An ultramicromethod for the determinations of phosphatase activity in serum or plasma

An ultramicromethod has been described for the determination of alkaline and acid phosphatase using dicyclohexylammonium salt of p-nitrophenylphosphate as substrate. The ammonium salt shares the advantages of the sodium salt, but it is more stable, which results in more stable working reagent. This has been incorporated into the Unopette System. All of the premeasured, individually packaged reagents are stable at room temperature for at least 1 year. The method has been validated by comparing the results obtained with clinical samples analyzed with the Auto-Analyzer.     

Sensitive and selective determination of glucose in human serum and urine based on the peroxyoxalate chemiluminescence reaction of a new fluorophore

A novel method for simple and sensitive determination of glucose based on the peroxyoxalate chemiluminescence (PO-CL) detection of enzymatically generated H(2)O(2) was investigated. Influence of various experimental parameters on glucose sensing, including the action time of the enzyme, solution pH, interferents and the concentration of CL reagents was investigated. Under the optimum condition, the linear response range of glucose was found to be 2.50×10(-6) to 1.75×10(-4) mol/L, and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) was 1.10×10(-6) mol/L. The present method has been used to determine the glucose concentrations in real serum and urine samples with satisfactory results.     

Sequential injection system for on-line analysis of total nitrogen with UV-mineralization

An automatic method for the determination of total nitrogen in wastewater by sequential injection analysis and mineralization with UV radiation has been developed. The method is based on the mineralization of the samples with sodium persulphate in basic medium under UV radiation. Small volumes of sample and reagents are firstly aspirated into a single channel and then propelled by flow reversal to the UV reactor and then to the detector. The organic and inorganic nitrogen compounds are oxidized to nitrate that is then measured at 226 nm. The sequential injection procedure has been optimized and the factors affecting the efficiency of the oxidation have been studied with a number of test substances with different chemical structures and properties. Solutions in the concentration range 1-56 g l⁻¹ of nitrogen can be analyzed with the described procedure. The sample rate is of 30-40 samples h⁻¹. The LOD is 0.6 mg l⁻¹ N and the reproducibility is 1.8% (28 mg l⁻¹ N). Organic carbon in the form of glucose was added to a number of test solutions to study the potential interference of organic matter.The method was compared with the Kjeldahl digestion method by analyzing 15 wastewater samples with both methods. The nitrate and nitrite content of the non-oxidized samples were subtracted from the corresponding nitrogen content determined after photo-oxidation and the value compared with the Kjeldahl nitrogen content.     

Arzneimittel- und Drogenscreening aus Urin mittels DC unter besonderer Berücksichtigung von Reagentien mit geringer toxischer Belastung für Laborpersonal und Umwelt

Summary A technique is presented for the extraction of free and conjugated drugs and related compounds out of small quantities of urine. The method is designed in such a way that many samples can be tested for a great number of substances at the same time. Furthermore, we tried to achieve a high quality analysis using when ever possible chemicals with relatively low toxicity to men and environment. Therefore we avoided e.g., halogenated hydrocarbons. The detection of the substances is only performed by thin-layer chromatography (TLC) using well known reagents, like ninhydrin, Dragendorff, iodoplatinate and ferric chloride solutions. If necessary, the extracts can also be used with other Chromatographic techniques, particularly with GC/MS, if a substance has to be clearly identified. Approximately 500 authentical urines have been analyzed in a 1 year period using the method described. We found about 75 different substances. These results are presented in a table.     

Fluorometric method for quantitative determination of glucose and its application to human serum.

By coupling the Fenton reaction with the glucose oxidase (GOD)-catalyzed reaction, we have developed a fluorometric method for the determination of glucose; the linear response range and the detection limit are 0.108-2.59 microg/ml and 0.0432 microg/ml, respectively. This approach is selective and has the advantages of using inexpensive reagents and avoiding interferences. Satisfactory results were obtained for the determination of glucose in human serum samples.     

耐压多样品微量衍生反应装置在气相色谱-质谱联用法分析极性杂环胺中的应用

设计并制作了耐压多样品微量衍生反应装置。在该装置中采用N-(叔丁基二甲基硅烷基)-N-甲基三氟乙酰胺(MTBSTFA,含1%叔丁基二甲基氯硅烷)硅烷化试剂高温衍生极性杂环胺,衍生产物可以直接在气相色谱-质谱联用仪上分析。使用该装置,既可以在比试剂沸点高的温度下实现衍生反应,也可以实现多个微量样品的同时衍生。着重考察了衍生化过程中反应瓶的顶空体积、试剂蒸发面积、温度、时间等实验条件的影响。结果表明,在90 ℃衍生时,与普通衍生装置相比,使用耐压衍生装置可以有效地减小挥发损失,显著增大衍生产量;在150 ℃衍生时,由于试剂挥发损失严重导致普通衍生装置无法使用,而采用耐压衍生装置却可以实现定量衍生,但通过加温加压方式来加快衍生反应速率的效果并不十分明显。     

Turbidimetric determination of sulphate in plant digests and natural waters by flow injection analysis with alternating streams

