孕激素的UFLC/DAD/ESI/MS/MS定性确证体系研究

目的:建立牛奶中21а-羟基孕酮、17а-羟基孕酮、炔孕酮、甲羟孕酮、醋酸甲地孕酮、醋酸氯地孕酮、醋酸甲羟孕酮和孕酮等8种孕激素的快速液相色谱/二极管阵列/电喷雾电离串联质谱(UFLC/DAD/ESI/MS/MS)定性鉴别体系。方法:牛奶样品经甲醇提取、Oasis HLB固相萃取小柱净化和快速液相色谱分离后,利用DAD检测器在线检测,采用标准紫外光谱和三维光谱图对照方式进行初筛;按照三离子定性原则,利用电喷雾电离串联质谱(ESI-MS/MS)进行确证。结果:DAD在线扫描光谱信息丰富,超快速液相色谱分离良好,电喷雾电离准分子离子强而稳定,二级质谱裂解碎片离子稳定可靠,初筛和确证的定性依据充分。结论:本方法建立的超快速液相色谱、紫外光谱及串联质谱的联合定性方法适用于孕激素残留的筛选和确证检测。     

葡萄酒中6种甜味剂的dSPE-UFLC-MS/MS快速确证检测

目的建立一种简便、快速的葡萄酒中安赛蜜、糖精、甜蜜素、阿斯巴甜、甜菊糖苷和纽甜的分散固相萃取-液相色谱/串联质谱(dSPE-UFLC-MS/MS)定性定量分析方法。方法样品以新型磁性纳米材料为吸附剂进行分散固相萃取,利用UFLC-ESI-MS/MS进行分离和串联质谱测定,采用保留时间结合三离子定性原则进行确证。结果磁性纳米材料是一种高效的分散固相萃取吸附剂,可有效去除葡萄酒中的干扰基质;电喷雾电离可获得稳定可靠的二级质谱裂解碎片离子,安赛蜜、糖精、甜蜜素、阿斯巴甜、甜菊糖苷和纽甜的定量离子对分别为m/z 162→82、m/z 182→42、m/z 178→80、m/z 293→200、m/z 803→641、m/z 377→200,6种甜味剂的精密度范围为1.1%~4.0%,回收率范围为83.4%~104.0%,定量检出限范围为0.1~5.0μg/L。结论建立的方法快速、灵敏、准确,适用于葡萄酒中安赛蜜、糖精、甜蜜素、阿斯巴甜、甜菊糖苷和纽甜的含量确证分析。     

高效液相色谱-串联质谱法测定酸奶中纳他霉素的含量

目的:利用液相色谱-串联质谱联用仪,建立酸奶中纳他霉素的液相色谱-串联质谱(LC-MS/MS)测定方法。方法:酸奶样品用乙醇超声波振荡提取,离心后,上清液待测。采用LC-MS/MS测定,色谱柱为C18反相色谱柱,流动相为乙腈-0.2%甲酸水溶液,电喷雾正离子模式电离,质谱多反应选择离子检测(MRM),检测离子对为m/z 666→504和m/z 666→486,其中m/z 666→504为定量离子对,外标法定量。结果:纳他霉素线性相关系数为0.9994,不同水平的回收率为93.4%~101.7%,检出限为10μg/kg。结论:该法简便快速、准确可靠。     

高效液相色谱/离子阱质谱快速鉴定茚满二酮类鼠药

目的建立鼠药药饵中4种茚满二酮类鼠药的高效液相色谱/离子阱质谱快速鉴定方法。方法鼠药药饵经丙酮提取后,采用固相萃取净化,选择液相色谱/离子阱质谱仪(LC-IT/MS)的最佳仪器条件,进行液相色谱的分离和二级质谱的裂解,根据质谱分析三离子原则进行定性。结果 4种茚满二酮类鼠药的二级质谱碎片离子具有较好的特征性和稳定性,母离子和子碎片离子的关系清晰,敌鼠的定性离子对为m/z339→167和m/z339→145,氯敌鼠为m/z373→201和m/z373→145,异杀鼠酮为m/z229→145和m/z229→187,杀鼠酮为m/z229→172和m/z229→145。结论本实验建立的方法简便,结果准确可靠,适合于茚满二酮类鼠药的定性鉴别。     

