Ion chromatography–inductively coupled plasma mass spectrometry determination of arsenic species in marine samples

Arsenic speciation analysis in marine samples was performed using ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP‐MS) detection. The separation of eight arsenic species, viz. arsenite, monomethyl arsonic acid, dimethylarsinic acid, arsenate, arsenobetaine, tetramethylarsine oxide, arsenocholine and tetramethylarsonium ion was achieved on a Dionex AS4A (weaker anion exchange column) by using a nitric acid pH gradient eluent (pH 3.3 to 1.3). The entire separation was accomplished in 12 min. The detection limits for the eight arsenic species by IC–ICP‐MS were in the range 0.03–1.6 µ g l^?1, based on 3σ of the blank response (n = 6). The repeatability and day‐to‐day reproducibility were calculated to be less than 10% (residual standard deviation) for all eight species. The method was validated by analyzing a certified reference material (DORM‐2, dogfish muscle) and then successfully applied to several marine samples, e.g. oyster, fish muscle, shrimp and marine algae. The low power microwave digestion was employed for the extraction of arsenic from seafood products. Copyright © 2004 John Wiley & Sons, Ltd.     

Echo-intensity compensation in echolocating bats (Pipistrellus abramus) during flight measured by a telemetry microphone

An onboard microphone (Telemike) was developed to examine changes in the basic characteristics of echolocation sounds of small frequency-modulated echolocating bats, Pipistrellus abramus. Using a dual high-speed video camera system, spatiotemporal observations of echolocation characteristics were conducted on bats during a landing flight task in the laboratory. The Telemike allowed us to observe emitted pulses and returning echoes to which the flying bats listened during flight, and the acoustic parameters could be precisely measured without traditional problems such as the directional properties of the recording microphone and the emitted pulse, or traveling loss of the sound in the air. Pulse intensity in bats intending to land exhibited a marked decrease by 30 dB within 2 m of the target wall, and the reduction rate was approximately 6.5 dB per halving of distance. The intensity of echoes returning from the target wall indicated a nearly constant intensity (-42.6 +/- 5.5 dB weaker than the pulse emitted in search phase) within a target distance of 2 m. These findings provide direct evidence that bats adjust pulse intensity to compensate for changes in echo intensity to maintain a constant intensity of the echo returned from the approaching target at an optimal range.     

On-line column preconcentration for the determination of cobalt in sea water by flow-injection chemiluminescence detection

A flow-injection method for the determination of dissolved cobalt(II) in sea water has been studied based on a combination of column preconcentration using 8-quinolinol immobilized on silica gel, fluoride containing metal alkoxide glass (8HQ-MAF) and chemiluminescence detection with a gallic acid-hydrogen peroxide system. Co(II) is selectively recovered from an acidified sample with 8-quinolinol immobilized on silica gel. After elution with dilute hydrochloric acid the resultant eluent is mixed with the reagent solutions, heated to 60^°C and then introduced into the CL cell. The analysis time including the 2-min sample load was 8 min per sea water sample with a corresponding detection limit of 0.62 ngl^-1 (3). The average standard deviation calculated for 10 replicate measurements of artificial sea water samples with a concentration of 10 ngl^-1 cobalt was ±2.1%. The method has been tested with the standard reference sea waters NASS and CASS.     

Specifications of a neutron exposure accelerator system for biological effects experiments (NASBEE) in NIRS

We developed a neutron irradiation facility, neutron exposure accelerator system for biological effect experiments (NASBEE) for biological studies in National Institute of Radiological Sciences, Japan. Irradiation field of 2 MeV average neutrons generated by a Be(d–n)B reaction is established. Dose uniformity of 240 mm in diameter irradiation field is producible within ±2.5% with a dose rate of 0.87 Gy/h at sample target distance of 1170 mm. Two irradiation rooms, a specific pathogen-free (SPF) conditioned one and a conventional, are now available. Irradiation protocols for in vitro experiments are now established and demonstrated by obtaining a relative biological effectiveness (RBE) of cell inactivation measured to be 3.54 with 10% survival dose (D₁₀).     

Surface structures of adsorption layers of sodium hyaluronate and bovine serum albumin complexes on poly(γ-methyl-l-glutamate) film and their surface properties

Two-dimensional structures and characteristics of the complexes between sodium hyaluronate (NaHA) and bovine serum albumin (BSA) were studied by using a quartz crystal microbalance method and an atomic force microscope (AFM). NaHA did not adsorb on poly(-methyl-l-glutamate) (PMLG) film. On the other hand, the complexes adsorbed on it and the adsorption behaviors were found to be Langmuir types. With increasing weight ratio of BSA to NaHA, W _BSA, the adsorption constants K decreased and the saturated adsorption masses increased. The adsorbed complexes were spherical particles and at saturated adsorption states they covered compactly on the PMLG film. The mean diameters d _AFM estimated from the topographic images decreased from 70 to 54 nm with increasing W _BSA. The adhesion force F _ad and the frictional force F _f between the complex layers and the AFM tip were obtained by using the contact mode of the AFM. With increasing W _BSA, the values of F _ad decreased and the values of F _f increased. Compared with the frictional coefficient of the NaHA adsorption layer on the BSA monolayer, the values for the NaHA–BSA complex layer were found to be much higher.     

