Yanbei Zhu

Multielement determination of trace metals in seawater by ICP-MS with aid of down-sized chelating resin-packed minicolumn for preconcentration.

The multielement determination of trace metals in seawater was carried out by inductively coupled plasma mass spectrometry (ICP-MS) with aid of a down-sized chelating resin-packed minicolumn for preconcentration. The down-sized chelating resin-packed minicolumn was constructed with two syringe filters (DISMIC 13HP and Millex-LH) and an iminodiacetate chelating resin (Chelex 100, 200-400mesh), with which trace metals in 50mL of original seawater sample were concentrated into 0.50mL of 2M nitric acid, and then 100-fold preconcentration of trace metals was achieved. Then, 0.50mL analysis solution was subjected to the multielement determination by ICP-MS equipped with a MicroMist nebulizer for micro-sampling introduction. The preconcentration and elution parameters such as the sample-loading flow rate, the amount of 1M ammonium acetate for elimination of matrix elements, and the amount of 2M nitric acid for eluting trace metals were optimized to obtain good recoveries and analytical detection limits for trace metals. The analytical results for V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U in three kinds of seawater certified reference materials (CRMs; CASS-3, NASS-4, and NASS-5) agreed well with their certified values. The observed values of rare earth elements (REEs) in the above seawater CRMs were also consistent with the reference values. Therefore, the compiled reference values for the concentrations of REEs in CASS-3, NASS-4, and NASS-5 were proposed based on the observed values and reference data for REEs in these CRMs.

Determination of REEs in seawater by ICP-MS after on-line preconcentration using a syringe-driven chelating column

A syringe-driven chelating column (SDCC) was applied to develop an on-line preconcentration/inductively coupled plasma mass spectrometry (ICP-MS) method for preconcentration and determination of rare earth elements (REEs) in seawater samples. The present on-line preconcentration system consists of only one pump, two valves, an SDCC, an ICP-MS, several connectors, and Teflon tubes. Optimizations of adsorption pH condition, sample loading flow rate, and integration range were carried out to achieve optimum measurement conditions for REEs in seawater sample. Six minutes was enough for a preconcentration and measurement cycle using 10 mL of seawater sample, where the detection limits for different REEs were in the range of 0.005 pg mL(-1) to 0.09 pg mL(-1). Analytical results of REEs in a seawater certified reference material (CRM), NASS-5, confirmed the usefulness of the present method. Furthermore, concentrations of REEs in Nikkawa Beach coastal seawater were determined and discussed with shale normalized REE distribution pattern.

Determination of Fe, Cu, Ni, and Zn in seawater by ID-ICP-MS after preconcentration using a syringe-driven chelating column

A hybrid method was suggested for preconcentration of trace metals and removal of matrix elements in seawater samples. In this method, seawater samples were loaded off-line into the syringe-driven chelating columns (SDCCs), which were then connected to a valve-switching system for on-line elution and on-line determination of Fe, Cu, Ni, and Zn by ID-ICP-MS. Optimizations of operating conditions were carried out for sample loading flow rate and pH. The removal of matrix elements was not carried out, because the concentrations of Mg, Ca, Na, and K were sufficiently low when 5 mL or less of the seawater sample was used for analysis. The usefulness of the present method was confirmed by analysis of NASS-5. Detection limits for Fe, Ni, Cu, and Zn were 0.03, 0.012, 0.018, and 0.009 ng mL−1, respectively.

Urinary 28-kD calbindin-D as a new marker for damage to distal renal tubules caused by cisplatin-based chemotherapy.

