气相色谱-质谱法测定叶酸片中三氯丙酮的残留量

建立了气相色谱-质谱联用方法测定叶酸片中三氯丙酮溶剂的残留量。叶酸片研磨过筛后采用N,N二甲基甲酰胺溶剂超声提取,Rtx-w ax毛细管色谱柱分离。通过气相色谱-质谱全扫描总离子图定性,单离子监测模式定量检测叶酸片中三氯丙酮的残留量。在0.5～15.0μg/mL质量浓度范围内,三氯丙酮的浓度和色谱峰面积线性拟合关系良好(r=0.9998),方法检出限为0.15μg/mL,相对标准偏差2.0%,加标回收率为93.0%～105.3%。建立的方法,能有效消除复杂基质带来的干扰,适用于叶酸片中三氯丙酮残留量的检测。     

间接荧光法测定奶粉中叶酸

研究了高锰酸钾氧化叶酸荧光体系的形成条件,并建立了测定叶酸含量的间接荧光法。在pH为4.0,80℃水浴中,高锰酸钾可将叶酸氧化为蝶呤-6-羧酸,氧化产物的荧光值较叶酸的荧光值大大增强。荧光强度与叶酸浓度在0~1.6 mg.L-1范围内呈线性关系,方法的检出限为51μg.L-1,将此方法应用到孕妇强化奶粉中叶酸含量的测定,RSD为2.52%(n=6)。     

反相高效液相色谱法测定叶酸及其相关物质

建立了反相高效液相色谱法对叶酸及其相关物质的分离测定方法。对叶酸原料药进行了测定,色谱柱为JASCO C18柱(250mm×4.6mmi.d.,5μm),流动相为V(0.05mol LKH2PO4):V(0.1mol LKOH)∶V(甲醇)=78∶2∶20,流速为1.0mL min,柱温为30℃。叶酸检出限为1.0ng,叶酸的质量分数为98.52%～99 87%;加标回收率为95.22%～100.83%。该法快速简捷,精密度高,重现性好,可用于叶酸的质量控制。     

HPLC法测定保健食品红曲片中β-谷甾醇的含量

采用高效液相色谱法测定保健食品红曲片中β-谷甾醇的含量。色谱条件为:C18柱色谱柱,4.6 mm×250 mm,5μm;流动相乙腈-异丙醇=70∶30(V/V);流速1.0 m L/min;检测波长210 nm。测定样品中β-谷甾醇含量的RSD为0.8%(n=6),回收率范围为98.4%~100.3%。该方法简便、快速、准确,适用于测定保健食品红曲片中β-谷甾醇的含量。     

铽-环丙沙星稀土敏化荧光猝灭法测定叶酸

在pH=5.0的醋酸-醋酸钠缓冲溶液中,铽(与环丙沙星反应形成1∶2的稳定络合物,其最佳激发、发射波长分别为λex=330nm、λem=545nm。在该反应体系中加入适量叶酸溶液,铽(与环丙沙星络合物的激发、发射波长位置不变,但荧光强度下降。利用这一现象,建立了简单、快速、灵敏的测定叶酸的荧光分析方法。该方法保持了叶酸结构的完整性,叶酸浓度在22~880μg/L范围内符合线性关系;方法检出限为7.8μg/L。用于片剂及胶囊中叶酸含量的测定,结果满意。6次平行测定该方法回收率为93.7%~107.9%,相对标准偏差为0.38%~2.8%。     

高效液相色谱法测定血浆中左亚叶酸钙的含量

建立了测定血浆中左亚叶酸钙含量的RPHPLC方法。采用DiamonsilC18色谱柱(150mm×4.6mm,5μm),乙腈50mmol/L磷酸氢二钾/磷酸二氢钾缓冲溶液(10∶90,V/V,用磷酸调pH至4.0)为流动相,用前经0.45μm的过滤膜,超声脱气,流速为1.0mL/min,紫外检测波长为290nm,柱温为35℃,进样量20μL。该方法最低检出限为0.2ng;线性范围为0.05～10mg/L,方法平均回收率在97.0%以上;日内及日间精密度的相对标准偏差分别小于4%和6%。该方法简单,快速,灵敏度高,重复性好。     

