Chromatographic methods for tetracycline analysis in foods.

The tetracyclines have served for decades as an important class of antibiotics in food animal health and production. As such, they have also been a source of concern for residue monitoring authorities around the world. In response to this concern a number of microbial inhibition, immunoassay and bacterial receptor methods have evolved for the detection of this class of compounds in various foods of animal origin. However, these methods often lack specificity and are subject to false positive and false negative results. For these reasons a number of chromatographic methods for the separation and determination of the tetracyclines isolated from foods have been developed that are capable of identifying and quantifying individual tetracycline drugs. We present here an overview of tetracycline analytical methods, including microbial inhibition, immunoassay and receptor technologies for detection, techniques for isolation from food matrices, and thin-layer chromatographic, high-performance liquid chromatographic, gas chromatographic and mass spectrometric procedures for determination of this class of compounds. A discussion of the variables involved in such methodology and a review of method criteria are offered.     

化学发光免疫分析技术在微生物检测中的应用

化学发光免疫分析技术凭借其化学发光的高灵敏性和免疫反应的高特异性在微生物快速检测中广泛应用。该文着重叙述了化学发光免疫分析技术核心检测体系在微生物检测中的研究进展,并对其涉及到的样品前处理和检测新方法进行了综述。化学发光免疫分析技术检测微生物用时短、成本低,但特异性识别方法和检测的灵敏度有待提升,新型的发光体系、发光放大方法、可替代抗体的识别分子以及相关的前处理技术是未来研究的重点。     

Amperometric homogeneous competitive immunoassay in a perfluorocarbon emulsion oxygen therapeutic (PEOT)

The effect of a perfluorocarbon emulsion oxygen therapeutic (PEOT) on the detection of the drugs theophylline and phenytoin was explored using a commercial enzyme multiplied immunoassay technique (EMIT®). The EMIT technique is based on the enzymatic production of NADH, which is typically detected in serum samples spectrophotometrically. Here, amperometry using the rotating disk electrode on a single drop of solution is demonstrated to detect theophylline and phenytoin in the presence of PEOT. In the study, 2,6-dichloroindophenol (DCIP) added to the immunoassay mixture is reduced by the NADH to DCIPH₂. Oxidation of DCIPH₂ is monitored electrochemically at +200 mV using a glassy carbon rotating disk electrode. Slopes of amperograms are proportional to the concentration of drug in the immunoassay sample. This technique yields excellent quantitative data in the therapeutic range for both drugs in 2–20 % PEOT.     

Über Dialkylidensulfamide

Aldehydes and ketones containing no α-hydrogen atoms yield the corresponding dialkylidene sulfamides both by reacting with sulfamide in presence of a proton acid or of SOCl₂ and by reacting with bis(trichlorphosphazo)-sulfone. The dialkylidene sulfamides of ketones also were obtained by treating ketone imines with sulfamide. Chloral did not react with sulfamide in this way but yielded 3,7-bis-(trichloromethyl)-perhydro-1,5,2,4,6,8-dithiatetrazocine-1,1,5,5-tetroxide.     

Paper-based enzyme-free immunoassay for rapid detection and subtyping of influenza A H1N1 and H3N2 viruses

Development of rapid screening in the ambulatory environment is the most pressing needs for the control of spread of infectious disease. Despite there are many methods to detect the immunoassay results, quantitative measurement in rapid disease screening is still a great challenge for point-of-care applications. In this work, based on the internal structural protein, i.e., nucleoprotein (NP), and outer surface glycoproteins, i.e., H1 and H3, of the influenza viruses, specific and sensitive immunoassay on paper-based platform was evaluated and confirmed. Detection and subtyping of influenza A H1N1 and H3N2 viruses found in people were demonstrated by colorimetric paper-based sandwich immunoassay. Concentration-dependent response to influenza viruses was shown and the detection limits could achieve 2.7 × 10³ pfu/assay for H1 detection and 2.7 × 10⁴ pfu/assay for H3 detection, which are within the clinical relevant level. Moreover, detection of influenza virus from infected cell lysate and clinical samples was demonstrated to further confirm the reliability of the paper-based immunoassay. The use of paper for the development of diagnostic devices has the advantages of lightweight, ease-of-use, and low cost and paper-based immunoassay is appropriate to apply for rapid screening in point-of-care applications.     

