高效液相色谱法测定灭尔痛片的组分含量

采用高效液相色谱法同时测定灭尔痛片中对乙酰氨基酚、异丙基安替比林、及咖啡因３种成分的含量。色谱条件为：ＯＤＳ柱，甲醇＋水（６０＋４０）为流动相，检测波长为２５４ｎｍ。方法线性范围分别为：２４～１２０ｍｇ／Ｌ（ｒ＝０９９７６）；１２～６０ｍｇ／Ｌ（ｒ＝０９９９４）；４～２０ｍｇ／Ｌ（ｒ＝０９９９４）。各组分的平均回收率（ｎ＝６）分别为：１００３％，ＲＳＤ＝０４２％；９９７％，ＲＳＤ＝０６９％；９９２％，ＲＳＤ＝０４６％。该法操作简便、快捷，结果准确。     

生物碱基的反相离子对色谱分离及茶叶中咖啡因测定的研究

报道了在ＹＷＧＣ１８柱上，以甲醇＋水（７．５＋９２．５）、含５ｍｍｏｌ／ＬｐＨ５．０磷酸盐缓冲溶液、１０ｍｍｏｌ／ＬＴＢＡ·Ｂｒ作流动相，同时分离尿嘧啶、９Ｎ二羟丙基腺嘌呤、腺嘌呤、可可碱、尿嘧啶丙酸、９Ｎ二羟丙基茶碱和咖啡因，并用于茶叶中咖啡因的测定，检出限为μｇ／Ｌ级，标准加入回收率为９５．３％～１０５．０％。     

赤霉素在钼蓝法测定砷,磷,硅中的应用——连续测定钢铁中的砷,磷,硅

将植物生长刺激素赤霉素引入光度分析作新显色剂，研究了赤霉素将砷、磷、硅杂多酸还原成相应杂多蓝的显色反应。在０８４、１２０、２１６ｍｏｌ／ＬＨＣｌ介质中，赤霉素能分别将砷、磷、硅杂多酸还原成相应的杂多蓝，其最大吸收波长分别为８３５、８２０和８１０ｎｍ，表观摩尔吸光系数分别为２６４×１０４、２５４×１０４和３５１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１。线性范围分别为０～２４ｍｇ／Ｌ、０～１ｍｇ／Ｌ和０～０８ｍｇ／Ｌ。该法应用于钢铁中砷、磷、硅的连续测定，结果令人满意。     

阿斯美胶囊中四种组分的高效液相色谱分析

建立了反相高效液相色谱法测定阿斯美胶囊中氨茶碱、盐酸甲氧非那明、马来酸氯苯那敏及那可汀四种组分的含量。色谱柱为ＳｐｈｅｒｉｓｏｒｂＣ８，５μｍ，２００ｃｍ×４０ｍｍＩＤ，流动相为体积分数０５％的三乙胺溶液（磷酸调节ｐＨ５５）＋乙腈＋甲醇（５５０＋３６８＋８２），检测波长为２６４ｎｍ，线性范围分别为：氨茶碱３１２５～２５０ｍｇ／Ｌ，γ＝０９９９６，盐酸甲氧非那明１５６２５～１２５０ｍｇ／Ｌ，γ＝１００００，马来酸氯苯那敏２５～２００ｍｇ／Ｌ，γ＝０９９９９，那可汀８７５～７００ｍｇ／Ｌ，γ＝０９９９９；回收率（ｎ＝３）分别为１０１２％，１００８％，９９９％，９９５％；精密度：日内平均ＲＳＤ（ｎ＝６）分别为０７％，０４％，０４％，０６％；日间平均ＲＳＤ（ｎ＝３）分别为１０％，１０％，１１％，１２％。     

气相色谱法测定作业场所空气中的黑索金

本文报道用毛细管气相色谱电子捕获鉴定器测定作业场所空气中黑索金（ＲＤＸ）含量的新方法在优化的实验条件下，ＲＤＸ在０４０１８．０ｍｇ／Ｌ范围内可进行定量分析，检测限为０．０８ｍｇ／Ｌ，变异系数为３．９８．２％（ｎ＝６），样品回收率在９０％以上     

