在做某元素的标准曲线时曲线截距的问题

应助达人

楼主问的应该说是校准曲线是否强制过零点的问题，通常在设定测定方法时，在选择曲线类型的时侯点击下拉箭头会出来很多选项其中包括非线性、线性截距、线性过零点等等。
选择不同的曲线类型需要针对不同的情况，具体哪种类型适合哪种情况有专门的说法，在这里我手头没有，明天找找再传上来。
大家一般都用线性截距，少数也有使用二次曲线或非线性曲线。

应助达人

这个关系到你选择什么样的拟合方式了。

我用的也是线性截距，但做出来有时空白是负的，我很尴尬。麻烦您再传下资料研究下啦。。

空白是负的也是很正常，截距比试样空白的吸光度高就会出现。不想出现这种空白是负的情况，就用强制过零点的方法吧。

好东西快点给大家分享分享啊哈哈，我也一直有这种疑惑，不知道什么情况下选择什么样的拟合方式，拜托拜托

好东西快点给大家分享分享啊哈哈，我也一直有这种疑惑，不知道什么情况下选择什么样的拟合方式，拜托拜托

应助达人

我从以前版友发的帖子中找的。当时复制后记不清放哪里，现在总算找到了。这些参考资料是英文的，由于种种原因一直没有翻译成中文，相信你有这个能力的

具体内容如下：

Nonlinear Through Zero（非线性过零点）
If you expect the concentrations of your samples to be outside the linear range of the calibration curve , select this option. This option covers the widest concentration range. This calibration curve is forced to go through the point defined by the calibration blank which is set at zero absorbance and zero concentration. The equation for Nonlinear zero intercept is:
C=K0*(K1*A+K3*A*A)/(K2*A-1)
In this expression, C is the concentration, A is the observed absorbance or emission, K1, K2, and K3 are coefficients determined during the calibration procedure, and K0 is the reslope coefficient that is set equal to 1.0 during the initial calibration. When the number of calibration standards used exceeds the number of coefficients, the method of least squares is used to determine the coefficients.
The blank is always analyzed first, and the reading obtained is automatically subtracted from the readings from all subsequent calibration standards.
Linear, Calculated Intercept（线性截距）
If you expect the concentrations of your samples to be within the linear range of the calibration curve, select this option. This is often the case at low absorbance values and low concentration values. The calibration blank is treated as another calibration standard by the system and the intercept with the absorbance axis is calculated rather than fixed at zero concentration.
The equation for linear calculated intercept is:A=K1+K2*C
Linear Through Zero（线性过零点）
If you expect the concentrations of your samples to be within the linear range of the calibration, select this option. This is often the case at low absorbance values and low concentration values. This calibration curve is forced to go through the point defined by the calibration blank which is set at zero absorbance and zero concentration. The equation used for zero intercept linear calibration is: C=K0(-K1*A)
In this expression, C is the concentration and A is the absorbance or emission, K1 is a proportionality coefficient, and K0 is the reslope coefficient, which is set to 1.0 for the initial calibration.
A calibration curve defined using this equation is forced to go through the point 0, 0, zero absorbance and zero concentration, defined by the blank. When two or more calibration standards are used, the method of least squares is used to determine K1 .
The blank is always analyzed first, and the reading obtained is automatically subtracted from the readings from all subsequent calibration standards.

应助达人

不好意思，耽搁这么久，主要是这份材料不容易找。是英文的，没来得及翻译成中文，先凑合看吧

Nonlinear Through Zero
If you expect the concentrations of your samples to be outside the linear range of the calibration curve , select this option. This option covers the widest concentration range. This calibration curve is forced to go through the point defined by the calibration blank which is set at zero absorbance and zero concentration. The equation for Nonlinear zero intercept is:
C=K0*(K1*A+K3*A*A)/(K2*A-1)
In this expression, C is the concentration, A is the observed absorbance or emission, K1, K2, and K3 are coefficients determined during the calibration procedure, and K0 is the reslope coefficient that is set equal to 1.0 during the initial calibration. When the number of calibration standards used exceeds the number of coefficients, the method of least squares is used to determine the coefficients.
The blank is always analyzed first, and the reading obtained is automatically subtracted from the readings from all subsequent calibration standards.
Linear, Calculated Intercept
If you expect the concentrations of your samples to be within the linear range of the calibration curve, select this option. This is often the case at low absorbance values and low concentration values. The calibration blank is treated as another calibration standard by the system and the intercept with the absorbance axis is calculated rather than fixed at zero concentration.
The equation for linear calculated intercept is:A=K1+K2*C
Linear Through Zero
If you expect the concentrations of your samples to be within the linear range of the calibration, select this option. This is often the case at low absorbance values and low concentration values. This calibration curve is forced to go through the point defined by the calibration blank which is set at zero absorbance and zero concentration. The equation used for zero intercept linear calibration is: C=K0(-K1*A)
In this expression, C is the concentration and A is the absorbance or emission, K1 is a proportionality coefficient, and K0 is the reslope coefficient, which is set to 1.0 for the initial calibration.
A calibration curve defined using this equation is forced to go through the point 0, 0, zero absorbance and zero concentration, defined by the blank. When two or more calibration standards are used, the method of least squares is used to determine K1 .
The blank is always analyzed first, and the reading obtained is automatically subtracted from the readings from all subsequent calibration standards.

好东西，谢谢啦，好好学习学习