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Toxicity testing of four heavy metals (Cd, Cu, Mn and As) using four species of tropical marine phytoplankton, Chaetoceros calcitrans, Isochrysis galbana, Tetraselmis tetrahele and Tetraselmis sp., was carried out in multiwell plates with test volumes of 2 mL and the results compared to those of standard, large volume, shake-flasks. IC50 values (concentrations of metals estimated to inhibit 50% growth relative to the control) were determined after 96 hours based on automated O.D. readings measured in Elisa microplates by a Multiskan spectrophotometer. Good agreement was achieved between O.D. readings and cell counts indicating that this new method is a simple, economical, practical and rapid technique for toxicity testing, and provides good reproducibility of IC50 values. Results of the toxicity tests indicate that Cu was the most toxic metal (average IC50 values ranging from 0.04 to 0.37 mg L(-1)), followed by Cd (0.06-5.7 mg L(-1)), Mn (7.2-21.4 mg L(-1)) and As (33.9-319.3 mg L(-1)). Test species had different degrees of sensitivity to the metals tested, with I. galbana and C. calcitrans the most sensitive to Cu, Cd and Mn. Based on these findings it is recommended that the existing Malaysian Interim Standards for Marine Water Quality for Cd and Cu be reviewed.

A convenient method, not involving ashing or acid digestion, for the determination of inorganic phosphorus content in crude palm oil, is developed. Direct extraction from solvent-diluted palm oil by dilute acid allows the inorganic phosphates to be analyzed by the usual phosphomolybdenum blue complex. Using this method, phosphate analyses in palm oil samples were correlated with other oil quality parameters and the results discussed.

Phospholipids, selectively extracted from crude palm oil and free of colored carotenoids, can be quantitatively determined by the phospholipid‐molybdenum blue complex in hexane. A study of the phospholipid in crude palm oil in relationship to other components affecting oil quality shows that they have a beneficial effect while any detrimental effect may be of an indirect nature.

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