原儿茶醛的电化学研究

用单扫示波极谱法，原儿茶醛在ＮＨ４Ｃｌ＋ＮＨ３·Ｈ２Ｏ缓冲液（ｐＨ＝８５０）中有一还原峰，峰电位为－１５５Ｖ（ｖｓ．ＳＣＥ）。峰电流与质量浓度在００８～１５０ｍｇ／Ｌ和１５６～２８４ｍｇ／Ｌ范围内有良好的线性关系，检测限为００４ｍｇ／Ｌ。用该法测定中药丹参中原儿茶醛的含量，结果令人满意。实验证明其电极过程为具有吸附性质的可逆双电子过程。在弱酸性介质中，原儿茶醛的电极反应过程为伴有双聚反应的可逆逐级电子过程，自由基阻聚剂能有效地抑制原儿茶醛的双聚反应。     

工业用水中总铁含量的快速测定

介绍了以菲咯嗪－醋酸钠－醋酸缓冲溶液为显色体系、用自制的铁含量比色测定仪快速测定工业用水中总铁含量的方法。总铁含量≤０５ｍｇ／Ｌ时，标准偏差≤００３ｍｇ／Ｌ；总铁含量＞０５ｍｇ／Ｌ时，相对标准偏差≤５％。单次测定时间（包括样品处理）为１０～１５ｍｉｎ。采用单色光源及微型流动比色池，由蠕动泵和电子线路实现自动进样，直接显示测定结果。     

固相萃取—紫外导数光谱法测定血中杀鼠迷和杀鼠灵

报道了血中杀鼠迷和杀鼠灵的固相萃取－紫外导数光谱测定方法。萃取使用ＧＤＸ３０１树脂吸附，二氯乙烷洗脱。该法操作简便快速，两种杀鼠剂以１０ｍｇ／Ｌ量加于血中，回收率分别为（８２９±２１）％及（９１０±２７）％（ｘ±ＲＳＤ）。血中两种杀鼠剂的检出限分别为１５ｍｇ／Ｌ和１２ｍｇ／Ｌ。     

高效液相色谱法检测人尿中皮质激素水平

建立了高效液相色谱法分析测定尿中皮质激素的方法，该法可同时测定尿中醛固酮、可的松及皮质醇的水平，最低检出限为０１ｍｇ／Ｌ，线性范围０５～２０ｍｇ／Ｌ，回收率达９５％。方法简便、灵敏度较高，可作为常规手段推广应用。     

高效液相色谱法测定垃圾渗出液中的苯酚和对甲苯酚

介绍用气相色谱－质谱联用技术对垃圾渗出液中的酚类物质进行定性，然后用反相高效液相色谱法对苯酚和对甲苯酚进行定量分析。苯酚和对甲苯酚的线性范围分别为：５０×１０～４０×１０３ｍｇ·Ｌ－１，５０×１０２～１２×１０４ｍｇ·Ｌ－１；最低检出限为１６ｍｇ·Ｌ－１，４００ｍｇ·Ｌ－１；相对标准偏差为１１％和２９％。     

Simple and rapid UV spectrophotometry of caffeine in tea coupled with sample pre-treatment using a cartridge column filled with polyvinylpolypyrrolidone (PVPP)

We have applied a sample pre-treatment method with a cartridge column filled with polyvinylpolypyrrolidone (PVPP) to the effective removal of polyphenols and simple UV spectrophotometry of caffeine in tea. The absorption maximum length (lambda(max)) for caffeine was close to those for tea catechins in aqueous 1% acetic acid; therefore, the UV spectrum of a non-treated green tea sample had a large absorption wave. In contrast, the absorbance of the green tea sample was gradually reduced by PVPP cartridge treatment using PVPP from 0 to 50 mg, and was nearly constant using a pre-treatment cartridge with more than 100 mg PVPP, because tea catechins were effectively removed and caffeine was mostly recovered from a green tea sample by means of PVPP cartridge treatment. The PVPP pre-treatment cartridge also removed polyphenols successfully from oolong and black tea samples. Comparison with conventional HPLC analysis indicated that the present pre-treatment method with a PVPP cartridge was useful for the simple and selective UV spectrophotometric determination of caffeine in green, oolong and black tea samples.     

Rapid, direct determination of polyphenols in tea by reversed-phase column liquid chromatography.

