共查询到20条相似文献,搜索用时 100 毫秒
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该研究通过采用高效液相色谱(HPLC)法测定苯乳酸含量,从50株鱼肠道来源的乳酸菌中筛选高产苯乳酸的菌株,通过形态观察、生理生化试验及分子生物技术对其进行菌种鉴定,并以苯乳酸产量为响应值,通过单因素试验和响应面试验对其产苯乳酸发酵条件进行优化。结果表明,筛选到1株产苯乳酸能力较好的菌株DY2,其苯乳酸产量达2.45 mg/m L,经鉴定,菌株DY2为融合魏斯氏菌(Weissella confuse)。菌株DY2产苯乳酸的最适发酵条件为初始pH 6.0,发酵时间50 h,接种量3%、发酵温度34℃。在此优化条件下,苯乳酸产量达2.99 mg/m L,是优化前的1.22倍。 相似文献
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原子吸收法测定牛奶中的乳酸 总被引:3,自引:0,他引:3
研究了原子吸收法测定牛奶中的游离乳酸。在弱碱性溶液中用乳酸与Cu3(PO4)2悬浮液作用,使乳酸置换出Cu3(PO4)2中的Cu,形成更稳定的乳酸铜,通过离心沉降未反应的Cu3(PO4)2,在上层清液中用原子吸收法测定乳酸铜中的铜,根据铜能与乳酸定量形成配合物,可间接求得乳酸的含量。对牛奶样品中乳酸的测定结果相对标准偏差小于1.4%,回收率在95%~98%之间。 相似文献
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本文研究了利用HPLC法测定生物硒醋和老陈醋中乳酸和醋酸的含量,并对其测定条件进行优化。应用以C18为色谱分析柱,检测波长为215 nm,流动相为2.5%NH4H2PO4缓冲液,样品稀释度为30倍,流速为1.0 min/m L,柱温为29℃,生物硒醋样品的最佳p H=2.5,老陈醋的最佳p H为2.7时,可以较好的分离、检测生物硒醋和老陈醋中乳酸和醋酸的含量,所有的检测在4 min内完成。同时当其他分析条件一定,p H=2.7时,醋酸和乳酸标样的回归方程分别为y=484.23x-81.373,R2=0.9992、y=441.37x-68.321,R2=0.9979。当p H=2.5时,醋酸和乳酸标样的回归方程分别为y=484.61x+72.201,R2=0.9993、y=389.82x+30.432,R2=0.9991。该检测方法重复性、准确度、精确度的相对标准偏差范围为0.00%1.07%,其中生物硒醋乳酸和醋酸标品的加标回收率分别为100.00%110.00%、99.00%100.83%,老陈醋乳酸和醋酸标品的加标回收率分别为100.00%101.00%、100.00%110.00%。此方法重复性好、准确性和精确性好,检测时间短。可以应用于生物硒醋和老陈醋的HPLC法有机酸的定量分析。 相似文献
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研究对HPLC法和酶催化光度法测定啤酒中甲醛含量的实验条件进行优化,对乙酰丙酮法、AHMT法、HPLC法和酶催化光度法测定啤酒中的甲醛含量进行比较和分析,实验结果表明,从实验重复率、甲醛回收率及检测限考察,酶法为最佳测定方法,HPLC法也能够满足实际检测的需要,但与酶法相比,其对实验设备的要求较高,不经济且不方便。AHMT法由于采用直接火加热导致甲醛提取率降低,从而降低了实验结果的可信度。乙酰丙酮法由于检测限偏高,较难满足实际检测的需要。 相似文献
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G Knupp G Bugl-Kreickmann C Commichau T Schmidt H Büning-Pfaue 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1987,185(6):472-476
The determination of nicarbazin residues in foodstuffs of animal origin by two different methods, polarography, HPLC with electrochemical detection, is described. By applying pulse polarography at the dropping mercury electrode to acetonitrile extracts of animal tissues and eggs, a detection limit of 50 micrograms/kg and mean recoveries of 79% were obtained. The same extracts were used for the HPLC determination with electrochemical detection. This led to a detection limit of 1 microgram/kg. Additional rapid confirmation can be obtained from HPLC using an internal standard (nifursol) and comparing peak area proportions of both substances at varied polarization voltages. The quantitative determination of nicarbazin in chicken eggs by both polarography and HPLC was found to be in good agreement. 相似文献
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Zusammenfassung Es wird eine HPLC-Methode zur Bestimmung des elementaren Schwefels in Lebensmitteln beschrieben. Der Schwefel wird mit Benzin aus den Lebensmitteln extrahiert, durch HPLC getrennt und bei 263 nm bzw. 254 nm gemessen.
