那为什么用1ppm浓度去做呢

得过且过，售后之大忌也！

2.5.1 Background Equivalent Concentration (BEC)背景值2.5.1.1 The BEC value is the concentration of an element, which would produce thesame emission intensity as the plasma background measured at the analytewavelength. The BEC serves as an indication of instrument sensitivity which isrelated to torch alignment, plasma viewing height, nebulizer gas flow rate, andincident RF power.背景值是测量一浓度元素在分析波长下产生相应的发射强度。BEC可指示仪器的灵敏度，它与炬管线性、等离子观测的高度，雾化气流量，射频功率有关。2.5.1.2 The BEC should be determined every three monthsBEC应每3个月测定一次。2.5.1.3 Measure the intensity of a 5% nitric acid blank solution (IB).测量5%的硝酸空白溶液的强度（IB）。2.5.1.4 Measure the intensity of a 1.0 ppm Mn standard in 5% nitric acid (ISTD)ata wavelength of 257.610.`在波长为257.610nm处测量基体为5%硝酸的1.0ppm Mn标准溶液的强度。2.5.1.5 Calculate the BEC = IB / (ISTD – IB) X CSTD计算 BEC = IB / (ISTD – IB) X CSTDWhere: CSTD = concentration of Mn STD = 1.0 ppm这里： CSTD=Mn 标准溶液浓度 = 1.0 ppmIB and ISTD have been automatically corrected to the darkcurrentIB和ISTD 已经被暗电流自动校正Record the BEC value. The BEC must not be greaterthan 0.04.记录BEC的值。BEC不能大于0.04。2.5.1.6 If the BEC is greater than 0.04, check the sample introduction system andthe torch for wear. Replace the torch and/or change o-rings and other wornparts as needed. Reanalyze the BEC by following steps §2.5.1.1.3 to§2.5.1.1.5. If the BEC still does not meet the acceptance limit, notify asupervisor immediately and take the instrument out of service.如果BEC大于0.04，检查进样系统和炬管装置。根据需要更换炬管和/或O形圈和其他损耗部件。按照步骤§2.5.1.1.3至2.5.1.1.5重新分析BEC。如果BEC仍然不符合接受限值，立即通知监管者和将仪器外修。2.5.1.7 The BEC shall be charted to show any trending.BEC应该标记显示出任何的变化趋势。Notice: For PE ICP instrument, the dark current is obtained by closing the shutter.注意： 对于PE的ICP，通过关闭快门获得暗电流。