脑脊液是一种体液。液体样品最适于PIXE的薄靶内标法分析。将已知量的某元素(通常是Y)加入样品中作为待测元素定量分析的内标准是PIXE常用的内标法。待测元素i对于内标元素Y的相对灵敏度系数定义为:i元素每个特征X射线计数所表 Cerebrospinal fluid is a body fluid. Liquid samples are most suitable for thin target internal standard analysis of PIXE. Adding a known amount of an element (usually Y) to the sample as the internal standard for quantitative analysis of the analyte is the usual internal standard for PIXE. The relative sensitivity coefficient of the test element i to the internal standard element Y is defined as: i-element X-ray count per characteristic chart