LC/UV/MS-MRM for the simultaneous determination of water-soluble vitamins in multi-vitamin dietary supplements

The purpose of this study was to optimize chromatographic and detection conditions for the simultaneous determination of water-soluble vitamins in multi-vitamin dietary supplements using a single chromatographic run. An approach using liquid chromatography with diode array and/or mass spectrometry for quantitation of seven B-complex vitamins [thiamine (B₁), riboflavin (B₂), nicotinamide (B₃), pyridoxine (B₆) pyridoxine, biotin, pantothenic acid, and folic acid] in multi-vitamin/multi-mineral daily supplements is described. This approach utilizes a reversed phase C18 column (4 μm; i.d.: 250×2.0 mm) with a gradient mobile elution profile, performed at a flow rate of 0.25 ml/min. After a 5-min isocratic elution at 100% A (0.1% formic acid in water), a linear gradient to 50% A and 50% B (0.1% formic acid in acetonitrile) at 15 min and then to 5% A and 95% B at 17 min was employed. Detection was performed with a photodiode array detector (DAD) in sequence with a triple-quad mass spectrometer in the multiple reaction mode (MS-MRM). Although good chromatographic separation of ascorbic acid was also obtained in extracts from multi-vitamin/multi-mineral supplements, the ascorbic acid could not be quantified properly due to rapid oxidation catalyzed by the minerals. This method was initially applied to determine water-soluble vitamins in representative multi-vitamin/multi-mineral tablets following the extraction of ground samples with a phosphate buffer (10 mM, pH 2.5). For multi-vitamin supplement tablets, this approach does not require any sample clean-up/pre-concentration steps except for centrifugation and filtration of the extract.      

微乳液相色谱法同时测定4种脂溶性维生素

建立了一种新的微乳体系,并成功地应用于微乳液相色谱法(MELC)快速分析脂溶性维生素VA、VD2、VD3和VE。通过对影响分离选择性的主要因素进行考察,得到最佳微乳体系组成为98%(v/v)(50 g/L十二烷基硫酸钠(SDS)-10%(质量分数)正丁醇-1.0%(质量分数)正辛烷-84%水(质量分数))-2%(v/v)乙腈。该微乳体系中,表面活性剂类型和浓度、油相正辛烷的含量、有机添加剂乙腈对脂溶性维生素的分离起到了重要的作用。以Venusil ASB C18色谱柱(150 mm×4.6 mm, 5 μm)为分离柱,流速为0.7 mL/min,检测波长为265 nm,柱温为40 ℃, VA、VD2、VD3和VE在20 min内达到基线分离。4种脂溶性维生素的保留时间和峰面积的相对标准偏差(RSD) (n=5)分别小于2.3%和3.0%; VA、VD2、VD3和VE的线性范围分别为22.0～88.0 mg/L、20.2～81.0 mg/L、24.3～97.2 mg/L和125.0～500.0 mg/L,相应的线性相关系数r2分别为0.9996、0.9994、0.9998、0.9998;检出限(S/N=3)分别为0.37、0.34、0.41和2.12 mg/L。本方法已成功应用于多维元素片(21)中VA与VE的测定,结果令人满意。     

7‐Decarboxymethyl‐cobyrinates: Vitamin B12‐Derivatives that Lack the c‐Side Chain

The synthesis of cobyrinic acid derivatives by reduction of dehydrocobyrinates is largely unexplored. It is, however, a rational path to B₁₂ analogues that lack specific substituents of the corrin moiety of natural B₁₂ derivatives. The partial syntheses of four epimeric 7‐decarboxymethyl‐cobyrinates is described, which is achieved by reduction of Δ7‐dehydro‐7‐de[carboxymethyl]‐cobyrinate with zinc or with the ‘prebiotic’ reducing agent formic acid. A direct and remarkably efficient route was found to 7‐decarboxymethyl‐cobyrinates, which are cobyrinic acid derivatives in which the c‐side chain at ring B of vitamin B₁₂ is missing. The structures of the hexamethyl‐7‐decarboxymethyl‐cobyrinates were characterized and the stereochemical and conformational properties at their newly saturated ring B were analyzed. The stereochemical outcome of the reduction was found to depend strongly on the reaction conditions. In 7‐decarboxymethyl‐cobyrinates, both peripheral carbon centres of ring B carry a hydrogen atom, and the characteristic quaternary carbon centre at C7 of the cobyrinic acid moiety of vitamin B₁₂ is lacking. The still highly substituted 7‐decarboxymethyl‐cobyrinates are readily dehydrogenated in the presence of dioxygen, furnishing 7‐de[carboxymethyl]‐Δ⁷‐dehydro‐cobyrinate as the common, unsaturated oxidation product. The noted stability of vitamin B₁₂ and of other Co^III‐cobyrinates in the presence of air is a consequence of their highly substituted corrin macrocycle, a finding of interest in the context of chemical rationalizations of the B₁₂ structure.     

