A simple and compact system was developed for the on-site analysis of lead in environmental water samples. The system consisted of a custom-made blue diode as a light source, a liquid core waveguide (LCW) as spectrophotometric cell and a compact UV-visible spectrometer. It weighed within 1.5 kg in total. Lead was detected using a spectrophotometric indicator reagent (TPPS: 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid, disulfuric acid, tetrahydrate) after masking interfering ions by coprecipitation with magnesium hydroxide. With an increase in the length of the LCW cell, the detection limit of lead was almost linearly enhanced, and the linear calibration range was shifted to a lower concentration range. The detection limit of lead by using 100 cm of a LCW cell was 2 nmol dm⁻³. The observed value (9.6 ± 0.4 μg dm⁻³) of lead in a river-water reference material (JSAC 0302-3) with this system was in good agreement with the certified value (9.9 ± 0.2 μg dm⁻³).

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The host-guest interaction in high-silica ferrierite (FER) with different structure-directing agents (SDA), pyridine and piperidine, was analyzed by solid-state ²⁹Si NMR relaxation experiments and molecular-orbital calculations. Qualitative and quantitative knowledge of the SDA structure obtained by these methods provides significant insight for understanding the functions in a template, and the stabilizing role of the SDA. Relaxation experiments show a larger magnetic dipolar interaction between the silicon and hydrogen atoms in piperidine as compared to that in pyridine, and the results correlate with the bonding property in terms of the distance between the zeolite framework and the SDA. The ¹H MAS NMR spectrum shows that the pyridine molecules mainly act as pore fillers in the pyridine-FER. In contrast, it was presumed that piperidine, adjacent to the aluminosilicate framework and framework defects, acted as a counter cation to balance the charge in the piperidine-FER. H⁺-FER synthesized with piperidine shows a lower hydrothermal stability as compared to that synthesized with pyridine. The hydrothermal stability of H⁺-FER is discussed by considering the contributions of framework defects and the different properties pertaining to the bonding between the zeolite framework and the SDA.

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A nitrate ion-selective electrode (NO_3⁻-ISE) has been developed based on tetradodecylammonium bromide as an anion exchanger and 2-nitrophenyl octyl ether as a plasticizer. The NO_3⁻-ISE shows an almost Nernstian response to nitrate ion over a concentration range between 1.0 × 10⁻⁶ and 1.0 × 10⁻¹ M, with an anionic slope of −57.7 ± 0.7 mV/decade. The selectivity coefficients of the NO_3⁻-ISE for nitrate ion against chloride and sulfate (log k^pot_NO3⁻Cl⁻ = −2.42 and log k^pot_{NO3⁻SO4²⁻} = −4.33) were obtained. A microfluidic polymer chip was fabricated using polystyrene plates and stainless-steel wires as a template for the channel. The microfluidic polymer chip is composed of a mixing chip and a NO_3⁻-ISE detector chip. The microfluidic polymer chip, integrated with a NO_3⁻-ISE detector consisting of the NO_3⁻-ISE and a Na⁺-ISE as a reference electrode, showed an almost Nernstian response to nitrate ion over a concentration range between 1.0 × 10⁻⁵ and 1.0 × 10⁻¹ M, with an anionic slope of −54.3 ± 1.3 mV/decade. The microfluidic polymer chip was then applied to the determination of nitrate ion in environmental water samples, such as a tap water, a well-water sample and water for agricultural use.

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The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) at the surface of a multiwall carbon nanotube-paste electrode (MCNTPE) modified with incorporate chloromercuriferrocene (CMF) was investigated. The voltammetric studies using the MCNTPE/CMF electrode show two well-resolved anodic peaks for AA and UA with a potential difference of 430 mV, revealing the possibility of the simultaneous electrochemical detection of these compounds. The optimum analytical conditions were sought. Linear calibration plots were obtained over the range of 8.0 × 10⁻⁶ − 6.9 × 10⁻⁴ M and 2.4 × 10⁻⁶ − 6.9 × 10⁻⁴ M with detection limits (3σ) of 2.6 × 10⁻⁶ and 7.9 × 10⁻⁷ M for AA and UA, respectively. The electrode with the best conditions is applied for selective determination of AA and UA in complex biological and clinical matrices.

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Prussian blue (PB) was deposited on multi-walled carbon nanotubes (MWCNT) in an aqueous solution. Multi-layer composites of the MWCNT-PB hybride material were obtained by layer-by-layer assembly with poly(diallyldimethylammonium chloride) (PDDA). The resulting {PDDA/MWCNT-PB}_n multilayer films immoblized on glassy carbon electrodes showed sensitive detection for the reduction of hydrogen peroxide. A sensor based on the {PDDA/MWCNT-PB}_n multilayer structure was fabricated and showed excellent sensitivity to the electrochemical reduction of hydrogen peroxide. Its response sensitivity increased with the number of the multilayers. A high response sensitivity of 0.83 mA M⁻¹ cm⁻² was obtained for a seven-layer sensor. This redox active multilayer structure offers potential applications in the development of high performance biosensors and biofuel cells.

