artificial neural nets represents an option that improves the answer to low concentration.Applications of the colorimetric method to the analysis of Ti in representative plastics, with content in mg g^? 1 level, are presented. Its validity was assessed by ICP-AES with standard addition. Results were in satisfactory agreement. The method is fast and reduces the analysis time.     

Temperature and sodium chloride effects on the solubility of anthracene in water

The solubility of anthracene was measured in pure water and in sodium chloride aqueous solution (salt concentration, m/mol · kg^?1 = 0.1006, 0.5056, and 0.6082) at temperatures between (278 and 333) K. Solubility of anthracene in pure water agrees fairly well with values reported in earlier similar studies. Solubility of anthracene in sodium chloride aqueous solutions ranged from (6 · 10^?8 to 143 · 10^?8) mol · kg^?1. Sodium chloride had a salting-out effect on the solubility of anthracene. The salting-out coefficients did not vary significantly with temperature over the range studied. The average salting-out coefficient for anthracene was 0.256 kg · mol^?1.The standard molar Gibbs free energies, Δ_trG°, enthalpies, Δ_trH°, and entropies, Δ_trS°, for the transfer of anthracene from pure water to sodium chloride aqueous solutions were also estimated. Most of the estimated Δ_trG° values were positive [(20 to 1230) J · mol^?1]. The analysis of the thermodynamic parameters shows that the transfer of anthracene from pure water to sodium chloride aqueous solution is thermodynamically unfavorable, and that this unfavorable condition is caused by a decrease in entropy.     

Multiparametric automated system for sulfate,nitrite and nitrate monitoring in drinking water and wastewater based on sequential injection analysis

An automated monitoring system for sulfate, nitrite and nitrate based on sequential injection analysis (SIA) was developed. For nitrite determination the modified Griess-Ilosvay method was used, whereas nitrate was previously reduced to nitrite using a cadmium column followed by nitrite determination. A turbidimetric method was carried out in order to determine sulfate. The results showed that the proposed SIA monitoring system constitutes an effective approach for nitrite, nitrate and sulfate determination since it is able to determine levels required by international agencies that regulate these parameters in water. Detection limits of 0.0207 mg N L^? 1, 0.0022 mg N L^? 1 and 3 mg SO₄^2? L^? 1 were obtained for nitrate, nitrite and sulfate, respectively. The developed method offers also typical characteristics of the multicommutated systems, as portability, low reagents consumption and the subsequently minimization of waste generation. The proposed system was successfully applied to drinking water and wastewater samples and validated with a certified river water sample (ION-96.3, LGC Standards).     

Polyaniline nanotubes for impedimetric triglyceride detection

Polyaniline nanotubes (PANI-NT) based film electrophoretically deposited onto indium–tin–oxide (ITO) coated glass plate has been utilized for covalent immobilization of lipase (LIP), via glutaraldehyde (Glu), for triglyceride detection using impedimetric technique. It is shown that fatty acid molecules produced during triglyceride hydrolysis result in change in charge transfer resistance (R_CT) of PANI-NT film with varying triglyceride concentration. LIP/Glu/PANI-NT/ITO bioelectrode has linearity as 25–300 mg dL^?1, sensitivity as 2.59 × 10^?3 KΩ^?1 mg^?1 dL, response time as 20 s and regression coefficient as 0.99. A low value of apparent Michaelis–Menten constant (～0.62 mM) indicates high enzyme affinity to tributyrin. The LIP/Glu/PANI-NT/ITO bioelectrode has been utilized to estimate triglyceride in serum samples.     

Spectrophotometric and titrimetric methods for the determination of nordiazepam in pure and pharmaceutical dosage form

A spectrophotometric method and two titrimetric methods for the determination of nordiazepam via its iodobismuthate complex are described. These methods depend on the reaction of nordiazepam with potassium bismuth iodide which give an orange precipitate. Determination of nordiazepam in the precipitated complex is done iodometrically using standard potassium iodate solution or complexometrically using standard EDTA solution and xylenol orange indicator. Alternatively, the complex is dissolved in ethanol and its absorbance is measured at 323 nm. The three methods were applied for the determination of reference samples of nordiazepam in the concentration range of 1–30 mg ml^?1 (for the iodometric method) and of 5–30 mg ml^?1(for the complexometric method) and of 0.04–3.2 mg ml^?1 (for the spectrophotometric method). The proposed methods were applied for the determination of nordiazepam in madar tablets and the validity of the proposed methods was assessed by applying the standard addition technique.     

