INTERSECTION POINT RULE OF THE RETENTION VALUE AND NORMAL BOILING POINT OF THE HOMOLOGUES IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

In this paper, a linear relationship between the logarithm of capacity factor k and normal boiling point to of the homologues has been derived, based on the basic retention equation of liquid chromatography according to statistical thermodyoamics proposed by professor Ln Peizhang and others, This equation has been verified by a large number of experimental data, all the strsight lines of lnk- of bumologues for different mobile phass coaiposltion cross each other at the same point, So the intereection point equation van proposed, wbich was used to prodict the retention valu, the result was satisfactory.

INTERSECTION POINT RULE OF THE RETENTION VALUE AND MOBILE PHASE COMPOSITION OF THE HOMOLOGUES IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Based on the intersection point rule of the retention value and normal boiling point of homologues in reversed-phase high-performance liquid chromatography(RPLC), the intersection point rule of the retention value of homologues and mobile phase composition has been derived, and was testified by a lot of experimental data from the literature. With this newly proposed equation, we can use the retention value of the compound in one mobile phase composition to predict its retention value in any other mobile phase composition. For fourteen groups of homologues in five mobile phase compositions on five Kinds of columns, the overall average absolute error of 721 data sets is 2.8%.

Quantitative analysis by reversed-phase high-performance liquid chromatography and retinal neuroprotection after topical administration of moxonidine

AIM:To determine moxonidine in aqueous humor and iris-ciliary body by reversed-phase high performance liquid chromatography(RP-HPLC),and to evaluate the retinal neuroprotective effect after topical administration with moxonidine in a high intraocular pressure(IOP)model.METHODS:The eyes of albino rabbits were administered topically and ipsilaterally with 0.2%moxonidine.A RPHPLC method was employed for the identification and quantification of moxonidine between 2 and 480 min,which presented in the aqueous humor and iris-ciliary body.Flash electroretinography(F-ERG)amplitude and superoxide dismutase(SOD)level were measured between day 1 and day 15 after topical administration with moxonidine in a rabbit model of high IOP.Histological and ultrastructural observation underwent to analyze the changes of retinal morphology,the inner retinal layers(IRL)thickness,and retinal ganglion cell(RGC)counting.RESULTS:Moxonidine was detectable between 2 and 480 min after administration,and the peak concentration developed both in the two tissues at 30 min,0.51μg/m Lin aqueous humor and 1.03μg/g in iris-ciliary body.In comparison to control,F-ERG b-wave amplitude in moxonidine eyes were significantly differences between day 3 and day 15(P<0.01)in the high IOP model;SOD levels were significantly higher at all time-points(P<0.01)with a maximum level of 20.29 U/mgprot at day 15;and RGCs were significantly higher(P<0.05).CONCLUSION:Moxonidine is a viable neuroprotective agent with application to high IOP model.All layers of retina,including RGC layer,retinal nerve fiber layer and INL,are more preserved after moxonidine administration.SOD plays a neuroprotective role in ocular hypertension-mediated RGC death.

Predicting a, c indices in reversed-phase high-performance liquid chromatography (RP-HPLC) from Kovats index in gas chromatography (GC)

KOVATS index is the most precise index system reflecting the interaction between the molecules of solutes and stationary phase in gas chromatography at present. Large quantity of Kovats in dex data have been published. It is a good way to use Kováts index in gas chromatography to predict the retention value in liquid chromatography, which is significant in theory and apphcation.

PEAK IDENTIFICATION FROM INTERACTION INDEX IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

The interaction index c which was derived from the fundamental retention equationlogk’ =a + cC_B in reversed--phase high--performancc liquid chromatography (RP-HPLC) quan-titatively describes the difference in the interaction between solute--strong. solvent andsolute--weak solvent; it has shown to be a constant for a specific solute even when columnsystems with different C18 packings are used. The theoretical basis for peak identificationby using interaction index has been proposed, which was based on the a,c values on stan-dard C18 column by utilizing linear a-a plots on column pairs and the linear relationship be-tween parameters a and c for the structural related compounds. Through the establishmentof parameters a,c data based on the standard C18 column for a certain type of compounds,the retention of thesc compounds on various C18 columns can be predicted. Typical exam-ples have been given to verify the correctness of this method.

Creation of reversed phase high-performance liquid chromatographic technique to assay platelet-activating factor

Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart disease. Methods: To measure PAF levels in 100 controls, 23 elderly patients with cerebral infarction and 65 cases with coronary heart disease by reversed phase high-performance liquid chromatographic technique (rHPLC). Results:rHPLC is more convenient, sensitive,specific, and less confusing, compared with bio-assay. The level of plasma PAF in patients with cerebral infarction was higher than that in the controls (P<0.01), and in patients with coronary heart disease. Conclusion: Detection of PAF with rHPLC is more reliable and more accurate. The new assay has important significance in PAF research.