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Two ion-selective sensors of the plastic membrane type were prepared for the determination of oxybutynin hydrochloride (OxCl). They depend on the incorporation of the ion-associates with phosphotungestic acid or phosphomolybdic acid in a PVC matrix. A comparative study is made between their performance characteristics in batch and FIA conditions. The sensors have nearly the same usable concentration, temperature and pH range. They have a wide range of selectivity and can be applied for the determination of the relevant drug with nearly the same precision and accuracy in vitro. Dissolution testing was applied using the sensors; this offers a simple, rapid, cheap way out of sophisticated and high cost instruments used in the pharmacopeial method using HPLC. The investigated drug was determined in its pure and pharmaceutical preparations. The results were accurate and precise, as indicated by the recovery values and coefficients of variation.

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A light-scattering sensor that incorporated zinc oxide (ZnO) nanoparticles was developed and characterized in this study. Evenly distributed nanostructured ZnO materials were formed on the sensing elements through the calcination of zinc acetate-treated sensing elements in a high-temperature oven. There was a large change in the scattering properties of the nanostructured ZnO materials after adsorption of the target compounds; this behavior was exploited for quantitative purposes. To investigate the detection of volatile compounds using this method, both static and flow cell-type devices were constructed. To determine the most suitable nanostructured ZnO material for the light scattering sensors, several factors that influenced their morphologies, including the calcination temperature, calcination time, and the amount of ZnO colloidal solution for calcination, were examined. Fiber-like ZnO structures were produced at temperatures below 400°C. Above 400°C, particles having round shapes were observed; the higher the calcination temperature, the larger the particle sizes. Based on an examination of the signals from several volatile organic compounds, the prepared ZnO sensor was selective for the detection of alcohols, and the observed signals followed the surface-adsorption mechanism. The prepared sensor is fast in response, and the detection time can be shorter than 2 min. For quantitative purposes, the linear range was limited to low concentrations of alcohols, i.e., up to ca. 200 ppm.

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The effective ion-exchange capacities of ion-exchange materials were determined by measuring the change in the equilibrium conductivity of a column packed with analyte. The developed instrumental method can provide effective ion-exchange capacities for both cation and anion exchangers with simple operations. The cation-exchange capacity of a weak-acid cation-exchange resin (TSKgel SuperIC-Cation column) depended on the conditioning pH and the molar concentration of the conditioning agent. Plots of effective cation-exchange capacities over the conditioning pH exhibited three inflection points, suggesting the presence of two carboxy groups and one phenolic OH group in the resin, probably due to the inherent base polymer. This method was applied to several commercial analytical columns for ion chromatography, and could provide scientifically useful results for characterizing the resin properties.

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Hydrophobic task specific ionic liquid (TSIL) functionalized 2-mercaptobenzothiazole (MBT) was synthesized and characterized by NMR and HRMS. The capability of TSIL-MBT for the selective separation and preconcentration of Cd²⁺, which was determined by flame atomic absorption spectrometry (FAAS) from water and food samples, was investigated. The TSIL-MBT with high selectivity for the extraction of Cd²⁺ was discussed by comparing with a traditional extractant, such as ammonium pyrrolidine dithiocarbamate (APDC) and diethydithiocarbamate (DDTC), and the recoveries of the extraction Cd²⁺ by TSIL-MBT were much better than APDC and DDTC. The proposed method was evaluated by analyzing two certified reference materials. The Cd²⁺ concentration, determined by the developed methodology, was in good agreement with certified values.

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An analytical method for the simultaneous determination of 12 pyrethroids in soil samples was developed using gas chromatography tandem quadrupole mass spectrometry. Pyrethroids were extracted by pressurized liquid extraction with optimized parameters such as solvent, temperature and extraction time. Then the graphitized carbon black cartridges were used for further purification. The method showed good linearity (R₂ > 0.9931) and good repeatability (RSD ≤12.6%) for all compounds, with the method detection limits ranging from 0.26 ng g⁻¹ for transfluthrin to 0.87 ng g⁻¹ for prallethrin. The recoveries of all compounds were 75 – 120%.