液相色谱-串联质谱法测定强化食品中叶酸的含量

采用液相色谱-电喷雾电离串联质谱法测定强化食品(饮料、大米、奶粉、含乳饮料、饼干及果冻)中的叶酸含量。采用多种方法确保叶酸检测的准确性:1优化前处理操作步骤,并使用铝箔避光保存;2加入二丁基羟基甲苯(BHT)作为叶酸的抗氧化保护剂;3加入甲氨蝶呤作为内标物,抵消复杂基质的干扰。方法系统考察了提取条件对回收率的影响,并采用Waters HSS T3(2.1 mm×50 mm,1.7μm)反相色谱柱,以甲醇-10 mmol/L醋酸铵(p H 6.3)为流动相进行梯度洗脱分离,多反应监测(MRM)正离子扫描模式,以内标法进行定性和定量分析。该方法在0.05~100 ng/m L浓度范围内线性关系良好,定量下限为0.01~0.5 mg/kg,回收率为72.0%~109%,相对标准偏差(RSD)为3.8%~11.8%。该方法简单快速,灵敏度、准确度和精密度均能满足强化食品中叶酸的测定要求。     

蔬菜中叶酸的催化氧化荧光法测定

建立了催化氧化荧光法间接测定叶酸的新方法。在pH5.0的HAc-NaAc缓冲溶液中,Co2+催化KIO4氧化叶酸产生强荧光,以262 nm为激发波长,在445 nm处测定叶酸的氧化产物蝶呤-6-羧酸的荧光强度,研究了反应的适宜条件及动力学参数,并探讨了反应机理。在优化实验条件下,叶酸浓度在1.0×10-8~1.0×10-5mol/L范围内与荧光强度呈良好线性关系,回归方程为ΔIF=10.82c(μmol/L)+2.867,相关系数r=0.998 5,方法的检出限为5×10-9mol/L。对5×10-7mol/L叶酸标准溶液进行11次平行测定,相对标准偏差(RSD)为0.1%。该法使用Co2+为催化剂,大大提高了方法的灵敏度。方法用于蔬菜中叶酸的测定,加标回收率为93%~104%,6次测定的相对标准偏差为0.98%~2.1%,结果令人满意。     

HPLC法测定党参中烟酸和党参炔苷的含量

建立HPLC法同时测定党参中烟酸及党参炔苷含量的方法。采用Syncronis AQ色谱柱(250 mm×4.6mm,5μm),以乙腈(A)–0.2%磷酸水溶液(B)作流动相进行梯度洗脱,流量为1 mL/min,紫外检测波长为285 nm,柱温为30℃,烟酸和党参炔苷可在24 min内实现与其它成分良好分离。烟酸的质量浓度在9.6~57.6μg/mL范围内与色谱峰面积线性关系良好(r=0.999 2),检出限为0.94μg/mL,测定结果的相对标准偏差为1.5%(n=6),平均加标回收率为99.5%;党参炔苷的质量浓度在9.92~59.52μg/mL范围内与色谱峰面积线性关系良好(r=0.999 6),检出限为0.12μg/mL,测定结果的相对标准偏差为1.9%(n=6),平均加标回收率为101.1%。该方法操作简便、快速、准确,具有良好的重复性,可作为党参中烟酸、党参炔苷测定的有效方法。     

高效液相色谱法测定2种中药片剂中紫丁香苷的含量

建立了测定2种中药制剂灭澳灵片和活络消痛片中紫丁香苷含量的高效液相色谱方法.采用KromasilC18反相色谱柱(5μm,250 mm×4.6 mm),以乙腈-1%冰醋酸溶液(体积比10∶90)为流动相,流速1.0 mL/min,检测波长265 nm,在15 min内完成分离检测.紫丁香苷在0.16~100μg/mL范围内呈良好的线性关系(r=0.9999),最低检出限0.1μg/mL(S/N=3).灭澳灵片的加样回收率为92.2%~97.6%,活络消痛片的加样回收率为94.0%~102.6%.     

