A portable colorimetric device is presented for arsenic ion detection in drinking water. The main purpose of this device -which was developed to complement a commercial water dearsenating station demanding regular (weekly to monthly) regeneration runs depending on its saturation -is to provide regular field measurements and easy, semi-automatic operation designed specifically for untrained, typically illiterate users e.g. the population of developing countries. The device exploits a commercially available, well established reagent kit, which is widely used in arsenic field-testing in many developing countries. The hereby presented custom-designed microfluidic system enhances the user-friendliness, the functionality and reliability of the test-strip based kit. The response for total inorganic arsenic ion concentrations (As(III) and As(V)) is linear in the 5-20 μg/l (ppb) range with a sensitivity of 1 μg/l, thus the device is capable to distinguish drinkable water based on the World Health Organization (WHO) guidelines of 10 μg/l. The average relative standard deviation of the measurements is 8 % in the linear range and it is below 2 % for higher arsenic concentrations (above 20 μg/l). The hardware construction of the device and the custom microfluidic system is presented in detail. The effect of elevated water sample temperature on the kinetics and performance of the device was also investigated in order to reduce the required time for the measurements. Stable and reliable arsenic concentration values were obtained after 60 min at 22 o C (ambient temperature) and after only 25 min at 50 o C water sample temperature, but at a cost of an increased relative standard deviation to 16 %, in the linear range.

AbstractOptimal detection of pathogens by molecular methods in water samples depends on the ability to extract DNA rapidly and efficiently. In this study, an innovative method was developed using a microfluidic biochip, produced by microelectrochemical system technology, and capable of performing online cell lysis and DNA extraction during a continuous flow process. On-chip cell lysis based on chemical/physical methods was performed by employing a sufficient blend of water with the lysing buffer. The efficiency of lysis with microfluidic biochip was compared with thermal lysis in Eppendorf tubes and with two commercial DNA extraction kits: Power Water DNA isolation kit and ForensicGEM Saliva isolation kit in parallel tests. Two lysing buffers containing 1% Triton X-100 or 5% Chelex were assessed for their lysis effectiveness on a microfluidic biochip. SYBR Green real-time PCR analysis revealed that cell lysis on a microfluidic biochip using 5% Chelex buffer provided better or comparable recovery of DNA than commercial isolation kits. The system yielded better results for Gram-positive bacteria than for Gram-negative bacteria and spores of Gram-positive bacteria, within the limits of detection at 103 CFU/ml. During the continuous flow process in the system, rapid cells lysis with PCR-amplifiable genomic DNA were achieved within 20 minutes.