Calbindin-D, a vitamin D-dependent calcium-binding protein of 28 kD, is found predominantly in the distal tubules of the kidney and central nervous system tissues in humans. To evaluate damage to the renal tubules caused by cisplatin-based chemotherapy, levels of urinary and serum calbindin-D were determined in patients treated with cisplatin- or carboplatin-based chemotherapies using a highly sensitive enzyme immunoassay system developed in our laboratory. Levels of urinary 28-kD calbindin-D were also determined in patients with benign and malignant urological diseases. The mean urinary calbindin-D level was 2.44 + or - 0.31 (mean + or - SE) ng/mg creatinine in 40 healthy subjects. Urinary calbindin-D levels were elevated (>10 ng/mg creatinine) in 2 of 33 patients (6%) with benign and 1 of 50 (2%) with malignant urological diseases. Urinary calbindin-D levels were significantly increased after cisplatin-based chemotherapy in 14 patients, with peaks (71.8 + or - 13.5 ng/mg creatinine) being found 8 days after administration of cisplatin, and then a gradual return to the baseline. On the other hand, 7 patients receiving carboplatin-based chemotherapy demonstrated no significant elevation (highest level 7.7 + or - 2.5 ng/mg creatinine). In 7 patients treated with cisplatin-based chemotherapy the serum calbindin-D level was also raised after treatment, with a good correlation to urinary values. These findings suggest that urinary and serum calbindin-D may be kidney-derived and that 28-kDa calbindin-D is a useful marker for damage to the distal renal tubules associated with cisplatin-based chemotherapy.

Determination of cadmium in food samples by ID-ICP-MS with solid phase extraction for eliminating spectral-interferences.

A solid phase extraction (SPE) method using chelating resin was developed to separate Cd from spectral-interferences prior to the analysis of food samples by isotope-dilution inductively coupled plasma mass-spectrometry (ID-ICP-MS). Two syringe-driven chelating columns (SDCCs), Nobias Chelate PB-1M and InertSep ME-1, were investigated in the present experiment. The results of the pH dependence of Mo removal rates showed that separation of Cd and Mo could be obtained at pH conditions over 7. In addition, 0.6 mL of NH(4)OH solution added into each 10 mL of digested sample solution (in 0.3M HNO(3)) followed by SPE was enough to remove the interfering elements, i.e. Mo, Zr, and Sn, in ID-ICP-MS analysis of Cd. Furthermore, it was found that InertSep ME-1 was more effective for separating Cd from the interfering elements, with removal rates approximately 100% for Mo, Zr, and Sn while the recovery of Cd was approximately 100%. The optimized SPE operations were as follows: 0.6 mL of NH(4)OH was added into each 10 mL of digested sample solution; the sample solution was loaded into each pre-cleaned SDCCs at a flow rate of 5 mL min(-1); after 5 mL of ultrapure water was passed through the SDCC for washing, 2 mL of 0.3M HNO(3) was passed through to elute Cd and the eluent was subjected to ICP-MS measurement. The present method was validated by analyzing five certified reference materials (CRMs) produced by the National Metrology Institute of Japan (NMIJ), and then was applied to a soybean powder sample.

Erratum to: Preparation and certification of Hijiki reference material, NMIJ CRM 7405-a, from the edible marine algae hijiki (Hizikia fusiforme)

Following online publication the authors regrettably found some mistakes and typographical errors in the article. The corrections are given below. Page 1714, section “Apparatus”, the end of the first paragraph should read: “And, He 1 mL/min + H2 3 mL/min was used for the measurement of Fe and He 3 mL/min + H2 1 mL/min was used for other elements”. Page 1714, section “Apparatus”, the third paragraph should read: “The typical operating parameters for the ICP-OES were as follows” Page 1716, section “Homogeneity study”, the end of the first paragraph should read: “The sbb was theoretically calculated from Mswithin and Msamong.” Page 1716, section “Homogeneity study”, equation 1 should read:

Quantitative analysis of the elements in powder samples by LA-ICP-MS with PMMA powder as the binder and Cs as the internal standard

A fine powder of poly(methyl methacrylate) resin (PMMA) was obtained by freezing pulverization and passing through nylon sieves with a pore-size of 250 μm. The PMMA powder was then mixed with an aqueous solution of CsCl to adsorb Cs, which was used as the internal standard for subsequent analysis by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). The Cs-adsorbed PMMA powder was used as the binder to make sample disks for analysis by LA-ICP-MS. The sample and the binder were simply mixed in a centrifuge tube and put into a laboratory-made disk presser, which was then put into an oven and heated at 110 °C for 2 h. After optimization of the operating conditions, the linear correlation between each of the signal intensities of 11 elements (Al, P, Ca, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Ba) and the mass fractions of the sample was investigated with a certified reference material (CRM) of tea leaf powder issued by the National Metrology Institute of Japan (NMIJ), i.e. NMIJ CRM 7505-a. The square of the correlation was in the range from 0.78 for Fe to 0.92 for Zn. After the internal standard correction using Cs, the square of each correlation for all of the elements investigated was better than 0.99. The usefulness of the present method was confirmed by the analysis of a tea leaf candidate reference material (RM), a white rice flour CRM, and a seaweed CRM.

