Isolation of bacterial culture capable of degrading triphenyltin pesticides

A bacterial culture capable of degrading triphenyltin hydroxide (TPTOH) was successfully isolated from soil samples taken at a dockyard area in Samutprakarn province, Thailand. It was purified, identified and designated as Pseudomonas putida no. C. The bacterium isolated was found to have the capability of degrading TPTOH at levels of 7.0 ppm in 24 h. The addition of glucose enhanced the extent of degradation of TPTOH. Experiments were also conducted to immobilize P. putida no. C on various supports such as sand, cotton fibre and alginate. It was found that alginate was the best support material. Immobilized P. putida no. C on alginate was found to possess suitable characteristics and potential for future development in the removal of TPTOH from water and waste water systems.     

Method development based on all injection analysis for the determination of phosphorus in soil and sediment extracts

In this work, we have modified the technique of all injection analysis (AIA) by changing the position of the detector. The detection is then located as a part of the circulatory loop. With this new detector position, we could monitor for many numbers of circulation. The sensitivity was improved by using the cumulative signal data obtained when the number of circulation rounds was increased. The dilution effect using this new detector location was also less than that with the previous system. We employed a four-channel peristaltic pump to aspirate four types of liquids into the system together at one time. The AIA method was then developed for determination of phosphorus in soils and sediment extracts. The method was optimized for the new harmonized scheme of extraction that has been developed by the European Commission.     

Zone fluidics for measurement of octanol–water partition coefficient of drugs

A novel zone fluidics (ZF) system for the determination of the octanol–water partition coefficient (P_ow) of drugs was developed. The ZF system consisted of a syringe pump with a selection valve, a holding column, a silica capillary flow-cell and an in-line spectrophotometer. Exact microliter volumes of solvents (octanol and phosphate buffer saline) and a solution of the drug, sandwiched between air segments, were sequentially loaded into the vertically aligned holding column. Distribution of the drug between the aqueous and octanol phases occurred by the oscillation movement of the syringe pump piston. Phase separation occurred due to the difference in densities. The liquid zones were then pushed into the detection flow cell. In this method, absorbance measurements in only one of the phase (octanol or aqueous) were employed, which together with the volumes of the solvents and pure drug sample, allowed the calculation of the P_ow. The developed system was applied to the determination of the P_ow of some common drugs. The log (P_ow) values agreed well with a batch method (R² = 0.999) and literature (R² = 0.997). Standard deviations for intra- and inter-day analyses were both less than 0.1log unit. This ZF system provides a robust and automated method for screening of P_ow values in the drug discovery process.     

Treatment of natural rubber latex serum waste by co-digestion with macroalgae, <Emphasis Type="Italic">Chaetomorpha</Emphasis> sp. and <Emphasis Type="Italic">Ulva intestinalis</Emphasis>, for sustainable production of biogas

Biogas production is proposed as an alternative approach to using natural rubber Hevea brasiliensis latex serum, a major waste product from the production of concentrated latex. To make the most efficient use of the reactor size, the addition of macroalgal biomass as a co-substrate to the fermentation system was investigated. The biogas yield of latex serum as a single substrate was (398 ± 14) L per kg of volatile solids added (VSA). For the co-digestion system, algae mixed with serum were investigated at wet mass ratios of Chaetomorpha sp. to Ulva intestinalis to serum at 3:0:1, 2:0:2, 1:0:3, 0:1:3, 0:2:2 and 0:3:1. Theco-digestion system with latex serum at 2 to 3 out of 4 parts produced the highest biogas yields within the range of 422–460 L kg^?1 of VSA. Other parameters such as carbon to nitrogen mass ratio, total solids content and initial pH value were investigated at the constant ratio of 1: 3 of Chaetomorpha sp. to latex serum, and the parameter settings of 15, 10.5 % and 7, respectively, were close to optimal, with an (888 ± 155) Lkg^?1 of VSA cumulative gas yield. The methane yield of the optimised system over 45 days was (197 ± 16) L kg^?1 of VSA and the reduction in COD was (40 ± 4) %. Latex serum, whether alone or co-digested with algae in biogas production, appears to be promising for the management of waste in concentrated latex production.     

Repeatability in column preparation of a reversed-phase C18 monolith and its application to separation of tocopherol homologues

This work investigated the repeatability of column preparation for a reversed-phase C18 monolith, namely stearyl methacrylate-co-ethylene glycol dimethacrylate (SMA-EDMA). The columns were thermally polymerised using three commonly available heating devices (GC oven, hot air oven and water bath) and their chromatographic performance evaluated using micro-liquid chromatography for separation of five test compounds. Precision in terms of %RSD of retention times were 9.0, 6.5, and 12.5 using GC oven, hot air oven and water bath, respectively. Between-batch precision for the hot air oven (n = 3 days) was less than 10.4% for retention time. The SMA-EDMA monolith was applied to the separation of tocopherol homologues by capillary electrochromatography. Usually tocopherol homologues cannot be completely separated by conventional reversed-phase C8- or C18-packed bed or C18-silica based monolithic columns. Polymer monolith has been shown to give remarkable selectivity towards the tocopherols compared to the conventional microparticulate phase and silica based monolith. Successful separation of the tocopherol isomers was achieved on the SMA-EDMA monolith without any column modification.