Speciation analysis of inorganic arsenic by magnetic solid phase extraction on-line with inductively coupled mass spectrometry determination.

Arsenic, one of the main environmental pollutants and potent natural poison, is a chemical element that is spread throughout the Earth's crust. It is well known that the toxicity of arsenic is highly dependent on its chemical forms. Generally, the inorganic species are more toxic than its organics forms, and As(III) is 60 times more toxic than As(V). In environmental waters, arsenic exists predominantly in two chemical forms: As(III) and As(V). In view of these facts, fast, sensitive, accurate and simple analytical methods for the speciation of inorganic arsenic in environmental waters are required. In this work, a new magnetic solid phase extraction with a hydride generation system was coupled on line with inductively coupled plasma mass spectrometry (MSPE-HG-ICP-MS). The new system was based on the retention of As(III) and As(V) in two knotted reactors filled with (Fe3O4) magnetic nanoparticles functionalized with [1,5-bis (2-pyridyl) 3-sulfophenylmethylene] thiocarbonohydrazide (PSTH-MNPs). As(III) and total inorganic As were sequentially eluted in different reduction conditions. The concentration of As(V) was obtained by subtracting As(III) from total As. The system runs in a fully automated way and the method has proved to have a wide linear range and to be precise, sensitive and fast. The detection limits found were 2.7 and 3.2 ng/L for As(III) and total As, respectively; with relative standard deviations (RSDs) of 2.5% and 2.7% and a sample throughput of 14.4 h-1. In order to validate the developed method, several certified reference samples of environmental waters including sea water, were analyzed and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the speciation analysis of inorganic arsenic in well-water and sea water.

Phase I and biomarker study of OPB-51602, a novel signal transducer and activator of transcription (STAT) 3 inhibitor, in patients with refractory solid malignancies.

BACKGROUND: The aim of this study was to determine the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of OPB-51602, an oral, direct signal transduction activator of transcription 3 (STAT3) inhibitor, in patients with refractory solid tumors. PATIENTS AND METHODS: Three cohorts were studied: cohort A, a sequential dose escalation of OPB-51602 administered intermittently (days 1-14 every 21 days); cohort B, an expansion cohort evaluating the dose lower than the MTD; cohort C, evaluating continuous daily dosing. RESULTS: Fifty-one patients were studied at 2, 4, and 5 mg per day dosing. The MTD was 5 mg; first-cycle dose-limiting toxicities (DLTs) were grade 3 hyponatremia in one patient, and grade 3 dehydration in another. Intermittent dosing of both 2 and 4 mg doses were tolerable, and the recommended phase II dose was 4 mg. Cohort B investigated 4 mg intermittently, whereas cohort C investigated 4 mg continuously. Common toxicities included fatigue, nausea/vomiting, diarrhea, anorexia, and early-onset peripheral neuropathy. Drug-induced pneumonitis occurred in two patients in cohort C. Continuous dosing was associated with a higher incidence of peripheral neuropathy and a lower mean relative dose intensity, compared with intermittent dosing. Steady-state pharmacokinetics was characterized by high oral clearance, mean elimination half-life ranging from 44 to 61 h, and a large terminal-phase volume of distribution. An active metabolite, OPB-51822, accumulated to a greater extent than OPB-51602. Flow cytometry of peripheral blood mononuclear cells demonstrated pSTAT3 (Tyr(705)) inhibition following exposure. Two patients achieved partial responses at 5 mg intermittently and 4 mg continuously; both had epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) with prior EGFR tyrosine kinase inhibitor exposure. CONCLUSION: OPB-51602 demonstrates promising antitumor activity, particularly in NSCLC. Its long half-life and poorer tolerability of continuous dosing, compared with intermittent dosing, suggest that less frequent dosing should be explored. CLINICALTRIALSGOV IDENTIFIER: NCT01184807.

Synthesis and characterization of a novel mesoporous silica functionalized with [1,5 bis(di-2-pyridyl)methylene thiocarbohydrazide] and its application as enrichment sorbent for determination of antimony by FI-HG-ETAAS.

