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1.
采用硝酸–高氯酸湿法消解或硝酸–双氧水微波消解植物样品,以电感耦合等离子体原子发射光谱法同时测定样品溶液中钾、钠、钙和镁含量。用该法测定灌木枝叶和茶叶标准样品,测定值均在标准值范围内,测定结果的相对标准偏差为0.45%~4.05%(n=8)。钾、钠、钙、镁的加标回收率分别为94.4%~107.6%,92.6%~107.9%,93.7%~105.4%,92.9%~107.2%。该方法操作简便,测量精密度和准确度完全满足植物中钾、钠、钙和镁含量的测定要求。 相似文献
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采用原子荧光法测定茶叶中的硒含量,对样品消解温度及仪器条件进行了优化。还原剂为1.0%硼氢化钾–0.5%氢氧化钾溶液,载流液为3%盐酸溶液。在优化条件下,硒的质量浓度在0~20 ng/mL范围内与荧光强度呈良好的线性关系,相关系数r=0.999,检出限为0.8 ng/mL。该法的加标回收率为88.08%~101.39%,测定结果的相对标准偏差为2.03%~4.84%(n=6)。该方法实际操作性强,准确度高,适用于日常检验工作中对批量茶叶中硒含量的测定。 相似文献
3.
林建原 《广东微量元素科学》2007,14(12):53-56
建立了石墨炉原子吸收光谱法测定茶叶中镉含量的分析方法。以1%磷酸二氢铵 1%硝酸镁的混合液为基体改进剂测定了茶叶中的镉,方法的回收率96.0%~103.0%,检出限为0.076ng/mL,测定结果令人满意。 相似文献
4.
微波消解-溶出伏安法对食品中铜、铅、镉的同时测定 总被引:3,自引:0,他引:3
采用微波消解结合同位镀汞阳极溶出伏安法对茶叶、紫菜和西洋菜等食品中的铜、铅、镉进行了测定,并优化了微波消解、电解缓冲液、富集电位等实验条件。采用标准加入法定量,Cu、Pb、Cd的线性范围分别为0.040~1.768、0.080~1.768、0.040~1.768 mg/L,相关系数分别为0.998 4、0.998 2、0.997 0,检出限分别为0.008、0.016、0.008 mg/L,相对标准偏差(n=5)分别为4.1%、0.92%、2.0%。该方法测定茶叶、紫菜、西洋菜等实际样品的铜、铅、镉含量,加标回收率分别为98%~109%、94%~103%、100%~112%;将测定结果与原子吸收光谱法检测结果对比,表明此方法简便、快速,且具有较高的灵敏度、较好的选择性和可靠性。 相似文献
5.
气相色谱法测定茶叶中邻苯二甲酸酯 总被引:1,自引:0,他引:1
建立了同时检测茶叶中5种邻苯二甲酸酯类(PAEs)的气相色谱(GC)-氢火焰离子(FID)检测方法,并对市售部分茶叶中的PAEs含量进行了测定。茶叶样品采用同时蒸馏萃取,处理后以HP-5石英毛细管柱分离,GC-FID法进行检测,外标法定量。5种PAEs在各自检测浓度范围内线性关系良好,其线性相关系数均达到0.999以上,检出限(LOD)为2.63~8.42μg/L,加标回收率在78.2%~111.3%之间,相对标准偏差(RSD)均小于5%,方法可以满足实际茶叶样品中5种PAEs的分析检测。 相似文献
6.
目的对样品前处理、酸度及茶叶中共存元素干扰的影响等因素进行探讨,方法用微波消解前处理样品,ICP-AES法同时测定茶叶中铅(Pb)、砷(As)、镉(Cd)、镍(Ni)等元素含量。结果该法的回收率在84.5%~115%之间,精密度RSD均小于9%,结论该法能满足茶叶测定要求。 相似文献
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应用搅拌棒吸附萃取-热脱附-气相色谱-质谱测定烟叶和茶叶中拟除虫菊酯类农药残留 总被引:6,自引:0,他引:6
应用搅拌棒吸附萃取(SBSE)技术分别萃取烟叶和茶叶中的5种拟除虫菊酯,并利用热脱附系统将萃取到的物质进行热脱附,然后通过气相色谱-质谱联用仪(GC-MS)进行分析测定。实验过程中对影响SBSE的因素及影响热脱附的条件进行了优化。在优化条件下,采用外标法分别对烟叶和茶叶中的5种拟除虫菊酯类农药残留进行了定量分析。结果表明,烟叶中5种拟除虫菊酯的检出限范围为3.3~11.4 ng,加标回收率为94.8%~103.4%,6次测定的相对标准偏差(RSD)为5.3%~8.6%;茶叶中5种拟除虫菊酯的检出限范围为4.2~10.5 ng,加标回收率为98.2%~110.1%,6次测定的RSD为5.0%~9.6%。实验证明该法具有较高的准确度、灵敏度和较好的重现性,可用于烟叶和茶叶中拟除虫菊酯类农药残留的快速分析测定。 相似文献
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液相色谱-串联质谱法与气相色谱-串联质谱法测定茶叶中苦参碱残留量 总被引:2,自引:0,他引:2
建立了茶叶中苦参碱残留检测的两种前处理方法,比较了液相色谱-串联质谱(LC-MS/MS)与气相色谱-串联质谱(GC-MS/MS)检测茶叶中苦参碱残留量分析方法的适用性。结果表明,在添加标准样品10~100μg/kg 3个水平时,两种前处理方法的回收率和精密度无显著差别;GC-MS/MS和LC-MS/MS回收率分别为81%~85%、82%~86%,相对标准偏差(RSD)分别为4.6%~11.5%和2.9%~4.2%。结果表明两种样品前处理方法以及LC-MS/MS与GC-MS/MS检测均能满足茶叶中苦参碱残留量的测定,但采用前处理方法二,LC-MS/MS检测茶叶中苦参碱残留更具优势。 相似文献
10.