食源性致病菌快速检测方法研究进展

食源性致病菌污染是导致食品安全问题的重要因素,食源性致病菌的检测已成为近年来研究的热点.以免疫分析、分子生物学、生物传感器、代谢组学、核酸适配体等技术为基础的快速检测方法发展迅速,已成为检测食源性致病菌的主要方法.该文结合近年来各种快速检测方法的相关研究进展,介绍了以上述技术为基础的快速检测食源性致病菌的方法,并讨论了...     

Reaction of sulfamides with diketene (III). Synthesis of N-sulfamoyl-2,6-dimethyl-4-pyrone-3-carboxamides

Preparation of N-(tetrahydropyran-2-yl)sulfamide, N-(2,3,4,6-tetra-O-aeetyl-β-D-glucopyranosyl)sulfamide and N-(2,3,5-tri-O-benzoyl-D-ribosyl)sulfamide is described. Reactions with diketene, in the presence of pyridine, yielded N-sulfamoyl-2,6-dimethyl-4-pyrone-3-carboxamide derivatives.     

Schwingungsspektroskopische Untersuchungen an Sulfamid-Einkristallen

The infrared (300 K) andRaman (300 and 90 K) spectra of single crystals of sulfamide are recorded. In addition theRaman spectra of the deuterated and N¹⁵-substituted polycrystalline sulfamide are measured. A vibrational assignment based on these data and a normal coordinate analysis is proposed. Lattice bands and factor group splittings are discussed.

     

荧光纳米颗粒标记免疫分析

荧光纳米颗粒标记是目前免疫分析研究中一个新兴的领域。由于荧光纳米颗粒标记可以有效地提高单个识别分子上标记的荧光量（F/P）,从而大大提高分析的灵敏度。但是由于在标记和免疫分析过程中具有很多不同于传统荧光染料的特点,需要很多经验的积累,在现阶段限制了其在实际医学诊断中的广泛应用。本文就近年来荧光纳米颗粒标记免疫分析中涉及到的标记方法、免疫模式、影响因素等方面进行了综述。     

免疫分析与细胞检测新原理与新方法研究

将分析化学与临床诊断相结合,发展临床检测新原理、新方法已成为人类健康的前沿领域之一,其中免疫分析,特别是多标志物同时免疫检测新方法的发展,与细胞检测已成为人们关注的课题。本文综述了近3年来这方面的研究进展, 并简要介绍了免分离、准无试剂和全无试剂安培免疫分析,空间分辨多通道安培芯片,底物区带分辨、通道分辨和通道-底物区带二维分辨化学发光免疫分析等多种免疫分析新概念,细胞检测与表面增殖监测、细胞毒效应研究与药敏检测新方法,对其在肿瘤临床诊断中的应用也作了总结。     

A rapid analytical method based on microwave-assisted extraction for the determination of drugs of abuse in vitreous humor

Robust and simple validated analytical methods are required in postmortem toxicology to confirm immunoassay screening analysis of drugs of abuse. In this work, microwave-assisted extraction (MAE) was evaluated as an alternative method for extraction of target compounds such as cocaine, benzoylecgonine, cocaethylene, morphine, codeine, 6-monoacetylmorphine, methadone, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine from vitreous humor. The MAE procedure parameters, namely, extraction temperature, time, and solvent volume, were optimized using a central composite design and applying desirability functions. The optimal conditions for extraction were 80 °C, 8 min, and 15 mL of dichloromethane solvent. The MAE–high-performance liquid chromatography–diode-array detection method was validated, showing its capability for the detection of concentrations in the range from 33 to 76 ng mL⁻¹ and recoveries in the range from 87 to 99.3% for all drugs. The MAE-based method was tested for 15 vitreous humor samples from forensic cases and its performance was compared with that of a solid-phase extraction method previously developed by our group. In general, better recovery and precision were achieved with the use of the MAE-based procedure.     