An improved flow injection system with alternating streams of reagents is described for the turbidimetric determination of sulphate. Samples are injected into an inert carrier stream which is mixed with barium chloride to form a barium sulphate suspension. The range of the method can be extended to low concentrations by continuously adding sulphate to the sample carrier stream. System performance is improved by automatic alternate pumping of the reagent stream and an alkaline EDTA solution at high flow rate. All operations are controlled by an electronically-operated proportional injector-commutator. Even after routine analysis of 3000 samples of natural waters and plant digests, baseline drift was not observed. The proposed method is suitable for 120 samples per hour with a relative standard deviation less than 1% for sulphate concentrations in the range 1–30 ppm (waters) or 5–200 ppm (plant digests). The results compare well with those obtained by standard manual procedures.     

Utilization of charge-transfer complexation in the spectrophotometric determination of some monosaccharides through their osazone intermediates

Monosaccharide osazones are utilized in the spectrophotometric determination of their parent compounds though charge-transfer complexation with two-electron acceptor reagents. The molar combining ratio and the optimum complexation conditions have been studied. The method has been used to analyse for glucose and fructose and in determining blood glucose.     

Detection of Nanomole Quantities of Reducing Sugar by Liquid Chromatography

Abstract

The alkaline ferricyanide and the Park-Johnson's methods were studied in order to determine glucose oligomers separated by liquid chromatography in nanomole quantities. In the alkaline ferricyanide method, high sensitivity was obtained by measuring ultraviolet absorbance of the reduced reagents. The presence of some kinds of salts or alcohols did not affect the colour development of the reagents. The applicability of the present measuring system to an automatic sugar analyzer has been demonstrated by examining several glucose oligomers.     

Direct Determination of Glucose in Blood Serum Using Trinder's Reaction

Abstract

A very simple flow injection analysis system for direct determination of glucose in blood serum based on Trinder's reaction is described. The sera samples (15 μl) can be injected directly to the system without the deproteinization or the use of a dialyzer.

Calibration curves are linear in the range 50–400 mg/dl. The sampling frequency is 60 samples per hour. Results obtained by the proposed procedure are compared with those acquired at a local hospital using their routine glucose procedure also based on Trinder's reaction. It is shown that a better mix between sample and reagents is achieved using the single bead string reactor (SBSR).     

Determination of trace amounts of Sb,Pb, Tl in water samples by inductively coupled plasma atomic emission spectrometry after a diantipyrylmethane-iodide third phase preconcentration

A preconcentration method based on third phase extraction has been developed and combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) for determination of Sb, Pb, Tl at trace levels in water samples. The reagents diantipyrylmethane and potassium iodide were applied for complexing Sb, Pb, Tl and producing a third phase extraction system. This third phase system produces relatively large enrichment factors and complete isolation of trace elements from high salt-containing matrices which influence strongly the plasma condition. Experimental parameters of the extraction, such as concentrations of complexing reagents, pH and extraction time have been optimized. Under the selected conditions, this third phase ICP-AES combination procedure gave multielemental detection limits for Sb, Pb, Tl which are superior by an order of magnitude or more to those obtained by ICP-AES alone without preconcentration. Precision of the technique is better than 10% at the 10 g/l level. The accuracy of this approach is demonstrated by its application to tapwater, artificial seawater and reference seawater samples.     

利用水热合成方法制备正交氮化硼微晶

利用水热方法制备了正交氮化硼微晶, 于400 ℃时制备的氮化硼结晶质量较高, 主要物相为正交氮化硼(oBN). 在反应原料中加入水合肼和氯化铵都有利于样品结晶质量的改善和产率的提高. 在合成氮化硼反应过程中, 适当减慢反应体系的升温速率有利于提高oBN的结晶质量和产率, 但是当升温速率过慢时, oBN的稳定性有所降低, 立方氮化硼(cBN)的稳定性则在一定程度上得到提高. 此外, 反应过程中的原料配比对样品的物相及其结晶质量也有很大影响.     

Investigation of a novel solid-phase chemiluminescent analytical system, incorporating photographic detection, for the measurement of glucose

A method has been developed for the rapid determination of substances by use of solid-phase reagents and a luminescence indicator reaction coupled with photographic detection of the light. The viability of the assay has been demonstrated for glucose estimations. The method uses small sample sizes (5-20 mul) and shows good sensitivity, e.g., detection of glucose down to 28 nmole.     

The Challenging Measurement of Protein in Complex Biomass-Derived Samples

Measurement of the protein content in samples from production of lignocellulosic bioethanol is an important tool when studying the adsorption of cellulases. Several methods have been used for this, and after reviewing the literature, we concluded that one of the most promising assays for simple and fast protein measurement on this type of samples was the ninhydrin assay. This method has also been used widely for this purpose, but with two different methods for protein hydrolysis prior to the assay—alkaline or acidic hydrolysis. In samples containing glucose or ethanol, there was significant interference from these compounds when using acid hydrolysis, which was not the case when using the alkaline hydrolysis. We evaluated the interference from glucose, cellulose, xylose, xylan, lignin and ethanol on protein determination of BSA, Accellerase® 1500 and Cellic® CTec2. The experiments demonstrated that the presence of cellulose, lignin and glucose (above 50 g/kg) could significantly affect the results of the assay. Comparison of analyses performed with the ninhydrin assay and with a CN analyser revealed that there was good agreement between these two analytical methods, but care has to be taken when applying the ninhydrin assay. If used correctly, the ninhydrin assay can be used as a fast method to evaluate the adsorption of cellulases to lignin.     

