Analysis of 12 beta-lactam antibiotics in human plasma by HPLC with ultraviolet detection

A simple and economical high performance liquid chromatography method was developed and validated for routine analysis of 12 Penicillin, Cephalosporin and Carbapenem antibiotics in 200 μL of human plasma. Antibiotics determined were Ceftazidime, Meropenem, Ceftriaxone, Ampicillin, Cefazolin, Ertapenem, Cephalothin, Benzylpenicillin, Flucloxacillin, Dicloxacillin, Piperacillin and Ticarcillin. There was a common sample preparation approach involving precipitation of proteins with acetonitrile and removal of lipid-soluble components by a chloroform wash. Separations were performed on a Waters X-bridge C18 column with, depending on analytes, one of three acetonitrile–phosphate buffer mobile phases. Detection was by UV at 210, 260 and 304 nm. Validation has demonstrated the method to be linear, accurate and precise. The method has been used in a pathology laboratory for therapeutic drug monitoring (TDM) of beta-lactams in critically ill patients.     

Concentration of enteroviruses from large volumes of tap water, treated sewage, and seawater.

Methods are described for the efficient concentration of an enterovirus from large volumes of tap water, sewage, and seawater. Virus in acidified water (pH 3.5) in the presence of aluminum chloride was adsorbed to a 10-inch (ca. 25.4 cm) fiberglass depth cartridge and a 10-inch pleated epoxy-fiberglass filter in a series at flow rates of up to 37.8 liters (10 gallons) per min. Adsorbed viruses were eluted from the filters with glycine buffer (pH 10.5 to 11.5), and the eluate was reconcentrated by using a combination of aluminum flocculation followed by hydroextraction. With this procedure, poliovirus in large volumes of tap water, seawater, and sewage could be concentrated with an average efficiency of 52, 53, and 50%, respectively. It was demonstrated that this method is capable of detecting surface solid-associated viruses originating from sewage treatment plants. No difference in virus recovery between laboratory batch studies and a set-up with acid-salt injection was found. This unified scheme for the concentration of viruses has many advantages over previously described systems. These include: high operating flow rates, low weight and small size, effectiveness with a variety of waters with widely varying qualities, and filters with a high resistance to clogging.     

Effect of disk rotational speed on heavy metal accumulation by rotating biological contactor (RBC) biofilms

The efficiency of a rotating biological contactor (RBC) in the treatment of waters contaminated with cadmium, copper and zinc, in particular the effect of rotational speed, namely 3, 15 and 25 rev min⁻¹, on heavy metal reclamation was evaluated. Atomic absorption spectrophotometric analysis indicated > 92% and < 20% removal of copper (Cu²⁺) and zinc (Zn²⁺), respectively. Cadmium (Cd²⁺) levels, however, remained constant. Similar results were obtained at all three rotation speeds tested.     

Determination of pentose sugars in fermentation solutions by a simple gas chromatographic procedure

Summary Pentoses in aqueous acidic solutions were analysed by conversion to furfurals in a gas chromatograph containing a porous polymer packed column at 200°C. Hexoses, volatile fatty acids and fermentation media did not interfere with the measurement of pentoses.     

Use of quin 2 to measure calcium concentrations in ovine anterior pituitary cells and the effects of quin 2 on secretion of growth hormone and prolactin

Intracellular free Ca2+ concentrations [Ca2+]i were measured in ovine anterior pituitary cells using the quin 2 technique. Thyrotropin-releasing hormone (TRH) increased, dopamine decreased and growth hormone-releasing hormone (GHRH) had no detectable effect on [Ca2+]i. Loading the cells with quin 2, at an intracellular concentration less than that used during calcium determination, reduced both basal growth hormone (GH) and (to a small extent) prolactin secretion. Loading cells with quin 2 also markedly reduced GHRH-stimulated GH secretion. However, TRH-stimulated prolactin secretion was 3-times basal irrespective of quin 2 loading. The results indicate that the use of quin 2 to measure [Ca2+]i in some cell types may be complicated by actions of quin 2 on cellular function.