Detection Of Monomer Content In Natural Rubber Latex And Rubber Dandelion And Relation Of Molecular Weight

Natural rubber(NR),as a kind of elastomeric material with superior physical and chemical properties,is widely used in aerospace,building materials,medical care and other fields related to people’s daily life and production.In recent years,due to the rapid development of the world economy,the annual consumption of natural rubber in the world has increased rapidly.Now the successful commercial natural rubber source is Brazilian trefoil rubber tree.However,due to the influence of South American leaf blight and other factors,the growth rate of its output has far lagged behind the growth rate of global natural rubber consumption.On the other hand,because of our geographical reasons,the area where Brazilian trefoil rubber can be planted is very limited.Its output is far from meeting our own consumption.Most of them need to be imported from Southeast Asian countries.Due to the existence of a series of problems such as the South China Sea dispute,the import of natural rubber and other commodities is also under potential threat.Therefore,it is urgent to develop the next natural rubber.At the same time,it is urgent to study the mechanism of natural rubber biosynthesis,which lays a good foundation for the future large-scale development and utilization of the second natural rubber and the ultimate realization of in vitro synthesis of natural rubber.In this paper,the precise quantification of natural rubber biosynthetic intermediates in Brazilian natural rubber latex and second natural rubber latex-Dandelion rubber and natural rubber biosynthetic intermediates in latex was carried out,and the potential relationship between the content,region,variety and some rubber properties was studied,which was divided into three parts.In the first part,Agilent 1290 high performance liquid chromatography and 6410 triple four-stage mass spectrometry were used to detect Brazilian natural rubber latex.Two intermediates,Dimethylallyl pyrophosphate(DMAPP)and Farneyl pyrophosphate(FPP),in the process of natural rubber biosynthesis were quantitatively detected by self-developed method.The results showed that the tested substances were mainly concentrated in the rubber particle layer after high speed centrifugation,but the content was very low;the concentrations of DMAPP and FPP were 70-96 ng/mL and 242-375 ng/mL,respectively;the quantitative limits of DMAPP and FPP were 28 ng/mL and 33 ng/mL,respectively.The recovery of this method is between 81-93%.The second part is to detect DMAPP and FPP in rubber dandelion by Waters ACQUIT ultra-high performance liquid chromatography in series with Waters Xevo TQ-MS triple four-stage mass spectrometer on the basis of the first part.The results show that both DMAPP and FPP have good linear relationship at the concentration of 1 ng/mL to 1000ng/mL,and the linear correlation coefficient is>0.999.The detection limit(LOD)and quantitative limit(LOQ)were 2.42 ng/mL,7.26 ng/mL and 1.02 ng/mL,3.05 ng/mL,respectively.The concentration of DMAPP and FPP in Taraxacum officinalis samples ranged from 23.32 ng/mL to 82.77 ng/mL and 12.03-85.67 ng/mL,respectively,which were much lower than that of natural rubber.The recovery of this method was between 99-117.1%.In the third part,the molecular weight of rubber dandelion samples in the second part was tested by GPC,and some properties of dandelion rubber were correlated with the content of intermediates in biosynthesis.The results showed that the molecular weight of natural rubber in dandelion rubber grass was smaller than that in Brazilian trefoil rubber tree,and the molecular weight of natural rubber in rubber grass and the middle of its biosynthesis process.The content of body DMAPP was positively correlated.By fitting the mass fraction and concentration of DMAPP and FPP with the weight average molecular weight,the empirical relationship between the concentration and the weight-average molecular weight of DMAPP was obtained,which was y=-19.722x3+2389.5x2-66384x+729632,and its R2=0.9104.The empirical relationship between the concentration and the weight-average molecular weight of the same FPP was y=-0.8768x4+159.9x3-9986.2x2+258x-2E+06,and R2=0.9832.The results are consistent with those obtained by qualitative relationship.The concentration of FPP can be used to predict the molecular weight of the samples,which has practical guiding significance.