DEVELOPMENT OF PAPER-BASED ANALYTICAL DEVICE FOR DETECTING DIAZEPAM IN URINE

Objective: The aim of this study was to develop Paper-based Analytical Devices (PADs) with colorimetric method as a presumptive test for detecting diazepam in urine Methods: Colorimetric method was used as a principle of this study. PADs were fabricated with wax-printing methods. Chosen colorimetric reagent was tested for selectivity with hydromorphone and codeine; and sensitivity by measuring the absorbance with UV-Vis spectrophotometer. PADs were tested for its sensitivity and stability. The intensity of color developed on PADs are measured with ImageJ. The ability of PADs to detect diazepam in urine was simulated with testing spiked urine sample to the PADs Results: Zimmermann gave the most obvious prominent color change from colorless to purple-red color out of the four reagents. PAD is selective to diazepam when tested with hydromorphone and codeine. PAD is sensitive with a cut-off concentration at 100 ppm. PAD can detect diazepam in urine with the highest recovery percent at 92.8%±4,6 Conclusion: It can be concluded that PAD is quite selective and sensitive to detect diazepam in urine and can be done easily and fast for onsite analysis

A simple paper-based biosensor for on-site visual detection of organophosphate residues

In general, the laboratory method of analyzing pesticides in vegetables is complicated due to the high cost of equipment and chemicals. The process of analyzing pesticide residues generally requires expertise as well as a significant period of time. In this study, a paper-based biosensor was developed for the detection of acetylcholinesterase (AChE) inhibitors, particularly organophosphate pesticides. The paperbased biosensor was constructed based on the Ellman colorimetric assay by immobilizing AChE on cellulose paper with 2% alginate gel, 0.25% glutaraldehyde and the colorimetric reagent 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB) in phosphate buffer (pH 8.0). As a substrate, acetylthiocholine chloride (ATChCl) was used. The results showed that the developed paperbased biosensor has been stable for 2 weeks with a detection limit of 0.03 mM of chlorpyrifos. The paper-based biosensor was applied to detect organophosphate pesticides in vegetables from the farmers’ market, Ratchaburi Province. It was found that the test results of the paper-based biosensor were similar to the commercial GT-test kit. The paper-based biosensor was 10 times faster than the GT-test kit in terms of testing time and the results were easy to identify due to the color-based indicator. As a result, a paper-based biosensor is rapid, portable and easy to use by the general population.

Arsenic Monitoring in Water by Colorimetry Using an Optimized Leucomalachite Green Method

Arsenic contamination of drinking water is a global concern. Standard laboratory methods that are commonly used for arsenic detection in water, such as atomic absorption spectroscopy and mass spectroscopy, are not suitable for mass monitoring purposes. Autonomous microfluidic detection systems combined with a suitable colorimetric reagent could provide an alternative to standard methods. Moreover, microfluidic detection systems would enable rapid and cost efficient in situ monitoring of water sources without the requirement of laborious sampling. The aim of this study is to optimize a colorimetric method based on leucomalachite green dye for integration into a microfluidic detection system. The colorimetric method is based on the reaction of arsenic (III) with potassium iodate in acid medium to liberate iodine, which oxidizes leucomalachite green to malachite green. A rapid colour development was observed after the addition of the dye. Beer’s law was obeyed in the range between 0.07–3 µg mL−1. The detection limit and quantitation limit were found to be 0.19 and 0.64 µg mL−1, respectively.

Who is ‘Molly’? MDMA adulterants by product name and the impact of harm-reduction services at raves

Methylenedioxymethamphetamine (MDMA), often sold as ‘Ecstasy’ or ‘Molly’, is commonly used at music festivals and reported to be responsible for an increase in deaths over the last decade. Ecstasy is often adulterated and contains compounds that increase morbidity and mortality. While users and clinicians commonly assume that products sold as Molly are less-adulterated MDMA products, this has not been tested. Additionally, while pill-testing services are sometimes available at raves, the assumption that these services decrease risky drug use has not been studied. This study analyzed data collected by the pill-testing organization, DanceSafe, from events across the United States from 2010 to 2015. Colorimetric reagent assays identified MDMA in only 60% of the 529 samples collected. No significant difference in the percentage of samples testing positive for MDMA was determined between Ecstasy and Molly. Individuals were significantly less likely to report intent to use a product if testing did not identify MDMA (relative risk (RR) = 0.56, p = 0.01). Results suggest that Molly is not a less-adulterated substance, and that pill-testing services are a legitimate harm-reduction service that decreases intent to consume potentially dangerous substances and may warrant consideration by legislators for legal protection. Future research should further examine the direct effects of pill-testing services and include more extensive pill-testing methods.