Determination of rare earth elements in seawater by on-line column preconcentration inductively coupled plasma mass spectrometry

A home made column of commercially available iminodiacetate resin, Muromac A-1 (50–100 mesh) was used to concentrate rare earth elements (REEs) (15 elements: Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in seawater. An automated low pressure flow analysis method with on-line column preconcentration/inductively coupled plasma mass spectrometry (ICP-MS) is described for the determination of REEs in seawater. Sample solutions (adjusted to pH of 3.0) passed through the column. After washing the column with water, the adsorbed elements were subsequently eluted into the plasma with 0.7 M nitric acid. Calibration curves were accomplished by means of purified artificial seawater with a sample loading time of 120 s. Detection limits (DLs) of the on-line column preconcentration/ICP-MS by eight replicate operations were between 0.040 and 0.251 pg ml⁻¹ for REEs in the artificial seawater. The precision was less than 8.9% for REEs and one sample can be processed in 7 min using a 7 ml of sample. The proposed method was applied to determine REEs in coastal seawater of Hiroshima Bay, Japan.     

Characteristics of hyaluronate-hydroxyethyl acrylate blend gel and release of cationic amphiphilic solutes

Hyaluronate-hydroxyethyl acrylate blend gel (HA-PHEA) were prepared to modify the brittleness of hyaluronate gel (HA) and the characteristics of HA-PHEA gel were compared with those of HA and polyhydroxyethyl acrylate (PHEA) gels. These gels were high in water content and transparent. HA-PHEA gel was improved in viscoelastic properties due to the elasticity and the high affinity with water of PHEA, and the drying-swelling cycles became reversible. The effective charge densities theta of the gels estimated from membrane potentials were -0.002, -0.008 and 0 mol dm(-3) for HA-PHEA, HA and PHEA gels. Effects of electro- static and nonelectrostatic interactions on absorptions and releases were studied using sodium benzoate (NaBA) as an anionic solute, and methylene blue (MB), chlorpromazine (CPHCl) and benzethonium chloride (BZTCl) as cationic solutes, in which CPHCl and BZTCl are cationic amphiphilic solutes. The releases of MB, CPHCl and BZTCl from HA-PHEA and HA gels were suppressed comparing with those of NaBA. By adding salts, the releases of MB and CPHCl were enhanced but those of BZTCl were suppressed due to enhancement of the intra- and intermicelle formation. In the releases of the cationic solutes from HA-PHEA gel, electrostatic and nonelectrostatic interactions with HA were found to play important roles. Behaviors of the releases from HA-PHEA gel were found to possess the features of HA gel.     

Trace metal enrichment by automated on-line column preconcentration for flow-injection atomic absorption spectrometry

An on-line column preconcentration technique for flow-injection atomic absorption spectrometry was developed. Diverse metal ions (Cd²⁺, Zn²⁺, Cu²⁺, Mn²⁺, Pb²⁺, Fe³⁺ and Cr³⁺) in solution were concentrated quantitatively by a microcolumn (7-mm × 4-mm i.d.) packed with Muromac A-1, which is an iminodiacetate chelate resin, in a flow-injection system. From the pH dependence of the uptake of the ions, all the divalent metals examined were recovered quantitatively in the pH range 3–5 and the trivalent metals were recovered at a maximum pH of 1. Enrichment factors using 20-ml samples were in the range 90–180-fold for the seven elements and the sampling rate was 13 h^?1. The 3σ detection limits were in the range 0.14–2.1 μg l^?1 and the relative standard deviations for replicate measurements (n=3–4) were in the range 0.7–1.7%. The method was compared with flame and graphite furnace atomic absorption spectrometry. Application to the determination of cadmium and copper in several standard reference materials is described.     

POSSIBLE ROLE OF METALLOTHIONEIN IN THE CELLULAR DEFENSE MECHANISM AGAINST UVB IRRADIATION IN NEONATAL HUMAN SKIN FIBROBLASTS

Abstract: The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS-K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40-HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation.
The sensitivity of HS-K and NB1RGB cells to UVB irradiation was similar; those of SV40-HSK and Pam 212 cells were two- and six-fold as sensitive to UVB irradiation as HS-K cells, respectively. The HS-K cells contained the greatest cellular reduced form of glutathione (GSH) levels compared to the three other skin cells: the levels were 13-, 7- and 6-fold of those in NB1RGB, SV40-HSK and Pam 212 cells, respectively. These results indicated that the sensitivity of skin cells to UVB irradiation was not always associated with their endogenous GSH levels. In particular, despite the fact that NB1RGB cells contained a relatively small amount of GSH, they were less sensitive to UVB irradiation.
NB1RGB cells contained 4–30 times more MT than those in other skin cells examined. The sulfhydryl residues of MT molecules in the NB1RGB cells were estimated to be mostly unoccupied by metals, suggesting they act in a similar way to those of GSH. Moreover, NB1RGB cells in which the MT content was elevated by dexamethasone (1 μ M ) or Zn²⁺ (7 μg/mL) treatment were more resistant to UVB irradiation than nontreated ones.
These results suggest that, at least in neonatal human skin fibroblasts, MT may play a role in protection against UVB irradiation.