The HPLC determination of elemental sulfur in foodstuffs
Summary A simple HPLC method for the determination of sulfur is described. Sulfur is extracted from foodstuffs with petroleum ether, separated by means of HPLC and measured at 263 or 254 nm.相似文献
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为了更准确地检测绿原酸的含量,对绿原酸含量分析的测定方法进行了综述。目前的检测方法主要有:紫外分光光度法、二阶导数光谱法、可见分光光度法、阻抑-催化褪色光度法、差示导数光谱法、二阶导数差示脉冲极谱定量分析法、胶束薄层色谱法、流动注射化学发光分析法、毛细管区带电泳法、薄层色谱扫描法(TLC法)、高效液相色谱法(HPLC法)、反相高效液相色谱法(RP-HPLC法)、系数倍率法、导数极谱法和HPLC法与其它方法的联用等,同时对绿原酸的检测方法进展进行了展望。 相似文献
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Truzzi C Annibaldi A Illuminati S Finale C Rossetti M Scarponi G 《Journal of food science》2012,77(7):C784-C790
In this work we compared 2 official methods for the determination of HMF in honey, the spectrophotometric White method and the HPLC method (International Honey Commission) for the determination of HMF in unifloral honey and honeydew samples with a very low HMF content (<4 mg/kg), which is the most critical determination in terms of accuracy and precision of methods. In honey solutions, the limits of quantification for HPLC and White methods are 0.83 mg/L and 0.67 mg/L, respectively, and the linearity range is confirmed up to 20 mg/L for the HPLC method and up to 5 mg/L for the White method. In honeys with HMF >5 mg/kg, the molar extinction coefficient is 15369, lower than the literature value of 16830, and should be used for HMF determination. For samples with HMF content in the range 1-4 mg/kg the accuracy of the 2 methods is comparable both for unifloral and honeydew samples, whereas as regards precision, the HPLC method gives better results (3.5% compared with 6.4% for the White method). So, in general, the HPLC method seems to be more appropriate for the determination of HMF in honey in the range 1-4 mg/kg thanks to its greater precision, but for samples with a HMF content of less than 1 mg/kg the analyses are inaccurate for both methods. PRACTICAL APPLICATION: This work can help governmental and private laboratories that perform food analyses to choose the best method for the determination of HMF at very low levels in unifloral honey and honeydew samples. 相似文献
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目的:建立蓝莓饮料中飞燕草定-3-O- 葡萄糖苷及锦葵定-3-O- 葡萄糖苷两种花青素类成分的高效液相色谱快速检测方法。方法:采用高效液相色谱法,使用安捷伦ZORBAX SB-C18(4.6mm × 75mm,3.5μm)色谱柱,以3% 磷酸溶液和甲醇为流动相,二极管阵列检测器在波长525nm 处进行检测。结果:该方法对飞燕草定-3-O- 葡萄糖苷和锦葵定-3-O- 葡萄糖苷的最低检出限分别为0.4ng 和2.5ng,标准曲线线性良好,相关系数大于0.9984,回收率在90.2%~98.3% 之间,相对标准偏差不大于1.79%。结论:该法简洁、快速且灵敏度高,适合于蓝莓类饮料中花青素的快速检测。 相似文献