Biomedical subjects

K R Lum

Publications and source records attributed to K R Lum.

3 recordsLinked to original sources

PubMed1996

Determination of alpha-, gamma(+ beta)-, and delta-tocopherols in a variety of liver tissues by reverse-phase high pressure liquid chromatography.

A modified version of a previously published extraction technique using acetone as the extracting medium and separation on an HPLC equipped with a Spherisorb C18 ODS2 column packed with 3 micron particles along with a suitable flow rate and mobile phase significantly improves the resolution of the chromatographic output (fluorescence detector), allowing for accurate measurement of alpha-, delta- and gamma(+ beta)-tocopherols. It was found that two extractions of the same sample yielded approximately 97% of the total extractable alpha-tocopherol. Vitamin C was not needed as an anti-oxidant to protect alpha-tocopherol during extraction from chicken liver but was needed when using fish liver. alpha-tocopherol was found not to be evenly distributed in beef, chicken or fish liver.

Animals↗

PubMed1987

Export of mirex from Lake Ontario to the St. Lawrence Estuary.

The relative importance of migrating eels and suspended particulate material (biotic and abiotic) as transporters of mirex from Lake Ontario to the St. Lawrence River Estuary is evaluated in the context of a possible adverse impact on the St. Lawrence beluga population. Our estimates suggest that transport of mirex out of Lake Ontario by eels (2270 g annually) is almost twice that due to suspended particulate flux (1370 g annually). Mass balance calculations for mirex in Lake Ontario indicate that transport by migrating eels and particulate matter, combined with coverage of surficial sediments by continuing deposition of new material, could effectively "cleanse" Lake Ontario of mirex inputs in 100 years or less. Using mirex as a prototype to simulate the fate of hydrophobic organic chemicals in Lake Ontario led to a revised sediment budget for this final lake in the Great Lakes-St. Lawrence system. According to this budget, 94% of the suspended particulate material entering Lake Ontario is retained in the depositional basins and, by inference, most hydrophobic organic contaminants and metal forms having a dominant association with the particulate phase, would be expected to behave in a similar fashion.

Animals↗

PubMed1983

Zeeman effect electrothermal atomic absorption spectrophotometry with matrix modification for the determination of arsenic in urine.

Arsenic was determined in urine by electrothermal atomic absorption spectrophotometry using Zeeman Effect background correction and after matrix modification with 5% nickel nitrate. Mean recovery of urine samples spiked with 100 micrograms . L-1 dimethylarsinic acid was 97.9 micrograms . L-1. Within-run CV was 2.4%, between-run CV was 7.3% and the detection limit was determined to be 10.0 micrograms . L-1. The method can be used for the rapid screening of urine samples for elevated arsenic levels.

Arsenic↗