Study On The Method Of Metal And Metalloid Analysis By Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Metal and metalloid elements play an immeasurable impact on human life activities.Appropriate amount of the trace elements is necessary for human health,which are the composition and activation of various enzymes,participating the process of biosynthesis,holding a direct effect on the synthesis of nucleic acids and proteins.In addition,due to its non-decomposable and cumulative effect,we can determine the source of raw materials based on the metal and metalloid content in the sample.At present,the most commonly used means of detecting metal and metalloid elements is that detecting ion content after digestion of the sample.However,the cumbersome pre-treating process can lead to contamination and loss of the sample easily.Laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)is a new detection method,which combines the advantages of laser ablation of solid sample introduction,high sensitivity and wide linear range of mass spectrometry.In this paper,a new method for the determination of metal and metalloid elements in samples by LA-ICP-MS was established.The main contents included the following:(1)A new method for the quantitative determination of metal elements in liquid samples by rhodium(Rh)as internal standard element method has been established by LA-ICP-MS directly.The study identified the carrier film of sample for laser ablation(polytetrafluoroethylene filter),and the appropriate color indicator for positioning image of the sample(eosin).Then optimized the conditions of laser ablation,and established the method of quantitative determination of 11 elements such as Mg,Mn,Cu,Zn,Al,Fe,Cs,Ni,Sr,Y and Tl in liquid samples.The advantage of this method is high sensitivity,wide linear range,less sample and it does not need to digest the sample.The method was applied to the determination of 11 elements in tea infusion,which was compared with the traditional microwave digestion solution for the determination of the results,and the results are accurate.In addition,risk assessments of effective elements in tea infusion were conducted according to the World Health Organization's recommended maximum metal tolerance.(2)A new method for the quantitative determination of metal elements in dryspot was established by LA-ICP-MS directly.For samples that have been dry stains can no longer add internal standard elements,so we need to search for a new method to quantitative determine the mental element of the dry spot without internal standard element.We optimized the conditions of laser ablation,and established the method of quantitative determination of 8 kinds of trace elements such as Y,Cs,Nd,Gd,Ho,Yb,Lu and Tl in dry spot sample.The advantage of this method is that the sensitivity is higher,the sample dosage is small,more suitable for the detection of trace elements and it does not need to digest the sample.The method was applied to the determination of 8 trace elements in blood stains.There was no significant difference between the determination results of the proposed method above and the results of traditional ICP-MS after microwave digestion.(3)A new method for quantitative determination of metal and metalloid elements in solid samples has been established by LA-ICP-MS directly.At present,the shortcoming of the solid analysis method is that the lack of matrix matching standard sample to establish the function relationship,which limits the development of LA-ICP-MS quantitative determination method.In this section,we quantitative assay 6 kinds of elements in pottery and 5 kinds of elements in teapot by using standard soil as the standard.Then optimized instrument parameters,and established a quantitative determination method.The results of the proposed method were compared with the traditional methods,which indicated that the results were good whatever the dried soil or the fired soil as standard.Moreover the accuracy of the results was better by the dry soil as standard.