Determination of Ca,K,Mg and Fe in Four Fish Species by FAAS

A method for determining calcium （Ca）, potassium （K）, magnesium （Mg） and iron （Fe） in four fish species was opti- mized and validated. It included microwave mineralization of the samples and subsequent quantification by flame atomic absorption spectroscopy （FAAS） with Zeeman-effect background correction. Using HNO3 （65%） and H202 （33%） as extraction solutions, the optimal conditions of extraction were established as follows： 0.5 g of sample mass; microwave time program of 300 W/5 min and 600 W/5 min. The method was free of matrix interferences. The linear correlation coefficients were ≥0.9991, the recovery percentage of analytes was from 99.31% to 103.70% and the RSD （relative standard deviation） was lower than 2.06%. The detection limits obtained were 32.3, 43.2, 14.0 and 68.6ng mL^-1 for Ca, K, Mg and Fe in FAAS respectively. It is shown that the method is rapid, simple, sensitive and accurate. The method was applied to the studies of digestibility and measurement of these nutrients in samples of fish collected from Norway, Japan and China.

Preconcentration and Separation of Trace Copper in Water Samples with Nanometer-Size TiO_2 Colloid and Determination by FAAS

A new absorbent of nanometer-size TiO2 colloid for Cu（Ⅱ ） was studied in this work. The adsorption rate could reach above 99% when the pH values were at the range of 5-6. The adsorption balance time, adsorption capacities, and the eluent were investigated. A novel method of trace Cu（ Ⅱ ） preconcentration and separation with nanometer-size titanium dioxide colloid and determination by flame atomic absorption spectrometry （FAAS） was advanced. The detection limit （3a） of the method was 1.15 μg · L^-1, and the relative standard deviation （R.S.D） was 1.53% （n=6）. Environmental sample experiments were also conducted to test the feasibility of the method, and it came out that the recovery rates were between 95.9% and 97.8%.

Primary Speciation Analysis on 6 Kinds of Microelements in Glycyrrhiza uralensis Fisch.

[Objective]The aim was to analyze the primary speciation of 6 microelements in Glycyrrhiza uralensis Fisch. and provide theoretical basis for explaining pharmacodynamic principle of liquorice and discussing quality control of liquorice planting. [Method]The 6 elements Cu,Zn,Ca,Fe,Mg and Mn in roots of G.uralensis were extracted based on traditional decoction method and were separated into water-soluble state and suspension state by micro porous filtering film. The elements in water-soluble state were detected by flame atomic adsorption spectrophotometry （FAAS）. [Result]The results showed that extractive rates of the elements were in the range of 1.71%-60.06%,and immerse-residue ratio in 0.018 3-1.682 0; the results also indicated that the immerse-residue ratio of Zn was biggest （1.68）,Zn played an important medical role and might be considered as the best characteristic element in G.uralensis; the recoveries of the elements were ranged from 95.72% to 103.15% and relative standard deviations （RSD） were less than 2.38%. [Conclusion]Because of its high accuracy,FAAS method is feasible for analyzing primary speciation of microelements in G.uralensis.

On-line Preconcentration and Determination of Trace Metals in Water Samples by Flow Injection Combined with Flame Atomic Absorption Spectrometry via Calix[4]arene Carboxylic Acid Packed Micro-column

An adsorbent calix[4]arene carboxylic acid was employed as the adsorption material for on-line flow in jection（FI） micro-column preconcentration coupled with flame atomic absorption spectrometry（FAAS） determination of trace heavy metals（Cu, Pb, Co, Ni and Cd）. Parameters such as the pH, loading time and flow rate of sample, and the concentration, volume and flow rate of eluent were optimized. The enrichment factors are 50.0, 56.5, 11.6, 12.1 and 19.1 for Cu, Pb, Co, Ni, and Cd, respectively, and a sample throughput of 20 h–1 was obtained. The limits of de tection for Cu, Pb, Co, Ni, and Cd were in a range of 1.56―3.91 μg/L, and the relative standard deviations（RSDs） were less than 2.76%（n=7）. Furthermore, the proposed method was successfully applied to the determination of Cu, Pb, Co, Ni, and Cd in certified reference materials and various water samples.