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Per- and polyfluoroalkyl substances (PFASs) are man-made chemicals that have been identified as global pollutants. Their widespread occurrence, including in food, is a potential concern for consumers. This work focuses on the application of a simple and reliable analytical method for the simultaneous determination of ten perfluoroalkyl acids in highly complex fatty matrices (fats and oils). The perfluoroalkyl substances were extracted by the QuEChERS method, based on the dispersive-Solid Phase Extraction using styrene–divinylbenzene bulk sorbent, and quantitatively analysed by micro-high performance liquid chromatography tandem mass spectrometry. Recoveries ranged from 72 to 104% with an acceptable relative standard deviation below 10%. Limits of quantification were within the range 0.002–0.075 ng/g depending on the perfluoroalkyl compound. The most predominant compound in fat and oil food samples was perfluorooctanoic acid (PFOA) with a detection frequency of 100%, and the highest levels were found for perfluorobutanoic acid (PFBA). The estimated exposure to PFOA, which was 46% and 19% of the existing TWI for the EU and Polish population, respectively, is relatively high and indicates a potential risk to human health.

The worldwide consumption of illicit drugs presents a big problem in terms of health care and prosecution. In the recent years, hundreds of novel psychoactive substances came up and were traded via the Internet, but there is still a big demand for classic illicit drugs such as cocaine, heroin, cannabis and ecstasy. Among these, cocaine particularly is frequently altered not only with excipients, but also with other physiologically active substances. The purpose of this work was to estimate the trend of cocaine purity and abundance of its adulterants in samples seized by Austrian police from 2012 to 2017. A micro-HPLC method for quantification of cocaine and its most common adulterants was developed and validated using gradient elution and UV detection at four wavelengths. 110 cocaine samples were analysed. In all the samples cocaine was present as hydrochloric salt. Caffeine, procaine, levamisole, phenacetin, lidocaine and benzocaine were the most abundant adulterants.

This review gives an overview of chiral separation principles and their application in enantioselective nano/micro high performance liquid chromatography (n/μ-HPLC) using chiral monolith. In particular, developments in silica and polymer chiral monolithic stationary phases are presented. The preparation and applications of chiral monoliths, the basic chiral separation principles and the mechanisms are discussed. Chirality 25:314–323, 2013. © 2013 Wiley Periodicals, Inc.

A highly sensitive and simple method for determining cryptotanshinone (Cry), tanshinone I (Tan I), and tanshinone IIA (Tan IIA) in Salvia miltiorrhiza was developed using micro HPLC with electrochemical detection (µHPLC-ED). The tanshinones were extracted using an ultrasonic method, with methanol as the extractant. The separation was carried out on a C18 (150 mm × 1.0 mm i.d., 3 µm particle size) analytical column. The mobile phase was acetonitrile-water-formic acid mixture (52:48:0.6, v/v/v) solution. The flow rate and the temperature of the column were set at 30 µL/min and 35°C. The applied potential was set at −0.4 V vs. Ag/AgCl. The peak heights for Cry, Tan I, and Tan IIA were found to be linearly related to the amounts injected, ranging from 0.145 µmol/L to 3.88 µmol/L, 0.226 µmol/L to 3.01 µmol/L, and 0.149 µmol/L to 3.98 µmol/L, respectively. The RSD values of intra-day precision and repeatability were not more than 3.0%, and the recovery of three analytes were ranged from 96.7% to 97.5%. The resu...

Micro-high-performance liquid chromatography is a miniaturized, economic and ecological chromatographic system allowing the use of reduced size chromatographic columns. Coupled with electrospray ionization tandem mass spectrometry, this technique can be used to detect and quantify low concentrations of peptides. In this study, hepcidin was used as the model compound and analysed using octadecylsilica stationary phase by means of a gradient elution mode at a flow rate of 4 μL/min. Several parameters were studied to optimize peak focusing. Using the methodology of experimental design, the mobile-phase gradient conditions and the sample composition were optimized in order to maximize the sensitivity and minimize retention time. Stability of the target peptide in solution was also demonstrated.