Natural radioactivity investigations in soil samples obtained from phosphate hills in the Russaifa region,Jordan

The specific activity, hazard index, and the annual effective dose of the terrestrial naturally occurring radionuclides (²³⁸U, ²³²Th, and ⁴⁰K) were determined in soil samples obtained from 20 sites of phosphate hills in the Russaifa region using an HPGe-detector of 50% relative efficiency. The resolution is 2 keV for the 1.33 MeV ⁶⁰Co. The soil activity ranged from 5.3 to 1201.1 Bq kg^?1 for ²³⁸U, 2.2 to 31.2 Bq kg^?1 for ²³²Th, and 19.4 to 288.4 Bq kg^?1 for ⁴⁰K. Annual effective dose was found in the range 0.03–0.69 mSv. The external hazard index ranged from 0.15 to 3.29 Bq kg^?1, while the global value given in UNSCEAR, 2000 publications is 1 Bq kg^?1. The average values of the radium equivalent activities were determined for all sites and they were found to be approximately 319 Bq kg^?1. This value is below the limit of 370 Bq kg^?1 recommended by . The average value of the radium equivalent activities for certain locations (sample numbers: 2, 3, 4, 9, 10, and 14) is above the same limit.     

Natural radioactivity in cultivated land in the vicinity of a phosphate fertilizer plant in Nigeria

Natural radioactivity in soil and vegetable samples in cultivated land in the vicinity of an active phosphate fertilizer plant in Kaduna, Nigeria was carried out to assess the potential radiological impact of the plant on its immediate environment. The activity counting was carried out using sodium iodide gamma spectrometry. The annual committed effective dose for two vegetables in the farmlands due to uranium (²³⁸U) and thorium (²³²Th) was assessed. The mean activity concentration of radionuclides in the soil samples ranges from 20.5±7.3 to 31.6±4.1 Bq kg^?1 for ²²⁶Ra, 19.6±1.6 to 53.2±3.7 Bq kg^?1 for ²³²Th and 203.9±6.3 to 253.6±9.5 Bq kg^?1 for ⁴⁰K. The annual intake of ²³⁸U and ²³²Th from consumption of okra were 1.9 Bq kg^?1 and 5.22 Bq kg^?1 and for tomatoes 2.66 Bq kg^?1 and 5.1 Bq kg^?1 respectively. The committed effective doses from consumption of okra and tomatoes were 0.1 μSv y^?1 and 0.12 μSv y^?1 respectively.     

High-Temperature Liquid Chromatography Inductively Coupled Plasma Atomic Emission Spectrometry hyphenation for the combined organic and inorganic analysis of foodstuffs

The coupling of a High-Temperature Liquid Chromatography system (HTLC) with an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) is reported for the first time. This hyphenation combines the separation efficiency of HTLC with the detection power of a simultaneous ICP-AES system and allows the combined determination of organic compound and metals. The effluents of the column were introduced into the spectrometer and the chromatograms for organic compounds were obtained by plotting the carbon emission signal at a characteristic wavelength versus time. As regards metals, they were determined by injecting a small sample volume between the exit of the column and the spectrometer and taking the emission intensity for each one of the elements simultaneously. Provided that in HTLC the effluents emerged at high temperatures, an aerosol was easily generated at the exit of the column. Therefore, the use of a pneumatic nebulizer as a component of a liquid sample introduction system in the ICP-AES could be avoided, thus reducing the peak dispersion and limits of detection by a factor of two. The fact that a hot liquid stream was nebulized made it necessary to use a thermostated spray chamber so as to avoid the plasma cooling as a cause of the excessive mass of solvent delivered to it. Due to the similarity in sample introduction, an Evaporative Light Scattering Detector (ELSD) was taken as a reference. Comparatively speaking, limits of detection were of the same order for both HTLC–ICP-AES and HTLC–ELSD, although the latter provided better results for some compounds (from 10 to 20 mg L^?1 and 5–10 mg L^?1, respectively). In contrast, the dynamic range for the new hyphenation was about two orders of magnitude wider. More importantly, HTLC–ICP-AES provided information about the content of both organic (glucose, sucrose, maltose and lactose at concentrations from roughly 10 to 400 mg L^?1) as well as inorganic (magnesium, calcium, sodium, zinc, potassium and boron at levels included within the 6–3000 mg L^?1) species. The new development was applied to the analysis of several food samples such as milk, cream, candy, isotonic beverage and beer. Good correlation was found between the data obtained for the two detectors used (i.e., ICP-AES and ELSD).     