Elevated levels of serum aldolase A in patients with renal cell carcinoma

SummaryTo clarify whether serum aldolase A is a useful biomarker for renal cell carcinoma (RCC), we determined serum levels of the aldolase A isozyme by an enzyme immunoassay in patients suffering from RCC, other urological tumors, and benign urological diseases. Fortysix of 126 patients with RCC (37%) had elevated serum aldolase A. The positive rates were 23% in stage I, 40% in stage II, 63% in stage III, and 46% in stage IV. In 10 (83%) of 12 patients whose serum levels had been elevated preoperatively, these were reduced to within the normal range after nephrectomy. Four of 7 patients (57%) with progressive disease had elevated of aldolase A. In contrast, the positive rates were only 9.9% in 71 patients with other urological tumors and 5.8% in 52 cases of benign urological diseases. High concentrations of aldolase A isozyme in RCC tissues might be reflected in elevated serum levels. The present findings indicate that serum aldolase A is a useful biomarker for monitoring the clinical course of patients with RCC.

Internal standard method coupled with a gravimetric standard addition method for elemental measurements by ICP-MS

An internal standard method coupled with a gravimetric standard addition method (ISM-SAM) with a single spiked sample was proposed as a strategy for elemental measurements. Equations are given for measurement of the element based on its ratios to the internal-standard in the spiked sample and to the non-spiked sample. Optimization of the relative quantity of the standard solution was carried out to improve the precision of the measurement, the results obtained showed that a high-precision measurement could be obtained when the concentration of the measurand in the spiked sample was over 2-fold of that in the non-spiked sample. Measurement of Cu in a test solution was performed in parallel to the measurement by inductively coupled plasma mass spectrometry (ICP-MS) and isotope dilution (ID-) ICP-MS, and the results indicate that the present method has similar reliability to those of ID-ICP-MS and ICP-MS. Furthermore, the ISM-SAM method was applied to the analysis of P in two certified reference materials (CRMs) issued by the National Metrology Institute of Japan (NMIJ) with different mono-isotopic elements (Be, Al, Sc, As, Y, Rh, and Cs) as the internal standard elements. All of the results agreed with the certified values of the CRMs. The results neither depended on the atomic number nor depended on the ionization rate of the internal standard element. The present method was also applied to the analysis of other elements in CRMs of tea leaf powder, seaweeds, and swordfish tissue, providing accurate results.

Selective encapsulation of cesium ions using the cyclic peptide moiety of surfactin: Highly efficient removal based on an aqueous giant micellar system

Cyclic peptide of surfactin (SF) is one of the promising environment-friendly biosurfactants abundantly produced by microorganisms such as Bacillus subtilis. SF is also known to act as an ionophore, wherein alkali metal ions can be trapped in the cyclic peptide. Especially, SF is expected to show high affinity for Cs(+) because of the distinctive cavity size and coordination number. In this study, we reported the specific interaction between SF and Cs(+) and succeeded in the highly efficient removal of Cs(+) from water using giant SF micelles as a natural sorbent. The specific interaction between SF and Cs(+) to form their inclusion complex was revealed by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy. We found that SF micelles selectively encapsulate Cs(+), which was suggested by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). A highly effective separation of Cs(+) immobilized on the surface of the SF micelles was also achieved through facile centrifugal ultrafiltration in 91% even in coexisting with other alkali metal ions such as Na(+) and K(+). Thus, the use of the giant micellar system of SF with its high Cs(+) affinity and distinctive assembling properties would be a new approach for the treatment of contaminated soil and water.