An Integration Method for Enzyme Multiplied Immunoassays

Abstract

Integration methods for measuring substrates via homogeneous immunoassays are presented along with their theoretical bases. Integrals of differences in measured responses over time are used with enzyme multiplied immunoassay techniques and show unique relationships between the net integral data and analyte concentrations. Changes in indicator response signals are integrated over several minutes for drugs of forensic interest, and results for integrations of both published response curve data and laboratory assays are evaluated.     

Synthesis,Characterization and Theoretical Study of the Chemical Reactivity of New Cyclic Sulfamides Linked to Tetrathiafulvalene

Abstract

The synthesis of the title compounds has been carried out by condensation via a Wittig-type reaction of a pyridinium hexafluorophosphate with a phosphonate ester to give the desired (4-nitrophenyl)tetrathiafulvalene the nitro group of which was reduced to an amino group. Reaction of the amine with chlorosulfonyl isocyanate and subsequently with tert-butyl alcohol gave the corresponding open-chain sulfamide. Cyclization under basic conditions and de-protection led to 2-[4-(4′,5′-dipropyltetrathiafulvalen-4-yl)]phenyl-1,2,6-thiadiazinane 1,1-dioxide. Finally, N-alkylated and N-acylated cyclic sulfamides linked to tetrathiafulvalene were obtained. Their electron donor ability was measured by cyclic voltammetry. A detailed DFT study based on B3LYP/6–31G (d,p) of electronic properties is also presented. The calculated molecular electrostatic potential shows that, the negative charge covers the nitro and sulfamide function, while positive charge is located at the hydrogen atoms of the amine and sulfamide rings. The calculated HOMO and LUMO energy reveals that charge transfer occurs within the molecule. The chemical reactivity parameters reveal that tetrathiafulvalene 1 is highly reactive, which facilitates the desired formation of the cyclic sulfamide. The first hyperpolarizability β_tot shows that compounds 1 and 5 are good candidates as a NLO material.     

Monitoring of serum or saliva theophylline concentrations by a new radioimmunoassay

Conclusions The new radioimmunoassay RIA-mat Theophylline appeared to be highly specific, as none of the drugs structurally related to theophylline or other substances tested showed a noticeable cross reaction. Precision and accuracy are better than comparable assays, the sensitivity of detection is much better than e.g. if using an enzyme immunoassay.Since the required reagents are available as ready-to-use solutions, it is possible to run individual determinations e.g. in emergency cases, as well as large series in a very brief period of time.

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Bestimmung von Theophyllin-Konzentrationen in Serum oder Speichel mit einem neuen Radioimmunoassay

     

Direct detection of Δ9-tetrahydrocannabinol in aqueous samples using a homogeneous increasing fluorescence immunoassay (HiFi)

The detection of the major active component of cannabis, Δ9-tetrahydrocannabinol (THC), becomes increasingly relevant due to its widespread abuse. For control purposes, some easy-to-use, sensitive and inexpensive test methods are needed. We have developed a fluorescence immunoassay utilising THC–fluorescein conjugate as tracer. Fluorescence spectroscopy of the conjugate revealed an unusual property: The relatively weak fluorescence of a dilute tracer solution was increased by a factor of up to 5 after binding of a THC-specific antibody. Fluorescence lifetime measurements in aqueous solutions suggested two different tracer conformations both associated with quenching of fluorescein fluorescence by the intramolecular THC moiety. After antibody binding, the tracer enters a third conformation in which fluorescence quenching of fluorescein is completely suppressed. Utilising this property, we established a homogeneous competitive immunoassay (homogeneous increasing fluorescence immunoassay) with low detection limits. The test requires only two reagents, the new tracer molecule and an anti-THC antibody. A single test takes only 8 min. The dynamic detection range for THC is 0.5 to 20 ng/mL in buffer, with a limit of detection (LOD) of 0.5 ng/mL. The test also works in diluted saliva samples (1:10 dilution with buffer) with an LOD of 2 ng/mL and a dynamic range of 2–50 ng/mL.     

