Kiyokatsu Jinno

Analysis of organophosphorus insecticides from environmental samples using solid-phase microextraction

Abstract Techniques for the analysis of pesticides are often complicated and time consuming. Solid-phase microextraction (SPME) using polyacrylate has been applied as an alternative simple method for the analysis of 20 organophosphorus insecticides from environmental water samples. Detection limits at the ng/1 level were achieved using selective detectors such as a nitrogen-phosphorus detection (NPD) system or mass spectrometry (MS). A wide linear range was obtained with precision typically below 15% R.S.D. Contaminated soil samples were qualitatively analyzed for the presence of the target analytes. Water samples from Southern Ontario were successfully analyzed qualitatively and quantitatively.

Analysis of pesticides in environmental water samples by solid-phase micro-extraction-high-performance liquid chromatography

Solid-phase micro-extraction (SPME) followed by high-performance liquid chromatography (LC) has been applied to analyze pesticides in water samples. A device interfaces SPME to the LC injection process by solvent extracting analytes from the fiber and then introducing the solvent into the LC injector. LC analysis with UV detection was performed first with a conventional column (4.6 mm I.D.). To enhance efficiency of SPME, three extraction conditions, stirring, temperature and salt concentration, were optimized. Subsequently, semi-microcolumn LC (1.5 mm I.D.) was evaluated for this method, giving lower detection limits and less solvent consumption. Detection limits were within Japanese regulatory limits for drinking water. The SPME-LC method was applied to real-world environmental water samples.

Miniaturized sample preparation combined with liquid phase separations

Miniaturized sample preparation methods designed as the sample pretreatment for liquid phase separations, such as liquid chromatography, capillary electrophoresis and capillary electrochromatography, have been reviewed especially for the on-line coupling of the sample preparation process and the separation process. The development of the desorption interfaces for the effective combining of the sample preparation and subsequent liquid phase separations is briefly described along with the applications of the combined analytical systems to the analysis of complex sample mixtures such as biological and environmental matrices. Novel use of fine polymeric filaments as the extraction medium for microscale liquid phase separation methods are investigated and a comparison is made with other sample preparation techniques. Polymer coating onto the fibrous material is also introduced to further develop microscale sample preparation methods with improved extraction performance. Several other microscale sample preparation methods having a potential compatibility to the liquid phase separations are also described for future applications of these techniques.

Computer-assisted retention prediction system for reversed-phase micro high-performance liquid chromatography

Abstract A retention prediction system for reversed-phase liquid chromatography was investigated. The system is based on the use of a retention description which was derived from studies of quantitative structure-retention relationships. A system for an octadecylsilica column was constructed on a 16-bit microcomputer and then evaluated by comparing measured and predicted retention data. Excellent agreement between both values were observed. This system can also work well for any other reversed-phase columns, such as octyl-, phenyl- and ethylsilicas.

Breath acetone analysis with miniaturized sample preparation device: In-needle preconcentration and subsequent determination by gas chromatography–mass spectroscopy

A new approach to the determination of human breath acetone with particle-packed sample preparation needle was developed. The extraction needle was packed with a copolymer of methacrylic acid and ethylene glycol dimethacrylate as the extraction medium. For the analysis of breath sample, exhaled breath was collected in a sampling bag, and 50 mL of the breath sample was extracted with the needle-type sample preparation device followed by analysis using gas chromatography-mass spectrometry (GC-MS). After the optimization of several basic extraction conditions for standard acetone samples, breath acetone concentration taken from controlled type-2 diabetic patients was determined. Furthermore, time variations of breath and urine acetone of four healthy individuals under fasting conditions were measured. Urine sample was collected in glass vial, and urine acetone concentration was also determined with the extraction needle by analyzing the corresponding headspace gas. The results demonstrated that the particle-packed extraction needle showed an excellent extraction performance for acetone in both breath and urine headspace samples, and that there is a clear correlation between the concentration of breath acetone and HbA1c level of controlled type-2 diabetic patients. The breath acetone level in controlled diabetic patients was in the range between 0.19 and 0.66 ppmv, where its concentration in medically untreated type-2 patient was 0.92 and 1.20 ppmv. The breath acetone concentration in healthy male was increased to 5.66 ppmv under the 24 h of fasting test, and a high correlation between the breath and urine acetone concentration was also observed. On the basis of the above results, the potential applications of the proposed method to the diagnosis of diabetes and/or ketoacidosis were suggested.