A simple, fast, sensitive, and environmental friendly micro-method is described for the determination of desmosterol and cholesterol in milk samples using isocratic normal phase high performance liquid chromatography and diode array detection. After sample micro-saponification, the chromatographic separation is achieved in 10 min, further reduced to 6 min when only cholesterol is expected to be present. The method is accurate, presenting cholesterol and desmosterol recoveries >96% and inter-day RSD lower than 3%. Quantification limits were clearly below the requirements for any milk sample, with 40 and 20 μg/100 mL for cholesterol and desmosterol, respectively. Several raw and UHT commercial milk samples, infant powder formulas, and human breast milks were analyzed, with cholesterol and desmosterol (present only in the latter) contents within reported amounts. The proposed method proved to be simple and feasible for determination of a large number of samples, requiring less solvent consumption (9–13 mL of hexane for all saponification/extraction/chromatographic steps) and simpler equipment than most ones reported, and a further possibility of partial solvent recycling due to the isocratic chromatographic mode.

The purpose of this study is to improve the detection limit for trace herbicides, and to separate all samples within a short time with the combination of temperature and flow programming with micro‐reversed‐phase liquid chromatography (RPLC). The optimum condition for separation was ACN:0.05 M NaH2PO4 (46:54) (v/v), pH = 4.3, 40°C. The mass sensitivity is in the range between 0.086 × 10−13 g and 3.34 × 10−13 g in micro‐HPLC (HPLC). Micro‐HPLC exhibits higher mass sensitivity and better heat transfer than conventional HPLC. Thus, in the case of micro‐HPLC, the retention behavior of herbicides is easily determined according to the change of temperature. Especially, retention of triazines is decreased to a lesser extent with the increase of column temperature than that of other herbicides. This tendency has been accounted for the thermodynamic parameters ΔH° and ΔS°. The ΔS° for triazines is less negative than that for phenoxy acids, esters, and others. The chromatograms of herbicides were obtained ...

Objectives: the development of a simple, rapid, sensitive, and accurate HPLC-UV method for the simultaneous determination of retinol and α-tocopherol in human plasma, suitable for the evaluation of these vitamins in pregnant women suffering from intrahepatic cholestasis of pregnancy (ICP). (b) Design and methods: chromatographic separation of vitamins was achieved with a microcolumn BDS HYPERSIL C18 (100 mm × 2.1 mm, 2.4 μm) using a C18 guard column. The developed and validated HPLC method proposed in this study was applied in the assessment of plasma concentrations of retinol and α-tocopherol in normal pregnancy (n = 37) and in pregnancy complicated with ICP (n = 19). (c) Results: the validation of the method showed excellent linearity for retinol and α-tocopherol (r2: 0.998 and 0.997), high sensitivity (LOD: 0.02 and 0.11 μM, LOQ: 0.07 and 0.36 μM), and high recovery (96.0–104.0% and 99.3–102.0%), respectively. The method requires a low sample volume and all procedures of sample preparation and analytical determination take less than 20 min to be completed. The evaluation of the results in ICP patients showed that α-tocopherol significantly diminished compared to normal pregnant women (13.1 ± 2.9 vs. 22.4 ± 2.2 μM, p < 0.05) whereas retinol remains unchanged (1.27 ± 0.21 vs. 1.25 ± 0.10 μM). (d) Conclusions: a simple, accurate, reliable, selective, highly sensitive and cost effective method suitable for routine determination of retinol and α-tocopherol in biological samples is proposed. It was possible to determine the decrease of α-tocopherol in ICP patients by this method. Fil: Martinefski, Manuela Romina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Scioscia, Silvia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina Fil: Contin, Mario Daniel. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Samassa, Paula. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentina Fil: Lucangioli, Silvia Edith. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tripodi, Valeria Paula. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Existing methods for preparing frits in packed fused silica capillaries as used for electrochromatography and micro HPLC are not applicable to all silica based packing materials and involve a high thermal stress for both the stationary phase and the fused silica tubing including the polyimide coating. A new procedure for the production of such on-column frits under mild conditions by a sol-gel type reaction of polydimethoxysiloxane (PDMOS) is described in this paper. Reaction conditions were established for optimum mechanical stability and high permeability of the frits. Frits produced in this manner showed no noticeable effect on the overall efficiency.