The determination of chromium species in natural waters

A method for the determination of chromium species has been developed and successfully applied to both fresh and sea water samples. The method utilizes pre-concentration of total chromium, chromium(ni) and particulate chromium at natural pH with accurate and precise analysis by a single flameless atomic absorption procedure. A minimal blank allows for a reliable detection limit of 0.02 nM, which is sufficient for most natural waters with chromium concentrations in the range 0.01–10 nM. Immediate shipboard preconcentration of the samples minimizes storage problems. The method is simple and rapid; 20 samples can be analysed in duplicate for total chromium, chromium(III) and particulate chromium in one day with routinely available reagents and equipment.     

Application of the microwave acid digestion method to the decomposition of rock samples

The microwave acid digestion method was applied to the decomposition of rock samples and optimum conditions were investigated. Samples of 10–100 mg were decomposed by changing the amount and composition of acid, heating time and number of reheating steps and then the concentrations of Si, Fe, Mn, Na, K and Mg in these samples were measured. The concentrations agreed with reported values when 10 mg of sample were decomposed by heating for 60 s with 0.3 ml of concentrated HNO₃ and 0.1 ml of concentrated HF. Similarly, 100 mg of sample were also decomposed successfully by heating for 45–110 s with 0.3–1.0 ml of concentrated HNO₃ and 0.4–0.7 ml of concentrated HF. It is concluded that the microwave acid digestion method decomposes rock samples with a very short heating time and with small amount of reagents compared with methods using conventional sealed PTFE vessels, which require several hours for the heating step and several millilitres of reagents.     

Flow-reversal flow injection analysis-II Determination of glucose with a double-pump system

A new type of flow-injection procedure is proposed in which the samples are reversely pumped to the detector. In this procedure the injected samples are pumped into the reaction loop of a 6-way valve, then the valve is rotated to reverse the flow and the sample/reagent plug is pumped to the detector by another pump. The dispersion of the sample zone is low and the consumption of the reagent is very small. Therefore, its analytical potential for analysis with expensive reagents or long reaction times is high. The procedure has been applied to the determination of glucose in serum with an enzyme kit.     

Simple Characterization of Green-Synthesized Silver Nanoparticles by Capillary Electrophoresis

The development of methodologies for the characterization of silver nanoparticles (AgNPs) synthesized using natural products has received increasing attention, especially to monitoring its stability and size for further application. In this paper, a capillary electrophoretic (CE) method is presented for characterization of AgNPs synthesized using honey or glucose as reducing agents. A simple electrolyte solution composed of 20 mM sodium borate and 20 mM sodium dodecylsulfate (SDS) at pH 8.5 was used for separation of AgNPs within a short analysis time (<12 min). The obtained results were compared with the traditional characterization techniques, such as transmission electron microscopy (TEM) and dynamic light scattering (DLS), showing satisfactory correlation in terms of size distribution. In addition, valuable information about electrophoretic mobility and zeta potential values of AgNPs was obtained by applying the CE-UV/Vis method. Thus, the proposed methodology represents a straightforward tool for the fast and cost-effective characterization of AgNPs within a single analysis, employing minimal amounts of reagents and samples.     

An enzyme electrode for the amperometric determination of glucose

An amperometric method utilizing a glucose electrode has been developed for the determination of blood glucose. The time of measurement is less than 12 s if a kinetic method is used and 1 min if a steady-state method is used. The long-term stability of the electrode is ca. 0.1% change from maximum response per day when stored at room temperature for over 10 months. The enzyme electrode determination of blood sugar compares favorably with commonly used methods with respect to accuracy, precision, and stability. The only reagent required for blood sugar determinations is a buffer solution. The electrode consists of a metallic sensing layer covered by a thin film of immobilized glucose oxidase held in place by means of cellophane. When poised at the correct potential, the current produced is proportional to the glucose concentration.     

Packed capillary HPLC: An attractive separation technique for small organic molecules

The feasibility of using packed capillary HPLC for the analysis of small organic molecules has been demonstrated by three examples: the separation of glucose and sucrose telomers, the separation of the different components of a solvent extraction reagent, and the separation of mono-, di-, and trioleins, all of which have been achieved with packed capillary columns of 0.32 mm inner diameter and eluent flow rates of 3 microliters per minute. Application to the analysis of the solvent extraction reagents has shown that this technique can be used as a quantitative tool in just the same way as any conventional HPLC method. The feasibility of a direct packed capillary HPLC – mass spectrometry interface has been demonstrated for the glucose telomer separation; direct coupling is only possible because of the microliter flow rates employed by the technique.