糙米、胚芽米、精白米中多种矿质元素和B族维生素含量的比较研究

对产自黑龙江省绥化市的同一批粳稻分别进行加工制得糙米、胚芽米和精白米,经过干灰化法或微波消解处理后,采用电感耦合等离子体发射光谱法（ICP—OES）、原子吸收光谱法（AAS）和原子荧光光谱法（AFS）测定了其中Al、As、B、Ba、Ca、Cd、Co、cr、Cu、Fe、Hg、K、Mg、Mn、Mo、Na、Ni、P、Pb、Rb、S、Se和zn共23种矿质元素的含量,,并采用高效液相色谱法（HPLC）和荧光分光光度法测定了其中维生素B．,烟酸,烟酰胺,维生素B。和维生素B：的含量。另外,还研究了经水淘洗后这3种类型大米中矿质元素和B族维生素含量的损失情况。结果表明,矿质元素和B族维生素含量呈现糙米,胚芽米,精白米由高到低的基本特征,淘洗可使各种矿质元素和B族维生素产生不同程度的损失,其中精白米中维生素B．经水淘洗后已损失殆尽。3种类型大米中cd、Cu、Mo、Ni、S、Se、Zn等元素含量差异相对较小,并且淘洗对Mo、S元素含量几乎没有影响,而cd、cu元素含量经水淘洗后反而略有增加。     

Rapid method for simultaneous determination of ascorbic acid and zinc in effervescent tablets by capillary zone electrophoresis with contactless conductivity detection

Ascorbic acid and zinc are essential nutrients that play important roles in nutrition, immune support, and maintenance of health. For this reason, both compounds are widely used as ingredients in dietary supplements. We report, for the first time, an analytical method for fast simultaneous determination of ascorbic acid and zinc. A single analysis run is possible every 80 s (45 injections/h). The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection using a fused silica capillary with 50 cm length (effective length of 10 cm). The separation was achieved by using a background electrolyte composed by 30 mmol/L of 2‐(morpholin‐4‐yl)ethane‐1‐sulfonic acid and 30 mmol/L of histidine, pH 6.1. The detection limits were 10 and 20 μmol/L and recovery values for spiked samples were 101 and 100% for zinc and ascorbic acid, respectively. The results obtained with the developed procedure were compared to those obtained by titration (ascorbic acid) and flame atomic absorption spectroscopy (zinc), and no statistically significant differences were observed (95% confidence level).     

高效液相色谱法测定盐地碱蓬汁中7种水溶性维生素和18种氨基酸

采用Ｓｈｉｍ－ｐａｃｋＣＬＣ－ＯＤＳＣ_（１８）色谱柱和ＡＡ０３反相键合相柱,对盐地碱蓬（以下称碱蓬）汁中７种水溶性维生素和１８种氨基酸进行了分离测定,结果令人满意。     

Supplementary Far-Red and Blue Lights Influence the Biomass and Phytochemical Profiles of Two Lettuce Cultivars in Plant Factory

Three different LED spectra (W: White light; WFR: W + far-red light; WB: W + blue light) with similar photosynthetic photon flux density (PPFD) were designed to explore the effects of supplementary far-red and blue lights on leaf color, biomass and phytochemicals of two cultivars of red-leaf lettuce (“Yanzhi” and “Red Butter”) in an artificial lighting plant factory. Lettuce plants under WB had redder leaf color and significantly higher contents of pigments, such as chlorophyll a, chlorophyll b, chlorophyll (a + b) and anthocyanins. The accumulation of health-promoting compounds, such as vitamin C, vitamin A, total phenolic compounds, total flavonoids and anthocyanins in the two lettuce cultivars were obviously enhanced by WB. Lettuce under WFR showed remarkable increase in fresh weight and dry weight; meanwhile, significant decreases of pigments, total phenolic compounds, total flavonoids and vitamin C were found. Thus, in the plant factory system, the application of WB can improve the coloration and quality of red leaf lettuce while WFR was encouraged for the purpose of elevating the yield of lettuce.     

A practical synthesis of (+)-biotin from L-cysteine

Alpha-amino aldehyde 4, which is readily derived from L-cysteine through cyclization and elaboration of the carboxy group, was subjected to the Strecker reaction, which, via sodium bisulfite adduct 16, afforded alpha-amino nitrile 5 with high diastereoselectivity (syn/anti=11:1) and in high yield. Amide 6, derived from 5, was converted to thiolactone 8, a key intermediate in the synthesis of (+)-biotin (1), by a novel S,N-carbonyl migration and cyclization reaction. The Fukuyama coupling reaction of 8 with the zinc reagent 21, which has an ester group, in the presence of a heterogeneous Pd/C catalyst allowed the efficient installation of the 4-carboxybutyl chain to provide 9. Compound 9 was hydrogenated and the protecting groups removed to furnish 1 in 10 steps and in 34 % overall yield from L-cysteine.     

Study on the chromatographic behavior of water-soluble vitamins on p-tert-butyl-calix[8]arene-bonded silica gel stationary phase by HPLC

In this paper, the chromatographic behavior of some water-soluble vitamins was studied on a new p-tert-butyl-calix[8]arene-bonded silica gel stationary phase (CABS, 5 μm particle size, the bonded amount 0.071 mmol g⁻¹) by using vitamin standards as probes for HPLC. The comparative study of the separation of these compounds was done by using CABS and ODS as stationary phases under the same chromatographic conditions. The better separation of six vitamins including: B₁, B₂, B₆, B₁₂, C, and nicotinic acid (B₅), on CABS can be achieved by using isocratic mode with methanol-phosphate buffer (25:75, (v/v)) as mobile phase within 20 min. The results show that the calix[8]arene-bonded phase exhibits high selectivity for water-soluble vitamins. We found that the elution order of B₂ (12.08 min) and B₁₂ (16.42 min) on CABS was very different from that of B₁₂ (7.76 min) and B₂ (18.47 min) on ODS, which indicate that different retention mechanisms exist in the chromatographic processes of the two stationary phases. According to the chromatographic data, it can be concluded that various chromatographic retention mechanisms are responsible for the separation of above compounds on CABS, such as hydrophobic interaction, hydrogen bonding interaction, and π-π interaction. The new packing has two advantages over ODS. On one hand, the polar and ionized analytes, such as C and B₅, exhibited stronger affinities to CABS because of hydrogen bonding interaction. On the other hand, the retention of B₂ and B₁₂ became shorter on CABS with weaker hydrophobicity in comparison with ODS. The new material exhibits the promising application in the separation of water-soluble vitamins.