摘要:
全国土地质量地球化学调查结果显示,我国氟过剩的土地面积约31.5万km2。氟作为一种与人体健康密切相关的元素而得到广泛关注和研究,尤其近年来农业活动中高氟化肥的使用成为土壤中氟的潜在来源,其在土壤、动植物体中的循环迁移方式尚待深入研究。为了迎接新一轮全国土壤普查和现代健康地质调查,需要研究建立准确测定化肥中的氟含量的分析方法。本次实验对比研究了HCl煮沸提取、HCl常温超声提取、NaOH熔融水提取、Na2O2熔融水提取4种不同的样品分解方式,结果表明:采用HCl常温超声提取分解样品,NaOH-H2SO4调节酸度,柠檬酸钠做离子缓冲剂是最佳的样品前处理方式; 并对超声提取时间及提取温度进行了考察,确定了超声提取时间为20 min,提取温度为20 ℃;在最佳的样品前处理条件下,测定了方法的主要质量参数:检出限1.63×10-6、精密度0.98%、回收率在91%~108%。该方法前处理简便快速、易于操作,以分段建立标准曲线的模式,测定的质量参数完全能够满足化肥的分析要求。
关键词:
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离子选择电极法
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氟
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化肥
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超声提取
Abstract:
As shown by the geochemical survey of national land quality, the land with excess fluorine in China covers an area of about 315 000 km2. As an element closely related to human health, fluorine has received wide attention and has been studied. Especially in recent years, the high-fluorine fertilizers used in agricultural activities have become a potential source of fluorine in soils. Moreover, the circulation and migration patterns of fluorine in soils, animals, and plants are yet to be further investigated. To prepare for a new round of national soil survey and modern health-related geological survey, it is necessary to develop a method to accurately determine the fluorine content in chemical fertilizers. Through experiments, this study compared four methods for sample decomposition, namely the extraction methods based on HCl boiling, NaOH molten water, and the Na2O2 molten water and the HCl ultrasonic extraction method at room temperature. The results show that the optimal method for sample pretreatment is to extract and decompose samples using ultrasound and HCl at room temperature, adjust the acidity using NaOH-H2SO4, and take sodium citrate as the ion buffering agent. Through investigation, the ultrasonic extraction time and temperature were determined to be 20 min and 20 ℃, respectively. The main quality parameters of the method were determined under the optimal sample pretreatment conditions, including the limit of detection of 1.63×10-6, the precision of 0.98%, and the recovery rate of 91%~108%. The results of this study show that the pretreatment of this method is simple, fast, and easy to operate. With the mode of establishing standard curves in sections, the quality parameters determined can fully meet the requirements for the analysis of chemical fertilizers.
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