Magnetic resonance angiography (MRA) is an imaging method to examine blood vessels based on the magnetic resonance imaging (MRI) technique. For this purpose, blood pool contrast agents have been developed to selectively increase the signal intensity of the intravascular lumen for improvement of the contrast-to-noise ratio in MR images. Here, we describe the design and the syntheses of six novel sulfonated contrast agents (KMR-Sulfo1 - 6), their chemical properties and their in vivo applications. In this study, we investigated the lipophilicity and the hydrophilicity of a gadolinium complex using a convenient two-step synthesis route, with the goal of prolonging the plasma half-life by binding mainly to human serum albumin. We confirmed that KMR-Sulfo5 fulfilled the requirements as a blood pool contrast agent: it showed a sufficient relaxivity r1 of 5.9 mM-1 s-1, a long plasma half-life of 25.7 min and complete elimination from the body within 12 h after the administration.
Supramolecular complex formation of phenylboronic-acid-modified β-cyclodextrin (1) with 1-methyl-4-(4-dimethylaminostyryl)pyridinium (C1SP) in aqueous solutions containing saccharides was fully clarified to gain an insight into the observed D-glucose (D-glc) selectivity of a supramolecular fluorescent probe composed of 1 and the 1-heptyl analogue of C1SP (Chem. Commun., 2006, 4319). At pH 9.6, where 1 was in its anionic form, both the stability and the fluorescence of the 1/C1SP complex were reduced by the formation of boronate esters of 1 with saccharides. Among the saccharides, D-glc had the smallest effect on destabilization of the 1/C1SP complex, almost completely retaining the fluorescence of the 1/C1SP complex that was reduced by other saccharides by approximately 2/3. Under neutral conditions, D-glc enhanced the fluorescence of the 1/C1SP complex by increasing the fraction of anionic 1 while minimally decreasing the stability and fluorescence of the 1/C1SP complex. Although other saccharides also increased the fraction of the anionic 1, their relatively large effects on the destabilization and reduction of fluorescence of the 1/C1SP complex limited the enhancement of the fluorescence of the 1-C1SP system under neutral conditions.
A novel method for determination of carbendazim in bananas is proposed in this study. After the bananas were simply extracted, the carbendazim was quantified under the interference of banana extract using the second-order calibration algorithms based on the parallel factor analysis (PARAFAC), the self-weighted alternating trilinear decomposition (SWATLD) and the alternating penalty trilinear decomposition algorithms (APTLD), respectively. For analysis of the complex samples, the so-called second-order advantage was adequately exploited and good results were obtained. Figures of merit, such as limit of detection, sensitivity and selectivity, were calculated to compare the performances of the three algorithms.
A single and rapid solid surface fluorescence-based flow-through optosensor has been developed for the screening of trace amounts of Zn(II) in drinking water samples. The proposed method is based on the transient immobilization of the target species: the complex formed between Zn(II) and the fluorogenic reagent p-(tosylamino)quinoline (p-TAQ) on an appropriate solid support (C18 silica gel). The fluorescence of the complex was continuously monitored at an emission wavelength of 495 nm upon excitation at 377 nm. The instrumental, chemical and flow-injection variables were carefully investigated and optimized. The sensor was calibrated over the range of 5 - 125 ng mL-1, obtaining a limit of detection of 0.9 ng mL-1, a RSD of 1.8%, with a sampling frequency of 20 h-1. The proposed method was successfully applied to different drinking water samples with recoveries between 98 and 104%.