建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同步检测食品中2-甲基咪唑(2-MEI)和4-甲基咪唑(4-MEI)的分析方法。大多数食品超声提取后可直接进样,基质极其复杂的样品(如酱油、咖啡、茶叶等)需经强阳离子交换柱(PCX)萃取净化,采用同位素内标法定量。在优化条件下,2-MEI和4-MEI的检出限分别可达0.5 ng/g和1.4 ng/g,回收率分别为82.6%~98.1%和89.5%~108.1%,日内相对标准偏差(RSD)分别为1.3%~4.5%和1.0%~5.0%,日间RSD分别为2.0%~5.4%和1.9%~6.5%。采用该方法对市售90余种加工食品进行抽样检测,结果发现2-MEI仅在少量食品中存在且含量较低,而4-MEI在多种食品中存在,含量较高的食品包括老抽酱油(3 224.20~18 795.93 ng/g)、咖啡(0~5 554.35 ng/g)、曲奇(63.48~584.78 ng/g)、焦糖色素饼干(373.12~1 899.60 ng/g)、可乐(44.13~342.77 ng/g)、大麦茶(3131.05~3 335.60 ng/g)等。该文还首次报道了不同品种茶叶(16~761.89 ng/g)中4-MEI的含量。 相似文献
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原子吸收光谱法测定比较5种不同品牌茶叶中微量元素含量 总被引:1,自引:0,他引:1
对市售茶叶崂山绿茶、茯茶、安溪铁观音、乌龙茶、茉莉茶王中微量元素Ca、Mg、Fe、Cu、Zn的含量进行考察.采用V(高氯酸)∶V(硝酸)=1∶4混酸消解的方法将样品在低温下消解,火焰原子吸收光谱法定量.实验测得5种茶叶中均含丰富的Ca、Mg,其中茯茶含Fe最多;崂山绿茶含Cu最多;安溪铁观音和崂山绿茶含Zn多.各元素工作曲线相关系数r0.9948,加标回收率94.38%~105.00%,相对标准偏差在2.26%以下.实验方法快速、定量准确,测得各品牌茶叶中微量元素含量可为消费者提供参考. 相似文献
13.
Jeong-Ho Oh Chan-Yang Lee Yeong-Eun Lee So-Hee Yoo Jin-Oh Chung Chan-Su Rha Mi-Young Park Yong-Deog Hong Soon-Mi Shim 《Molecules (Basel, Switzerland)》2021,26(6)
The aim of this study was to profile the bioaccessibility and intestinal absorption of epicatechins and flavonols in different forms of green tea and its formulation: loose leaf tea, powdered tea, 35% catechins containing GTE, and GTE formulated with green tea-derived polysaccharide and flavonols (CATEPLUS™). The bioaccessibillity and intestinal absorption of epicatechins and flavonols was investigated by using an in vitro digestion model system with Caco-2 cells. The bioaccessibility of total epicatechins in loose leaf tea, powdered tea, GTE, and CATEPLUS™ was 1.27%, 2.30%, 22.05%, and 18.72%, respectively, showing that GTE and CATEPLUS™ had significantly higher bioaccessibility than powdered tea and loose leaf tea. None of the flavonols were detected in powdered tea and loose leaf tea, but the bioaccessibility of the total flavonols in GTE and CATEPLUS™ was 85.74% and 66.98%, respectively. The highest intestinal absorption of epicatechins was found in CATEPLUS™ (171.39 ± 5.39 ng/mg protein) followed by GTE (57.38 ± 9.31), powdered tea (3.60 ± 0.67), and loose leaf tea (2.94 ± 1.03). The results from the study suggest that formulating green tea extracts rich in catechins with second components obtained from green tea processing could enhance the bioavailability of epicatechins. 相似文献
14.
