高效液相色谱法测定保健食品中维生素D3的含量

目的建立用半制备型反相高效液相色谱系统纯化、正相高效液相色谱硅胶柱色谱分离测定保健食品中维生素D_3含量的方法。方法通过皂化排除样品中的干扰物质,再经乙醚萃取浓缩,将浓缩后供试品溶液注入反相高效液相色谱仪净化分离去除杂质,排除维生素A的干扰,再用正相分析色谱进行定量分析,以正己烷-正戊醇(997:3,V:V)为流动相,流速为1.0 mL/min,采用色谱柱Waters Nova-Pak?Silia分离,在254 nm检测波长下经紫外或二极管阵列检测器检测,外标法定量。结果维生素D_3浓度在0.297~9.506μg/mL范围内呈良好的线性关系,相关系数为1,平均回收率为100.55%~100.58%,相对标准偏差值为0.44%~0.72%。结论该方法快速准确,可适用于保健食品中维生素D_3含量的测定。     

正相高效液相色谱法测定鱼肝油中的维生素D3

建立一种正相高效液相色谱法测定鱼肝油中VD3含量的新方法。采用Agilent ZORBAX Rx-SIL色谱柱,以95%正己烷-5%异丙醇为流动相,流速为1.0 mL/min,PDA检测波长264 nm。结果表明:VD3浓度在0.2μg/mL～20μg/mL范围内,峰面积与含量具有良好的线性关系(r=0.999 7);平均相对标准偏差为0.62%,平均回收率为94.2%。该方法可作为鱼肝油中VD3含量的一种快速检测方法。     

液相萃取-反相高效液相色谱法联用测定植物油中的苯并芘

建立液相萃取-反相高效液相色谱法测定植物油中苯并芘的方法,以乙腈饱和的正己烷-正己烷饱和的乙腈作为萃取试剂,采用反相高效液相色谱仪对植物油中苯并芘的含量进行测定。所得线性方程Y=0.717 823X+0.159 747,相关系数r=0.999 99,线性范围在2～100 ng/m L,当乙腈饱和的正己烷与正己烷饱和的乙腈体积比为2∶5时(即4 m L乙腈饱和的正己烷,10 m L正己烷饱和的乙腈),其回收率在82.62%,精密度为1.1%,检出限为0.4μg/kg。该方法稳定、高效、检测成本低,适用于植物油中苯并芘的检测。     

微波辅助萃取-超高效液相色谱法快速测定纸制品中松香酸含量

建立了一个快速测定纸制品中松香酸含量的超高效液相色谱方法,该方法以甲醇为萃取溶剂,在85℃下微波萃取纸制品中的松香酸,萃取物直接进行超高效液相色谱分析,外标法定量。在S/N(信噪比)=3的条件下,该方法的检出限为0.1mg/kg,精密度为1.36%,加标平均回收率为80.00%~95.20%。该方法操作简单,灵敏度高,分析耗时只有3.5min,适用于纸制品中松香酸含量的快速测定。     

反相高效液相色谱法测定维生素K2中 七烯甲萘醌的含量

目的建立维生素K2产品中七烯甲萘醌(MK-7)的反相高效液相色谱定量检测的方法。方法采用Diamonsil C18(4.6 mm×250 mm,5μm)色谱柱,流动相为50%甲醇/水(含0.1%乙酸)(95:5=V:V),50%异丙烷。流速为等速1.0 m L/min,检测波长270 nm,柱温40℃。结果 MK-7在浓度0.355~2.132 mg/m L的范围内具有良好的线性关系,相关系数在0.9999以上。重复性实验中相对标准偏差为0.41%,加标回收率为98.15%。结论此方法准确性高、重现性好、操作简单,可用于维生素K2中MK-7含量测定。     

微波萃取-高效液相色谱法测定食品塑料包装材料中双酚A含量

建立了微波萃取-超高效液相色谱法(MAE-HPLC)检测塑料包装食品中双酚A的分析方法。选择甲醇为萃取溶剂,对微波萃取条件进行了优化,结果表明最佳的萃取条件为:萃取温度为80℃,萃取时间为20min。在试验选定的最佳条件下,方法线性范围0.10~20mg/L,相关系数为0.9998,方法检出限为0.1 mg/kg,样品加标回收率为88.9%~99.6%,相对标准偏差小于2.2%。     