A portable total reflection X-ray fluorescence spectrometer was applied to commercial bottled drinking water containing 62 ppb (µg/L) V, 7.5 ppm (mg/L) Ca, and 1 ppm K. A dry residue, prepared by repeated pipetting and drying a 20 µL portion of drinking water on a sample holder six times, and another dry residue, prepared by pipetting and drying a 120 µL portion of the drinking water, were measured. The size of the dry residue of the drinking water was reduced by repeating the pipetting and drying. Calcium and potassium were easily detected in these two dry residues. Vanadium was detected in the dry residue prepared by repeated pipetting and drying. Vanadium, calcium, and potassium were quantified by using an internal standard, and the average quantified concentrations of V, Ca, and K were 91 ppb, 8.2 ppm, and 1.5 ppm, respectively. Although these quantified concentrations deviated from the certified concentrations (62 ppb of V, 7.5 ppm of Ca, and 1 ppm of K), it was possible for this portable spectrometer to estimate approximate concentrations.
In this research, a simple, sensitive chemiluminescence (CL) method for the determination of humic acid (HA) in water samples was first developed based on the redox reaction between humic acid and cerium(IV) in the acidic condition. Different with the former redox CL reaction which occurred in alkaline solution, no enhancers were needed and neither precipitation nor a second contamination would occur in the present CL system. Comparing with other spectrometric methods, we find that the proposed analysis system had better applicability and accuracy. Under the optimal experiment conditions, the CL peak height was linear with the concentration of HA in the range of 0.03 to 10.0 µg mL-1. The detection limit is 0.01 µg mL-1 (S/N = 3), and the relative standard deviation was 2.3% for 0.5 µg mL-1 HA solution with eleven repeated measurements. The present CL method was successfully applied to the determination of HA in tap water, spring water and river water samples with good recovery from 90.0 to 110.0%. A possible CL mechanism was proposed based on the results of UV and fluorescence spectrometry and the CL spectrum of HA. It was speculated that the semi-quinone radicals in the excited state were the emitters.
An on-line low gas pressure cell device has been developed for elemental analysis using laser ablation-ICP-mass spectrometry (LA-ICPMS). Ambient gas in the sample cell was evacuated by a constant-flow diaphragm pump, and the pressure of the sample cell was controlled by changing the flow rate of He-inlet gas. The degree of sample re-deposition around the ablation pit could be reduced when the pressure of the ambient gas was lower than 50 kPa. Produced sample aerosol was drawn and taken from the outlet of the diaphragm pump, and directly introduced into the ICP ion source. The flow rate of He gas controls not only the gas pressure in the sample cell, but also the transport efficiency of the sample particles from the cell to the ICP, and the gas flow rate must be optimized to maximize the signal intensity of the analytes. The flow rates of the He carrier and Ar makeup gas were tuned to maximize the signal intensity of the analytes, and in the case of 238U from the NIST SRM610 glass material, the signal intensity could be maximized with gas flow rates of 0.4 L/min for He and 1.2 L/min for Ar. The resulting gas pressure in the cell was 30 - 35 kPa. Using the low gas pressure cell device, the stability in the signal intensities and the resulting precision in isotopic ratio measurements were evaluated. The signal intensity profile of 63Cu obtained by laser ablation from a metallic sample (NIST SRM976) demonstrated that typical spikes in the transient signal, which can become a large source of analytical error, were no longer found. The resulting precision in the 65Cu/63Cu ratio measurements was 2 - 3% (n = 10, 2SD), which was half of the level obtained by laser ablation under atmospheric pressure (6 - 10%). The newly developed low-pressure cell device provides easier optimization of the operational conditions, together with smaller degrees of sample re-deposition and better stability in the signal intensity, even from a metallic sample.