Column liquid chromatography on a C18-bonded silica column with water-methanol-acetic acid as eluent was used to determine polyphenols and caffeine in tea. Without any pretreatment, catechin, epicatechin gallate, epigallocatechin gallate, epigallocatechin, epicatechin and caffeine were separated successfully within 15 min. The detection limits (S/N = 3) of polyphenols studied were 1.8-24 mg/l at a detection wavelength 270 nm. The linear range of the peak area calibration curves for the analytes were over two orders of magnitude with a correlation coefficient of 0.996-0.999. Using this method, some Chinese tea samples were analyzed with a good reproducibility (RSD are below 5%).     

Improved sample pre-treatment for determination of caffeine in tea using a cartridge filled with polyvinylpolypyrroridone (PVPP)

We have improved sample pre-treatment for the effective removal of polyphenols and simple analysis of caffeine in tea using a cartridge filled with polyvinylpolypyrroridone (PVPP). Nearly 100% of catechins were removed from the green tea sample and caffeine was completely recovered in the range of 98.2-101.3% by sample pre-treatment with a PVPP cartridge. Reproducibility of preparing PVPP pre-treatment cartridges was sufficient for quantitative analysis, because RSDs of analytical values for caffeine obtained by using three individual pre-treatment cartridges filled with 10-200 mg PVPP were 0.60-2.8%. The PVPP pre-treatment cartridge also removed polyphenols perfectly and recovered caffeine faultlessly from oolong and black tea samples. Comparison with the conventional method without sample pre-treatment indicated that the present pre-treatment method with a PVPP cartridge was useful for the simple and precise analysis of caffeine in green, oolong and black tea samples.     

Rapid analysis of methylated xanthines in teas by an improved high-performance liquid chromatographic method using a polyvinylpolypyrroridone pre-column.

We have developed a new high-performance liquid chromatography (HPLC) method for the analysis of methylated xanthines in tea by removing polyphenols using a polyvinylpolypyrroridone (PVPP) pre-column. The PVPP pre-column was connected with the upstream of analytical column to remove catechins in tea extract. Using this pre-column, caffeine and theobromine in tea, which belong to methylated xanthines, could be rapidly determined in less than 10 min with an isocratic solvent system. RSDs of standard solutions of caffeine and theobromine were about 0.3 and 0.3% for the retention time, and were about 1.6 and 2.5% for the peak area. The quantitation curves of caffeine and theobromine were linear from 5 to over 1000 ng.     

Study on South African Indigenous Teas—Antioxidant Potential,Nutritional Content,and Hypoxia-Induced Cyclooxygenase Inhibition on U87 MG Cell Line

Background: This study comparatively assessed seven indigenous traditional tea plants on several attributes that included antioxidant, nutritional, caffeine contents, and cyclooxygenase activity. Methodology: Nutritional content of all tea plants were determined for energy, fat, carbohydrates, total sugars, dietary fiber and amino acids. Antioxidant potential and the antioxidant potentiating secondary metabolites were also measured and compared. Further, we investigated the tea plants for any role they would have on cyclooxygenase (COX) activity on cobalt chloride (CoCl₂) induced human glioma cell lines (U87MG). Results: The tea plants were found non-cytotoxic at concentrations tested against the human Chang liver and HeK 293 kidney cells and were found to be naturally caffeine free. The lowest and highest extraction yield among the tea plants was 7.1% for B. saligna and 15.48% for L. scaberrimma respectively. On average, the flavonol content was 12 to 8 QE/g, ORAC 800 µmol TE/g, TEAC 150 µmol TE/g, FRAP 155 µmol AAE/g, polyphenols 40 mg GAE/g, flavanols 0.35 mg CE/g, flavonols 12 mg QE/g and total flavonoid content (TFC) 180 µg QE/mg. The COX activity has been found to be inhibited by a dose-dependent manner by L. scaberrimma, B. saligna and L. javanica. Conclusion: The results further support competitive value of tea plants and need for improved and further development.     