Preparative Optimization of Cellulose Microspheres Applied as Supports for High-Performance Liquid Chromatography

The aim of this work is optimizing the techniques to prepare pure cellulose microspheres, which are used as packing adsorbents for high-performance liquid chromatography. Thereupon, cellulose was dissolved in a pre-cooled NaOH/urea solution, from which various-size microspheres were prepared. The volume-average diameters were controlled approximately at 30 p,m, 8 ~tm and 4 pm grades when cyclohexane, liquid paraffin and pump oil were used as dispersants, respectively. The present investigations reveal that higher viscosity dispersant is suitable for the preparation of smaller-size microspheres, while larger size microspheres are prepared preferably using lower-viscosity dispersant. The chiral stationary phase derived from 8 μm grade microspheres can separate the enantiomers of efavirenz.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF FULLERENES

High-performance liquid chromatographic systems for the separation of buckminsterfullerene(C_(60)) and related fullerene C_(70) were investigated with methanol/benzene or methanol/toluene (35/65-60/40 in Ⅴ/Ⅴ) as eluant in C18 reversed phase column. The system is suitable for fast analysis of fullerenes at lower percentage of methanol, and repeatly large scale perparation at higher percentage of methanol.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC ANALYSIS OF KR-008 IN BIOLOGICAL FLUIDS

A high-performance liquid chromatographic method for the simultaneous determination of KR-008 and its metabolite in biological fluids was developed The samples were injected directly without further treatment,the compounds were separated and analysed on a reversed- phase column under isocratic conditions,including ion pairing.Concentrations in urine and bile were determined by an external standard method.The detection limit was 0.8μg/ml in urine.Preliminary data showed that,following i.p.administration(120mg/kg)of KR-008 to rats,approximately 2.8% of the dose was excreted in urine as unchanged compound and more than 8.9% was as a metabolite;in bile it was 0.73% excreted as unchanged form and above 0.29% as the metabolite.The peak biliary concentration of KR-008 was 0.39mg/ml at 20min after dosing.

High-performance liquid chromatographic fingerprint analysis of Oxytropis falcata Bunge and Oxytropis chiliophylla Royle

A simple, sensible and reliable HPLC-DAD fingerprint analysis method for the raw materials of Oxytropisfalcata and Oxytropis chiliophylla, both of which were used as ＂Er-Da-Xia＂ in Tibetan medicines, was developed and then subsequently applied to analyze samples collected from different locations or times. 19 common fingerprint peaks for O. falcata, 24 for O. chiliophylla, and 11 for the two herbs were designated respectively, including 7 identified characteristic peaks existing in both herbs and 1 uniquely presenting in O. chiliophylla. Although there were some slight differences in the chemicals of O. falcata and O. chiliophylla, the main components of both herbs were consistent generally. The results provided scientific basis, at least from the chemical point of view, for the reasonablity of two herbs being used as the same drug in Tibetan medicines and for the necessary of further investigation on their detailed chemical and pharmacological differences.

Determination of Amantadine Residue in Honey by Solid-phase Extraction and High-performance Liquid Chromatography with Pre-column Derivatization and Fluorometric Detection

Amantadine （AMA） is an anti-viral drug used in apiculture to protect honeybee against the sacbrood virus （Morator aetatulae）. This study described a reliable high-performance liquid chromatographic （HPLC） method for analyzing AMA in honey using a solid-phase extraction （SPE） cartridge （Plexa PCX） for purification, 4-fluoro-7- nitro-2,1,3-benzoxadiazole （NBD-F） as a pre-column derivatization agent, and fluorometric detection （λex =470 nm, λem=530 nm）. The chromatographic separation was performed on an XDB C18 column （150×4.6 mm i.d.） using 0.1% trifluoroacetic acid/acetonitrile （35 ; 65, V/V） as the mobile phase at a flow rate of 1.0 mLomin 1 with a run time of 20 min. Under these optimal conditions, a linear relationship was observed in the range of 0.025--1.0μg·mL-1 with a good correlation coefficient （0.998） and low limit of detection （0.0080 μg·g-1）, the recoveries were all above 90%, and the intra-day and inter-day precision （RSD） ranged from 3.4%--5.1%.