A chelating resin, cross-linked chitosan modified with the glycine moiety (glycine-type chitosan resin), was developed for the collection and concentration of bismuth in aquatic samples for ICP-MS measurements. The adsorption behavior of bismuth and 55 elements on glycine-type chitosan resin was systematically examined by passing a sample solution containing 56 elements through a mini-column packed with the resin (wet volume; 1 ml). After eluting the elements adsorbed on the resin with nitric acid, the eluates were measured by ICP-MS. The glycine-type chitosan resin could adsorb several cations by a chelating mechanism and several oxoanions by an anion-exchange mechanism. Especially, the resin could adsorb almost 100% Bi(III) over a wide pH region from pH 2 to 6. Bismuth could be strongly adsorbed at pH 3, and eluted quantitatively with 10 ml of 3 M nitric acid. A column pretreatment method with the glycine-type chitosan resin was used prior to removal of high concentrations of matrices in a seawater sample and the preconcentration of trace bismuth in river water samples for ICP-MS measurements. The column pretreatment method was also applied to the determination of bismuth in real samples by ICP-MS. The LOD of bismuth was 0.1 pg ml-1 by 10-fold column preconcentration for ICP-MS measurements. The analytical results for bismuth in sea and river water samples by ICP-MS were 22.9 ± 0.5 pg ml-1 (RSD, 2.2%) and 2.08 ± 0.05 pg ml-1 (RSD, 2.4%), respectively.
The Al(III) and Ga(III) complexes formed by morin (M) in aqueous solution were investigated by means of electrospray ionization mass spectrometry (ESI-MS). In the full scan mass spectra, Al:M showed 1:2 and 2:3 stoichiometric ratios. When (S)-N-acetylserine methyl ester (Ser), as a partial mimic of the serine residue in silk, was added to Al:M and Ga:M complexes in aqueous solution, the mass spectra of Ser:Al:M showed 1:1:1 and 1:1:2 stoichiometric ratios. The patterns of the mass spectra of Ga:M and Ser:Ga:M complexes were similar to those for the corresponding Al(III) complexes. Calculated heats of formation of potential structures of the complexes, with and without bound water, were obtained using semiempirical PM3 calculations.
Spectral data during a chelatometric titration were utilized for determining an equivalence point of the titration. Three-dimensional titration data were analyzed by fitting to a theoretical equation that was derived from equilibrium equations among a metal ion, an indicator and EDTA. The equation with optimized parameters successfully explained the three-dimensional titration data. This method was applied to EDTA titration systems of zinc, cadmium and lead with xylenol orange (XO) as an indicator. These systems were analyzed while taking the formation of 1:1 and 2:1 metal-indicator complexes into account. By this method, an accurate equivalence point was determined as well as stability constants and molar absorption spectra of metal-indicator complexes in each titration system. Moreover, the comparability among the concentrations of the metal standard solutions prepared from pure metals (Zn, Pb, and Cd) was also confirmed by the proposed evaluation method.
This study developed an acid hydrolysis coupled to a solid-phase microextraction method employing a semi-microcolumn liquid chromatography system, instead of enzyme hydrolysis with solid-phase extraction for the pretreatment of human urine samples, to detect urinary 1-hydroxypyrene (1-OHP). The complete separation and detection of urinary 1-hydroxyprene was performed using a high-performance liquid-chromatography fluorescence detection system with an analytical C18 semi-microcolumn, 60% (v/v) aqueous acetonitrile elution, and a λex/em = 348/388 nm pair detection wavelength. Calibration graphs were linear with very good correlation coefficients (r = 0.9997), and the detection limit was 1.0 ng/L. These important parameters for acid hydrolysis and solid-phase microextraction were investigated. The total recovery was above 83% in acid hydrolysis with solid-phase microextraction. The proposed method provided a relatively simple, convenient, and practical procedure to determine the level of urinary 1-hydroxypyrene in biological samples, and was successfully applied to detect the urine of students.
Zinc ions form a yellow complex with di-2-pyridyl ketone salicyloylhydrazone (DPKSH). This complex showed maximum absorption at 376 nm, and it was used to develop spectrophotometric flow injection methods for Zn(II) determination in different samples. Two types of flow systems were proposed. In the first system, a linear analytical curve was obtained in a concentration range from 0.217 to 4.60 mg L-1 Zn(II), with a detection limit of 48.8 µg L-1. In the second system, a minicolumn packed with an anion exchanger resin was used to concentrate Zn(II) as a chlorocomplex, and a linear analytical curve within a concentration range from 0.0824 to 2.06 mg L-1 Zn(II) was obtained, having a detection limit of 13.9 µg L-1. The developed methods were applied to biological and pharmaceutical samples, and a great compliance was observed by comparing the results with ones obtained by an atomic absorption technique.
