Validation and application of reporter gene assays for the determination of estrogenic and androgenic endocrine disruptor activity in sport supplements.

Previously developed estrogen and androgen mammalian reporter gene assays (RGAs) were assessed for their potential use as a quantitative screening method in the detection of estrogenic and androgenic endocrine disruptors (EDs) in sport supplements. The validation of both RGAs coupled with dispersive solid phase extraction (dSPE) was performed in accordance with European Commission Decision EC/2002/6579 for biological screening methods. Decision limits (CCa) and detection capabilities (CCß) were established for both the estrogen and androgen RGAs. All samples were compliant with CCa and CCß in both bioassays. Recovery rates were 96 % for 17ß-estradiol and 115 % for dihydrotestosterone as obtained in their corresponding RGA. Both estrogens and androgens were stable in samples for more than 3 weeks, when stored at -20 °C. Specificity, good repeatability (coefficients of variation (CV), 12–25 %), reproducibility and robustness of both bioassays were also observed. Four different ED modes of action were determined for estrogens and androgens in 53 sport supplements, using the validated RGAs. This study revealed that 89 % of the investigated sport supplements contained estrogenic EDs and 51 % contained androgenic compounds. In conclusion, both bioassays are suitable for sport supplement screening of estrogenic and androgenic EDs.

Determination of diclofenac from paediatric urine samples by stir bar sorptive extraction (SBSE)-HPLC-UV technique

A novel stir bar sorptive extraction (SBSE) method coupled with high performance liquid chromatography (HPLC) and UV detection for the extraction of diclofenac (DIC) from paediatric urine samples has been developed and validated. Selectivity and sensitivity being the prime objectives of the bioanalytical method for clinical samples, an optimised SBSE protocol was developed that selectively extracted DIC from various concurrently administered drugs. The validated assay was found to be linear (r=0.9999) over a concentration range of 100-2000 ng mL(-1). SBSE showed consistent recoveries (similar to 70%) of DIC across the validated linearity range. Overall, the method exhibited excellent accuracy and precision across all QC concentrations, tested over three days. Calculated LOD and LOQ were found to be 12.03 ng mL(-1) and 36.37 ng mL(-1), respectively, however, for the experimental purposes, 100 ngmL(-1) was considered as the validated LOQ(accuracy and precision at this LQC was

Standardisation and comparison of methods employed for microbial cell surface hydrophobicity and charge determination

Whilst there are a number of methods available to characterise the cell surface hydrophobicity (CSH) and cell surface charge (CSC) of microorganisms, there is still debate concerning the correlation of results between individual methods. In this study, the techniques of bacterial adherence to hydrocarbons (BATH) and hydrophobic interaction chromatography (HTC) were used to measure CSH. Electrostatic interaction chromatography (ESIC) and zeta potential (ZP) measurements were used to determine CSC. To allow meaningful comparisons between the BATH and HIC tests, between ESIC and ZP and also between CSH and CSC, the buffer systems employed in each test were standardised (phosphate buffered saline, pH 7.3, 0.01 mM). Isolates of Staphylococcus epidermidis derived from microbial biofilm were used as the test organism in this study. The isolates examined exhibited primarily medium to high CSH and a highly negative CSC. Good correlation of CSH measurement was observed between the BATH and HIC tests (r = 0.89). Good correlation was observed between ESIC (anionic exchange column) and ZP measurements. No correlations were observed between isolate CSC and either increased or decreased CSH. It is recommended that whenever comparisons of various methods to determine either CSC or CSH (by partitioning methods), the buffer systems should remain constant throughout to achieve consistency of results.

Strength development of mortars containing ground granulated blast-furnace slag: Effect of curing temperature and determination of apparent activation energies

The strength development of mortars containing ground granulated blast-furnace slag (ggbs) and portland cement was investigated. Variables were the level of ggbs in the binder, water-binder ratio and curing temperature. All mortars gain strength more rapidly at higher temperatures and have a lower calculated ultimate strength. The early age strength is much more sensitive to temperature for higher levels of ground granulated blast-furnace slag. The calculated ultimate strength is affected to a similar degree for all ggbs levels and water-binder ratios, with only the curing temperature having a significant effect. Apparent activation energies were determined according to ASTM C1074 and were found to vary approximately linearly with ggbs level from 34 kJ/mol for portland cement mortars to around 60 kJ/mol for mortars containing 70% ggbs. The water-binder ratio appears to have little or no effect oil the apparent activation energy. (c) 2005 Elsevier Ltd. All rights reserved.

Determination of the drug solubility at the melt temperature in silicone intravaginal rings using dynamic mechanical analysis

92

Confidence factor determination for performance evaluation of lighting pattern

In this paper the authors propose a new technique for determining a confidence factor applied to the performance prediction of individual luminaires within an overall pattern of luminaires. This work has relevance to any application where it is necessary to determine the performance of a lighting pattern e.g. street lighting, signal lighting etc. In this paper we apply our technique to a transportation application, namely, an airport landing lighting pattern. In the aviation industry it is imperative that the landing lighting pattern at individual airports performs according to standards. We have developed an automated technique which can be used to access the performance of luminaires within this pattern. We extend this work to also derive a confidence factor related to this prediction based on the quality of the data being utilised. ©2010 IEEE.

Development of a solid-phase extraction coupling chemiluminescent enzyme immunoassay for determination of organophosphorus pesticides in environmental water samples

Solid-phase extraction (SPE) and direct competitive chemiluminescence enzyme immunoassay (dcCL-EIA) were combined for the detection of organophosphorus pesticides (OPs) in environmental water samples. dcCL-EIA based on horseradish peroxidase labeled with a broad-specificity monoclonal antibody against OPs was developed, and the effects of several physicochemical parameters on dcCL-EIA performance were studied. SPE was used for the pretreatment of water samples to remove interfering substances and to concentrate the OP analytes. The coupling of SPE and dcCL-EIA can detect seven OPs (parathion, coumaphos, phoxim, quinalphos, triazophos, dichlofenthion, and azinphos-ethyl) with the limit of quantitation below 0.1 ng/mL. The recoveries of OPs from spiked water samples ranged from 62.5% to 131.7% by SPE-dcCL-EIA and 69.5% to 112.3% by SPE-HPLC-MS/MS. The screening of OP residues in real-world environmental water samples by the developed SPE-dcCL-EIA and their confirmatory analysis using SPE-HPLC-MS/MS demonstrated that the assay is ideally suited as a monitoring method for OP residues prior to chromatographic analysis.