Apparent molar volumes and apparent molar heat capacities of aqueous KI,HIO3, NaIO3, and KIO3 at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

We determined apparent molar volumes V_? at 298.15 ? (T/K) ? 368.15 and apparent molar heat capacities C_p,? at 298.15 ? (T/K) ? 393.15 for aqueous solutions of HIO₃ at molalities m from (0.015 to 1.0) mol · kg^?1, and of aqueous KIO₃ at molalities m from (0.01 to 0.2) mol · kg^?1 at p = 0.35 MPa. We also determined V_? at the same p and at 298.15 ? (T/K) ? 368.15 for aqueous solutions of KI at m from (0.015 to 7.5) mol · kg^?1. We determined C_p,? at the same p and at 298.15 ? (T/K) ? 393.15 for aqueous solutions of KI at m from (0.015 to 5.5) mol · kg^?1, and for aqueous solutions of NaIO₃ at m from (0.02 to 0.15) mol · kg^?1. Values of V_? were determined from densities measured with a vibrating-tube densimeter, and values of C_p,? were determined with a twin fixed-cell, differential temperature-scanning calorimeter. Empirical functions of m and T were fitted to our results for each compound. Values of K_a, Δ_rH_m, and Δ_rC_p,m for the proton ionization reaction of aqueous HIO₃ are calculated and discussed.     

Synthesis and characterization of nanoparticles of α-Bi2Mo3O12 prepared by co-precipitation method: Langmuir adsorption parameters and photocatalytic properties with rhodamine B

Nanoparticles of α-Bi₂Mo₃O₁₂ were prepared by co-precipitation method at calcination temperatures of 250, 300, 400 and 480 °C. The characterization of α-Bi₂Mo₃O₁₂ synthesized at different temperatures was carried out by X-ray diffraction (XRD), thermal analysis (TGA/DTA), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). Adsorption parameters and photocatalytical activity under visible light irradiation of α-Bi₂Mo₃O₁₂ were evaluated using the rhodamine B (rhB) dye as model. The adsorption constant (K) and maximum amount of dye adsorbed (q_max) on the surface of the samples synthesized were evaluated following the Langmuir isotherm. The sample calcinated at 250 °C showed the maximum adsorption percentage of dye, which ranged between 20 and 46% for initial concentrations of rhB from 5 to 15 mg L^?1, with a K = 6.96 × 10⁵ L mol^?1 and q_max = 2.73 mg g^?1. All samples were able to induce the oxidative photodegradation of rhB, however, the bleaching of dye solution was reached more quickly for the sample calcinated at 250 °C.     

Trace Cd,Co, and Pb elements distribution during Sulcis coal pyrolysis: GFAAS determination with slurry sampling technique

A simple and fast method based on graphite furnace atomic absorption spectrometry (GF AAS) and slurry sampling technique (SlS) was developed to determine trace Cd, Co and Pb in high-sulphur coal (Sulcis, Italy) and coal chars derived at 600, 750 and 950 °C under N₂ atmosphere for developing a clean coal for electricity production. The proposed method was then coupled to a four-step sequential chemical extraction method for assessment of metals distribution in coaled samples. The slurries were prepared by varying sample mass (1–50 mg), volume (1–3 mL) and kind of dispersing medium (1% v/v Triton X-100 and 2 N HNO₃), and sonication time (5–30 min). Pyrolysis/atomization temperatures as well carrier gas flow rate were optimised. Pd(NO₃)₂ and NH₄H₂PO₄ were employed to stabilize Cd and Pb, respectively, in the pyrolysis stage of furnace program. The use of HNO₃ as dispersing agent was found to be effective in lowering the high level of background absorption on the Cd analytical signal produced by raw coal matrix. Conversely, coal charred samples did not show significantly level of background interferences, so that Triton X-100 dispersing agent could be used for all analytes. Calibration curve against acid-matched standards was allowed for Cd, whereas the standard addition calibration was used for Co and Pb owing to chemical matrix interferences. The precision, expressed as relative standard deviation (% RSD, n = 5), was better than 5% for Cd, Co, and Pb at 1, 10, and 15 μg L^? 1 levels, respectively. The accuracy of the analytical method was checked by analyzing a BCR No. 182 steam coal certificated reference material and the results were in good agreement with certificated and informed values. The solid detection limits (3σ_blank) were as low as 0.001 Cd, 0.01 Co, and 0.01 Pb mg kg^? 1, using 30 mg sample mass and slurry concentration of 30 m v^? 1 for Cd, and 50 mg sample mass and 50 m v^? 1 slurry concentration for Co and Pb. The content of elements in Sulcis coal was found to be 0.33 Cd, 4.0 Co, and 3.8 Pb mg kg^? 1 and mostly associated to sulphates and di-sulphides as indicated by the leaching test. Under pyrolysis conditions Cd significantly volatilised (about 64%) at temperature higher than 600 °C, whereas residue chars at 950 °C are enriched in Co and Pb up to 20%. The proposed method is suitable for routine metals monitoring in coaled samples.     