Recently, a novel electron spin resonance (ESR) spin-trapping agent, 2-(diphenylphosphinoyl)-2-methyl-3,4-dihydro-2H-pyrrole N-oxide (Diphenyl-PMPO), was synthesized. Because it had some advantages in stability and reactivity over conventional spin-trapping agents, we applied it to the ESR analyses of superoxide anion radical scavenging activity (SOSA) of superoxide dismutase (SOD) and of well-known natural antioxidants (green tea, oolong tea, and red wine). At the same time, the results with Diphenyl-PMPO were compared with 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Our results revealed that Diphenyl-PMPO showed higher detectability than DMPO in the SOSA assays of SOD and natural antioxidants, so it could be available for the ESR analyses as an alternative to conventional spin-trapping agents.
The performance of fluorescence correlation spectrometry (FCS) was examined for studying the solutions suspended with the fluorescent particles of various sizes from 50 nm to 10 µm in diameter and for different sizes of pinholes: the particles were made to move by simply stirring the solution in the quartz fluorescence cuvette. Without using any magnification tool for the optical image, this FCS system successfully distinguishes images with a size of smaller than 1 µm. This system was applied for determination of the sizes of microalgae.
Second derivative-spectrophotometric and high-performance liquid chromatographic methods for the determination of prednisolone in pharmaceutical formulations have been developed. Determination of prednisolone in tablets was conducted by using a second-order derivative UV spectrophotometric method at 250 nm (n = 5). Standards for the calibration graph ranging from 5.0 to 35.0 µg/ml were prepared from stock solution. The proposed method was accurate, with 98% recovery value, and precise, with a coefficient of variation (CV) of 1.38. These results were compared with those obtained by an exclusively developed isocratic reversed-phase high-performance liquid chromatography (HPLC) method. An isocratic reversed-phase Bondapak C18 column with acetonitrile-citrophosphate buffer (pH 5; 45:55 v/v) mobile phase was used and UV detector was set to 241 nm using 11 α-hydroxyprogesterone as an internal standard. Calibration solutions used in HPLC were in the range from 2 to 300 µg/ml. Results obtained by derivative UV spectrophotometric method were comparable to those obtained by HPLC method, as far as analysis of variance (ANOVA) test, Fcalculated, 0.762 and Ftheoretical, 3.89, results were concerned.
We confirmed that concentrations of polycyclic aromatic hydrocarbons (PAHs) obtained by isotope dilution mass spectrometry (IDMS) using the corresponding 13C-labeled internal standards are reliable even after clean-up steps. Change in the ratio of phenanthrene to 13C6-phenanthrene was less than 0.2%, although the recovery yield of 13C6-phenanthrene decreased to 60%. Since changes in the ratios were commonly within the relative standard deviations of the concentrations (1.5 - 5.4%) obtained using gas chromatography-mass spectrometry in combination with pressurized-liquid extraction, concentrations obtained by IDMS with 13C-PAHs should be reliable.
Measurements of time of flight (TOF) mobility of organic semiconductors become difficult when the mobility values are high, since the electronic signals overlap with the noise of the short part in drift time. Such noise of the short part in the drift time in the TOF method for measurements of carrier mobility was reduced by three methods: (1) longer distance (3.5 m) between sample and the N2 laser, (2) optical connection (photo coupler) between the N2 laser and the pulse generator, and (3) using a digital filter to remove characteristic pulses caused by N2 laser. Each method showed significant reduction of the noise. When all three methods were applied, 94% of the noise was reduced. The measurement of TOF mobility was demonstrated with TPD (N,N′-diphenyl-N,N′-di(meta-tolyl)benzidine) film. Electronic signals in TOF measurements were clearly observed and the TOF mobility was determined to be 9.0 × 10-4 cm2/V s.