Electrochemical treatment of textile dyes and their analysis by high-performance liquid chromatography with diode array detection

Several textile dyes were individually exposed to electrochemical treatment. Chromaticity variation and the formation of degradation products were followed using a UV spectrophotometer and HPLC with diode array detection. Dyes studied belong to the azo (color index, C.I. 15,510), methine (C.I. 48,013), indigo (C.I. 73,040), natural (C.I. 75,760) and arylmethane (C.I. 42,000) classes. Aliquots of the solutions treated at constant potential were analyzed and compared with control dye solutions. The final electrolysis solutions obtained by using different electrode materials: Pt, Ti and diamond presented different chromatograms. It was found that the novel (in this application) diamond electrode is efficient in studying the degradation of various dyes. Possible fragmentation and molecule moiety rearrangement are proposed as a result of the electrochemical treatment.     

Identification of cosmetic dyes by ion-pair reversed-phase high-performance liquid chromatography

A method based on ion-pair reversed-phase high-performance liquid chromatography with detection at four wavelengths between 400 and 600 nm is reported for the separation and identification of the most common synthetic colour additives in cosmetic products. All the dyes generally employed in the U.S.A. and almost all those in current use in cosmetics in the European Community have been taken into account. The chromatography was performed on a C8 bonded silica packed column, with a 60-min gradient changing from 10 to 95% acetonitrile in water containing 10(-2) M sodium perchlorate (pH 3.0) as mobile phase (flow-rate 2.5 ml/min). Detection limits are in the range 20-100 ng for all dyes investigated. The method has been applied to the analysis of commercial lipsticks.     

Celite column chromatography followed by reversed-phase high-performance liquid chromatography: a simple, two-step method for separating 14 testicular steroids

The separation of 14 major testicular steroids has been effected by a simple, two-step procedure involving Celite column chromatography followed by reversed-phase high-performance liquid chromatography. The technique does not alter the resolved steroids, which are then available for subsequent analysis.     

Ion-pair reversed-phase high-performance liquid chromatography for trace metal preconcentration followed by ion-interaction chromatography

Ion-interaction chromatography of Plasmocorinth B (a disulphonated azo dye) complexes of Co(III), Cu(II), Fe(III), Ga(III), In(III), Ni(II), V(V) and Zr(IV) was studied. The behaviour of two different reversed-phase C₁₈ columns (5 and 10 μm) was compared and an on-line enrichment procedure was developed following the optimization of eluent (pH, ligand concentration, ionic strength and organic modifier). The described technique, applied to the analysis of metal ions at μg/1 levels in natural waters, gave satisfactory precision and accuracy in comparison with inductively coupled plasma atomic emission spectroscopic results.     

Separation of polyesters by gradient reversed-phase high-performance liquid chromatography on a 1.5 microm non-porous column

Efficient separation of polyesters composed of a large number of individual oligomers was achieved on a 1.5 microm "non-porous" octadecylsilyl (ODS) silica support by gradient high-performance reversed-phase liquid chromatography (gRP-HPLC) with a mobile phase of acetonitrile, aqueous trifluoroacetic acid (0.2%) and tetrahydrofuran at ambient temperature and signal monitoring by UV absorption at 280 nm. Substantial signal splitting of oligomers in the low molecular weight (Mr) region is indicative that separation not only occurs with respect to molecular weight distribution (MWD) but also to chemical composition distribution (CCD) and functionality type distribution (FTD). Although separation according to CCD and FTD decreases with increasing number of oligomers, co-elution of species with identical number of repeat units but differing in either structure of repeat units or end-groups can be assumed from the relatively broad signals succeeding the aforementioned peaks showing at least partial resolution. Despite the observation that high Mr oligomers elute as sharp signals, the preceding observations suggest that each of these peaks presumably composes of more than one individual component. The polyester oligomers are eluted in the range of increasing Mr and therefore, either separation according to MWD or CCD/FTD was at least achieved for the low Mr sample constituents. Some principal mechanistic aspects of separation are discussed and adsorption seems to play the dominant role. The detection limit, defined as that sample amount yielding an unequivocal recognition on the base of its characteristic chromatographic fingerprint pattern was about 5,000 ppm for the pair Alftalat 3258 - Alftalat 3352 and 10,000 ppm for the pair Crylcoat 430 - Crylcoat 801.     

Analysis of insulin preparations by reversed-phase high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic system is described for the rapid and complete separation of bovine and porcine insulin from their readily formed monodesamido derivatives under isocratic conditions in the presence of the ion-pairing agent cetrimide. The system is suitable for the direct analysis of formulations of insulins of mixed bovine and porcine origin, and gives satisfactory results with a number of readily available commercial packings. Human insulin is not resolved from porcine in this system, but an alternative system allows the complete separation of all three insulins and their monodesamido derivatives, although acceptable peak shapes were obtained only on a limited number of packings.     

