标准曲线Calibration curve

一般配制 5–7 个浓度水平的标准溶液（包括空白），浓度范围应覆盖样品浓度。用最小二乘法线性回归得到 y = a + bx，相关系数 r（通常要求 ≥ 0.999）或决定系数 R² 衡量线性好坏，斜率 b 为灵敏度。线性范围的上限受检测器饱和或朗伯-比尔定律偏离限制，下限为定量限。待测样品浓度应落在线性范围内，否则需稀释或浓缩，不能外推。

Typically five to seven standards, including a blank, spanning the sample range are prepared. Least-squares regression gives y = a + bx; the correlation coefficient r (usually required to be at least 0.999) or R² measures linearity, and the slope b is the sensitivity. The upper limit of the linear range is set by detector saturation or deviations from the Beer–Lambert law, and the lower limit by the LOQ. Samples must fall within the linear range, being diluted or concentrated if necessary, never extrapolated.

样品基质（共存物质）可能增强或抑制信号，导致外标法误差。对策包括：基质匹配标准曲线（标准溶液用空白基质配制）、标准加入法（在样品中加入不同量的标准，外推求原含量，适合基质复杂、无空白基质的情况）和内标法（加入已知量的内标物，用信号比定量，可校正进样体积和仪器波动）。

Sample matrices can enhance or suppress signals and bias external calibration. Remedies include matrix-matched calibration (standards made up in blank matrix), standard addition (spiking the sample with increasing amounts of standard and extrapolating, for complex matrices without a blank) and internal standards (adding a known amount of a reference compound and quantifying by signal ratio, correcting for injection volume and instrument drift).

标准曲线是几乎所有仪器定量分析的基础：分光光度法测铁、磷，原子吸收测重金属，色谱法测药物和农残，酶联免疫吸附测定（ELISA）测蛋白质，荧光法测核酸，以及临床生化检验。

Calibration curves underlie almost all instrumental quantification: spectrophotometric iron and phosphate, heavy metals by atomic absorption, drugs and pesticide residues by chromatography, proteins by ELISA, nucleic acids by fluorescence, and clinical biochemistry.