An inductively coupled plasma-mass spectrometer (ICP-MS) equipped with a dynamic reaction cell (DRC) was used as a liquid chromatographic detector for the determination of chromium species. In this study, ionic chromium species (Cr III and Cr VI ) were separated by reversed-phase liquid chromatography (LC) with a C 8 column as the stationary phase and 0.6 mmol l 21 EDTA, 2 mmol l 21 tetrabutylammonium phosphate and 2% v/v methanol solution (pH 6.9) as the mobile phase. The potentially interfering 40 Ar 12 C z , 35 Cl 16 OH z , 40 Ar 12 CH z and 37 Cl 16 O z at the chromium masses m/z 52 and 53 were reduced in intensity by approximately three orders of magnitude by using 0.65 ml min 21 NH 3 as reaction cell gas in the DRC. Effluent from the LC column was delivered to the nebulization system and the ICP-MS for the determination of chromium. The repeatability of the peak area was better than 2% at m/z 52. The limits of detection for Cr III and Cr VI were 0.063 and 0.061 ng ml 21 Cr at m/z 52, respectively, based on peak height. The concentrations of chromium species have been determined in several water samples collected from Kaohsiung area. The recovery was in the range of 90-110% for all the determinations.
An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with a dynamic reaction cell (DRC) was used for the determination of chromium in water and urine samples. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio. The potentially interfering 40 Ar 12 C z , 35 Cl 16 OH z , 34 S 18 O, 40 Ar 12 CH z and 37 Cl 16 O z ions at the chromium masses m/z 52 and 53 were reduced in intensity by approximately 2-3 orders of magnitude by using 1.0 ml min 21 NH 3 as reaction cell gas in the DRC while a q value of 0.6 was used. The limits of detection for 52 Cr and 53 Cr were 0.015 and 0.024 ng ml 21 Cr, respectively. This method was applied to determine Cr in NRCC SLRS-3 Riverine Water reference sample, NIST SRM 1643d Trace Elements in Water, NIST SRM 2670 Urine reference sample and several water and urine samples collected locally. The external calibration method and isotope dilution method were used for the determination of Cr in selected samples. The results for the reference samples agreed satisfactorily with the reference values. Results for other samples analyzed by different quantitation methods agreed satisfactorily. Precision between sample replicates was better than 20% for most of the determinations.
This research work aims to characterize and model the failure initiation in bainite-aided dual-phase (DP) steel. Combined electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) measurements were applied to quantify the constituents (ferrite, martensite, and bainite) in the microstructure. Mini tensile test with digital image correlation (DIC) analysis was carried out and linked to local scanning electron microscopy (SEM) analysis to identify macroscopic failure initiation strain values. SEM measurements showed that the crack initiation occurs in martensite islands. A microstructure-based approach by means of representative volume elements (RVE) modeling combined with extended finite element method (XFEM) was utilized to model martensite cracking on mesoscale. The identified parameters were validated by comparing the predictions with the experimental results.
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