A Robust Method for the Determination of Cr(VI) and Cr(III) in Industrial Wastewaters by Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry Combined with a Chelating Pretreatment with 2,6-Pyridinedicarboxylic Acid.

We have developed a method for the determination of Cr(VI) and Cr(III) in industrial wastewater by liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) combined with a chelating pretreatment with 2,6-pyridinedicarboxylic acid (PDCA). The PDCA unified the chemical forms of the Cr(III) species in water samples by the formation of a stable Cr(III)-PDCA complex, which was then separated by a LC column. The chromatographic mobile phase at neutral pH and the column of a mixed-bed of anion and cation exchangers successfully separated not only the chromium species without any redox conversion, but also chloride, which interfered with ICP-MS detection.

A Simple and Robust Method for Determination of Alkylmercury in Seawater and Industrial Wastewater by Phenylation Pretreatment Combined with GC-MS.

For determination of methylmercury (MeHg) and ethylmercury (EtHg) in seawater and industrial wastewater, a simple and robust analytical method was developed based on phenylation and solvent extraction followed by GC-MS measurement. Alkylmercury compounds were directly phenylated with sodium tetraphenylborate in water and extracted into toluene. The method detection limits obtained for MeHg and EtHg in pure water were 53.

Relation of dietary inorganic arsenic exposure and urinary inorganic arsenic metabolites excretion in Japanese subjects.

Inorganic arsenic (InAs) is a ubiquitous metalloid that has been shown to exert multiple adverse health outcomes. Urinary InAs and its metabolite concentration has been used as a biomarker of arsenic (As) exposure in some epidemiological studies, however, quantitative relationship between daily InAs exposure and urinary InAs metabolites concentration has not been well characterized. We collected a set of 24-h duplicated diet and spot urine sample of the next morning of diet sampling from 20 male and 19 female subjects in Japan from August 2011 to October 2012.

Circular Permutation Probes for Illuminating Phosphorylation of Estrogen Receptor.

The present protocol demonstrates a new strategy for imaging ligand-triggered protein phosphorylation using circularly permutated luciferases (cpLuc): (1) a luciferase is first fragmented into two segments for creating new N- and C-terminal ends in the hydrophilic region, (2) the original N- and C-terminal ends are circularly permutated and linked via a GS linker, whereas the new ends made by fragmentation are correspondingly linked with two proteins of interest. When the new ends of the cpLuc are linked with the ligand-binding domain of estrogen receptor (ER LBD) and Src homology two domain of Src (SH2), the estrogen can trigger phosphorylation of the ER LBD and consequent intramolecular ER LBD-SH2 binding. This interaction triggers an approximation of the adjacent fragments of split-cpLuc recovering the enzyme activity.

Single-Chain Probes for Illuminating Androgenicity of Chemicals.

The present protocol introduces a single-chain probe carrying a functional peptide in the N-terminal domain of the androgen receptor (AR NTD) for illuminating androgenicity of ligands. In the single-chain probe, a functional peptide in the AR NTD was genetically fused to the ligand-binding domain of AR (AR LBD) via a flexible linker, and then sandwiched between the N- and C-terminal fragments of split-firefly luciferase (FLuc) dissected at D415. This single-chain probe exerts (1) a high signal-to-background ratio and (2) sensitive discrimination between agonists and antagonists, where the dimerization of AR LBD is not involved.

An Evaluation of Sensor Performance for Harmful Compounds by Using Photo-Induced Electron Transfer from Photosynthetic Membranes to Electrodes.

Rapid, simple, and low-cost screening procedures are necessary for the detection of harmful compounds in the effluent that flows out of point sources such as industrial outfall. The present study investigated the effects on a novel sensor of harmful compounds such as KCN, phenol, and herbicides such as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine), and 2-N-tert-butyl-4-N-ethyl-6-methylsulfanyl-1,3,5-triazine-2,4-diamine (terbutryn). The sensor employed an electrode system that incorporated the photocurrent of intra-cytoplasmic membranes (so-called chromatophores) prepared from photosynthetic bacteria and linked using carbon paste electrodes.

Long-term retention of pristine multi-walled carbon nanotubes in rat lungs after intratracheal instillation.

As a result of the growing potential industrial and medical applications of multi-walled carbon nanotubes (MWCNTs), people working in or residing near facilities that manufacture them may be exposed to airborne MWCNTs in the future. Because of concerns regarding their toxicity, quantitative data on the long-term clearance of pristine MWCNTs from the lungs are required. We administered pristine MWCNTs well dispersed in 0.

Creation of artificial luciferases for bioassays.