聚茜素红-多壁碳纳米管复合膜修饰电极的研制及叶酸含量测定

采用电聚合方法将茜素红（AR）非共价修饰到多壁碳纳米管（MWCNTs）上,制得了PAR/MWCNTs/GC电极,该电极对叶酸（FA）具有良好的电催化作用. 结果表明,在最佳实验条件下,在-0.63 V处叶酸还原峰电流与浓度（1.25×10^-6 ~ 4.00×10^-5 mol·L^-1）呈现良好线性关系,相关系数0.9985. 用标准加入法检测了回收率,其值达92.0% ~ 102.0%. 该电极制作简单,有良好的稳定性．     

叶酸的低温磷光分析

叶酸有光、酸中强、碱中弱、HCl浓度高,光强,但不稳定。叶酸经紫外光照射后光增强,增强量与叶酸含量成比例,建立了叶酸的低温光分析法,并用作小鼠,豚鼠肝中叶酸含量分析     

表面活性剂与叶酸的相互作用及其对光氧化降解的影响

表面活性剂与有机小分子作用不仅能提高表面活性剂的聚集能力,还能提高小分子的溶解度、稳定性等应用性能,因此研究二者之间的相互作用机理对于促进表面活性剂的发展和实际应用具有重要意义。本工作提出了一种利用功能有机小分子调控表面活性剂聚集行为,进而提高不稳定小分子自身稳定性的新策略。利用表面张力、紫外可见吸收光谱、荧光光谱、动态光散射、等温滴定量热和核磁共振技术研究了在p H为7.0时,叶酸分别与十二烷基硫酸钠(SDS)、十二烷基三甲基溴化铵(DTAB)、季铵盐Gemini 12-6-12和季铵盐线性三聚12-3-12-3-12四种表面活性剂之间的相互作用及其导致的叶酸光氧化降解性能的变化,结果表明,阴离子表面活性剂SDS抑制叶酸光氧化降解的效率较低,而阳离子表面活性剂都能够显著抑制叶酸的光氧化降解,且随着表面活性剂寡聚度的增加,抑制效果增强,所需表面活性剂的浓度显著降低,寡聚表面活性剂12-3-12-3-12的抑制效率高达96%。     

Chemiluminometric and Fluorimetric Determination of Folic Acid

Abstract

Folic acid was found to inhibit the chemiluminogenic reaction of N‐bromosuccinimide with dichlorofluorescein in alkaline medium. The analyte has also been determined after generation of a fluorescing compound by the action of hexacyanoferrate(III) or N‐bromosuccinimide in alkaline medium. Both procedures were further investigated and an attempt to propose the corresponding mechanisms was also made. The chemiluminogenic procedure allows the determination of folic acid within the range 6.0 to 114 µg/ml with limits of detection and quantification equal to 2.0 and 6.0 µg/ml, respectively and rsd at 11.4 µg/ml equal to 1.0% (n=12) while the fluorogenic procedure allows the determination of folic acid within the range 0.022–1.10 µg/ml with limits of detection and quantification equal to 0.002 and 0.005 µg/ml, respectively and rsd at 0.022 µg/ml equal to 0.7 (n=10). The methods are compared and successfully applied to commercial preparations containing folic acid.     

Determination of Folic Acid at a Bismuth Film Electrode by Adsorptive Stripping Voltammetry

This article reports a new simple and sensitive method for the determination of folic acid by adsorptive stripping voltammetry. The method is based on the accumulation of folic acid at a bismuth film plated in situ on a glassy carbon substrate. In order to stabilize bismuth ions, sodium potassium tartrate was added to the supporting electrolyte. The bismuth film formation and folic acid accumulation conditions were optimized and measurements were carried without solution deaeration. The calibration graph was linear from 5 × 10^?10 to 2 × 10^?8 mole per liter with an accumulation time of 180 seconds with a limit of detection of 2 × 10^?10 mole per liter. The relative standard deviation for 5 × 10^?9 mole per liter of folic acid was 3.1 percent (n = 5). The method was successfully applied for determination of folic acid in pharmaceutical preparations.     

Voltammetric Determination of Folic Acid Using Adsorption of Methylene Blue onto Electrodeposited of Reduced Graphene Oxide Film Modified Glassy Carbon Electrode

This work presents a sensitive voltammetric method for determination of folic acid by adsorbing methylene blue onto electrodeposited reduced graphene oxide film modified glassy carbon electrode (MB/ERGO/GCE) in 100 mM KCl‐10 mM sodium phosphate buffer solution (pH 7.40). The surface morphology of the MB/ERGO/GCE modified electrode was characterized using scanning electron microscopy, displays that both MB and ERGO distributed homogeneously on the surface of GCE. The MB/ERGO/GCE modified electrode shows more favorable electron transfer kinetics for potassium ferricyanide and potassium ferrocyanide probe molecules, which are important electroactive compounds, compared with bare GCE, MB/GCE, and ERGO/GCE. The electrochemical behaviors of folic acid at MB/ERGO/GCE were investigated by cyclic voltammetry, suggesting that the modified electrode exhibited excellent electrocatalytic activity towards folic acid compared with other electrodes. Under physiological condition, the MB/ERGO/GCE modified electrode showed a linear voltammetric response from 4.0 μM to 167 μM for folic acid, and with the detection limit of 0.5 μM (S/N=3). The stability, reproducibility and anti‐interference ability of the modified electrode were examined. The developed method has been successfully applied to determination of FA in tablets with a satisfactory recovery from 96 % to 100 %. The work demonstrated that the electroactive MB adsorbing onto graphene modified electrode showed an enhanced electron transfer property and a high resolution capacity to FA.     