Analysis of pesticide residues by fast gas chromatography in combination with negative chemical ionization mass spectrometry

A combination of fast GC with narrow-bore column and bench top quadrupole mass spectrometer (MS) detector in negative chemical ionization (NCI) mode (with methane as reagent gas) is set up and utilized for the ultratrace analysis of 25 selected pesticides. The observed pesticides, belonging to the endocrine disrupting chemicals (EDCs), were from different chemical classes. A comparative study with electron impact (EI) ionization was also carried out (both techniques in selected ion monitoring (SIM) mode). The programmed temperature vaporizer (PTV) injector in solvent vent mode and narrow-bore column (15 m × 0.15 mm I.D. × 0.15 μm film of 5% diphenyl 95% dimethylsiloxane stationary phase) were used for effective and fast separation. Heptachlor (HPT) as internal standard (I.S.) was applied for the comparison of results obtained from absolute and normalized peak areas. Non-fatty food matrices were investigated. Fruit (apple – matrix-matched standards; orange, strawberry, plum – real samples) and vegetable (lettuce – real sample) extracts were prepared by a quick and effective QuEChERS sample preparation technique. Very good results were obtained for the characterization of fast GC–NCI-MS method analysing EDCs pesticides. Analyte response was linear from 0.01 to 150 μg kg^?1 with the R² values in the range from 0.9936 to 1.0000 (calculated from absolute peak areas) and from 0.9956 to 1.0000 (calculated from peak areas normalized to HPT). Instrument limits of detection (LODs) and quantification (LOQs) were found at pg mL^?1 level and for the majority of analytes were up to three orders of magnitude lower for NCI compared to EI mode. In both ionization modes, repeatability of measurements expressed as relative standard deviation (RSDs) was less than 10% which is in very good agreement with the criterion of European Union.     

Nano TiO2-based preconcentration for the speciation analysis of inorganic selenium by using ion chromatography with conductivity detection

A simple, sensitive, and cost-effective analytical method was developed for the speciation analysis of inorganic selenium by combining a nano-TiO₂ preconcentration with an ion chromatography-conductivity detection (IC-CD) system. The experimental conditions for the simultaneous adsorption and desorption of Se(IV) and Se(VI) were carefully investigated. Under the established optimum condition, the Se(IV) and Se(VI) ions could been simultaneously adsorbed onto the nano-TiO₂ surface at pH 4.0, and then effectively desorbed by 0.1 M sodium hydroxide eluent. The adsorption process was fast and reached adsorption equilibrium within 10 min. The nano-TiO₂ also exhibited high adsorption capacity with 11.3 mg g^? 1 for Se(IV) and 8.34 mg g^? 1 for Se(VI). The enrichment factors for Se(IV) and Se(VI) were calculated to be 39 and 30, respectively, with sample volume of 50 mL. The detection limits (3σ) were 0.8 μg L^? 1 for Se(IV) and 0.4 μg L^? 1 for Se(VI), which were sensitive enough for the routine analysis of water and drink samples. The relative standard deviation was calculated to be < 4% (n = 6) for detection of 30 μg L^? 1 Se(IV) and 30 μg L^? 1 Se(VI). The results of the present work confirmed that our developed nano-TiO₂-IC-CD method could be applied for the detection of inorganic selenium species in tap water and drink samples with good recoveries in the range of 82%–108%.     

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N₂ adsorption–desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L^?1 HCl–3% thiourea solution at a flow rate of 2.0 mL min^?1. The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g^?1 for Pd(II).The detection limit (3σ) of the method was 0.29 ng mL^?1, and the relative standard deviation (RSD) was 3.1% (n = 11). The method was validated using certified reference material, and has been applied for the determination of trace Pd(II) in actual samples with satisfactory results.