在磺胺甲基异口恶唑的激发峰 2 6 9.4nm处记录一阶导数发射光谱 ,采用峰 -谷法测量导数信号 ,在甲氧苄胺嘧啶存在下 ,不经分离和掩蔽实现磺胺甲基异口恶唑的测定 ;用二阶导数激发光谱 ,在磺胺甲基异口恶唑存在下 ,实现甲氧苄胺嘧啶的测定 .磺胺甲基异口恶唑的线性范围是 0～ 4.0 μg/ m L,甲氧苄胺嘧啶的线性范围是 0～ 3.0 μg/ m L. The first derivative emission spectra were recorded at the excitation peak of sulfamethoxazole at 2694 nm and the derivative signal was measured by the peak-valley method. In the presence of trimethoprim, the sulfamethoxazole group was not isolated and masked Determination of isooxazole The determination of trimethoprim in the presence of sulfamethoxazole was carried out by second order derivative excitation spectroscopy.The linear range of sulfamethoxazole was 0-4.0 μg / mL, the linear range of trimethoprim was 0-3.0 μg / m L.