锂是绿色能源和轻质合金的理想材料, 作为一种重要的战略资源而备受各国重视。 锂主要来源于盐湖卤水, 我国盐湖卤水资源丰富, 但主要分布在西部偏远地区, 现场勘探和开采急需便携分析仪器的支持, 然而目前现有实验分析技术均达不到野外现场分析的目标。 近十年来, 基于大气压液体阴极辉光放电光谱仪(SCGD-AES)因无需燃气, 载气等气流条件及真空环境而受到关注。 在前人研究基础上, 自行开发了基于CCD光谱仪检测系统的便携式大气压液体阴极辉光放电光谱仪(简称Li-K分析仪), 仪器长, 宽, 高分别为35, 19和27 cm, 重约为10 kg, 十分有利于便携。选择Li的分析谱线波长为670.78 nm, 以取自西藏两种不同卤水水化学类型样品为研究对象, 建立了卤水中Li的快速分析方法。在最佳工作条件下测得Li的检出限为4 ng·mL-1, 方法的精密度(RSD)＜2%。 研究表明, 不同稀释倍数时, Li的分析结果与ICP-MS分析结果相差较大, 这可能与溶液的基体效应有关, 而采用标准加入法可有效减小基体效应的影响, 获得了与ICP-MS较为一致的分析结果, 可提高分析结果的准确度。 大量实验结果表明, 标准加入法只需2个点即可得到Li准确的分析结果, 大大减少了实验工作量, 为便携式Li-K分析仪在野外现场测定盐湖卤水中的Li奠定了方法学基础。

In 21st century, many countries pay much attention to lithium because lithium is an ideal material for green energy and light alloys as well as an important kind of strategic resources. The main source of lithium is from salt lake brine. China has rich resources of salt lake brine, but these brine resources are mainly distributed in the remote western region, which are in urgent need of portable analytical instrument for on-site exploration and exploitation. However, the available experimental techniques at present can not achieve the target of on-site analysis. Over the past decade, based on atmospheric pressure solution cathode glow discharge-atomic emission spectrometry (SCGD-AES) has been paid attention to analytical researchers because it runs without common air conditions such as fuel gas, carrier gas and vacuum environment. On the basis of previous studies of other researchers, we have developed a portable SCGD based on a charge coupled device (CCD) detector by ourselves, which is short for Li-K analyzer. The length, width, height and weight of the portable Li-K analyzer is 35 cm, 19 cm, 27 cm and 10 kg, respectively, which is very conducive to carry. This work selected the wavelength of 670.78 nm as the characteristic spectral line of Li and has established a rapid analytical method for Li in salt lake brine based on two different types of brines from Tibet. Under the optimum operating conditions, the detection limit of Li was 4 ng·mL-1 and the measured precision (RSD) was better than 2%. The analytical results of Li were much different from those obtained by inductively coupled plasma-mass spectrometry (ICP-MS) with different dilution ratios by standard curve method, which may be related to the matrix effect of solution. However, the analytical results of Li agreed well with the results obtained by ICP-MS using standard addition method, which showed that standard addition method can effectively reduce the matrix effect and improve the analytical accuracies. A great deal of experimental results showed that standard addition method could obtain accurate results of Li using only two points and can greatly reduce the workloads. This work laid a methodological foundation for on-site determination of Li in salt lake brine by the portable Li-K analyzer.