Synthesis of 4-substituted 3-hydroxy-and 3-amino-6H-1,2,6-thiadiazine 1,1-dioxides

Reaction of sulfamide with ethoxymethylene derivatives yielded 4-ethoxycarbonyl-, 4-cyano-, and 4-nitro-2H,6H-1,2,6-thiadiazine 1,1-dioxide. In some cases, the corresponding open chain sulfamidomethylene derivatives were isolated. Preparation of 4-amino- and 4-amino-5-methyl-2H,6H-1,2,6-thiadiazin-3-one 1,1-dioxide is also described. Reaction of sulfamide with ethyl 3,3-ethoxypropionate afforded 3,7-bis(etlioxycarbonylmethyl)perhydro-1,5,2,4,6,8-dithiatetra-zocine 1,1,5,5-tetroxide.     

Capillary isoelectric focusing immunoassay as a new nanoscale approach for the detection of oligoclonal bands

The detection of oligoclonal bands (OCBs) in cerebrospinal fluid is an indicator of intrathecal synthesis of immunoglobulins which is a neurochemical sign of chronic inflammatory brain diseases. Intrathecally synthesized IgGs are typically observed in patients with multiple sclerosis. The current standard protocol for the detection of OCBs is IEF on agarose or polyacrylamide gels followed by immunoblotting or silver staining. These methods are time consuming, show substantial interlaboratory variation and cannot be used in a high throughput‐approach. We have developed a new nanoscale method for the detection of OCBs based on automated capillary IEF followed by immunological detection. Evidence for intrathecal IgG synthesis was found in all tested patients (n = 27) with multiple sclerosis, even in two subjects who did not have oligoclonal bands according to standard methods. The test specificity was at 97.5% (n = 19). Our findings indicate that the novel OCB‐CIEF‐immunoassay is suitable for the rapid and highly sensitive detection of OCBs in clinical samples. Furthermore, the method allows for a higher sample throughput than the current standard methods.     

Enhanced chemiluminescent enzyme immunoassay for cannabinoids in urine

An enhanced chemiluminescent enzyme immunoassay was developed for the detection of cannabinoids in urine. It utilises an antiserum specific for tetrahydrocannabinol and its major metabolite, a donkey anti-sheep antiserum and a horseradish peroxidase labelled antigen conjugate. The bound enzyme is detected via its catalytic activity on the chemiluminescent luminol-H2O2 reaction in the presence of an enhancer. This immunoassay employs mild experimental conditions and is extremely sensitive (0.13 microgram l(-1), making it suitable for the detection of cannabinoids in samples obtained several days following drug use. None of several medicinal and other drugs of abuse tested interfered in the assay. Greater sensitivity and simplicity make it a feasible non-isotopic alternative to radioimmunoassay and it is amenable to automation and routine screening to large sample batches.     

Fluorescence polarization immunoassays for pesticides

Fluorescence polarization immunoassay methods for the detection of pesticides and their metabolites or degradation products are reviewed. Advantages and limitations for application to pesticide detection in environmental and food samples are discussed. The influence of the structure of fluorescent-labeled tracers and the affinity and specificity of antibodies on analytical performance is examined. The methods are simple, readily automated, and rapid (total time for assay of a water sample is about 1 min) with sensitivity of 1 - 10 ng/ml pesticide in 0.01 - 0.1 ml sample.     

细胞分裂素检测方法的研究进展

细胞分裂素是一类重要的植物生长调节激素,对这类激素进行超微定量检测对于揭示其在植物体内的信号转导机理、发挥其对作物生长的调控作用具有重要意义.本文综述了近年来细胞分裂素各种分析方法的研究进展,包括免疫分析法、气相色谱法、高效液相色谱法、毛细管电泳法和电化学方法等,介绍了实际样品常用的前处理方法,并讨论了未来的研究发展方向.