LC-M/SMS法测定大鼠血浆中的6,7-二甲氧基香豆素

目的:建立快速、灵敏的液相色谱-串联质谱方法测定大鼠血浆中6,7-二甲氧基香豆素浓度。方法:40μl血浆样品中药物经含内标的甲醇溶液蛋白沉淀,于12000 rpm离心取上清液稀释后,以乙腈-0.1%甲酸10 mmol/L甲酸铵溶液为流动相,梯度洗脱方式分离。使用电喷雾电离源以多反应监测(MRM)方式进行正离子检测。结果:确定丰度最高的2对离子m/z 207.2→m/z 107.0(6,7-二甲氧基香豆素)和m/z 147.0→m/z 91.0(香豆素),用于定性定量分析。该方法在0.5 ng/ml~2500 ng/ml的浓度范围内线性良好,相关系数r=0.9951。结论:本文首次建立了简便、快速、灵敏、专属的测定大鼠血浆中6,7-二甲氧基香豆素的LC-MS/MS分析方法。     

直接进样离子阱质谱法快速鉴定鼠药药饵中敌鼠和氯敌鼠

目的:建立鼠药药饵中敌鼠和氯敌鼠的直接进样离子阱质谱鉴定方法。方法:鼠药药饵经丙酮提取,固相萃取小柱净化后,采用直接进样进行二级质谱裂解,根据质谱分析三离子原则进行定性。结果:在适宜的二级质谱裂解条件下,以敌鼠和氯敌鼠的准分子离子m/z 339和m/z 373为母离子的二级质谱碎片离子具有较好的特征性和稳定性,母离子和子离子的关系清晰,敌鼠的定性离子对为m/z 339→167和m/z 339→145,氯敌鼠为m/z 373→201和m/z373→145;阐明了敌鼠和氯敌鼠的二级质谱裂解机理。结论:本实验建立的方法简便,可用于敌鼠和氯敌鼠鼠药药饵的快速鉴定。     

液相色谱-质谱联用检测食品中苯甲酸、山梨酸、糖精钠

目的：建立高效液相-质谱联用仪检测各类食品中苯甲酸、山梨酸、糖精钠的方法。方法：采用HPl00高效液相色谱一质谱联用系统；C18柱；流动相：甲醇：0．02mol／L乙酸铵=5：95；流速：1ml／min；检测波长：230nm；质谱扫描（m／z）：50～500amu；苯甲酸、山梨酸、糖精钠选择性荷质比（m／z）为：121；111；182。结果：在质量范围内线性良好，r=0．9999，苯甲酸、山梨酸、糖精钠回收率92％～105％。结论：方法具有高度的灵敏性和专属性，能对食品中苯甲酸、山梨酸、糖精钠进行准确定性和定量检测，是可行有效的检测方法。     

大田软海绵酸液相色谱串联质谱检测方法的研究

目的:利用高效液相色谱-串联质谱法建立海产品中大田软海绵酸(Okadaic acid,OA)的检测方法。方法:贝样品提取液经AccuBondⅡSPE silica固相萃取小柱预分离和富集,用三级四极杆串联质谱(MS/MS)作为HPLC的检测器,使用正离子电喷雾(ESI)电离方式,多反应监测(MRM)扫描模式,选择母→子离子对m/z827→m/z723,m/z827→m/z809作为定量检测的离子对,HPLC的流动相为乙腈:1%甲酸-水(体积比70:30),色谱柱为Agilent Extend-C18(2.1×150 mm,Φ5.0μm),对OA标准品及加标样品和实际样品进行HPLC-MS/MS检测。结果:方法线性回归方程为Y=193.07X-780.6(Q1/Q3:m/z827.4→723.5);Y=83.021X-335.6(Q1/Q3:m/z827.4→809.5),相关系数r2均为0.9991;线性范围为10~800μg/L。样品平均回收率为83.99%,平均RSD为4.34%。结论:建立的HPLC-MS/MS方法灵敏、快速、准确,可用于海产品中贝类样品OA限量标准检测。     