A simple, sensitive, low-cost and rapid flow injection (FI) on-line sorption preconcentration/hydride generation system has been synchronously coupled to an electrothermal atomic absorption spectrometer (ETAAS) for the determination of trace amounts of Sb in aqueous environmental samples (river and sea water samples). The system is based on retention of the analyte onto a micro-column filled with a novel mesoporous silica functionalised with [1,5 bis(di-2-pyridyl) methylene] thiocarbohydrazide placed in the injection valve of the FI manifold. The adsorption capacity of the resin for Sb was found to be 160.8 µmol g(-1). Chemicals and flow variables affecting the continuous preconcentration of antimony, the direct generation of antimony hydride and the final determination of this element by ETAAS were evaluated. The optimized operating conditions selected were: sample pH 5.0, sample flow rate 2.5 ml min(-1), eluent flow rate 5.4 ml min(-1), eluent 2.0% thiourea in 4.0% nitric acid. Under the optimum conditions, the calibration graph obtained was linear over the range 0.025-2.5 µg L(-1). At a sample frequency of 20 h(-1) and 120 s preconcentration time, the enrichment factor was 22. The detection limit of the method (3Æ¡) was 1 ng L(-1) for a 5.0 mL sample volume and the precision was 0.9% (RSD) for 11 replicate determinations at 1.0 µg L(-1) Sb. The preconcentration factor and detection limit can be improved by increasing the preconcentration time, which can be increased at least up to 5 min. The accuracy of the proposed method was demonstrated by analyzing two certified reference materials and by determining the analyte content in spiked environmental water samples. The results obtained using this method were in good agreement with the certified values of the standard reference materials and the recoveries for the spiked river and sea water samples were 91.3-109.9%.

Body fat composition impacts the hematologic toxicities and pharmacokinetics of doxorubicin in Asian breast cancer patients.

Body surface area (BSA)-based dosing leads to wide inter-individual variations in drug pharmacokinetics and pharmacodynamics, whereas body composition has been shown to be a more robust determinant of efficacy and toxicity of certain chemotherapeutic agents. We correlated various parameters of body composition with doxorubicin pharmacokinetics and hematologic toxicities in Asian patients with locally advanced or metastatic breast cancer. Our analysis included 84 patients from two studies who received pre- or post-operative single-agent doxorubicin; pharmacokinetic parameters were available for 44 patients. Body composition parameters were derived from CT cross-sectional images and population pharmacokinetic analysis was conducted using mixed-effects modeling. Higher intra-abdominal fat volume and fat ratio (intra-abdominal:total abdominal fat volume) correlated with greater incidence of grade 4 leukopenia on cycle 1 day 15 (mean intra-abdominal fat volume: 97.4 ± 46.5 cm(3) vs 63.4 ± 30.9 cm(3), p = 0.014; mean fat ratio: 0.43 ± 0.11 vs 0.33 ± 0.09, p = 0.012, grade 4 vs grade 0-3 leukopenia). On subset analysis, this relationship was maintained even in underweight patients. Concordantly, there were positive correlations between doxorubicin AUC and intra-abdominal fat volume as well as total abdominal fat volume (r (2) = 0.324 and 0.262, respectively, all p < 0.001). BSA and muscle volume did not predict for doxorubicin pharmacokinetics or toxicities. High-intra-abdominal fat volume but not BSA predicted for greater doxorubicin exposure and hematologic toxicities, suggesting that body composition is superior to BSA in determining doxorubicin pharmacokinetics and pharmacodynamics. Body composition has an emerging role in chemotherapy dose determination.

Pharmacokinetics and pharmacodynamics of docetaxel with or without ketoconazole modulation in chemonaive breast cancer patients.

BACKGROUND: We previously found 70 mg flat-dose docetaxel coadministered with ketoconazole to modulate CYP3A4 to be the maximum tolerated dose that resulted in comparable docetaxel area under the plasma concentration-time curve (AUC) as 75-100 mg/m² docetaxel. PATIENTS AND METHODS: We compared cycle 1 docetaxel pharmacokinetics and pharmacodynamics between ketoconazole-modulated (70 mg flat-dose docetaxel, n = 31) and conventional-dosed docetaxel (75 mg/m², n = 51) in chemonaive breast cancer patients in two sequential phase II studies. RESULTS: Ketoconazole-modulated docetaxel resulted in reduced docetaxel clearance (22.05 ± 8.29 versus 36.52 ± 13.39 l/h, P < 0.001), similar docetaxel AUC (3.93 ± 2.77 versus 3.77 ± 2.70 mg/l·h, P = 0.794) and tumor efficacy (cycle 1 responder 52% versus 55%) and less day 8 neutrophil suppression (1.24 ± 1.02 × 109/l versus 0.47 ± 0.56 × 109/l, P < 0.001), grade 4 neutropenia (32.3% versus 72.0%, P < 0.001) and febrile neutropenia (3.2 versus 23.5%, P = 0.015), compared with conventional-dosed docetaxel. Chinese had the lowest docetaxel clearance, highest AUC and most myelosuppression, followed by Malays and Indians, in response to ketoconazole-modulated docetaxel, while no significant interethnic differences were observed with conventional-dosed docetaxel. CONCLUSIONS: Ketoconazole-modulated docetaxel achieved similar docetaxel AUC and tumor efficacy but reduced neutrophil suppression and febrile neutropenia at ∼40% reduced dose, representing a feasible alternative to conventional-dosed docetaxel. Interethnic differences in CYP3A4 inhibition by ketoconazole exist and are important when evaluating the impact of concomitant medications.

Mercury speciation in sea food by flow injection cold vapor atomic absorption spectrometry using selective solid phase extraction.