The main difficulty in micro-HPLC separation is the manipulation with the composition of the mobile phase (degassing of solvents and a slow establishment of equilibrium) but the problem of elution can be solved by temperature optimalization. The effect of temperature in micro-HPLC separation of the 16 polycyclic aromatic hydrocarbons (PAHs) (mixture SRM 1647 of the US EPA) has been studied using conventional C18 and new developed AP phase (an amide group localized in the hydrophobic ligands). All the investigations have been performed under isocratic conditions (binary hydroorganic mobile phase: acetonitrile/water). The results have shown that, in the case of AP phase, application of temperature gradient (from 298 to 303 K), enabled the attainment of complete 16 PAHs separation (especially of the first 4 solutes).

In this study, packed capillary columns were prepared using supercritical carbon dioxide as a packing carrier. A factorial design was used to examine the effect that four selected factors have on the packing performance. The investigated factors were: 1)

医薬部外品の薬事申請用試験及び安定性を中心とした品質管理試験等には, 効率化のためグラディエントHPLC法による多薬剤同時分析法が多く用いられている。本報では, 溶媒使用量が汎用HPLCの1/10程度に削減可能なセミミクロHPLC装置を用い, 汎用HPLCで設定した分析条件の直接適用可能性及び分析精度等の基本的検討を行った。また, 実試料例として6薬剤配合の育毛剤を用い, 複雑なグラディエント法による定量分析への応用を検討した。保持時間の再現性は良好であり, 注入量の再現性に関しても2μl以上ではC.V.%1-2%程度であり, 良好であった。また, グラディエント法では, 高濃度有機溶媒領域で保持時間が若干早くなる現象が見られたが分離に影響はなく, 微量金属の影響を受けやすいヒノキチオールのピークに関しても良好であった。6薬剤配合育毛剤の定量分析において汎用HPLCの精度と同様な値であることが確認された。

A micro high-performance liquid chromatography (HPLC) method has been developed for the determination of the anti-coccidial drug nicarbazin in chicken tissues, eggs, poultry feeds and litter. The 4,4′-dinitrocarbanilide (DNC) component of nicarbazin was extracted from foods, feeds and litter with acetonitrile. The extracts were purified by liquid-liquid partitioning, evaporated to dryness and taken up in methanol-acetonitrile-water (50:30:20, v/v). Micro HPLC of the 4,4′-dinitrocarbanilide (DNC) portion of nicarbazin is performed isocratically using a small bore column (1 mm I.D.) packed with reversed-phase and a UV detector set at 340 nm. The average recoveries of nicarbazin added to muscle, liver and egg were 92.8, 84.3 and 85.2%, respectively, 95.9% in poultry feed and 76.8–95.9% in different litters. The limit of detection was 25 pg, based on a detector signal-to-noise ratio of 3. These results were achieved with a simplified step extraction without the solid-phase extraction used by various researchers. This method offers a sensitive, selective, rapid, and less expensive alternative to conventional HPLC for such evaluations.

Micro-HPLC separation and UV detection of some metal thenoyltrifluoroacetonates has been achieved. Cyano, octadecyl, and HTT A modified silica gels were used as stationary phases. Data about separation and detection parameters optimization are also described.

The generation of a micro-gradient for micro HPLC capillary columns is described. The system used is a modified and improved version of a split flow gradient elution device. Gradient tests have been performed and have shown good reproducibility under all conditions. The system has been successfully coupled with a particle beam LC-MS interface and the analysis of a mixture of twenty seven basic or neutral pesticides is reported.

The purpose of the study was to develop a micro HPLC system with physically changeable selectivity. This was done using two series-coupled beds of chemically differing stationary phases in a packed fused silica column. The selectivity change, in fine repeatable steps, was possible by the stepwise moving of a tube oven, covering only 50% of this “tandem column”. Each step of selectivity started with a position change of the oven, thus heating up a fresh position of the more polar and the non-polar column bed. As the chromatogram is thus repeated under these new selectivity conditions, multiple chromatograms result. For this reason we call the technique “Multi Micro HPLC”. This very simple mode of operation provides an analytical tool for developing separation conditions and which allows optimizing for a given special sample and checking for one of the most critical problems in HPLC: unidentified peak overlapping. The selectivity changes are nonlinearly correlated with the oven position with regards to temperature field distribution and are greater than is possible by simple change of column temperature. Micropacked columns are ideal for quick temperature changes. Elevated temperatures in HPLC help to shorten analysis time. The concepts discussed above provide an explanation of how a normal, formerly chemically homogeneous, column can become very temperature sensitive after detoriation at the inlet. In fact the column has become an unintentional “tandem column” and peak positions tend to move erratically as its selectivity changes drastically by inhomogeneous temperature changes along the separation path.