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A stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been developed for the determination of terbutaline sulfate (TBS) as a bulk drug and in pharmaceutical formulations (submicronized dry powder inhalers). The separation was achieved on TLC aluminum plates precoated with silica gel 60F-254 using chloroform-methanol (9.0:1.0 v/v) as mobile phase. The densitometric analysis was carried out at 366 nm wavelength. Compact spots appeared at R_f = 0.34 ± 0.02. For the proposed procedure, linearity (r² = 0.9956 ± 0.0015), limit of quantification (28.35 ng spot⁻¹), limit of detection (9.41 ng spot⁻¹), recovery (97.06 – 99.56%), and precision (≤1.86) were found to be satisfactory. TBS was subjected to acid and alkali hydrolyses, oxidation and photodegradation treatments. The degraded products were well separated from the pure drug. Statistical analysis reveals that the developed method has potential for routine analysis and stability testing of terbutaline sulfate in pharmaceutical drug delivery systems.

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Two new silica-gel phases were produced directly via the chemical interaction of 3-chloropropyltrimethoxysilane modified silica gel with 8-aminoquioline, phase I and 2-aminopyridine, phase II under reflux conditions. The selectivity properties exhibited by the phases under investigation for the uptake of Ca(II), Mg(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) were determined at different pH values and shaking times under static conditions. The immobilization process and binding of metal ions to the phases were proved via infrared spectra. The phases showed high performance towards Ca(II) extraction at pH 10.00. The equilibrium data were better fitted with a Langmuir model (r² = 0.985). The adsorption kinetics data were best fitted with the pseudo-second-order type. Good validation was obtained on applications of the two phases for the separation and determination of Ca(II) in natural water and pharmaceutical samples with no matrix interferences at pH 10.00 under dynamic conditions prior to determination by AAS.

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A new solid phase, nanoparticles of alumina functionalized with pyridine groups, was synthesized and used for extraction and preconcentartion of palladium(II) ions from some water samples. The effects of various parameters such as pH, flow rates of sample and eluent, type and volume and concentration of eluent, sample volume, amount of adsorbent and cationic interferences have been studied and optimum conditions for best recovery have been obtained. The limit of detection of the method based on three times the standard deviation of the blank (3S_b) was obtained: 0.6 ng mL⁻¹. The preconcentration factor and the adsorption capacity were also calculated to be 60 and 37 mg g⁻¹, respectively. The recovery of extraction of palladium ions on nano-alumina particles was determined to be 98.5%. The utility of the modified nano-alumina was tested in some samples and showed an RSD value of <0.8%, reflecting its accuracy and reproducibility.

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Five simple, sensitive, accurate and rapid visible spectrophotometric methods (A, B, C, D and E) have been developed for estimating Amisulpride in pharmaceutical preparations. These are based on the diazotization of Amisulpride with sodium nitrite and hydrochloric acid, followed by coupling with N-(1-naphthyl)ethylenediamine dihydrochloride (Method A), diphenylamine (Method B), β-naphthol in an alkaline medium (Method C), resorcinol in an alkaline medium (Method D) and chromotropic acid in an alkaline medium (Method E) to form a colored chromogen. The absorption maxima, λ_max, are at 523 nm for Method A, 382 and 490 nm for Method B, 527 nm for Method C, 521 nm for Method D and 486 nm for Method E. Beer’s law was obeyed in the concentration range of 2.5 – 12.5 μg mL⁻¹ in Method A, 5 – 25 and 10 – 50 μg mL⁻¹ in Method B, 4 – 20 μg mL⁻¹ in Method C, 2.5 – 12.5 μg mL⁻¹ in Method D and 5 – 15 μg mL⁻¹ in Method E. The results obtained for the proposed methods are in good agreement with labeled amounts, when marketed pharmaceutical preparations were analyzed.

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A novel simple kinetic spectrophotometric method for the determination of N-acetyl-L-cysteine (NAC) has been developed and validated. The proposed method is based on a coupled redox-complexation reaction, the first step of which is the reduction of Fe³⁺ by NAC; the second one includes the complexation of Fe²⁺, resulting from the preceding redox reaction, with 2,4,6-trypyridyl-s-triazine (TPTZ). The stable Fe(TPTZ)₂²⁺ complex exhibits an absorption maximum at λ = 593 nm.
The initial rate and fixed-time (at 5 min) methods were utilized for constructing calibration graphs. The graphs were linear in concentration ranges from 4.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹ for the initial rate method and 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹ for the fixed-time method, with detection limits of 1.0 × 10⁻⁶ and 1.7 × 10⁻⁷ mol L⁻¹, respectively. The proposed methods were successfully applied for the determination of NAC in its commercial pharmaceutical formulations.