浅论绿茶与乌龙茶氟含量对人体健康的影响 总被引:2,自引:0,他引:2
分别用重蒸水和自来水,通过蒸煮法和浸泡法制出不同浓度的绿茶液和乌龙茶液,对比测定研究茶液中氟含量,结果表明,茶液中的氟含量随茶叶浓度增加而增加,且乌龙茶高于绿茶,当茶叶浓度超过10.0g/L时,茶液中的氟含量即超过国家饮水卫生标准,提示人们饮用水茶液浓度在5.0g/L左右为宜。 相似文献
15.
Maciej Chowaniak Marcin Niemiec Zhiqiang Zhu Naim Rashidov Zofia Grdek-Szostak Anna Szelg-Sikora Jakub Sikora Maciej Kubo Salimzoda Amonullo Fayzullo Usmon Mamur Mahmadyorzoda Agnieszka Jzefowska Andrzej Lepiarczyk Florian Gambu 《Molecules (Basel, Switzerland)》2021,26(12)
Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term “wild tea” is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu’Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas. 相似文献
16.
采用多种方法对同一种茶叶进行消解,用原子吸收光谱法测定不同方法消解的茶叶中有害微量元素铅和镉的含量并进行对比,探索了茶叶中微量元素铅和镉低损耗的最佳消解条件.实验结果表明,不同的消解方式对茶叶中微量元素的测定结果影响很大.测定茶叶中铅和镉元素时,采用硝酸-高氯酸加盖浸泡过夜方法较为理想. 相似文献
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Abhijith KS Kumar PV Kumar MA Thakur MS 《Analytical and bioanalytical chemistry》2007,389(7-8):2227-2234
An amperometric principle-based biosensor containing immobilized enzyme tyrosinase has been used for detection of polyphenols
in tea. The immobilized tyrosinase-based biosensor could detect tea polyphenols in the concentration range 10–80 mmol L−1. Immobilization of the enzyme by the crosslinking method gave good stable response to tea polyphenols. The biosensor response
reached the steady state within 5 min. The voltage response was found to have a direct linear relationship with the concentration
of polyphenols in black tea samples. Enzyme membrane fouling was observed with number of analyses with a single immobilised
enzyme membrane. The tyrosinase-based biosensor gave maximum response to tea polyphenols at 30°C. The optimum pH was 7.0.
This biosensor system can be applied for analysis of tea polyphenols. Variation in the biosensor response to black tea infusions
gave an indication of the different amounts of theaflavins in the samples, which is an important parameter in evaluating tea
quality. A comparative study of the quality attributes of a variety of commercially available brands of tea were performed
using the biosensor and conventional analytical techniques such as spectrophotometry. 相似文献
19.
《Analytical letters》2012,45(14):2244-2253
Abstract This paper describes the application of the common and variation peak ratio dual-index sequence analysis methods to evaluate the quality of several tea samples obtained from different species and different areas based on 1HNMR fingerprint spectra (FPS). The method is able to determine the most similar sample groups and identify accurately the varieties and qualities of Blank tea, Longjing tea, and other green tea samples. Longjing tea is a famous brand of local green tea and has its own distinct characteristics. There were obvious differences between Uji tea from Japanese and Chinese green tea. The results showed that the dual index sequent analytical method provides a good approach to accurately describe the resemblance and differences among tea samples. It also can reflect tea's integrity and individual difference, and is an effective method to evaluate the quality of tea samples. 相似文献
20.
Vuong QV Stathopoulos CE Golding JB Nguyen MH Roach PD 《Journal of separation science》2011,34(18):2468-2474
Theanine is a unique non-protein amino acid found in tea (Camellia sinensis). It contributes to the favourable umami taste of tea and is linked to various beneficial effects in humans. There is an increasing interest in theanine as an important component of tea, as an ingredient for novel functional foods and as a dietary supplement. Therefore, optimal conditions for extracting theanine from tea are required for the accurate quantification of theanine in tea and as an efficient first step for its purification. This study examined the effects of four different extraction conditions on the yield of theanine from green tea using water and applied response surface methodology to further optimise the extraction conditions. The results showed that temperature, extraction time, ratio of water-to-tea and tea particle sizes had significant impacts on the extraction yield of theanine. The optimal conditions for extracting theanine from green tea using water were found to be extraction at 80 °C for 30 min with a water-to-tea ratio of 20:1 mL/g and a tea particle size of 0.5-1 mm. 相似文献