Reducing the channel diameter of polydimethylsiloxane fluidic chips made by a 3D-printed sacrificial template and their application for flow-injection analysis.

Fluidic chips have attracted considerable interest in recent years for their potential applications in analytical devices. Previously, we developed a method to fabricate polydimethylsiloxane (PDMS) fluidic chips via templates made using a low-priced commercial Fused Deposition Modeling (FDM) type 3D printer and polymer coatings. However, in general, methods using a template cannot form a flow channel thinner than the template thickness and the width. In this study, the inner wall of a PDMS fluidic chip was coated with PDMS to create a chip with a channel inner diameter smaller than a template. Then, by measuring the flow signal of methyl orange with a single line, the basic properties of the non-coated and coated chip were investigated. As a result, almost the same flow profile was obtained in non-coated and coated chips at the same linear velocity and the same sample injection length. By coating and narrowing the channel width, it is possible to save the amount of sample and carrier solution. Measuring hydrazine in water using a coated chip was also tried. The calibration curve indicated good linearity in the range of 1-6 ppm. However, a concentration point of 7 ppm deviated. The reason for this deviation was presumably due to inadequate mixing of the sample and reagent. By decreasing the flow rate, the calibration curve indicated good linearity in the range of 1-7 ppm.

Low-cost Methods for Making 3D Fluidic Polymer and Glass Chips Using Metal Templates.

Microfluidics is a rapidly growing field in which small volumes of liquid are moved through channels in a large variety of applications. Fabricating such channels can be expensive. Here, we describe an inexpensive method for making 3D channels in fluidic chips by using a sacrificial template made of coated metal wire or metal tubes. A 3D template is embedded in polymer or glass and then dissolved, leaving channels in the chip, without the need for expensive instruments. By changing the mold, chips of various shapes can be made.

Separation of adenine, adenosine-5'-monophosphate and adenosine-5'-triphosphate by fluidic chip with nanometre-order diameter columns inside porous anodic alumina using an aqueous mobile phase.

Adenine, adenosine-5'-monophosphate and adenosine-5'-triphosphate were separated by fluidic chip with PAA membranes using an aqueous mobile phase.

Study of solid-phase extraction for the determination of sequestering agents in river water by high-performance liquid chromatography.

Anion-exchange solid-phase extraction accompanied with high-performance liquid chromatography has been developed for the determination of six kinds of aminopolycarboxylic acids (APCAs) in river water [N-(2-hydroxyethyl)ethylenediaminetriacetate (HEDTA), ethylenediaminetetraacetate (EDTA), 1,3-propanediaminetetraacetate (PDTA), diethylenetriaminepentaacetate (DTPA), 1,2-propanediaminetetraacetate (MeEDTA), and O,O'-bis(2-aminoethyl)ethyleneglycoltetraacetate (GEDTA)]. The enrichment of APCAs using an anion-exchange cartridge was successfully done by the removal of anions, which competed with APCAs in anion-exchange processes. Barium chloride solution was added to river water and the mixture was passed through On Guard II Ag and H cartridges and then a Bond Elut Jr.SAX cartridge to enrich APCAs. After elution, APCAs were analyzed on two reversed phase C30 columns connected in series and detected with ultraviolet detection. The enrichment using solid-phase extraction permitted the determination of APCAs in river water at concentrations as low as 1nM. Good recoveries (83-111%) were obtained for each APCA by the standard addition method on three river water samples with high accuracy (RSD 1.8-9.5%). Applying this method, two kinds of APCAs, EDTA and DTPA, were determined in samples from the Oyabe and Senbo Rivers in Japan.