Determination of Polysaccharide in Radix pseudostellariae Extract by Size-Exclusion High-Performance Liquid Chromatography

A simple size-exclusion high-performance liquid chromatographic method was developed for rapid molecular mass screening to determine the average molecular mass, polydispersity, and quantity of Taizishen polysaccharides extract. The screening used a TOSOH TSK-GEL G3000SW high-performance liquid chromatographic column with 0.1 mol/L NaNO3 buffer as the mobile phase and refractive index detector. The molecular mass calibration curve was linear for polysaccharide standards from 10 to 100 kDa with a correlation coefficient of 0.9991. The method can be used to analyze the quantity, average molecular mass, and polydispersity of polysaccharides. In addition, the screening method is suitable for quality control of polysaccharide preparations in Chinese medicines and pharmaceutical products.

Freshwater algae chemotaxonomy by high-performance liquid chromatographic(HPLC)analysis

The study of community composition of algae is essential for understanding the structure and dynamics of the aquatic ecosystem and for evaluating the eutrophic level of the water body.A high-performance liquid chromatographic(HPLC)method based on a reversephase C_(18) nonpolar column was developed for the main algal taxa,which includes cyanophytes,bacillariophytes,euglenophytes,dinophytes,and chlorophytes.Based on the elution order using HPLC,19 pigments were identified,and they were chlorophyllide a,19′-butanoyloxyfucoxanthin,chlorophyll c_(1)+c_(2),phephorbides a,peridinin,methyl-chlorophyllide a,fucoxanthin,neoxanthin,violaxanthin,myxoxanthophyll,diadinoxanthin,diatoxanthin,lutein,zeaxanthin,chlorophyll b allomer,chlorophyll b,chlorophyll a allomer,chlorophyll a,andβ,β-carotene.A comparison study of cell microscopic counts and accessory pigment analysis indicated that HPLC analysis could be a useful tool for monitoring phytoplankton communities and their abundance.

Preparation and Evaluation of Silicon Quantum Dots-Bonded Silica Stationary Phase for Reversed-Phase Chromatography

In this paper,silicon quantum dots(SiQDs)with green fluorescence are synthesized by solvothermal reaction of 3-(2,3-epoxypropoxy)propyltrimethoxysilane(GPTMS)and ethylenediaminetetraacetic acid(EDTA),and then SiQDs are bonded to the surface of silica to obtain a new nano-on-micro stationary phase(SiO_(2)-SiQDs)for reversed-phase chromatography.The successful preparation of SiO_(2)-SiQDs stationary phase is demonstrated by a variety of characterizations,such as transmission electron microscopy,laser confocal microscopy,elemental analysis and Fourier infrared spectroscopy.In addition,the chromatographic performance of the prepared stationary phase is evaluated and it shows good separation performance for non-polar substances such as alkylbenzene,aniline and polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.It is also verified that the stationary phase has good methyl selectivity and shape selectivity.More interestingly,the separation of prednisolone and hydrocortisone isomers can also be achieved at a low ratio of organic solvents,indicating that this new stationary phase has a good application prospect in isomer separation.

Assay and Evaluation of Flavonoid Content in Chinese Celery

Flavonoids were the most important secondary metabolites in celery （Apium graveolens L.）.In this study,the flavonoid （apigenin and luteolin） contents of leaves and petioles in 44 Chinese celery varieties,an American celery variety ‘Ventura＇ and an European celery variety ‘Princer＇ were assayed by reversed-phase high-perfor mance liquid chromatography （RP-HPLC）.The results showed that significant differences in the apigenin and luteolin contents of the leaves and petioles were found among 46 celery varieties,and the variation coefficients of leaf apigenin content,leaf luteolin content,leaf flavonoid content,petiole apigenin content,petiole luteolin content and petiole flavonoid content were 30％,10％,30％,20％,30％ and 20％,respectively.There was no correlation between the leaf flavonoid content and petiole flavonoid content.The apigenin content was about 18 to 50 times of luteolin in celery leaf and about 19 to 40 times of luteolin in celery petiole.The flavonoids in most of the Chinese celery varieties were higher than in ‘Ventura＇ and ‘Princer＇.The flavonoid contents of Chinese celery varieties from the Yangtze Valley and southern China were higher than those from northern China.Our results suggested that Chinese celery varieties with high petiole apigenin contents could be used for vegetable breeding because the petiole was the main edible part,and Chinese celery varieties with high leaf apigenin contents could be used for apigenin production.