叶酸的能量转移荧光测定法及其应用

报道了一种灵敏检测叶酸的荧光新方法。 在叶酸-KMnO4-Eu3+-H2O2体系中,以pH=4.7的乙酸-乙酸钠（浓度为0.2 mol/L）为缓冲溶液,利用高锰酸钾和过氧化氢将叶酸氧化形成蝶呤-6-羧酸,与Eu3+配位成配合物,该配合物被激发后,蝶呤-6-羧酸通过分子内能量转移将吸收的能量传递到Eu3+,从而发射出Eu3+的特征荧光。 在4×10-8~4×10-5 mol/L范围内,Eu3+的荧光强度与叶酸的浓度呈线性关系,相关系数为0.9902,检测限达到1.2×10-8 mol/L。 用于实际样品中叶酸的检测,得到了满意的结果。     

Centri‐Voltammetric Folic Acid Detection

The need for practical detection of folic acid (FA) has been increased day by day. For this reason in this work, a two steps electroanalytical technique, centri‐voltammetry was utilized for FA detection for the first time. In order to get rid of the slow electrode kinetics of FA oxidation, the working electrode was modified with graphene‐Pt hibrid nanomaterial. Also for increasing the sensitivity, 1‐Chloro‐2‐[2‐(2‐methoxyethoxy) ethoxy]ethane (TEG?Cl) and 1,2‐di{2‐[2‐(2‐methoxyethoxy)ethoxy] ethoxy}‐4‐nitrobenzene (4NC?NO₂) was used as a carrier material. After the characterization of graphene‐Pt hybrid nanomaterial, experimental parameters like, 4NC?NO₂ amount, adsorption time, centri‐voltammetric parameters like centrifuge time and speed were optimized. After that, analytical characteristics such as linear range, relative standard deviation (R.S.D), limit of detection (LOD) and limit of quantification (LOQ) values were found. In this manner, linear range was obtained for FA between 1.0 μM–1000 μM with the equations of (R²=0.9977). R.S.D value was calculated for 0.83 mM FA (n=3) as 1.86 % while LOD and LOQ values were found as 1.00 μM and 3.34 μM respectively. After the examination of interference effect of substances like ascorbic acid and uric acid, established centri‐voltammetric technique was enforced for FA detection in pharmateutical tablets. As a result, the recovery value was calculated as 96.4 %.     

Development and validation of a high‐performance liquid chromatography method for the simultaneous determination of aspirin and folic acid from nano‐particulate systems

Attention has shifted from the treatment of colorectal cancer (CRC) to chemoprevention using aspirin and folic acid as agents capable of preventing the onset of colon cancer. However, no sensitive analytical method exists to simultaneously quantify the two drugs when released from polymer‐based nanoparticles. Thus, a rapid, highly sensitive method of high‐performance liquid chromatography analysis to simultaneously detect low quantities of aspirin (hydrolyzed to salicylic acid, the active moiety) and folic acid released from biodegradable polylactide‐co‐glycolide (PLGA) copolymer nanoparticles was developed. Analysis was done on a reversed‐phase C₁₈ column using a photodiode array detector at wavelengths of 233 nm (salicylic acid) and 277 nm (folic acid). The mobile phase consisted of acetonitrile–0.1% trifluoroacetic acid mixture programmed for a 30 min gradient elution analysis. In the range of 0.1–100 μg/mL, the assay showed good linearity for salicylic acid (R² = 0.9996) and folic acid (R² = 0.9998). The method demonstrated good reproducibility, intra‐ and inter‐day precision and accuracy (99.67, 100.1%) and low values of detection (0.03, 0.01 μg/mL) and quantitation (0.1 and 0.05 μg/mL) for salicylic acid and folic acid, respectively. The suitability of the method was demonstrated by simultaneously determining salicylic acid and folic acid released from PLGA nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd.