应用亲水作用色谱检测鸡蛋和肉中三聚氰胺及三聚氰酸二酰胺

应用亲水作用色谱(HILIC)对从市场上购买的鸡蛋和肉中的三聚氰胺及三聚氰胺降解产物三聚氰酸二酰胺进行了检测。采用的色谱柱为ZIC-HILIC柱,流动相为3 mmol/L磷酸二氢铵溶液(pH 6.9)-乙腈(20:80, v/v),流速为0.8 mL/min,检测波长为220 nm。在该体系下,三聚氰胺和三聚氰酸二酰胺的保留时间适中,与样品中的内源性物质有良好的分离。样品经0.1%磷酸提取,偏磷酸及乙腈沉淀蛋白质和糖类物质,以及P-SCX固相萃取柱净化。三聚氰胺和三聚氰酸二酰胺在0.4～40 mg/L范围内与峰面积呈良好的线性关系,样品定量限(按信噪比(S/N)不小于10计)为2 mg/kg,在2～10 mg/kg添加水平下的平均回收率为80%～105%,相对标准偏差小于10%。该方法具有良好的分离选择性,可用于鸡蛋和肉中三聚氰胺和三聚氰酸二酰胺的同时检测。     

亲水作用色谱-串联质谱法同时测定液态奶中三聚氰酸和三聚氰胺

建立了亲水作用色谱-串联质谱同时测定液态奶中三聚氰酸和三聚氰胺的方法。液态奶样品经体积分数2.5%甲酸溶液提取、离心后乙腈稀释,亲水作用色谱柱分离,电喷雾串联四极杆质谱检测器检测,分别在负、正离子模式下测定三聚氰酸和三聚氰胺。三聚氰酸和三聚氰胺分别在0.5～100μg/L、0.1～50μg/L范围内线性关系良好。在0.25～15mg/kg、0.1～7.5mg/kg添加水平范围内,三聚氰酸平均回收率为84.5%～98.0%(RSD为2.1%～6.1%),三聚氰胺平均回收率为85.5%～88.9%(RSD为3.2～5.8%)。三聚氰酸、三聚氰胺定量限分别为0.25mg/kg、0.1mg/kg。     

HPLC法测定鸡精中谷氨酸钠的含量

以邻苯二甲醛与谷氨酸钠中的氨基进行柱前在线衍生化反应,采用C18色谱柱分离、荧光检测器（激发340nm,发射450nm）进行测定,建立了柱前衍生反相高效液相色谱测定鸡精中谷氨酸钠含量的方法。该方法相对标准偏差为0．69％,加标回收率为99．1％～101％,在0．10~50．0mg／L范围内,谷氨酸钠的峰面积和浓度之间的相关系数为0．9999,保留时间和峰面积的相对标准偏差分别为1．22％和0．71％,鸡精中谷氨酸钠定量下限为0．2μg／g。     

固相萃取-亲水相互作用色谱/串联质谱法同时测定食品中三聚氰胺和三聚氰酸

建立了固相萃取-亲水相互作用色谱/串联质谱同时测定食品中三聚氰胺和三聚氰酸残留量的方法。采用乙腈和水提取试样中残留的三聚氰胺和三聚氰酸,正己烷脱脂,提取液经亲水性键合硅胶和阳离子交换树脂复合填料柱(MCT柱)净化。采用亲水相互作用色谱柱进行分离,质谱采用正、负离子切换模式电离,多反应监测模式检测,同位素内标法定量。三聚氰胺和三聚氰酸在10～2500 μg/L范围内呈线性相关,相关系数(r)均大于0.99,定量限分别为25和50 μg/kg。本方法在动物源性食品、植物源性食品、乳及乳制品等不同样品中的三聚氰胺和三聚氰酸高、中、低3个添加水平的回收率分别在70.0%～129.6%和70.0%～128.6%之间,相对标准偏差分别在1.4%～23.3%和2.8%～18.7%之间。该方法可满足食品中三聚氰胺和三聚氰酸同时定量测定的需要。     

高效液相色谱法检测化妆品中着色剂罗丹明B、金光红C和颜料红57

采用N,N-二甲基甲酰胺提取样品中的待测物,建立了化妆品中禁、限用着色剂罗丹明B、颜料红57和金光红c的高效液相色谱检测方法。以XDB-C18柱为分析柱,5mmol／L四丁基氢氧化铵-氢氧化钾水溶液（磷酸调至pH7．00）和甲醇为流动相,梯度洗脱。550am（罗丹明B）和480nm（颜料红57和金光红C）为检测波长,柱温30℃,流速1．0mL／min,保留时间定性,外标法定量。结果表明在0．25-20mg／L（罗丹明B和金光红C）、0．5-40mg／L（颜料红57）浓度范围内线性关系良好,检出限分别为5,20,20mg／kg（S／N=10）,实际样品中的加标回收率分别为94．8％～100．5％,95．1％～103．1％,82．5％-90．5％,相对标准偏差为0．9％～4．6％。该方法前处理简单、易操作,检测结果准确可靠。能够满足化妆品中这3种着色剂的检测要求和监管需要。     

RP-HPLC内标法测定土壤中甲磺隆和氯磺隆的残留量

采用反相高效液相色谱-内标法测定了土壤中甲磺隆和氯磺隆的含量．以苯甲醇为内标物,C18反相柱（250mm×4．6mm i．d．,5μm）为分析柱,甲醇／1％醋酸钠水溶液（Ф=50／50）为流动相,流速1．0mL/min;检测波长254nm,柱温30℃．在甲磺隆浓度3．92-39．2mg／L,氯磺隆浓度2．02～20．2mg／L范围内,各对照品与苯甲醇的色谱峰面积比呈良好的线性关系．该方法准确、快速、灵敏度高、重现性好．     

柱切换直接进样高效液相色谱法测定蜂蜜中3种抗生素的残留量

建立了柱切换反相高效液相色谱法直接进样分离、测定蜂蜜中3种四环素族抗生素(土霉素OTC、四环素TC、金霉素CTC)残留量的分析方法。方法包括：用缓冲溶液溶解样品、直接进样、二次蒸馏水作流动相在C18预柱上在线富集和净化，然后用柱切换阀将预柱与一个C18分析柱接通，草酸溶液-乙腈-甲醇作流动相、紫外检测器在350nm处检测。各组分回收率均大于85％；相对标准偏差小于10％；标准曲线的相关系数在0．9983～0．9991之间；最低检出浓度(≤0．02mg／kg)，满足欧盟和日本等国要求(0．05mg／kg)。     

柱前衍生高效液相色谱法测定减肥药中的芬氟拉明

建立了柱前衍生反相高效液相色谱—紫外检测方法用于测定减肥药中的芬氟拉明。样品用三氯甲烷萃取,异丙醇转溶,再在四氢呋喃中和60℃下,用苯异氰酸酯衍生35min,然后用甲醇／水(72／28,V／V)为流动相和Kromasil C18分离柱,在240nm检测衍生物。方法的线性范围在2．52—126mg／L(r=0．9994),检出限和定量限分别为0．36ng(S／N=3)和1．2ng(S／N=10),平均回收率为98．4％,相对标准偏差(RSD)小于3．00％。     

柱后衍生-荧光检测高效液相色谱法快速测定鲜牛奶中链霉素残留量

牛奶样品经磷酸溶液提取，提取液用苯磺酸阳离子交换柱和C18固相萃取柱净化，链霉素残留液用甲醇从C18固相萃取柱上洗脱，经旋转蒸发器减压蒸干，残渣用0．01mol／L庚烷磺酸钠溶液溶解，用柱后衍生-高效液相色谱荧光检测器在激发波长263nm和发射波长435nm测定．方法线性范围为0.01～0．10mg／kg；在0．01～0．10mg／kg范围，三个添加水平的回收率为78．3％～80．2％，变异系数(CV)为7．4％～12．4％，方法检出限为0．005mg／kg．     