An on-line inorganic and organomercury species separation, preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS or CV-ETAAS) coupled to a flow injection (FI) method was studied. The inorganic mercury species was retained on a column (i.d., 3 mm; length 3 cm) packed to a height of 0.7 cm with a chelating resin aminopropyl-controlled pore glass (550 A) functionalized with [1,5-bis (2 pyridyl)-3-sulphophenyl methylene thiocarbonohydrazyde] placed in the injection valve of a simple flow manifold. Methylmercury is not directly determined. Previous oxidation of the organomercurial species permitted the determination of total mercury. The separation of mercury species was obtained by the selective retention of inorganic mercury on the chelating resin. The difference between total and inorganic mercury determined the organomercury content in the sample. The inorganic mercury was removed on-line from the microcolumn with 6% (m/v) thiourea. The mercury cold vapor generation was performed on-line with 0.2% (m/v) sodium tethrahydroborate and 0.05% (m/v) sodium hydroxide as reducing solution. The determination was performed using CV-AAS and CV-ETAAS, both approaches have been used and compared for the speciation of mercury in sea food. A detection limit of 10 and 6 ng l(-1) was achieved for CV-AAS and CV-ETAAS, respectively. The precision for 10 replicate determinations at the 1 microg l(-1) Hg level was 3.5% relative standard deviation (R.S.D.), calculated from the peak heights obtained. Both approaches were validated with the use of two certified reference materials and by spiking experiments. By analyzing the two biological certified materials, it was evident that the difference between the total mercury and inorganic mercury corresponds to methylmercury. The concentrations obtained by both techniques were in agreement with the certified values or with differences of the certified values for total Hg(2+) and CH(3)Hg(+), according to the t-test for a 95% confidence level. It is amazing how this very simple method is able to provide very important information on mercury speciation.

Quantitative determinations of SiC and SiO2 in new ceramic materials by Fourier transform infrared spectroscopy.

Silicon carbide-based biomorphic ceramics have been fabricated by the pyrolysis and infiltration of natural wood (mukali and pine) with molten silicon. The results of the process of synthesis have been studied in this and other biomorphic ceramics using thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) analysis and scanning electron microscopy (SEM). For evaluating the yield of the synthesis, a new method by Fourier transform infrared spectrometry (FTIR) has been developed for the direct determination of SiC and the simultaneous determination of SiC and SiO2 by absorbance measurements in KBr pellets. The procedure was based on the use of the ratio between the absorbance of the characteristic band of silicon carbide or silica and those of an acetate internal standard added to samples. A multivariate calibration strategy based on inverse least squares and the standard addition approach were employed for quantification. The results obtained for all biomorphic ceramics studied and synthetic samples prepared by mixing pyrolyzed wood with pure SiC were satisfactory. The relative standard deviation for all samples was lower than 2.9%.

Lead ultra-trace on-line preconcentration and determination using selective solid phase extraction and electrothermal atomic absorption spectrometry: applications in seawaters and biological samples.

In this work, a new chelating resin [1,5-bis (2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 A; PSTH-cpg) was synthesised and packed in a microcolumn which replaced the sample tip of the autosampler arm. The system was applied to the preconcentration of lead. When microliters of 10% HNO3, which acts as elution agent, pass through the microcolumn, the preconcentrated Pb(II) is eluted and directly deposited in a tungsten-rhodium coated graphite tube. With the use of the separation and preconcentration step and the permanent modifiers, the analytical characteristics of the technique were improved. The proposed method has a linear calibration range from 0.012 to 10 ng ml(-1) of lead. At a sample frequency of 36 h(-1) with a 90 s preconcentration time, the enrichment factor was 20.5, the detection and determination limits were 0.012 and 0.14 ng ml(-1), respectively and the precision, expressed as relative standard deviation, was 3.2% (at 1 ng ml(-1)). Results from the determination of Pb in biological certified reference materials were in agreement with the certified values. Seawaters and other biological samples were analysed too.

Preconcentration of cadmium, cobalt, copper, nickel and zinc by solvent extraction into methyl isobutyl ketone with 1,5-bis [1-(2-pyridyl) ethylidene] thiocarbonohydrazide and 1,5-bis [phenyl-(2-pyridyl) methylene] thiocarbonohydrazide.

The synthesis, physicochemical properties and interactions of two new thiocarbohydrazones, namely 1,5-bis[1-(2-pyridyl) ethylidene] thiocarbonohydrazide (APTH) and 1,5-bis[phenyl-(2-pyridyl) methylene] thiocarbonohydrazide (BPTH) have been studied as well as the use of both compounds as extracting reagents. These thiocarbohydrazones form yellow complexes with bivalent metal ions, and these are extractable into methyl isobutyl ketone. Conditions for quantitative extraction of Cd(II), Co(II), Cu(II), Ni(II) and Zn(II) are established from a critical study of the effect of pH, shaking time, reagent concentration in the organic phase, ionic strength and volume ratio of aqueous to organic phase.