Biomedical subjects

H K Hansen

Publications and source records attributed to H K Hansen.

At least 19 recordsLinked to original sources

PubMed2001

Removal of Cu, Pb and Zn in an applied electric field in calcareous and non-calcareous soils.

The pH dependency of the removal of Cu, Zn and Pb by electrodialytic soil remediation from different industrially polluted soils was examined. From 18 experiments performed with five different soils, it was found that the order of mobilization due to a pH decrease was Zn>Cu>Pb. It was found, too, that each of the elements was removed at higher soil pH in calcareous soils (about 12% carbonates) than in soils with a carbonate content of less than 3.7%. In soils rich in carbonates, precipitation of heavy metal carbonates is an important retention mechanism and the heavy metal carbonates are dissolved at higher pH values than the pH at which heavy metals are desorbed in non-calcareous soils. Thus, the relation between the soil pH and the mobility of the heavy metal in the electric field is not only dependent on the heavy metal in focus, but also on the fraction of the heavy metal precipitated as carbonates.

Carbonates↗

PubMed2001

Speciation and mobility of cadmium in straw and wood combustion fly ash.

Two fly ashes from biomass combustion have been analysed regarding cadmium speciation and mobility. A fly ash from straw combustion contained 10 mg Cd/kg dry matter, and around 50% of the cadmium was leachable in water. The possible main speciation of cadmium in this fly ash was CdCl2. When adding this fly ash to agricultural soil a threat for groundwater contamination and plant uptake is existing. A fly ash from wood chip combustion had 28.6 mg Cd/kg dry matter. In this fly ash, the cadmium was bound more heavily, with only small amounts of cadmium leached in mild extractants. A possible speciation of cadmium in this fly ash was as oxide or as CdSiO3. Long-term effects and accumulation of cadmium could be a problem when adding this fly ash to agricultural or forest soils.

Agriculture↗

PubMed1999

Comparison of high-performance liquid chromatography and capillary electrophoresis methods for quantitative determination of glycyrrhizinic acid in pharmaceutical preparations.

A high-performance liquid chromatographic (HPLC) and a capillary electrophoretic (CE) method have been developed for the determination of glycyrrhizinic acid in pharmaceuticals. The two methods have been validated and have been compared with respect to their suitability for the said purpose as well as in relation to requirements from the legal authorities. The HPLC method provide a repeatability of the quantitative analysis of glycyrrhizinic acid below 1% relative standard deviation (RSD) which makes the method suitable when the legal authorities requires the content to be within +/-5% of the declaration. The repeatability of the CE method is in the order of 3-5% RSD when using internal standardization. However, using internal standardization as well as peak normalisation (peak area/migration time) indicate that the RSD may be reduced to about 1%. The CE method is suitable as a stability indication method as the degradation product glycyrrhetinic acid can be determined simultaneously.

Anti-Infective Agents↗

PubMed1995

PCDDs, PCDFs, and PCBs in human milk from different parts of Norway and Lithuania.

Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) as well as 16 polychlorinated biphenyls (PCBs) have been determined in pooled samples of breast milk from 10-12 mothers living in three different geographical areas in both Norway and Lithuania. The results indicate no apparent dependency of the PCDD/PCDF levels, expressed as toxic equivalents (TEQs), and total PCB levels on the geographical residence of the donors within a country. This confirms the findings from a corresponding Norwegian study in 1985/1986 where individual samples from the same areas were analyzed. Teh total TEQs, including dioxin-like PCBs, ranged from 31 to 42 pg TEQs/g fat in Norway and from 45 to 49 pg TEQs/g fat in Lithuania. The mean concentration of PCDDs/PCDFs in teh Norwegian samples (10.4 pg TEQs/g fat) was slightly lower than in the Lithuanian samples (14.8 pg TEQs/g fat). Dioxin-like PCBs were found to contribute two to three times more to the total TEQs than the PCDDs and PCDFs. Major contributors among the dioxin-like PCBs were PCBs 126, 156, 114, 118, and 170. Comparison of the present data with those obtained in the Norwegian study in 1985/1986 shows that for PCDDs/PCDFs the mean TEQ levels have decreased by about 37% in the 7-yr time span, while the levels of total PCBs, as determined by packed-column gas chromatography, have remained unchanged or only slightly decreased. Future studies are necessary to confirm this potential temporal trend.

Animals↗

PubMed1988