Graphite Furnace Atomic Absorption Spectrometry In Tea And Tea Garden Soil Cd,Pb Method

As one of world's three major non-alcoholic beverage,tea is admired all over the world.With the development of tea industry and the spread of tea culture,tea industry development in China is facing a great opportunity and challenge.Tea heavy metal content exceeding the provided standard,especially lead?Pb?and cadmium?Cd?,has been a serious threat to the development of tea industry in our country.According to relevant study,Pb and Cd pollution in tea leaves mainly caused by the heavy metal pollution of tea garden soil.How to detect the amount of Pb and Cd in tea leaves and tea garden soil fast and accurately,is a key to promote the development of tea industry in our country.Graphite furnace atomic absorption spectrometry,and microwave digestion were used to study the whole process of analysis Pb and Cd in tea leaves and tea garden soil.Effective method have been specifically developed to determine the amount of Pb and Cd in tea leaves and tea garden soil.The method was applied to determine practical samples,and satisfactory results were obtained.The main results are as follows:?1?The key parameters of graphite furnace atomic absorption were optimized.The optimal method for the determination of Pb content: The optimal temperature for cineration and atomization were 800 ? and 1750?,the optical time for cineration and atomization were 20 s and 4s;The optimal method for the determination of Cd content: The optimal temperature for cineration and atomization were 500 ? and 1550?,the optical time for cineration and atomization were 20 s and 4s.?2?The determination linear range of Pb and Cd were identified: 2.83 ug/L²5ug/ L for Pb;0.105 ug/L⁵ug/L for Cd.?3?The sample processing methods in the determination of Pb and Cd in tea leaves and tea garden soil were compared and optimized.After comparing dry ashing method,wet ashing method and microwave digestion method,microwave digestion method was chosen to process the tea leaves samples and tea garden soil samples.HNO₃-H₂O₂?4:1?was used as a microwave digestion agent for tea leaves samples.HNO₃-HF-H₂O₂?6:2:2?was used as a microwave digestion agent for tea garden soil samples.?4?Validity study of sample preparation and graphite furnace atomic absorption spectrometry was carried out.Sample analyses results showed that the relative standard deviations of the determination of Pb and Cd are 1.08% and 2.06% in tea leaves;1.28% and 1.01% in tea garden soil.The relative standard deviations are all less than 4%.The accuracy of the sample determination is in accordance with the requirement.The average standard addition recoveries of Pb and Cd were 98.92% and 99.69% in tea leaves samples and 98.16% and 96.94% in tea garden soil samples.The standard addition recoveries of all samples were in the range of 94.80%-105.70%.The precision of the sample determination is in accordance with the requirement.?5?Pb and Cd amount in tea leaves and tea garden soil in some region were determined.The results show that the test sample tea samples of Pb and Cd content of safety standards in line with the quality of tea,tea garden soil samples for Pb and Cd content of soil pollution in line with environmental quality standards for tea.