UPLC法同时测定食品中5种添加剂

[目的]建立超高效液相色谱UPLC快速分离和测定食品中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸等的方法.[方法]样品经沉淀蛋白、超声提取、离心、过滤等预处理,采用乙酸铵(0.02 mol/ml)-甲醇(体积比93:7),检测波长230 nm,二极管阵列检测器,外标法定量.[结论]该方法精密度高、准确性好,样品处理简单,测得安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸在0.2～20 mg/kg范围内线性良好,回收率在90.1～105.3之间,检出浓度为安赛蜜、苯甲酸、山梨酸0.02 mg/kg,糖精钠、脱氢乙酸0.04 mg/kg.[结论]该方法具有简便、快速、准确的优点,可用于食品中安赛蜜、脱氢乙酸、苯甲酸、山梨酸、糖精钠的检测.     

反相高效液相色谱法同时测定食品中的苯甲酸、山梨酸和脱氢乙酸

目的建立反相高效液相色谱法同时测定食品中的苯甲酸、山梨酸和脱氢乙酸的方法。方法食品中的脱氢乙酸、苯甲酸和山梨酸经前处理后,过0.45μm超滤膜,经高效液相色谱C18柱的分离,二极管阵列检测器(DAD)于230nm处检测,以保留时间定性,峰高或峰面积定量。样品经溶解超滤后用反相高效液相色谱仪测定。结果该方法对苯甲酸、山梨酸和脱氢乙酸的分离度好,RSD分别为0.50%、0.46%和0.66%,回收率分别为104.8%、107.2%和96.9%,检出限分别为12、8和10ng。当样品量为5g,定容体积50ml,进样量30μl时,最低检出浓度分别为0.004、0.003和0.003g/kg。色素、乙酰磺胺酸钾、糖精钠均不干扰其测定。结论该方法精密度高、准确度好、选择性强,适用于食品中苯甲酸、山梨酸和脱氢乙酸的定性定量分析。     

Docosahexaenoic acid and arachidonic acid prevent essential fatty acid deficiency and hepatic steatosis

Objectives: Essential fatty acids are important for growth, development, and physiologic function. α‐Linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, the authors hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids. Methods: Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, the authors provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis. Results: Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks. Conclusion: Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without α‐linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model.     

Gamma-linolenic acid, arachidonic acid, and eicosapentaenoic acid as potential anticancer drugs

Several in vitro studies and limited in vivo investigations showed that some cis-unsaturated fatty acids (c-UFAs) such as gamma-linolenic acid, arachidonic acid, and eicosapentaenoic acid have selective tumoricidal actions. This cytotoxic action of c-UFAs is produced by augmentation of free-radical generation and lipid peroxidation in tumor cells but not in normal cells. Moreover, lymphokines such as interferon and tumor necrosis factor seem to produce their antitumor effects by inducing the release of c-UFAs from the cell-membrane lipid pool and free-radical generation, and several anticancer drugs, especially doxorubicin and vincristine, have the capacity to augment free-radical generation and promote lipid peroxidation. Tumor cells are known to contain low amounts of c-UFAs, have decreased capacity to generate free radicals and lipid peroxides, and are highly susceptible to free radical-induced cytotoxicity compared with normal cells. In addition, c-UFAs and their products can modulate the immune response, augment the respiratory burst of neutrophils and free-radical generation by macrophages, and modify genetic damage induced by mutagens and carcinogens. These evidences, coupled with the observation that the cancer incidence is low in Eskimos on traditionally high-c-UFA diets, suggests that c-UFAs can be exploited as possible anticancer agents either alone or in combination with lymphokines and cancer chemotherapy.     

复方苯甲酸酊剂中苯甲酸及水杨酸的含量检测

目的:探索复方苯甲酸酊剂两种主要成分稳定有效的含量测定方法.方法:用中和法测定两酸的总量,用紫外分光光度法测定水杨酸的含量,从总量中减去水杨酸的含量即为苯甲酸的含量.结果:回收实验苯甲酸平均回收率为100.13%,RSD为0.73%;水杨酸平均回收率为99.95%,RSD为0.23%.结论:结合使用中和法和紫外分光光度法能较好地同时检测复方苯甲酸酊剂中两种主要成分的准确含量.     