Organic-silica hybrid monolithic columns have drawn more and more attention due to the ease of preparation and good mechanical stability in recent years. Many synthetic approaches have been developed and a variety of hybrid monolithic capillary columns have been prepared. The sol-gel process is well recognized in the fabrication of hybrid monolithic columns, which can be mainly classified as one-step, acid/base two-step procedures. The new approaches such as the " one-pot'' and nano-scaled inorganic-organic hybrid reagent of polyhedral oligomeric silsesquioxane used as a cross-linker have also emerged for the preparation of hybrid monolithic columns. The applications of the organic-silica hybrid monolithic capillary columns for capillary electrochromatography, micro high-performance liquid chromatography, solid-phase microextraction and enzymatic reactor etc. are included in this review.

A new sampling procedure for individual raindrops with volumes of 4 nl - 4 μl is presented. It is demonstrated that analyte concentrations in small volumes can be analysed using micro-HPLC and capillary zone electrophoresis (CZE). Results for the analysis of cations such as Na+, NH4 +, K+, Mg2+, Ca2+, and anions such as Cl−, SO4 2-, NO3 −, NO2 − and organic acids are given and discussed.

This article reviews the works published since 2001 (included) on the micro/nano-HPLC analysis of bioactive and biomarker peptides. The main achievements related to the improvement of the detection sensitivity, quantitation repeatability and reproducibility, and separation selectivity are highlighted. A wide attention is paid to the application of micro/nano-HPLC to the analysis of bioactive peptides in biological matrices. The uses of micro/nano-HPLC in peptidomics to discover new endogenous bioactive peptides and to develop quantitation procedures to compare the levels of peptides of interest in two different biological samples are also considered. Finally, the application of micro/nano-HPLC to the analysis of biomarker peptides for various diseases is also included in this review.

A micro high-performance liquid chromatographic (micro-HPLC) procedure for the assay of digitoxin tablets and deslanoside injections has been developed. Micro-HPLC is performed on an ODS micro column, with acetonitrile-methanol-water (10:20:17) for digitoxin tablets and acetonitrile-water (21:70) for deslanoside injections. The effluent is monitored by UV absorption at 220 nm. Quantitation of cardiac glycosides in tablets and injections is carried out by the internal standard method. The composite assay results for digitoxin tablets and deslanoside injections provide average values of 101.2 and 99.9% with standard deviations of 1.2 and 0.93%, respectively. This micro-HPLC method is sensitive, quantitative, and reproducible. It is suitable for use in examining the content uniformity of pharmaceutical preparations.

This work deals with the application of stereoselective antibodies against L-T3 as a tailor-made chiral selector in micro-HPLC. The separations were performed in microbore columns using commercially available anti-L-T3 antibodies chemically bonded to 5 microm silica gel. The enantiomers of T3 were baseline separated under mild continuous isocratic elution conditions using 10 mM phosphate buffer, pH 7.4. The D-enantiomer eluted with the void volume, while the L-enantiomer was retained by the antibody phase and eluted second. An indirect competitive and non-competitive enzyme linked immunosorbent assay (ELISA) was used for testing the stereoselectivity of anti-L-T3 antibodies.

A highly sensitive determination method for troglitazone stereoisomers was developed by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). The oxidation behavior of troglitazone was investigated for the application of ECD by measuring the cyclic voltammogram. The separation was performed on a semi-micro chiral column (Chiralcel OJ-RH) using a mobile phase consisting of methanol-acetic acid (1000:1, v/v) containing 50mM LiClO4 at a flow rate of 20 microl/min. The peak areas of the stereoisomers separated from 0.1 to 50 ng/ml of troglitazone had good linearity with correlation coefficients of >0.999, and had similar response. The limit of detection was 1.3 fmol (signal-to-noise ratio of 3). This method was applied to the determination of troglitazone stereoisomers in rat plasma. The levels of troglitazone stereoisomers in rat plasma could be monitored until 24h after the oral administration.