Rapid method for evaluating reversed-phase high-performance liquid chromatography column stability

A procedure is presented for the rapid evaluation of HPLC stationary phase stability at pH 8.4 or 10.1 using a temperature of 60 degrees C. Mobile phase (MeOH-0.1 mol l(-1) aqueous NaHCO3, 50:50, v/v) is continuously passed through the column with periodic injections of a test solution until the several chromatographic parameters of the resulting chromatograms are degraded. The tests were applied to several commercial and laboratory-made stationary phases. After degradation two of these phases, one commercial and one laboratory-made, were examined by elemental analysis and scanning electron microscopy to elucidate the degradation process.     

Comparison of reversed-phase column materials for high-performance liquid chromatography of proteins

Nine reversed-phase materials with various bonded phases from different suppliers were studied for the separation of hydrophilic proteins with two solvent systems. Protein retention, resolution and recovery were not correlated with the nature of the hydrocarbonaceous ligand. Peak volumes increased with molecular weight, which led to broad, irregular peaks for the larger proteins on some columns. Four columns that performed equally well were selected for the purification of hydrophobic Sendai virus membrane proteins. In this case, more distinct differences were found between columns. Recovery of the membrane proteins strongly depended on the combination of column and solvent systems.     

Faster analysis by reversed-phase high-performance liquid chromatography

Summary Many analysts are not taking full advantage of the high speed possibilities of modern LC. Some analytical procedures reported in the literature, and many in regular use in control laboratories, could be achieved in less time without loss in precision. Some factors which affect retention times are discussed and the advantages and disadvantages of employing shorter column lengths and finer packing materials in reversed-phase HPLC are examined. The effect on efficiency of increased flow rates with 10,5 and 3 m ODS materials is shown. The ability to couple shorter column lengths without loss of efficiency is also demonstrated. This allows a minimum length to be selected that gives adequate resolution. Examples of high speed separations are shown and limitations in state of the art HPLC equipment and chromatographic data systems are discussed briefly.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Identification of natural dyes in archeological Coptic textiles by liquid chromatography with diode array detection

Reversed-phase HPLC with diode-array UV-Vis spectrophotometric detection has been used for identification of natural dyes in extracts from wool and silk fibres from archeological textiles. The examined objects originate from 4th to 12th Century Egypt and belong to the collection of Early Christian Art of the National Museum in Warsaw. Extraction from fibres was carried out with HCl solution containing ethanol or with warm pyridine. As the main individual chemical components of natural dyes, anthraquinone, indigoid and flavonoid dyes including alizarin, purpurin, luteolin, apigenin, carminic acid, ellagic acid, gallic acid, laccaic acids A and B and indigotin were found. For pyridine extracts another mobile phase with an optimized gradient of organic modifier concentration was used. With such an eluent the appearance of double peaks for indigotin and indirubin was eliminated. For acidic extraction of dyes from fibres, ethanol was used. Due to its higher boiling point than methanol it evaporates slower from the extraction solution enabling a more efficient extraction of dyes.     

高效液相色谱-二极管阵列检测法测定护发产品中肌酸

建立了护发产品中肌酸的高效液相色谱(HPLC)测定方法.样品经流动相溶解并提取,采用偏磷酸溶液为流动相,流速为1.0 mL/min,以C8色谱柱(250 mm×4.6 mm 5μm)进行分离,二极管阵列检测器进行检测,检测波长为210 nm.在上述条件下,目标物质与样品的杂质获得有效分离,在2～100 mg/L范围内,质量浓度与峰面积呈良好的线性关系.对护发产品进行添加回收,回收率为92.5%～101.6%,RSD为2.0%～3.7%.已用于护发产品中肌酸含量的分析.     

Sensitive, indirect photometric detector for high-performance liquid chromatography using a light-emitting diode

A low-noise detector for indirect photometric detection has been constructed using a highly stable source--a light-emitting diode (LED). Use of the detector is demonstrated for reversed-phase liquid chromatography by adding methylene blue to the mobile phase to make a background signal. The indirect determination of alcohols by their effect on methylene blue concentration distribution is demonstrated, and an investigation is made into the conditions for high sensitivity. Because the source exhibits low noise, the detection limits for alcohols are as low as more complex and expensive detection methods, despite the lower radiant power of the LED. Detection limits for nine alcohols are below micrograms injected amounts.