树脂对茶多酚与咖啡因的吸附分离

从低档绿茶末的水提取液中，利用离子交换，吸附树脂成功地分离出茶多酚与咖啡因，并详细考察了其交换与吸附性能。与其它方法相比，该树脂法具有产品收率高，成本低廉等特点。     

Determination of caffeine in black tea leaves by Fourier transform infrared spectrometry using multiple linear regression

A simple and fast analytical procedure was developed for the determination of caffeine in black tea leaves. The method is based on multiple linear regression treatment of Fourier transform infrared spectrometric data obtained in the wave number range 1800–1300 cm⁻¹ after extraction of caffeine in CHCl₃ from tea samples, wetted with an aqueous solution of NH₃ (0.1 M). The procedure requires no complex sample preparation. It provided a limit of detection of 0.035 mg/ml, a sampling frequency of 6 h⁻¹ and a coefficient of variation of 0.8% for five independent measurements of a tea sample with 3.68% w/w caffeine content. This procedure provides a drastic reduction in the consuming organic solvent for each sample compare to that of the reference chromatographic determination. The accuracy of technique is evaluated by comparing the obtained results with those of a reference HPLC technique. An average value of 3.60±0.07% w/w was obtained by HPLC for a powdered tea sample which is compromising when is compared to 3.68±0.03% (w/w) obtained by this FTIR technique.     

Bioassay-guided purification and identification of antimicrobial components in Chinese green tea extract

The Chinese green tea extract was found to strongly inhibit the growth of major food-borne pathogens, Escherichia coli O157:H7, Salmonella Typhimurium DT104, Listeria monocytogenes, Staphylococcus aureus, and a diarrhoea food-poisoning pathogen Bacillus cereus, by 44-100% with the highest activity found against S. aureus and lowest against E. coli O157:H7. A bioassay-guided fractionation technique was used for identifying the principal active component. A simple and efficient reversed-phase high-speed counter-current chromatography (HSCCC) method was developed for the separation and purification of four bioactive polyphenol compounds, epicatechin gallate (ECG), epigallocatechin gallate (EGCG), epicatechin (EC), and caffeine (CN). The structures of these polyphenols were confirmed with mass spectrometry. Among the four compounds, ECG and EGCG were the most active, particularly EGCG against S. aureus. EGCG had the lowest MIC90 values against S. aureus (MSSA) (58 mg/L) and its methicilin-resistant S. aureus (MRSA) (37 mg/L). Scanning electron microscopy (SEM) studies showed that these two compounds altered bacterial cell morphology, which might have resulted from disturbed cell division. This study demonstrated a direct link between the antimicrobial activity of tea and its specific polyphenolic compositions. The activity of tea polyphenols, particularly EGCG on antibiotics-resistant strains of S. aureus, suggests that these compounds are potential natural alternatives for the control of bovine mastitis and food poisoning caused by S. aureus.     

Determination of adenine,caffeine, theophylline and theobromine by HPLC with amperometric detection

A relatively simple method for quantifying caffeine, theobromine, theophylline and adenine by HPLC with amperometric detection was developed. A C₁₈-column and an isocratic elution with phosphate buffer pH 3.5/methanol (90 : 10) were employed for the chromatographic separation of the investigated compounds. The optimal detection potential was +1.4 V. The limits of detection were 0.4 ng for adenine, 1 ng for theophylline and 2.5 ng for caffeine and theobromine. The method was applied to the determination of these purine alkaloids in beverages, tea, coffee and cacao. The determination was carried out directly or after solid-phase extraction.     

Comparative analysis of tea catechins and theaflavins by high-performance liquid chromatography and capillary electrophoresis

This paper describes the simultaneous determination of catechins and theaflavins in green and black teas, using reversed-phase high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). The tea polyphenols analyzed included (+)-catechin, catechin gallate, (-)-epicatechin, epicatechin-3-gallate, epigallocatechin, epigallocatechin-3-gallate, theaflavin, theaflavin-3-monogallate, theaflavin-3'-monogallate and theaflavin-3,3'-gallate. These polyphenols together with six other tea ingredients such as caffeine, adenine, theophylline, quercetin, gallic acid and caffeic acid were separated within 27 min by HPLC and in less than 10 min by CE. The optimal analytical conditions of both chromatographic methods were investigated for the convenience and reliability for routine analysis. Both HPLC and CE were found to be reliable and compatible. The reproducibility of the within-day assay using both methods was generally >90%. The day-to-day variation of retention time was <5% for HPLC, while the variation of migration time for CE was <2%. The analysis time of CE was three-times faster, however it is five-times less sensitive than HPLC, which has detection limits of 0.05 microg/ml and 0.5 microg/ml for catechins and theaflavins, respectively.