Extraction of hydrocarbon contamination from soils using accelerated solvent extraction.

Accelerated solvent extraction was studied as a method for the extraction of hydrocarbon contamination from wet and dry soils. Temperatures from 125 to 200 degrees C and six different solvents were investigated. Nonpolar solvents could not achieve complete recovery from wet soils at the temperatures studied. Optimum conditions were found to be 175 degrees C with dichloromethane-acetone (1:1, v/v) with 8 min heat-up time and 5 min static time. Quantitative recoveries for diesel range organics (DROs) and waste oil organics (WOOs) were obtained using the optimized conditions. The recovery of DROs and WOOs from three matrices at two concentrations (5 and 2000 mg/kg) averaged 115%. These results show that accelerated solvent extraction can generate results comparable to those obtained using Soxhlet or sonication.

The supercritical fluid extraction of polar drugs (sulphonamides) from inert matrices and meat animal products.

The objective of this study was to examine the extension of supercritical fluid extraction (SFE) to the extraction of polar drugs. The ultimate aim was to extract veterinary residues from food animal products and thereby demonstrate the versatility of SFE. This technique is shown to have many facets that require careful thought and understanding if it is to be successfully used. Our initial studies indicate that polar drugs may be readily solubilized from relatively inert matrices such as sand, with high recoveries and very little discrimination between related compounds while using only moderate extraction conditions and times. SFE of the same drugs from spiked chicken liver and swine muscle is significantly more difficult and requires more drastic conditions. Close to complete recoveries are achieved for some drugs, while considerably less is found in the worst case. For sulphamerazine, sulphamethizole, sulphamethazine, sulphamethoxypyridazine, sulphamethoxazole, and the major metabolite N4-acetyl-sulphamethoxazole, the recoveries are 97, 66, 94, 79, 53, and 65%, respectively, from spiked liver and 95, 27, 86, 91, 96 and 70%, respectively, from spiked swine muscle. Incurred sulphamethazine is recovered from swine muscle in good general agreement with the reference values provided.

Analysis of various classes of drugs by capillary supercritical fluid chromatography.

Three classes of drugs were screened for analysis feasibility by capillary column supercritical fluid chromatography. These included steroids, therapeutic antibiotic drugs, and drugs of abuse, such as cannabinoids. Supercritical fluid carbon dioxide was used as the mobile phase in conjunction with a methylpolysiloxane stationary phase capillary column and a flame ionization detector. All compounds considered were analyzed either as single component solutions, simple mixtures, or in actual complex mixtures.

Comparison of serum total calcium, dialyzable calcium, and dialyzable magnesium in well and sick neonates.

We studied the relation of serum total calcium, dialyzable calcium, and dialyzable magnesium in 61 well and sick newborn infants aged 7-76 h. The infants' serum total calcium, dialyzable calcium and magnesium concentrations (ion chromatography method) were studied in comparison with the infant's history and sickness scale. We found that serum total calcium and dialyzable magnesium were lower in sick infants compared to well infants. Both serum total and dialyzable calcium concentrations initially decreased and then increased by about 30 h of age. Serum dialyzable magnesium concentrations increased with our infants' age. Serum total calcium values correlated significantly with the infant's birth weight, gestational age, 1-min Apgar score, respiratory distress, severity of sickness, serum bilirubin and sodium concentrations.