Biopolymer Test Kit for Colorimetric Detection of Chlorine in Water

The objective of the study was to fabricate the colorimetric sensor of biodegradable material for free chlorine determination. The colorimetric reagent of N,N-diethyl-p-phenylenediamine sulfate (DPD) was entrapped in the hybrid biopolymer film of agar (AG) and tapioca starch (TAS) and it was coated on the plastic micro-PCR tube. The pink product obtained from the reaction between DPD reagent and chlorine could indicate the presence of residual chlorine in the water.  The condition for the sensor film synthesis was optimized by the digital image analytical technique with mobile phone application. The results were showed that Red-Green-Blue (RGB) intensity of reaction product was not changed, even through the DPD reagent was added over 0.2 g/mL. The addition of 16 g/L EDTA in the buffer solution could reduce the interference effect from some metals, especially Fe3+, contaminated in water sample. The water pH could be maintained for best analysis at the volume ratio between buffer and DPD solution of 0.5:1. The incubation of colorimetric film at 60 °C and 60 minutes provided the best sensor performance with fast analysis of 1 min reaction time. In conjunction with the digital image colorimetry (DIC), the developed test kit did not provided only the qualitative information, but the rapid quantitative analysis could be also fulfilled. A wide linear range of 0.3 to 15 mg/L chlorine concentration with good linearity (R2 > 0.99) was achieved by this coupled technique. The application of biopolymer film to various kind of real water samples showed the good performances, which were comparable with the standard spectrophotometry (no significantly different results at 95% confidence level). These could promote the use of biopolymer test kit as the environmentally-friendly analytical method for chlorine in water

Plastic/Natural Fiber Composite Based on Recycled Expanded Polystyrene Foam Waste

A novel reinforced recycled expanded polystyrene (r-EPS) foam/natural fiber composite was successfully developed. EPS was recycled by means of the dissolution method using an accessible commercial mixed organic solvent, while natural fibers, i.e., coconut husk fiber (coir) and banana stem fiber (BSF) were used as reinforcement materials. The treatment of natural fibers with 5% (w/v) sodium hydroxide solution reduces the number of –OH groups and non-cellulose components in the fibers, more so with longer treatments. The natural fibers treated for 6 h showed rough surfaces that provided good adhesion and interlocking with the polymer matrix for mechanical reinforcement. The tensile strength and impact strength of r-EPS foam composites with treated fibers were higher than for non-filled r-EPS foam, whereas their flexural strengths were lower. Thus, this study has demonstrated an alternative way to produce recycled polymer/natural fiber composites via the dissolution method, with promising enhanced mechanical properties

A comprehensive chromatographic comparison of amphetamine and methylamphetamine extracted from river water using molecular imprinted polymers and without the need for sample derivatization

This work explores the differences between two GCMS instruments for the determination of amphetamine and methylamphetamine extracted from water samples (ultra pure water and river water) without the necessity for derivatization. The instruments contained different generations of gas chromatograph and mass selective detector components and revealed significantly different results when presented with the same samples. The extraction methodology also compared two SPE systems. The extraction efficiency of commercially available molecular imprinted polymers as a sorbent in SPE was compared with commonly used hydrophilic balance sorbent. Molecular imprinted polymers provided excellent recoveries (81 +/- 2% and 108 +/- 3% at 30 mu g L-1, and 94 +/- 2% and 94 +/- 2% at 200 mu g L-1 for amphetamine and methylamphetamine, respectively). The best LOD obtained was sufficient for the determination of both drugs extracted from river water (0.029 +/- 0.003 and 0.015 +/- 0.004 mu g L-1 for amphetamine and methylamphetamine, respectively). These were comparable to literature values obtained through conventional extraction and analysis using LC-MS/MS but had the advantage of being achieved using an underivatized GCMS method