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Twenty-five species of fish, shrimp and prawn from local markets in Bangladesh were analysed for concentrations of total Fe, haem Fe and non-haem Fe by ICP-MS. Total Fe and non-haem Fe concentrations were measured in nitric acid-digested samples and haem Fe was extracted using acidified 80% acetone for 60 min. Total Fe concentrations ranged from 0.55-14.43 mg/100 g FW, and haem Fe% ranged from 18%-93% of total Fe. Repeat extractions with 80% acetone recovered additional haem Fe, suggesting that previous measurement by this technique may have underestimated haem Fe content. Calculation of Fe balance (summing Fe in acetone extracts and Fe in the residue after haem Fe extraction) was not significantly different from total Fe, indicating the two processes recovered the different forms of Fe with similar effectiveness.

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A unique method for chloride analysis of botanical samples by axially viewed ICP-OES with a modified optical system is described. Calibration on the most sensitive wavelength (134.7 nm) between 1 and 200 mg Cl L À1 yielded a curvilinear relationship (R 2 ¼ 1.000) across three orders of magnitude. The instrumental limits of detection in solution of 0.041 mg L À1 and background equivalent concentration of 5.29 mg L À1 are similar to those of other methods using pneumatic nebulisers. Matrix matching of calibration standards with respect to nitric acid concentration (4% v/v) and carbon levels (0.15% sucrose m/v) of extracted sample solutions produced consistent responses from plant material. High carbon concentrations (up to 8% sucrose m/v) caused matrix interferences that decreased blank values by 4.5 mg L À1 and suppressed Cl signals by 20%. No interferences from countercations were observed. A simple extraction process for dried plant samples (0.1 g in 40 mL of 4% HNO 3 ) was developed and tested with plant standard reference materials. Recovery of Cl from the majority of materials was close to 100% of established values while relative standard deviations were below 4% except when chloride concentration was close to the method detection limit. The extraction method was robust to modifications for samples with low mass or high Cl concentrations.

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