Anthocyanins of red orange juices were analyzed by micro-HPLC coupled on-line with an MS detector equipped with an ESI source. The use of microcolumn HPLC greatly enhanced detection performance, allowing direct identification of the anthocyanins present in the orange juices. The use of a soft ionization technique allows detection of the molecular ions of the aglycons. Eight components were identified, five of them for the first time in red orange juice. Three additional anthocyanins were detected, of which only the aglycon was identified.

A dry-packing method has been developed which enables the preparation of packed capillary columns for micro HPLC from 250 μm i.d. tubing and 5 μm packing materials. Pressurized gases, such as hydrogen and argon, were used to transport the packing media, and ethanol or methanol were used as discharge agents. By changing the gas pressure, the packing density could be easily adjusted. It was found that, within experimental limits, the higher the packing density, the greater the column efficiency. Comparison between dry- and slurrypacked columns showed that the former had greatly improved stability; the efficiency of dry-packed columns was about the same as, or even better than, that obtained by slurry-packing.

Thermal lensing (TL) permits ultrasensitive measurements of optical absorption of analytes in very small volumes. Separation-detection conditions of non-labeled amino acids with micro-HPLC/UV absorption detector are optimized, and direct determination of non-labeled amino acids by micro-HPLC/UV-excitation TL detection in a gradient elution is successfully demonstrated. Non-labeled amol-level amino acids is detectable with the TL detection system, which has thousand times better sensitivity than a conventional UV detector.

Plastic tubing of polyetheretherketone (PEEK) is used for the preparation of HPLC packed capillary columns. The polymer is rigid but not fragile, has great resistance to chemical and physical agents and comes in standard 1/16″ O.D. These features can extend the column lifetime and facilitate the overall employment of HPLC capillary columns. Serial connection of short columns is also possible with no increase in dead volume. A new, rapid and effective packing method has been developed to be compatible with the characteristics of the material. Several C8 and C18 columns have been prepared and tested and some applications are shown.

A new method is introduced for packing micro-columns with an ID (inner diameter) of 320 μm. The advantage of this method is the extraordinary economy of the packing material employed and the high reliability in production. The theoretical plate height ranges from 7 to 8 μm for 3 μm particles.

In view of the importance of cyclodextrins in various pharmaceutical areas, methods for their determination in plasma are necessary for pharmacokinetic studies. Cyclodextrins show almost no UV absorption. This paper describes indirect detection of cyclodextrins in micro-HPLC

The retention and selectivity behaviour of some antiepileptic drugs were studied by micro high-performance liquid chromatography on nine types of phenyl-modified glasses, prepared with xylene solution containing phenyldimethylchlorosilane (P), diphenylmethylchlorosilane (D) or triphenylchlorosilane (T), using three types of glass with various mean pore diameters and/or specific surface areas. From elemental analysis data for carbon, the maximum number of accessible phenyl surface groups per 100A2 of glass (mean pore diameter: 335A, specific surface area: 69m2/g) in P, D and T gel was calculated to be 2.38, 1.58 and 0.76, respectively. Using various CH3CN−0.01 M KH2PO4 mixtures as eluents, the antiepileptic drugs were separated on all the glasses studied, but with different degrees of resolution. With an increase in the specific surface area, the k′ values of some antiepileptic drugs also increased.

Recherche des parametres optimisants, qui sont nombreux: type de pompe, melange initial, nature des solvants, debits, geometrie de la cellule de melange, etc...

Microcolumn techniques involving pre-column concentration and post-column derivatization make good use of micro-scale high-performance liquid chromatography. The efficient use of microcolumns is illustrated by some applications to the analysis of amino acids, bile acids and catecholamines. The potential of new detector techniques based on the multichannel photodiode array detector, and on immobilized enzyme post-column reaction systems with fluorimetric detection, is also discussed.

Infrared monitoring was accomplished in reversed phase HPLC on using deuterated solvents. The end of a micro HPLC column was flattend and used as a flow cell for on-column IR detection. Detection of alkylbenzenes and oil-soluble vitamins which were separeted on ODS packing with CD3CN/D2O and CD3OD, respectively, was performed at 2940 cm−1.

