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A new portable instrument that includes a high voltage power supply, a bipotentiostat, and a chip holder has been especially developed for using microchips electrophoresis with electrochemical detection. The main unit of the instrument has dimensions of 150 x 165 x 70 mm (wxdxh) and consists of a four-outputs high voltage power supply with a maximum voltage of +/-3 KV and an acquisition system with two channels for dual amperometric (DC or pulsed amperometric detection) detection. Electrochemical detection has been selected as signal transduction method because it is relatively easily implemented, since nonoptical elements are required. The system uses a lithium-ion polymer battery and it is controlled from a desktop or laptop PC with a graphical user interface based on LabVIEW connected by serial RS232 or Bluetooth. The last part of the system consists of a reusable chip holder for housing the microchips, which contain all the electrical connections and reservoirs for making the work with microchips easy. The performance of the new instrument has been evaluated and compared with other commercially available apparatus using single- and dual-channel pyrex microchips for the separation of the neurotransmitters dopamine, epinephrine, and 3,4-dihydroxy-L-phenyl-alanine. The reduction of the size of the instrument has not affected the good performance of the separation and detection using microchips electrophoresis with electrochemical detection. Moreover, the new portable instrument paves the way for in situ analysis making the use of microchips electrophoresis easier.

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A novel ready-to-use portable microfluidic platform was adapted for analysis of uric acid and related compounds in urine samples. Microfluidic devices, especially microchips electrophoresis (ME), are very attractive for clinical and pharmaceutical analysis. Thus, a novel portable and easy-to-handle instrument, HVStat (165 Â 150 Â 85 mm), based on microfluidic electrophoresis chips with amperometric detection was used for the determination of uric acid and interfering compounds (ascorbic acid, paracetamol, epinephrine.) in urine samples. Moreover, the microfluidic platform performance is controlled by a user-friendly PC interface (MicruXÒ Manager) especially designed for the use of microchips electrophoresis with electrochemical detection. The adapted analysis methodology at portable microfluidic platform allows the separation and detection of uric acid and related compounds in less than 90s with minimal sample pre-treatment. Thus, the uric acid is directly detected without previous enzymatic based-reactions or other complex pretreatment. The urine sample is simply diluted in the buffer solution and injected directly in the microchip where the uric acid is separated and detected at the platinum electrode of a SU-8/Pyrex microfluidic chip. The microfluidic chips were used for several analyses with a good performance and precision, decreasing drastically the cost and time per analysis.Thus, the complete microfluidic platform, including the main instrument, reusable holder and microchips, has been demonstrated as an excellent analytical tool for fast and reliable urine analysis.