Preparation and Characterization of a New Quercetin-bonded Stationary Phase for High Performance Liquid Chromatography

A quercetin-bonded silica gel stationary phase （QUSP） containing natural flavonoid ligand was first prepared via γ-glycidoxypropyltrimethoxysilane （KH-560） as a coupling reagent for high-performance liquid chromatography. Its chemical structure was characterized by Fourier infrared spectroscopy, elemental analysis, thermal thermogravimetry and 13C cross polarization/magic angle spinning nuclear magnetic resonance （CP/MAS NMR）. The chromatographic property of QUSP was systematically evaluated by using neutral, basic and acidic aromatic com- pounds as probes. In order to clarify its retention mechanism, a comparative study of QUSP with conventional oc- tadecylsilyl-bonded stationary phase （ODS） was also carried out under the same conditions. The results showed that the new quercetin-bonded phase exhibited an excellent reversed-phase chromatographic property with relatively weak hydrophobicity. However, it has an advantage over ODS in the fast separation of polar aromatic compounds because the quercetin ligand could provide various sites besides hydrophobicity, such as hydrogen bonding, dipole-dipole, n-n staking and charge transfer interactions. QUSP was performed in the baseline separations of ion- ized polar basic or acidic compounds, including pyridines, anilines, pyrimidines, purines and phenols with symmet- ric peak shape in common mobile phases without buffer salt within relatively short time. The natural ligands from herbs are readily available and contain a variety of active sites, which facilitate the exploration of industrial chromatographic separation materials for green products.

Sequence-specific Hydrolysis of Single-stranded DNA by PNA-Cerium （Ⅳ） Adduct

A novel artificial site specific cleavage reagent, with peptide nucleic acid （PNA） as sequence-recognizing moiety and cerium （IV） ions as “scissors” for cleaving target DNA, was synthesized. Subsequently, it was employed in the cleavage of target 26-mer single-stranded DNA （ssDNA）, which has 10-mer sequence complementary with PNA recognizer in the hybrids, under physiological conditions. Reversed-phase high-performance liquid chromatogram （RPHPLC） experiments indicated that the artificial site specific cleavage reagent could cleave the target DNA specifically.

新型吡咯烷键合反相高效液相色谱固定相的制备与研究（英文）

A new ionic liquid-based high-performance liquid chromatography stationary phase is reported.A derivative of N-methyl pyrrolidinium tetrafluoroborate was covalently immobilized on the surface of silica particles to prepare silica-based N-methyl pyrrolidinium tetrafluoroborate(SilprMP BF4)stationary phase.The obtained ionic liquid-modified silica was evaluated and confirmed by elemental analysis,infrared spectroscopy,and thermogravimetric analysis.A column was packed with the modified particles.The retention behavior of aromatic compounds,alkyl benzenes,and acidic and basic compounds on the SilprMP BF4 stationary phase was studied under reversed-phase liquid chromatography conditions.The effect of the eluent pH on the separation of the acidic and basic compounds was also studied.The new stationary phase involves multiple retention mechanisms,such as electrostatic,hydrophobic,ion-dipole,and anion-exchange interactions,which might lead to multipurpose separation media.

Production and stability study of a hospital parenteral nutrition solution for neonates

Standard parenteral nutrition solutions are mixtures comprising interacting components that may degrade themselves over time. The objective of this study was to investigate the physicochemical and microbiological stability of a hospital preparation for parenteral nutrition in neonatology. The analyses were performed throughout the storage of the preparations at 2–8 °C(up to 4 months). The extent of stability was based on the determination of amino acids dosage, visual and physicochemical properties(glucose and electrolytes concentrations, pH and osmolality measurements, particle counting) and microbiological analysis(sterility test). A thermal degradation of ascorbic acid was conducted to evaluate the antioxidant properties of the parenteral mixture. Physicochemical and microbiological controls were found to comply with the specifications. Amino acids showed a good stability throughout the 4 months storage except for cysteine, which was progressively degraded to cystine, conferring a yellow coloration to parenteral solutions. Parenteral nutrition standards solutions remain stable for 4 months at 2–8 °C,ensuring safe administration in preterm infants.

Determination of Ciprofloxacin in Human Plasma and Urine by Precolumn Derivatization High Performance Liquid Chromatography with Fluorescence Detection

A sensitive, simple and selective high-performance liquid chromatographic （HPLC） method was developed for the determination of ciprofloxacin in biological fluids. The method is based on the reaction between the drug and 4-chloro-7-nitrobenzofurazan （NBD-C1） in borate buffer of pH 9.0 to yield a highly fluorescent derivative that is measured at 535 nm after excitation at 464 nm. The calibration curves were linear over the concentration ranges of 25--3000 and 50--3000 ng·mL -1 for plasma and urine, respectively. The mean recovery of ciprofloxacin from plasma and urine was 98.37% and 98.40%, respectively. The method was found to be sensitive, precise, accurate, and reproducible. All of the validation parameters were within the acceptance range.