高效液相色谱法检测食品接触产品中的三聚氰胺及其衍生物的迁移量

建立了高效液相色谱同时检测三聚氰胺(MEL)及其衍生物——三聚氰酸二酰胺(ANE)、三聚氰酸一酰胺(ADE)和三聚氰酸(CYA)单体迁移量的方法.样品分别采用水、4％乙酸、10％乙醇作为食品模拟物,在70℃浸泡4h,浸泡液过0.45μm微孔薄膜后进入色谱柱.色谱分离采用Luna NH2柱,柱温:30℃,流动相为V(乙腈...     

Analysis of amino acids using serially coupled columns

Single conventional columns in reversed‐phase liquid chromatography are insufficient for analysing the isoindoles of primary amino acids due to their limited functionality. An interesting possibility for increasing the separation power is the combination of several columns of different nature, where the length is modified by coupling small segments. This approach may require a considerable investment to have multiple lengths for each stationary phase. However, the combination of only two columns of fixed length can be enough to resolve satisfactorily relatively complex mixtures, provided that an optimised gradient program is applied. In this work, a mixture of 19 primary amino acid isoindoles found in proteins was analysed. Four stationary phases were assayed: C18, pentafluorophenyl‐C18, C4 and cyano. The mixture of isoindoles was successfully resolved in practical times using a pentafluorophenyl‐C18 column coupled to a C4 column, in spite of the extremely poor performance obtained when each column is used isolatedly, independently of the length. The extreme diversity in the polarities of the isoindoles and the need of extrapolating the retention behaviour in certain regions of the solvent content domain makes the modelling of the retention behaviour of the isoindoles particularly difficult. Nevertheless, the predicted optimal separations were very satisfactory.     

Mechanism of retention loss when C8 and C18 HPLC columns are used with highly aqueous mobile phases

We describe investigations into the cause of retention losses encountered when C8 and C18 HPLC columns are used with highly aqueous (> 90% water) mobile phases. A procedure for quantifying these losses is described, involving stopping and restarting the flow. This procedure was used to study the dependence of retention loss on the pore size, surface concentration, and chemical structure of the bonded phase. Experiments were also carried out to determine how to restore the original retention of the columns by changing the composition of the mobile phase, or by increasing the pressure applied to the column. The results are shown to be consistent with a mechanism based on the theory of pore filling by non-wetting liquids, as employed in Mercury Porosimetry. The retention losses are attributed to the highly aqueous mobile phase being forced out of the pores when the flow is stopped and the pressure released. Retention is lost because the mobile phase is no longer in contact with the interior surface of the particles, where most of the surface area is located. The implications of this phenomenon for maximizing the reversed phase retention of polar analytes are discussed.     

Characterization of immobilized artificial membrane (IAM) and XTerra columns by means of chromatographic models

Immobilized artificial membranes (IAMs) prepared from phosphatidylcholine analogs are used as stationary phases in liquid chromatography systems to model drug partitioning between an aqueous phase (mobile phase) and a cell membrane (IAM column). Two different chromatographic models, which describe retention as a function of solute and column-mobile phase properties, have been applied to characterization of an IAM and two reversed phase C18 columns (Waters XTerra MSC18 and XTerra RP18) with acetonitrile-water mobile phases. The comparison of the results shows that the phosphatidylcholine group makes IAM column more polar than both XTerra columns, specially in terms of hydrogen-bond acceptor ability. XTerra RP18 is slightly more polar than XTerra MSC18 because of the presence of the embedded carbamate polar group.     