Retention behaviour of large polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography on a polymeric octadecylsilica stationary phase

Abstract Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and differential scanning calorimetry experiments were performed in order to study the retention mechanism in reversed-phase liquid chromatography for large polycyclic aromatic hydrocarbons. The effects of changing the mobile phase composition and column temperature were evaluated. The results suggest that a change in mobile phase composition from pure methanol to pure dichloromethane induces further non-planarity in non-planar solutes and also slightly changes the conformation of a polymeric octadecyl stationary phase. Conversely, a change to higher column temperatures drastically changes the structure of the stationary phase from solid-like to liquid-like, with only a small change of non-planar solutes to more non-planar conformations

Solid phase micro extraction coupled with semi-microcolumn high performance liquid chromatography for the analysis of benzodiazepines in human urine

SPME/semi-microcolumn HPLC (SPME/LC) was investigated to analyze benzodiazepines in human urine samples. SPME conditions such as extraction time, extraction temperature, salt concentration and pH of matrix, flush volume and desorption time were optimized by extracting various drugs from a prepared water matrix. Combination of adding saturated salts to the matrix and controlling pH ranged from neutral to weakly alkaline conditions makes the increase of extraction efficiency. Under optimal condition SPME/LC is more sensitive than direct HPLC analysis without the SPME process. The limits of detection (LODs) was several ppb level and the relative standard deviation (RSD) was < 15% when human urine samples were analyzed by this analytical system. The system is very useful and is enough to assay benzodiazepines in a human urine sample without tedious and complex analytical procedures. In this paper the applicability of SPME/LC to the analysis of benzodiazepines in human urine samples was reported. In addition, the extension to the evaluation of SPME/LC/MS system was also described.

Eluation behaviour of planar and non-planar polycyclic aromatic hydrocarbons on various chemically bonded stationary phases in liquid chromatography

The elution behaviour of planar and non-planar polycyclic aromatic hydrocarbons has been studied on various stationary phases in reversed-phase and normal-phase liquid chromatography. The results show that the elution behaviours of the isomer sets which have distinctly different planarities such as triphenylene, triphenylmethane or o-terphenyl reflect the characteristics of the chemically bonded stationary phases. The phases studied included polymeric C18, monomeric C18 (with end capping), monomeric C18 (without end capping), triphenyl, naphthylethyl and pyrenylethyl phases.

Silicas chemically bonded with multidentate phenyl groups as stationary phases in reversed-phase liquid chromatography used for non-planarity recognition of polycyclic aromatic hydrocarbons

Abstract Multidentate phenyl-bonded phases have been evaluated as stationary phases which can recognize molecular non-polarity of polycyclic aromatic hydrocarbons. The results clearly indicate that these multidentate give a higher non-polarity recognition capability than that with typical octadecylsilicas such as polymeric and monomeric phases. The reason for this mechanism can be interpreted by the molecular—molecular interaction between a solute and a stationary phase and this kind of approach will open the possibility of designing new stationary phases which offer more selective of specific separations.

“Buffer memory” technique for the combination of micro-high-performance liquid chromatography and infrared spectrometry

Abstract The buffer memory technique was applied to the combination of micro-high-performance size-exclusion chromatography and Fourier transform infrared spectrometry. A series of polystyrene standards with known molecular weights was studied and the molecular weight calibration was established. Polyethylene glycol of unknown molecular weight was determined from the calibration. The utility of the technique is discussed.