Corrections for the response time and delay of mass spectrometers.
Corrections for the response time and delay of mass spectrometers.
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校正质谱仪的响应时间和延迟。
DOI：
10.1152/jappl.1981.51.6.1417
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
VanLiew,HD
中科院分区：
文献类型：
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作者：
Arieli,R;VanLiew,HD
基于质谱仪（MS）输出的计算将是不正确的，除非将样品吸入仪器的延迟和仪器的响应时间考虑在内。当我们在两个不同的质谱仪中突然改变浓度时，响应是S形的而不是指数的，并且从响应曲线的主要部分导出的时间常数为43-60 ms;使用这些值的单指数校正导致校正的波形过冲。为了更好的校正，我们使用了双指数校正，C2 = Co +（Y1 + Y2）（d2C 0/dt）+Y1 Y2（d2C 0/dt 2），其中C 0是作为时间t的函数的MS输出，C2是校正浓度，Y1和Y2是时间常数。第三个指数的假设没有什么价值。对于成功的校正，Y1必须小于测量的单指数时间常数。我们使用Y1测量值的三分之二，然后从一次校正的响应计算Y2。二阶校正响应于平方输入来近似平方输出。为了以一种能够提供良好的动态变化分辨率并与我们的响应时间校正兼容的方式处理延迟时间，我们校正了输入事件的时间与输出达到完全响应的20%的时间之间的差异。我们验证了我们的方法的整合量的气体吸入和排出注射器和人类呼吸。
Computations based on mass spectrometer (MS) outputs will be incorrect unless the delay for drawing the sample into the instrument and response time of the instrument are accounted for. When we changed concentration abruptly in two different mass spectrometers, the responses were sigmoid shaped not exponential, and time constants derived from the main part of the response curves were 43–60 ms; single-exponent corrections using these values caused the corrected waveform to overshoot. For a better correction, we used a two-exponent correction, C2 = Co + (Y1 + Y2) (d2C0/dt) + Y1Y2 (d2C0/dt2), where C0 is MS output as a function of time t, C2 is corrected concentration, and Y1 and Y2 are time constants. Assumption of a third exponent was of little value. For a successful correction Y1 must be smaller than a measured one-exponent time constant. We used two-thirds of the measured value for Y1 and then calculated Y2 from the once-corrected response. The second-order correction approximates a square output in response to a square input. To deal with delay time in a way that would give good resolution of dynamic changes and also be compatible with our response-time correction, we corrected for the difference between time of the input event and time that the output reaches 20% of full response. We validated our methods by integrations of amounts of gases drawn into and out of a syringe and in human breaths.