The present study demonstrates the creation of artificial luciferases (ALuc) for bioassays, inspired by a sequence alignment of copepod luciferases. Extraction of the consensus amino acids from the alignment enabled us to generate a series of ALucs with unique optical properties and sequential identities that are clearly different from those of any existing copepod luciferase. For example, some ALucs exhibited heat stability, dramatically prolonged optical intensities, broad full width at half-maximum, and strong optical intensities.

Inorganic arsenic in the Japanese diet: daily intake and source.

The concentrations of arsenic (As) species in 19 food composites prepared from 159 food items purchased in Shizuoka city, Japan, were determined (1) to estimate total daily intake of inorganic As (InAs) and some organic As species and (2) to determine food contributing to total daily InAs intake. As analysis included extraction of As species with a synthetic gastric juice (0.07 mol/L HCl + 0.

Online TOC analysis based on reagent-free oxidation of dissolved organic matter using a mercury lamp-pass-through photoreactor.

The reagent-free mineralization of dissolved organic matter (DOM) in river water was achieved within 1 min using a lamp-pass-through photoreactor containing a narrow reaction tube (2 mm i.d.) passing through a 40 W mercury lamp.

Effect of Mg or Ag addition on the evaporation field of Al.

It is known that the distribution of the charge-states as well as the evaporation field shift to higher values as the specimen temperature is decreased at a constant rate of evaporation. This study has explored the effect of Mg or Ag addition on the evaporation field of Al in terms of the charge state distribution of the field evaporated Al ions. The fractional abundance of Al(2+) ions with respect to the total Al ions in Al-Mg alloy is lower than that in pure Al, whereas it shows higher level in the Al-Ag alloy at lower temperatures.

Influence of speciation on the response from selenium to UV-photochemical vapor generation.

By exposure to appropriate UV intensities, rapid and quantitative oxidation/reduction of inorganic selenite, selenate and several organoselenium compounds representative of those of biochemical/metabolic interest, including selenomethionine, selenobetaine, L-selenocystine, selenomethylselenocysteine, γ-glutamyl-seleno-methylselenocysteine and selenocystamine, is achieved. In the presence of acetic acid, quantitative conversion to volatile SeH(2) and SeCO occurs using a flow-through system comprising a highly efficient 40 W UV lamp for oxidation in tandem with a lower power 8 W UV photocatalytic reactor utilizing a thin-film coating of titania. The volatile reduced species are detected by atomic absorption spectrometry using a heated quartz tube atomizer.

Daily intake of inorganic arsenic and some organic arsenic species of Japanese subjects.

The daily dietary intake of inorganic arsenic (InAs) and some of organic arsenic (OrAs) species of Japanese subjects were estimated by determining the concentrations of As species in two different sets of total diet sample: duplicated diet samples collected from 25 subjects in Japan and a certified reference material with total diet matrix (NIES CRM No. 27 Typical Japanese Diet, TJD). The concentration of InAs and OrAs in diet samples were determined by LC-ICP-MS using a photo-oxidation and hydride generation system.

Superluminescent variants of marine luciferases for bioassays.

In this study, a rational synthesis of superluminescent variants from marine luciferases with prolonged bioluminescence has been demonstrated. A putative active site of a model marine luciferase, Gaussia princeps Luciferase (GLuc), was assigned and modified by a site-directed mutagenesis. The potent variants were found to generate up to 10 times stronger bioluminescence, emitting red shifts of up to 33 nm with natural coelenterazine than native GLuc, rendering an efficient optical signature in bioassays.

Pulmonary toxicity of well-dispersed multi-wall carbon nanotubes following inhalation and intratracheal instillation.

Multi-walled carbon nanotubes (MWCNTs), dispersed in suspensions consisting mainly of individual tubes, were used for intratracheal instillation and inhalation studies. Rats intratracheally received a dose of 0.2 mg, or 1 mg of MWCNTs and were sacrificed from 3 days to 6 months.

Exposure to polycyclic aromatic hydrocarbons, arsenic and environmental tobacco smoke, nutrient intake, and oxidative stress in Japanese preschool children.

The association between oxidative stress and exposure to environmental chemicals was assessed in a group of Japanese preschool children. The concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), 1-hydroxypyrene (1-OHP), inorganic arsenic (iAs) and monomethylarsonic acid (MMA), and cotinine in spot urine samples, collected from 134 children (3-6 yrs) from a kindergarten in Kanagawa, Japan, were measured as biomarkers of oxidative stress or exposure to environmental chemicals. For 76 subjects of the 134, intakes of anti-oxidant nutrients (vitamins A, C, and E, manganese, copper, zinc and selenium (Se)) were estimated from a food consumption survey carried out 2-4 weeks after urine sampling and by urine analysis (Se).

