In this study, the concentrations of selected toxic metals (Pb, As, Cd) and essential elements (Zn, Cu) of local canned seafood including sardines, tuna, anchovies, shellfish (mussels and cockles), prawns, mackerel and cuttlefish were determined. All 30 samples were purchased from supermarkets in Nilai, Negeri Sembilan. The highest concentration of trace metals in all samples was Zn which is 38.96 +/- 0.56 mg/kg, followed by Cu (2.40 +/- 0.57 mg/kg), Pb (1.71 +/- 0.71 mg/kg), As (0.96 +/- 0.70 mg/kg) and Cd (0.25 +/- 0.70 mg/kg). The average concentration of toxic elements were the highest in anchovy species with concentration of 6.93 mg/kg followed by shellfish (4.24 mg/kg), mixed seafood (4.17 mg/kg), cuttlefish (3.63 mg/kg), prawns (3.28 mg/kg), sardines (2.65 mg/kg), tuna (1.68 mg/kg) and the lowest which is mackerel (1.36 mg/kg). The results were compared with the previous studies.

The microwave digestion method was developed and verified for the determination of arsenic in shrimp paste samples. Experimental design for five factors (HNO3 and H2O2 volumes, sample weight, microwave power and digestion time) were used for the optimisation of sample digestion. For this purpose, two level half factorial design, which involves 16 experiments, was adopted. The concentration of arsenic was analysed by graphite furnace atomic absorption spectrometry. Design Expert(R) 7.0 software was used to interpret all data obtained. The combination of 2 mL HNO3 and 1 mL H2O2 volumes, 0.1 g sample weight, 1400W power and 5 min digestion time was found to be the optimum parameters required to digest the shrimp paste samples. Tests with spiked samples presented good recoveries with relative standard deviations between 0.32% and 5.35%. (C) 2012 Elsevier Ltd. All rights reserved.

Determination of Al(III) from aqueous samples using Chrome Azurol S (CAS) as reagent immobilized in polymer inclusion membranes (PIMs) was discussed. The PIMs was prepared using poly (vinyl chloride) (PVC), 2-nitrophenyl octyl ether (2-NPOE) and Aliquat 336 as polymer matrix, solvent and ion carriers respectively. Experimental designs for four factors (weight of PVC, Aliquat 336, 2-NPOE, and the concentration of CAS) were used for the optimization of the membrane fabrication. For this purpose, a two level half factorial design, which involves eight experiments, was adopted. The combination of 200 mg of PVC, 50 mg of Aliquat 336, 50 mg of 2-NPOE and 1 x 10(-3) mol/L CAS was found to be the optimum formulation for the preparation of PIMs. Wide dynamic range of Al(III) determination (0.2-50 ppm), better reproducibility within the same batch, good repeatability and photostability with RSD 1.21% and 0.93%, respectively. The calculated t values indicated that there is no significant difference between the two methods at the 95% confidence level and thus there is no bias in the method. (C) 2014 Elsevier B.V. All rights reserved.