反相高效液相色谱法测定香菜中芦丁的含量

本文建立了香菜中芦丁含量的反相高效液相色谱法的测定方法,并测定了不同采收期芦丁的含量。优选测定香菜中芦丁含量的色谱条件为：色谱柱为ODSC18分析柱（4.6mmx250mm,5μm）,流动相为甲醇-0.4%的磷酸水溶液（55：45）;DAD检测器,检测波长360nm,流速lml/min,柱温为25℃。实验结果表明,香菜中芦丁含量测定的线性回归方程为y=1064.3349x＋18.1259,r=0.9990,线性范围为0.05～0.2μg。香菜样品中芦丁平均含量为4.2551mg/g,平均回收率为96.40%（RSD=1.34%）。结果显示,本实验方法稳定、可靠,重复性好,提示可以作为香菜中芦丁含量的测定方法;不同采收期的香菜中芦丁含量略有差别。     

正己烷提取-高效液相色谱法及其串联质谱法分别测定婴幼儿配方奶粉中维生素A、D3含量

目的 建立了正己烷提取、液相色谱和液相色谱串联质谱分别测定婴幼儿配方奶粉中维生素A(VA)和维生素D₃(VD₃)含量的方法。方法 样品中加入VD₃-d₃内标后皂化,正己烷提取,去离子水清洗正己烷提取液以去除提取液中的氢氧化钾,加入氯化钠促进水和正己烷两相分层,将洗至中性的正己烷提取液浓缩至干,甲醇定容至10 mL,取1 mL溶液用液相色谱法测定VA,剩余的9 mL定溶液浓缩至干后再用1 mL甲醇复容,液相色谱串联质谱测定VD₃。结果 VA的线性范围为0.2～6.0 μg/mL,方法检出限为30 μg/100g,方法定量限为100 μg/100g;VD₃的线性范围为0.01～0.20 μg/mL,方法检出限为0.5 μg/100g,方法定量限为1.0 μg/100g。通过质控样品验证方法准确度和精密度,测定值均在质控区间内,且批内相对标准偏差和批间相对标准偏差均小于5%。使用该方法成功通过了2020年婴幼儿配方奶粉中VA、VD₃样品能力验证考核。结论 该方法所用提取试剂少,且操作简单快捷,适用于婴幼儿配方奶粉中VA和VD₃的测定。     

高效液相色谱法同时测定维生素D3和维生素K2的含量

目的建立高效液相色谱法同时测定维生素D_3和维生素K_2的含量的分析方法。方法以95%甲醇水:异丙醇=(98:2, V:V)为流动相,梯度洗脱,样品经C_(18)色谱柱(250 mm×4.6 mm, 5μm)分离,并于264 nm波长检测。结果维生素D3在浓度0.1282～1.2818μg/mL之间呈现良好的线性关系,r~2=0.9999,平均回收率为95.7%～100.7%,相对标准偏差为1.7%;维生素K_2在浓度0.51397～5.1397μg/mL之间呈现良好的线性关系,r=0.9999,平均回收率在97.3%～100.7%之间,相对标准偏差为1.3%。结论该方法操作简便、准确、重现性好,能同时测定维生素D_3和维生素K_2含量,可在实验室推广。     

固相萃取-高效液相色谱法测定饮料中维生素B12

利用AgelaPCX固相萃取柱对饮料中的维生素B12进行浓缩和净化,建立了测定饮料中维生素B12的固相萃取-高效液相色谱法。方法的线性范围为0.1～20.00μg/mL,相关系数为0.99996。方法检出限为0.2ng/mL。三个浓度水平的加标回收率分别为78.7%、83.0%、83.3%,相对标准偏差小于3%。     

Vitamin D₂ impairs utilization of vitamin D₃ in high-yielding dairy cows in a cross-over supplementation regimen

