Simultaneous determination of 20 pharmacologically active substances in cow's milk, goat's milk, and human breast milk by gas chromatography-mass spectrometry

This paper reports a systematic approach to the development of a method that combines continuous solid-phase extraction and gas chromatography-mass spectrometry for the simultaneous determination of 20 pharmacologically active substances including antibacterials (chloramphenicol, florfenicol, pyrimethamine, thiamphenicol), nonsteroideal anti-inflammatories (diclofenac, flunixin, ibuprofen, ketoprofen, naproxen, mefenamic acid, niflumic acid, phenylbutazone), antiseptic (triclosan), antiepileptic (carbamazepine), lipid regulator (clofibric acid), β-blockers (metoprolol, propranolol), and hormones (17α-ethinylestradiol, estrone, 17β-estradiol) in milk samples. The sample preparation procedure involves deproteination of the milk, followed by sample enrichment and cleanup by continuous solid-phase extraction. The proposed method provides a linear response over the range of 0.6-5000 ng/kg and features limits of detection from 0.2 to 1.2 ng/kg depending on the particular analyte. The method was successfully applied to the determination of pharmacologically active substance residues in food samples including whole, raw, half-skim, skim, and powdered milk from different sources (cow, goat, and human breast).     

Microbial removal of lead from solid media and soil

We have isolated a Pseudomonas aeruginosa strain designated CHL004 which is able to remove lead from solidified media and soil. The process for testing removal was generally the same for all experiments. A piece of sterile filter paper was placed on the surface of a plate containing solidified media and lead carbonate or lead contaminated soil and incubated at 29 °C for 30 days. Lead was removed from yeast malt plates but generally not from R2A plates. Dextrose was shown to be a critical component in the YM; without it almost no lead was removed. Sucrose, maltose and lactose could not be substituted for the dextrose although these carbon sources allowed for survival and growth of the isolate. In order to study the initial kinetics of lead uptake, lead nitrate was used in an aqueous environment. The rate of uptake of lead nitrate by CHL004 was very rapid initially then decreased greatly. Sodium azide treated cells did not remove lead. The removal of lead from an urban soil was affected by the pH of the soil. The pH of the soil in YM was 6.9 and 3.3% of the total lead in the soil was removed. When the pH was adjusted to a pH of 5, 8% of the total lead was removed but at a pH of 6, 6.4% was removed.