Comparison of Various Columns for the High-Speed HPLC Analysis of Drugs of Forensic Interest

Abstract

A comparison of the use of various commercially available columns for the high-speed reverse-phase ion-pair high performance liquid chromatographic separation of drugs of forensic interest is discussed. The columns include a Partisil 5 ODS-3 RAC, a Partisil 5 C8 RAC, a Radial Pak microBondapak C18 cartridge, a Perkin-Elmer HS/5 C18 and a Perkin-Elmer HS/3 C18. The mobile phases employed contain water, acetonitrile, phosphoric acid, and sodium hydroxide, with or without hexylamine. When a mobile phase without an amine modifier is employed, retention times were at least halved, except with a HS/3 C18 column, over those obtained with conventional columns. Basic drugs did not elute when the above mobile phase is used with a HS/3 C18 column. In addition, the selectivities of the other high speed columns were similar. Further reductions in retention times and different selectivities were obtained when an amine modifier is utilized. Column performance parameters such as n, V and v are presented for the colupns examined. A new column performance parameter S which is (n/V)^1/2 is introduced and discussed.     

Characterization of retentivity of reversed phase liquid chromatography columns

There are dozens of commercially available reversed phase columns, most marketed as C-8 or C-18 materials, but with no useful way of classifying their retentivity. A useful way of ranking these columns in terms of column "strength" or retentivity is presented. The method utilizes a value for ln k'(w), the estimated retention of a solute from a mobile phase of 100% water, and the slope of the plot of ln k' vsE(T)(30), the solvent polarity. The method is validated with 26 solutes varying in ln k'(w) from about 2 to over 20, on 14 different reversed phase columns. In agreement with previous work, it is found that the phase volume ratio of the column is the most important parameter in determining retentivity. It is strongly suggested that manufacturers adopt a uniform method of calculating this value and that it be made available in advertising, rather than the uninterpretable "% carbon".     

Identification of the factors that influence the reproducibility of chromatographic retention data

Principal component analysis was used to identify the parameters that influence the column-to-column and batch-to-batch reproducibility of retention times and retention factors measured on Symmetry C18, Kromasil C18, Luna C18 (2) and Vydac RP C18, all reversed-phase silica columns. We devised a procedure that allows the determination of the differences in column volume and packing density between two columns, provided that these columns are packed with identical stationary phases (i.e., phases that originate from the same batch). Principal component analysis of the retention times confirmed that the column-to-column variations of the column volume and the total porosity of the bed are the factors that influence the reproducibility of the retention times, the column volume being the major factor. For the fluctuations of the retention factors, the column phase ratios (or the bed porosities) and some specific, secondary retention mechanisms are responsible. All the C18 columns investigated proved to behave in a very similar fashion. Two principal components were always sufficient to characterize the variations of either the retention times or the retention factors.     

一种提高色谱指纹谱保留时间重现性的新方法

通过色谱热力学分析发现，在相同的分析条件下，即使采用不同的液相色谱系统或不同的色谱柱，组分的保留时间存在简单的线性关系，应用该线性关系可提高不同反相C18柱间保留时间重现性，经过实际样品在不同操作条件下的验证，表明该方法是正确而可行的。     

Preparative separation of isoquinoline alkaloids from Corydalis impatiens using middle chromatogram isolated gel column coupled with positively charged reversed‐phase liquid chromatography

Positively charged reversed‐phase liquid chromatography was employed for the efficient preparative separation of isoquinoline alkaloids from Corydalis impatiens. Ten commercially available columns were compared for isoquinoline alkaloids analysis. While tailing, overloading, lower resolution, and buffer salts limited the application in purification of isoquinoline compounds of many of these columns, one positively charged reversed‐phase C18 column (XCharge C18) overcame these drawbacks, allowing for favorable separation resolution, even when loading isoquinoline compounds on a larger, preparative scale. The general separation process is as follows. First, isoquinoline alkaloids are enriched with Corydalis impatiens extract via a middle chromatogram isolated gel column. After column selection, separation is performed on an XCharge C18 analytical column, from which two evident chromatographic peaks are readily obtained. Finally, two isoquinoline alkaloids (protopine and corydamine) are selectively purified on the XCharge C18 preparative column. These results demonstrate that a middle chromatogram isolated gel column coupled with positively charged reversed‐phase liquid chromatography is effective for the preparative separation of isoquinoline alkaloids from Corydalis impatiens.