A Damping System for Syringe Pumps Used for Microdialysis with On-Line Electrochemical Detection

Abstract

A syringe pump damping system for microdialysis, coupled on-line with amperometric detection, was developed. The damping system consisted of an air bubble and a fused silica capillary. A bubble volume of 20 µL and a 15 cm capillary, 50 µm i.d., were found to be optimal for flow rates between 1 and 5 µL min -1 . Enhancements of detection limit by 2 orders of magnitude were obtained with this experimental setup.

Development of an On-Line Electrochemical Biosensor for Glucose Determination in Rat Brain Using Microdialysis Sampling

“…The temporal resolution was strongly related to the band spreading phenomenon, which was already described in [27]. We should mention that the repetitive sinusoidal shape of the recorded signal in vivo was caused by syringe pump¯uctuations and may eventually be suppressed in further experiments by implementing a pulse damping system [28]. Interestingly, the ultrathin layer of polyphenol did not exhibit any pulse-damping effects as it has been reported for thick layers [15].…”

Bubble-induced damping in displacement-driven microfluidic flows

“…(11)]; i.e., the responses of ε 1 * , ε 2 * in the diagonalized system [Eq. (12)] are significantly different from each other. Since the fluctuations in flow rates, δ 1 * , δ 2 * , are a linear combination of ε 1 * , ε 2 * , i.e., δ *…”

“…Writingq * i = ∞ n=0 (a i,n e jω n t +ā i,n e −jω n t ) and ε * i = ∞ n=0 (b i,n e jω n t +b i,n e −jω n t ), whereā i,n andb i,n are complex conjugates of a i,n and b i,n , and substituting these series into Eq. (12) reveals that the amplitude ratios |b i ,n |/|a i ,n | are damped for inputs with frequencies above λ 1 and λ 2 , respectively:…”

“…The effect of radial vibration of air bubbles to damp external pressure waves was theoretically explored in detail by previous studies [9][10][11]. Pravda et al [12] achieved 2 orders of magnitude improvement in accuracy of electrochemical detection in microdialysis by introduction of air bubbles in syringes associated with high-resistance microchannels. Very recently, Kang and Yang [13] employed a similar approach and experimentally showed the effects of various parameters such as bubble volume, input frequency, resistance of channels, and other factors on amplitude of output signal with respect to periodic input signal.…”

A non-oxidative electrochemical approach to online measurements of dopamine release through laccase-catalyzed oxidation and intramolecular cyclization of dopamine

“…Among the methods reported so far for DA determination (Uutela et al, 2009;Karimi et al, 2006; measurements, the online measurements are advantageous with respect to their less technical demanding and cost-effective features and near real-time and continuous analytical properties. However, the avoidance of sample collection and separation steps in the online measurements eventually renders the selective electrochemical detection to be a challenge (Niwa, 2005;Kurita et al, 2006;Osborne et al, 1998;Hayashi et al, 2002;Pravda et al, 1996Pravda et al, , 1997. While some excellent strategies have so far been demonstrated to achieve the selectivity both for online electrochemical measurements of other kinds of physiologically important species and for in vivo monitoring of DA, the strategies reported so far are not well applicable to achieve the selectivity for the online electrochemical measurements of DA.…”