Chlorogenic acid and caffeic acid are absorbed in humans

Chlorogenic acid, an ester of caffeic acid and quinic acid, is a major phenolic compound in coffee; daily intake in coffee drinkers is 0.5-1 g. Chlorogenic acid and caffeic acid are antioxidants in vitro and might therefore contribute to the prevention of cardiovascular disease. However, data on the absorption of chlorogenic acid and caffeic acid in humans are lacking. We determined the absorption of chlorogenic acid and caffeic acid in a cross-over study with 4 female and 3 male healthy ileostomy subjects. In such subjects, degradation by the colonic microflora is minimal and absorption can be calculated as the amount ingested minus the amount excreted in ileostomy effluent. The ileostomy subjects ingested 2.8 mmol chlorogenic acid and 2.8 mmol caffeic acid on separate days in random order and subsequently collected ileostomy fluid and urine for 24 h. Absorption of chlorogenic acid was 33 +/- 17% (mean +/- SD) and of caffeic acid 95 +/- 4%. Traces of the ingested chlorogenic acid and 11% of the ingested caffeic acid were excreted in urine. Thus, one third of chlorogenic acid and almost all of the caffeic acid were absorbed in the small intestine of humans. This implies that part of chlorogenic acid from foods will enter into the blood circulation, but most will reach the colon.     

Ascorbic acid and erythorbic acid metabolism in nonpregnant women

Ascorbic acid (AA) metabolism and requirements were studied in 11 adult nonpregnant women maintained in a metabolic unit and fed a formula diet devoid of AA for 54 d. After depletion for 24 d, the subjects received increasing supplements of AA in the presence or absence of 600 mg/d of erythorbic acid (EA). Various analytical procedures were used to measure AA concentrations in blood components. The depletion period resulted in a marked decrease in AA in all blood indices. During the study scorbutic signs developed in some of the subjects. AA supplements of 30 mg/d for 10 d failed to increase plasma ascorbate concentrations; 60 mg/d for 10 d produced a small increase; 90 mg/d resulted in a mean AA concentration of 29 mumol/L. EA did not present any adverse effects, but rather had a small sparing effect. Vitamin C requirements for adult nonsmoking, nonpregnant women would be marginally met by an intake of 60 mg/d of AA whereas 90 mg/d would provide an allowance for body storage.     

High branched-chain alpha-keto acid intake, branched-chain alpha-keto acid dehydrogenase activity, and plasma and brain amino acid and plasma keto acid concentrations in rats

Diets containing high quantities of individual branched-chain alpha-keto acids (BCKAs) or a combination of BCKAs as used for treatment of renal disease were fed to rats. When the diet contained a single BCKA, its concentration was high in plasma and the concentration of its corresponding amino acid was high in plasma and brain. Liver BCKA dehydrogenase (BCKD) was 42% active in control rats. Consumption of diets containing 0.38 mol/kg diet of alpha-ketoisocaproate (KIC), alpha-keto-beta-methylvalerate (KMV), or alpha-ketoisovalerate (KIV) resulted in complete activation of liver BCKD. Consumption of the diet containing the combination of BCKAs increased basal BCKD activity of liver twofold. Muscle BCKD was activated after feeding the KIV diet (2-fold), the KIC diet (3-fold), and the KMV diet (15-fold). Total BCKD activity of liver and muscle was unaffected by dietary treatments. Activation of liver and muscle BCKD by dietary BCKA is consistent with their ability to inhibit BCKD kinase in vitro.     

Ascorbic acid and dehydroascorbic acid measurements in human plasma and serum

We investigated whether circulating ascorbic acid in humans is protein bound or free and whether ascorbic acid exists in its reduced form alone as ascorbic acid or in its reduced and oxidized forms as ascorbic acid and dehydroascorbic acid, respectively. Ascorbic acid and dehydroascorbic acid were determined by using HPLC with coulometric electrochemical detection, and protein binding was determined by centrifugal ultrafiltration. Ascorbic acid was free in plasma and serum of normal, healthy volunteers, 10 men and 10 women. Ascorbic acid was detectable only in its reduced form. However, dehydroascorbic acid could be made to appear in samples processed under oxidizing conditions. Because circulating ascorbic acid is free and is detected only as reduced vitamin, ascorbic acid may be available without intermediates for peripheral utilization. Dehydroascorbic acid may not be present in plasma and serum of normal humans unless assay conditions permit ascorbic acid oxidation.