基于STM32的电喷雾萃取电离温控系统设计与实现

为了研究离子源温度对电喷雾萃取电离质谱(EESI-MS)信号的影响,设计了一种基于STM32的电喷雾萃取电离温控系统.系统以ARM Cortex-M3核的STM32系列单片机为核心控制器,采用模糊PID算法和PWM控制,实现了加热元件温度在室温至200℃范围内的连续调控.系统的控制精度为± 1 ℃,静态误差小于1 ℃,超调量在2.5%之内,温度上升的平均速度为1 ℃/s.将内置该系统的EESI源耦合在LTQ-XL线性离子阱质谱仪上,使用氨基酸标准溶液进行测试与表征.结果表明,加热元件温度为180 ℃时,组氨酸的信号强度相比室温时提高5.1倍,其检出限(LOD)从0.053 μg/L降低至0.011 μg/L,相对标准偏差(RSD)为4.7%(n=6).该温控系统增强了氨基酸的EESI-MS信号,提高了EESI源的检测灵敏度.

Design and implement of temperature control system based on STM32 for extractive electrospray ionization

In order to research the effect of extractive electrospray ionization(EESI) source temperature on the signal of mass spectrometry(MS), a temperature control system was designed based on ARM Cortex-M3 STM32 microprocessor, using fuzzy PID algorithms and PWM control.The temperature of the heating element is adjusted continuously within the range of room temperature to 200 ℃.The temperature control accuracy of the system is ±1 ℃, the maximum overshoot is less than 2.5%, the static error is less than 1℃, and the temperature rises at 1 ℃/s average.The temperature control system and EESI source coupled with LTQ-XL MS were applied in direct detection of amino acids.The results show that the signal intensity of histidine increases 5.1 times at 180 ℃ than that at room temperature, the limit of detection(LOD) of histidine decreases from 0.053 μg/L to 0.011 μg/L, and the relative standard deviation(RSD) is 4.7%(n=6).It effectively improves the signal intensity of amino acids and improves the detection sensitivity of EESI source.