A determination method of pristine multiwall carbon nanotubes in rat lungs after intratracheal instillation exposure by combustive oxidation-nondispersive infrared analysis.

This paper describes a method for determination of multiwall carbon nanotubes (MWCNTs) in rat lungs after intratracheal instillation exposure. The MWCNTs were quantitatively decomposed to CO(2) by combustive oxidation and were then determined by non-dispersive infrared analysis. Samples were pretreated by acid digestion, muffle ashing and in situ preheating to remove interferences due to coexisting biological carbon from the lung tissue sample, while preserving the MWCNTs as in its their original form.

Clearance kinetics of fullerene C₆₀ nanoparticles from rat lungs after intratracheal C₆₀ instillation and inhalation C₆₀ exposure.

Fullerene (carbon sixty [C(60)]) has potential industrial and medical applications. In the future, people working in or residing near manufacturing facilities may be exposed to C(60). Therefore, quantitative data on long-term C(60) clearance from the lungs are required.

Electrochemical gene sensor arrays prepared using non-contact nanoliter array spotting of gene probes.

A capillary-based pitch-variable array spotter, designed to dispense solutions in nanoliter volumes with high precision and density, was used to immobilize gene probes on a microelectrode array chip. Small volumes of the probe solutions were dispensed onto the microelectrodes, without any physical contact between the capillary ends and the electrode surfaces, to fabricate an electrochemical gene sensor array chip. The fabricated gene sensor array chip showed sequence-selective responses, expressed on a pseudocolor scale, to a target DNA sample.

Determination of the androgenicity of ligands using a single-chain probe carrying androgen receptor N-terminal peptides.

The present study demonstrates a single-molecular bioluminescent probe carrying functional peptides in the N-terminal domain of the androgen receptor (AR NTD) with an improved sensorial property to androgens. The N-terminal peptides in AR were genetically fused to the ligand binding domain of AR (AR LBD) with a flexible linker, and then sandwiched between the N- and C-terminal fragments of split-firefly luciferase (FLuc) dissected at D415. We found that the proline-rich region in AR NTD efficiently interacts with AR LBD and exerts (i) an enhanced signal-to-background ratio and (ii) discrimination between agonists and antagonists with (iii) a 100-times improved sensitivity to androgens, upon comparison with previous references.

Molecular tension-indexed bioluminescent probe for determining protein-protein interactions.

This study demonstrates a unique, nontranscriptional assay system based on molecular tension of a luciferase artificially appended by protein-protein binding. We hypothesized that an artificially appended molecular tension to a full-length luciferase may diversify the enzymatic activity through a modification of the active site. For the basic probe design, a full-length luciferase was sandwiched between two component proteins of interest.

Phylogenetic analysis of Rhodococcus erythropolis based on the variation of ribosomal proteins as observed by matrix-assisted laser desorption ionization-mass spectrometry without using genome information.

Rhodococcus erythropolis strains characterized as antibiotic producers can be classified into three groups according to their antibiotic spectrum and growth compatibility. Due to their high genotypic similarity, the taxonomic relationship of these strains has not been elucidated. In this study, ribosomal protein profiling using matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) was employed to classify twenty-one strains of R.

Genetically encoded bioluminescent indicators for stress hormones.

This study demonstrates bioluminescent indicators for determining stress hormones in mammalian cells. A genetically encoded bioluminescent probe for stress sensing was first synthesized with a LXXLL motif-linked ligand binding domain of the glucocorticoid receptor (GR LBD), which was then sandwiched between the fragments of Gaussia luciferase (GLuc). This prototype of the bioluminescent indicators was carefully modified with a circular permutation (CP) and/or a corepressor motif.

Surface cleaning of germanium nanodot ionization substrate for surface-assisted laser desorption/ionization mass spectrometry.

In surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS), a chemical background signal, arising from organic contaminants such as plasticizers, is frequently observed mainly under m/z ca. 600, which impairs the advantages of the matrix-free approach. Silver salts, which are used for the cationization of aromatic compounds, are also difficult to remove completely after the measurements.

Plasma gas-switching method for gas chromatography/inductively coupled plasma mass spectrometry and determination of polybrominated diphenylethers with high precision and sensitivity.

The drift in sensitivity due to carbon deposition on the sampling cone, skimmer cone and ion lenses has been a serious problem in gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS). To overcome this problem, a high-speed switching method between a mixed-gas plasma and a pure-argon plasma (named plasma gas-switching method) using an oxygen permeation tube and a switching valve was developed. This enabled both the cleaning of deposited carbon and an enhancement of the sensitivity; as a consequence, both the repeatability and the sensitivity of polybrominated diphenylether (PBDE) were improved by more than 3 and 4 times, respectively.