Vitamin D exists in 2 forms that are important regarding vitamin D status and supply in cattle: vitamin D₂ (D₂) and vitamin D₃ (D₃). To become physiologically active, both D₂ and D₃ must undergo 25-hydroxylation in the liver. The resulting 25-hydroxyvitamin D₂ [25(OH)D₂] and 25-hydroxyvitamin D₃ [25(OH)D₃] are measured as indicators of the physiological vitamin D status of cattle. The study used 14 Danish Holstein cows housed without access to sunlight. The cows were orally administered 250 mg (1.0 × 10⁷ IU) of D₂ and D₃ in a cross-over design with 2 treatment groups and 2 study periods, rendering 4 treatments when carryover effects were taken into account: D₂ given first, D₂ given last after D₃, D₃ given first, and D₃ given last after D₂. Two weeks elapsed between the treatment in the first study period and the treatment in the second study period. Blood samples were collected 0, 3, 6, 14, 17, 20, 23, 26, 40, 48, 70, 94, 166, and 214 h after providing the oral bolus of vitamin to the cows. Comparisons between plasma levels of the metabolites D₂, D₃, 25(OH)D₂, and 25(OH)D₃ over time were made by comparing areas under the plasma concentration curves. Oral administration of D₃ increased plasma D₃ (182.6 ± 17.1 ng/mL; mean ± SEM) and 25(OH)D₃ (103.5 ± 10.0 ng/mL) more efficiently than oral administration of D₂ increased plasma D₂ (49.1 ± 32.6 ng/mL) and 25(OH)D₂ (27.9 ± 2.1 ng/mL). The D₃ given after an oral dose of D₂ was less efficient for increasing plasma concentrations of 25(OH)D₃ (61.2 ± 12.0 ng/mL) compared with D₃ given without previous D₂ administration (103.5 ± 10.0 ng/mL), whereas the plasma concentrations of D₃ itself were the same when given first (182.6 ± 17.1 ng/mL) as when given after D₂ (200.0 ± 123.9 ng/mL). The same occurred for plasma concentrations of D₂ metabolites both if D₂ was given first (49.1 ± 32.6 ng/mL) and after D₃ (54.7 ± 7.7 ng/mL). In conclusion, D₃ given after D₂ is less efficient at increasing the plasma status of 25(OH)D₃ than D₃ given without previous D₂ administration.     

Estimation and fortification of vitamin D3 in pasteurized process cheese

The objective of this study was to develop methods for the estimation and fortification of vitamin D3 in pasteurized Process cheese. Vitamin D3 was estimated using alkaline saponification at 70 degrees C for 30 min, followed by extraction with petroleum ether:diethyl ether (90:10 vol/vol) and HPLC. The retention time for vitamin D3 was approximately 9 min. A standard curve with a correlation coefficient of 0.972 was prepared for quantification of vitamin D3 in unknown samples. In the second phase of the study, pasteurized Process cheeses fortified with commercial water- or fat-dispersible forms of vitamin D3 at a level of 100 IU per serving (28 g) were manufactured. There was no loss of vitamin D3 during Process cheese manufacture, and the vitamin was uniformly distributed. No losses of the vitamin occurred during storage of the fortified cheeses over a 9-mo period at 21 to 29 degrees C and 4 to 6 degrees C. There was an approximately 25 to 30% loss of the vitamin when cheeses were heated for 5 min in an oven maintained at 232 degrees C. Added vitamin D3 did not impart any off flavors to the Process cheeses as determined by sensory analysis. There were no differences between the water- and fat-dispersible forms of the vitamin in the parameters measured in fortified cheeses.     

在线固相萃取-高效液相色谱法快速测定奶粉中的维生素K1与维生素K2

目的：建立一种在线固相萃取-高效液相色谱分析方法快速测定奶粉中维生素K1与K2。方法：加入脂肪酶水溶液酶解奶粉样品;酶解液加入异丙醇与KOH水溶液进行定容后,在线固相萃取装置上进行上样、转移、分析测定和清洗平衡后,进入液相色谱仪上进行洗脱将维生素K1、K2分开,荧光检测器检测,外标法定量。结果：VK1、MK-4和MK-7在0.002-0.1ug/mL范围内良好线性;检出限分别0.12ug/100g、0.14ug/100g、0.19ug/100g。结论：这种快速测定法溶剂消耗少,大幅缩短了检测时间,节省了人力,实现了自动在线净化检测,提高了灵敏度,保证了测试结果的准确性和稳定性。     

