Design and experiment of high-field asymmetric waveform ion mobility spectrometry chip based on an integrated temperature control printed circuit board structure.

RATIONALE: During the detection of volatile organic compounds (VOC) using high-field asymmetric waveform ion mobility spectrometry (FAIMS), the ambient temperature significantly impacts the accuracy of planar FAIMS. To mitigate the influence of ambient temperature on detection accuracy and enhance resolution, a FAIMS system based on the inner impedance characteristics of a printed circuit board (PCB) was designed for temperature control. METHODS: This study, conducted under standard atmospheric pressure, aimed to assess the signal stability of a planar FAIMS instrument with and without temperature control, and the effect of temperature change on the detection ability of acetone, ethanol, and their mixture was studied using PCB self-heating. RESULTS: Experimental results demonstrated that the base noise in FAIMS with temperature control was 0.2 pA, whereas that in FAIMS without temperature control was 1.8 pA. Notably, with increasing temperature, the detection ability of FAIMS changes accordingly. The optimal relative detection ability of acetone was observed when the electrode plate was heated to 45°C under an electric field of 15 kV/cm. CONCLUSIONS: This study provides a novel approach to improve the resolving power of FAIMS systems and their signal-to-noise ratio. The utilization of a PCB-based temperature control proved effective in stabilizing FAIMS signal characteristics and optimizing detection capabilities, particularly for VOCs such as acetone. These findings have significant implications for improving the accuracy and resolving power of FAIMS systems in VOC detection applications.

Interaction Study of Ferrocene Derivatives and Heme by UV-Vis Spectroscopy.

The interaction between ferrocene derivatives, such as Fc(COOH)2(λmax=286 nm), Fc(OBt)2(λmax=305 nm), Fc(Cys)(λmax=289 nm) and heme(λmax=386 nm) were studied by UV-Vis spectroscopy, respectively. The results show that, when the concentration of heme is fixed, the absorbance of heme increases with the increase of Fc(COOH)2 and Fc(Cys) concentration, the absorbance of heme almost keep the same when Fc(OBt)2 concentration increases; when the concentration of ferrocene derivatives are fixed, the absorbance of Fc(COOH)2 and Fc(Cys) also increases with the increase of heme concentration, the absorbance of Fc(OBt)2 almost keep the same when heme concentration increase. It is demonstrated that the hydrogen bonding interactions happen between Fc(COOH)2, Fc(Cys) and heme, none of Fc(OBt)2, the formation of hydrogen bonding lead to the growth of molecular chain, the bigger molecule can absorb more energy and increase the absorbance. Meanwhile, the stability of molecule is affected by the formation of hydrogen bonding, when the reaction time increases from 0.5 h to 18 h and 48 h, the absorbance at λmax=384 nm change from 2.64 to 2.53 and 2.51 with fixed concentration of Fc(COOH)2, the absorbance at λmax=384 nm change from 1.76 to 1.72 and 1.68 with fixed concentration of heme, the absorbance at λmax=397 nm change from 2.74 to 2.63 and 2.55 with fixed concentration of Fc(Cys), and the absorbance at λmax=397 nm change from 1.82 to 1.58 and 1.49 with fixed concentration of heme, respectively.