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A simple, selective and sensitive kinetic method has been developed for the determination of trace amounts of iodide. This method is based on a catalytic effect of iodide on the reaction between Janus Green and bromate in acidic media. Trace amounts of iodide increase the rate of a reaction that is monitored spectrophotometrically at 618 nm by a fixed-time method at 30 s. Effective parameters on the reaction rate, such as the concentration of reactants, temperature and reaction time, were investigated and the optimum conditions were obtained (6.0 × 10⁻² mol L⁻¹ of sulfuric acid, 2.50 × 10⁻⁵ mol L⁻¹ of Janus Green, 1.75 × 10⁻² mol L⁻¹ of bromate, 30°C and 180 s). The calibration curve was linear between 0.5 – 190.0 μg L⁻¹ of iodide, and the relative standard deviations (n = 5) for 10.0 and 100.0 μg L⁻¹ of iodide were 1.2 and 1.8%, respectively. The limit of detection was 0.12 μg L⁻¹ of iodide concentration. The effects of various substances upon the reaction rate were determined for assigning the selectivity of the method. The proposed method was successfully applied to the determination of iodide in food samples. The new developed method was found to have fairly good selectivity, sensitivity, simplicity and rapidity.

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We have developed a simple, labor-saving, inexpensive, and rapid single nucleotide polymorphism (SNP) genotyping method that works directly on whole human blood. This single-tube genotyping method was used to successfully and reliably genotype ADH1B and ALDH2 polymorphisms without DNA isolation using a 1.2-mm disc of dried blood and the KOD FX PCR enzyme kit. SNP genotyping was performed by a polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) method. In addition to the labor and expense advantages, the possibility of sample contamination was considerably decreased, since the DNA extraction step was eliminated. In the post-genome era, a simple and inexpensive method for diagnostic analysis is in high demand, and this method will be very useful for genetic diagnoses in biological and medical laboratories.

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A tube radial distribution chromatography (TRDC) system was previously developed using an open capillary tube and an aqueous–organic solvent (water–acetonitrile–ethyl acetate) mixture as a carrier solution. In this study, we introduced double capillary tubes having different inner diameters to the system. The tubes were fused-silica capillary tubes with 100 and 250 μm i.d.; the smaller tube was inserted into the larger one through a T-type joint. Water–acetonitrile mixture (volume ratio 3:1) and acetonitrile–ethyl acetate mixture (volume ratio 4:1) solutions were delivered into the large tube from the inside through the small tube and from the outside through the joint, respectively, and then mixed through the large tube to provide a water–acetonitrile–ethyl acetate carrier solution. The carrier solution was further fed into the large tube and then to an absorption detector. By changing the flow rates of the mixture solutions in both tubes, we could control the component ratio of carrier solvents in the carrier solution, yielding either organic solvent-rich, water–acetonitrile–ethyl acetate (volume ratio 3:33:8) or water-rich, water–acetonitrile–ethyl acetate (volume ratio 24:12:1). A model analyte-mixture solution of 1-naphthol and 2,6-naphthalenedisulfonic acid was eluted in this order with the organic solvent-rich carrier solution and eluted in the reverse order with the water-rich carrier solution. We discussed the chromatographic data together with the analytical conditions from the viewpoint of the tube radial distribution of the carrier solvents.

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The retention behavior of inorganic anions on a pyridine stationary phase commercially available for hydrophilic interaction chromatography was examined in ion chromatography. Inorganic anions were retained on a protonated pyridine stationary phase under acidic eluent conditions (pH 3.1 – 3.3) in the ion-exchange mode. The logarithm of the retention factor of analytes was linear to the logarithm of the eluent concentration, and the slopes of the plots were −0.55 to −0.64, except for nitrite (−0.39). The smaller slope for nitrite was due to the fact that nitrous acid is weak (pK_a 3.25 at 25°C) and was partially ionized under the operating conditions. The elution order of the examined anions was the same as that observed in common ion chromatography. The present system was applied to the determination of UV-absorbing anions contained in saliva.

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Solid phase extraction using a mini cartridge packed with 22 mg of chelate resin immobilizing carboxymethylated pentaethylenehexamine was successfully utilized for separation/preconcentration of cadmium in water samples prior to liquid electrode plasma atomic emission spectrometric (LEP-AES) determination. The combined method with the extraction and LEP-AES was applicable to the determination of cadmium in the certified reference materials (EU-L-1 wastewater and ES-L-1 groundwater); the detection limit was 0.20 μg in 200 mL of sample solution (500-fold preconcentration).

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In this study, nitrobenzene in water and ice samples collected from the Songhua River after the explosion of a petrochemical plant was determined by GC/MS. The results showed that nitrobenzene was detected in most of the water and ice samples taken from the Songhua River. However, the concentration of nitrobenzene in all water and ice samples was from 0 to 0.65 μg L⁻¹; this range was sufficiently lower than the permissible level (0.017 mg L⁻¹) for drinking water in China. The enclosing behavior of nitrobenzene in ice was also investigated. The amount of nitrobenzene enclosed in ice was lower than that reported by UNEP.

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