Determination Of Trace Metal Impurities In Medical Temperature Controlling Liquid Crystal By ICPMS

Temperature control is very important for production and research in the field of medicine.Compared with the traditional test medium of mercury,liquid crystal(LC)display is clear and precise,fast response,diversified,long life,and so on.Meanwhile,the heat capacity of the liquid crystal is small,its resolution can reach up to 0.001?,and the small difference of temperature can lead to a distinct color change.Combined with the fast and accurate camera techniques,the temperature controlling liquid crystals are widely used in the field of oral temperature testing,skin temperature record,gynecology,neurology,oncology,pediatrics,surgery,sports medicine,hematology and so on.Liquid crystals for medical applications have high requirements for purity,metal impurities are an important index to determine the photoelectric properties of liquid crystal products.As the mostly used liquid crystal in medicine,the systemic analytical procedure for determination of the composition and metal impurities in cholesteric phase liquid crystal is developed in this thesis,which could provide instructions and new insights for the monomer purification production of liquid crystals.The main contents and conclusions of this paper are as follows,The applications of ICP-MS for characterization of temperature controlling liquid crystals were investigated,including hardware configuration,equipment for specified organics and the corresponding principles.For the cholesteric phase liquid crystal used in medical temperature control,a straightforward detection method for trace metal impurities(Na,K,Ca,Mg,Al,Zn,Cr,Mn,Cu,Fe,Ni,Ag,Pb,etc.)in LCs was established,which provided a new strategy for analysis of metal impurities in LC.The content of metal impurities was accurately measured,and their influences on the electro-optical properties of liquid crystal were analyzed.A complete quantitative test method was established from the sample pretreatment,method development and method verification.The origin of various disturbances during the detection process were investigated through the setting of parameters for ICP-MS,including matrix inhibition,double charge interference,polyatomic ion interference,oxide interference,et al.The different pre-processing methods were compared,the physical disturbance was solved by the matrix matching.Some problems in trace testing were overcame by standard addition method.The recovery,relative standard deviation and detection limit of this method were investigated,and the verification of methodology was conducted.The detection limit of this method is between 0.0026 ug/kg-0.0258 ug/kg,the relative standard deviation is between 0.9%-2.4%,and the recovery rate is between 92.39%-109.43%.According to the characteristics of medical temperature controlling liquid crystals,a suitable VHR test method was constructed by comparing the parameters including voltage,frequency,temperature,UV,etc.With the increase of metal content,VHR decreased,and the data were consistent with each other.The effectiveness of metal determination using ICP-MS was validated by traditional electrical indicators of liquid crystal.