高效液相色谱法测定牛奶中的维生素C含量

建立了高效液相色谱法测定牛奶中的维生素C的含量的方法。样品用0.1 mol/L盐酸常温下超声提取,采用高效液相色谱法,维生素C,并与标准系列比较,以保留时间定性,峰面积定量。结果表明,以0.05 mol/L磷酸二氢钾:甲醇(96:4)为流动相,经C18色谱柱分离,回收率为93%~100%,相对标准偏差为0.6%~1.1%。本方法灵敏度高,选择性好,操作简便快捷,具有很好的实用价值。     

高效液相色谱法测定能量饮料中多种水溶性维生素

研究利用反相液相色谱法测定能量饮料中七种水溶性维生素(VC、VPP、VB1、VB2、VB5、VB6、叶酸)的方法。样品利用Supelco C18固相萃取柱(500mg/6ml)萃取后,直接注入高效液相色谱柱Phenomenex C18(250mm×4.6mm,5μm),采用等度洗脱,流动相为0.1mol/L KH2PO4(pH7.0)-甲醇(90:10,V/V),流速为0.5ml/min。根据各个化合物的保留时间以及UV谱图与标准谱图的对比可以确认各化合物。该方法的检测限为0.05～0.2mg/L,平均回收率为94.71%～97.03%。     

复合型固相萃取-离子对反相液相色谱法测定蔬菜中的灭蝇胺残留

为建立复合型固相萃取-离子对反相液相色谱(IS-RPLC)快速、准确测定蔬菜中灭蝇胺残留的方法,采用碳酸氢铵溶液多次超声萃取方式提取目标物,经复合型固相萃取小柱净化,结合离子对反相液相色谱系统分离、测定。在0.1～2 μg/mL线性范围呈线性(相关系数大于0.998),方法检出限(LOD)达0.012 mg/kg,满足各类蔬菜基质对灭蝇胺残留的监管判定要求。通过加标验证,回收率在77.7%～87.0%范围,相对标准偏差(RSD)为1.6%～3.7%。方法解决了灭蝇胺萃取回收率低、净化困难的问题,结合离子对试剂的C8色谱柱反相保留,使灭蝇胺出峰良好,抗干扰强。     

Vitamin D3 synthesis in the entire skin surface of dairy cows despite hair coverage

How hair-coated animals such as dairy cows synthesize endogenous vitamin D₃ during exposure to summer sunlight has been unclear since vitamin D₃ and its relation to sunlight was discovered. The fur of fur-bearing animals is thought to be comparable to clothing in humans, which prevents vitamin D₃ synthesis in the skin during exposure to sunlight. Different scenarios have been suggested but never tested in cows; for example, that vitamin D₃ is synthesized from sebum on the hair and ingested by cows during grooming or that body areas such as the udder and muzzle that have scant hair exclusively produce the vitamin. To test different scenarios, 16 Danish Holstein dairy cows were subjected to 4 degrees of coverage of their bodies with fabric that prevented vitamin D₃ synthesis in the covered skin areas. The treatments were horse blanket (cows fitted with horse blankets), udder cover (cows fitted with udder covers, horse blanket + udder cover (cows fitted with both horse blankets and udder covers), and natural (cows without any coverage fitted). The cows were let out to pasture daily between 1000 and 1500 h for 4 wk in July and August 2009. Blood samples were collected 15 times during the study and analyzed for content of 25-hydroxyvitamin D₃ [25(OH)D₃] indicative of the animals’ vitamin D₃ status. Results showed that uncovered cows had a higher 25(OH)D₃ concentration in plasma after 28 d of access to sunlight compared with covered cows and that the plasma concentration of 25(OH)D₃ was strongly inversely correlated to the body surface area covered. These results are consistent with findings in humans, wherein the vitamin D₃ status of different individuals was inversely proportional to the amount of clothing worn during exposure to artificial sunlight. Hence, it appears that human clothing and cow hair are not comparable with respect to prevention of vitamin D₃ synthesis and that cows, like humans, synthesize vitamin D₃ evenly over their body surface. That vitamin D₃ should be synthesized from sebum on the hair and obtained by cows as a result of grooming is not supported by the findings in the present study either, because large differences were found between the treatment groups. If grooming were the source of vitamin D₃, then a relatively even 25(OH)D₃ concentration between treatments would be expected, because covered cows would obtain vitamin D₃ by grooming uncovered herdmates.