長鎖脂肪族カルボン酸の誘導体化試薬として,Arイオンレーザーの励起光に近接した波長領域に吸収を示す4-ニトロ-4'-N・メチル,N・β-ヒドロキシエチルアミノアゾベンゼンを合成した.カルボン酸は二塩化オキサリルで酸クロライドとした後,誘導体化試薬を用いてエステル誘導体とした.これらの誘導体は逆相セミ・ミクロカラムで分離後,その溶離成分を1343cm-1のラマンバンドに設定して共鳴ラマン検出した.その結果,ラウリン酸では5～200ppmの濃度範囲で検量線は直線を示した.20 ppmでの相対標準偏差(n=5)は4.4%と良好であった.

Detecteurs optiques, a barette de diodes, laser, electrochimiques, du type CG, a induction de plasma

The advantages of short microbore columns packed with a sorbent having a particle diameter of 3µm, such as the speed of analysis, the high solute concentration in the effluent and the detectability of small quantities are experimentally verified. The broadening in the valve is eliminated by the peak compression technique reached by adding a ion-pairing agent into the sample. The examples of catecholamines show the dependence of the height equivalent to a theoretical plate on the velocity of the mobile phase. The optimum is h=3 for a column 30mm long, i.d. 0.7mm, particle diameter 3µm. The minimal detectable quantity with a two-electrode amperometric detector with a gold electrode is from 30 to 40fmol for catecholamines.

Utilisation des techniques de spectrometrie IR a transformee de Fourier, de la chromatographie en couche mince avec de l'alumine et de la chromatographie HPLC en phase inverse afin d'identifier des composes de melanges complexes

The chromatographic performance of deuterated solvents, heavy water and deuteriobenzene, has been investigated in reversed phase and normal phase micro-HPLC. The performance of heavy water in separation was comparable or superior to that of light water in reversed phase mode. A slight improvement was also observed in catecholamines separation with heavy water. The performance of deuteriobenzene was observed as complicated in metal complexes separation, but a little difference was present. From those results, the combinations of micro HPLC and IR via flow-cell technique, proton-NMR, and ICP could be accomplished free from absorption or signals from mobile phase solvents.

A simple scheme was developed by utilization of a micro-HPLC technique in order to monitor synthetic reactions in-situ. The application of this system for the organic reaction of bromination of toluene was successfully presented.

High-performance micro packed fused-silica and open-tubular glass capillary columns were prepared and applied to separations of complex mixtures. Solvent-gradient elution proved quite useful for the separation of solutes with wide polarity. Instruments and some applications are described.

The capcity factors determined by reversed-phase micro high performance liquid chromatography (micro-HPLC) can be used as one of the descriptors in Quantitative-Structure-Activity-Relationships (QSAR) studies. The present method gives a more simple and convenient way to study relationships between physicochemical properties and biological activities of some drugs.

A miniaturized continuous gradient elution system with variable gradient profile was designed. A retention time reproducibility below 1% was achieved. The system was applied to the separation of phenolic compounds with a wide range of polarities.

Phenol-formaldehyde resins of the Novolak and Resol type were chromatographed on a reverse-phase micro-column packed with octadecylsilane on silica gel. A good separation of most components was achieved by the use of gradient elution with methanol-water; the contents of methanol in the mobile phase increased continually from 10 to 90%. The gradient was generated in a simple tubular mixer with an internal volume of 1.5 ml. Samples were applied to the column in a non-eluting solvent, using a six-port injection value with a 10 μl sample loop. The method, which shows a good reproducibility, is suitable for the characterization of phenol-formaldehyde resins. Phenol-Formaldehyd-Harze vom Novolak- und Resol-Typ wurden durch Chromatographie an einer mit Octadecylsilan auf Kieselgel bepackten Umkehrphasen-Mikro-Saule getrennt. Eine gute Auftrennung der meisten Komponenten wurde durch die Verwenndung der Gradientelution mit Methanol und Wasser erzielt. Der Gradient wurde in einer Rohr-Mischkammer (Volumen 1,5 ml) erzeugt; der Anteil von Methanol in der mobilen Phase wurde im Verlauf der Analyse von 10 auf 90% kontinuierlich gesteigert. Die Probenaufgabe erfolgte mit Hilfe eines Dosierventils und einer Probenschleife (Volumen 10 μl). Das Verfahren ergab reproduzierbare Ergebnisse; es erwies sich als gut geeignet zur Charakterisierung von Phenol-Formaldehyd-Harzen.