Analysis of Ascorbic Acid in Single Human Neutrophils by Electrochemical Detection

Ascorbic acid in individual human neutrophils was determincd by capillary zone clectrophoresis with electrochemical detection. In order to overcome the influence of the adsorption of the substances in cells on the inner surface wall of the capillary on the migration time and the unmber of theorctical plates, a proccdure for treating capillaries has bccn described.     

Expression Levels of RFP in Normal and Cancer Human Tissues via Real-time RT-PCR Detection

IntroductionRet finger protein(RFP) was first identified as apart of the human recombined transforming gene, ret,and was a member of the tripartite motif(TRIM) pro-tein family. Itwas postulated thatmultimeric complexesmade of TRIM proteins defined differe…     

The Simultaneous Determination of Δ9-Tetrahydrocanna-Binol and 11-Hydroxy -Δ9 -Tetrahydrocannabinol in Plasma

Abstract

A technique capable of determining both Δ⁹-tetrahydrocannabinol and 11-hydroxy-Δ⁹-tetrahydrocannabinol is described. The method is based on the reactivity of the phenolic functionality common to both compounds, and is sensitive to 5 ng of Δ⁹-tetrahydrocannabinol and 1 ng of 11-hydroxy-Δ⁹-tetrahydrocannabinol per ml of plasma.     

Reference measurement procedure for Δ9-tetrahydrocannabinol in serum

An isotope dilution gas chromatography/mass spectrometry (ID-GC/MS) reference measurement procedure for Δ9-tetrahydrocannabinol (THC) in serum was developed and validated. The method complies with the concept of a ratio primary reference measurement procedure. The uncertainty was determined for two concentrations of THC in serum (1 ng/mL and 2.4 ng/mL). The calculation procedure is based on the Guide to the Expression of Uncertainty in Measurement (GUM). The relative expanded uncertainty was found to be less than 2% for both concentration levels, corresponding to a 95% confidence interval. For the reference method, it was shown that the measurement of THC within the concentration range covered by the current threshold values is very accurate. The method has the potential to provide traceability for the methods used in practical forensics.     

Metabolites of Icariin in Urine Following Oral Administration

YinyanghuohasbeenusedinfolkmedicineforthousandsofyearsinChina.ItbelongstoplansofgenusEpimedinm(Berberidaceae).ChinaPharmcopoeia(l995Ed.)c0llectedfivespeciesofEpAnedium,inwhichflavanoidsareregardedastheprinciPalcomPonentsresponsibleforthePharmacologicalactivitiesofYinyanghuo,suchastonic,anti-hyPertensiveandami-inflarnmatoryactions.Icariinisoneofthemainflav0n0idconstituentsinYinyanghuo"'andextensivelyusedtocontrolthequalityofthecmdedrug."'TherearemanyrePortsonthepharmac0l0gical,chendcaland…     

Cloud point extraction of Δ9-tetrahydrocannabinol from cannabis resin

A cloud point extraction coupled with high performance liquid chromatography (HPLC/UV) method was developed for the determination of Δ⁹-tetrahydrocannabinol (THC) in micellar phase. The nonionic surfactant “Dowfax 20B102” was used to extract and pre-concentrate THC from cannabis resin, prior to its determination with a HPLC–UV system (diode array detector) with isocratic elution. The parameters and variables affecting the extraction were investigated. Under optimum conditions (1 wt.% Dowfax 20B102, 1 wt.% Na₂SO₄, T?=?318 K, t?=?30 min), this method yielded a quite satisfactory recovery rate (~81 %). The limit of detection was 0.04 μg?mL^?1, and the relative standard deviation was less than 2 %. Compared with conventional solid–liquid extraction, this new method avoids the use of volatile organic solvents, therefore is environmentally safer.     

Differential pulsed voltammetry of Δ9-Tetrahydrocannabinol (THC) on disposable screen-printed carbon electrodes: A potential in-field method to detect Δ9-THC in saliva

Due to recent legalization of marijuana across many states in the U.S., there is an increased concern of users driving while impaired/intoxicated with Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the principal psychoactive constituent of cannabis/marijuana. Hence, there is a need for a rapid roadside detection of this drug that can be used to accurately screen drivers. Current field sobriety tests rely on a series of physical and mental exercises administered during DUI investigations to help determine a driver's level of impairment. Due to their portability and effectiveness, screen printed carbon electrodes (SPCEs) are ideal to work with when it comes to devising a low-cost screening device for roadside testing. SPCE's can potentially detect low levels of Δ⁹-THC in an individual's saliva via electrochemical oxidation of Δ⁹-THC. Herein we report a fast, cheap, and accurate approach to electrochemically detect 1–20 μM Δ⁹-THC in a 1 mL sample of artificial oral fluid (AF-OF) diluted to 50 % with a buffer/electrolyte solution using differential pulse voltammetry (DPV) at the surface of a small SPCE. Implications for the use of this method to screen intoxicated drivers are discussed.     

Metabolites of Icariin in the Gastrointestine of Rats Following Oral Administration

YinyanghuohasbeenusedasafolkmedicineforthousandsofyearsinChina.ItbelongstothegenusofEpimedium(Berberidaceae).ChinaPharmacopoeia(1995Ed.)collects5speciesofEpimedium,whereflavanoidsareregardedastheprincipalcomponentsresponsibleforthepharmacologicalactivitiesofYinyanghuo,suchasitstonic,antihypertensiveandantiinflammatoryactions.IcariinisoneofthemainflavonoidconstituentsinYinyanghuo"'andisextensivelyusedtocontrolthequalityofthecrudedrug"'.Inpreviouspapers"',wereportedtheisolationandidentificat…     

Advances in Detection Methods of β-Amyloid Protein

Alzheimer's disease (AD) is a neurodegenerative disease with unknown etiology. β-amyloid protein (Aβ) is one of the specific biomarkers of AD, and many clinical studies suggest that abnormal levels of Aβ in blood, cerebrospinal fluid and brain tissue are closely related to the progression of AD. The analysis and evaluation of Aβ are important for early detection, tracking, prevention, and treatment of AD. In this paper, the present situations of the commonly used detection methods of Aβ at home and abroad were summarized and compared. Specifically, the latest application of new electrochemical biosensor in Aβ detection was mainly described, and the summary of its future directions and the potential applications was given.     

Separation and Determination of Methylnaltrexone in Human Plasma Samples After Oral Administration by HPLC Coupled with Electrochemical Detection

Introduction Opioidmedicationsarewidelyusedclinically forrelievingpainandasantidiarrhealsandantitus- sives.Opioidantagonistsconsistofagroupofnat- ural,semisynthetic,orsyntheticcompoundsacting onaseriesofreceptors.Concomitantwiththeabil- itytorelievepain,thesedrugshaveadverseef- fects.Side-effectsofopioidtreatmentincludenau- sea,constipation,urinaryretention,pruritus,fa- tigue,psychomimeticdisturbance,difficultmic- turition,vomitinganddependence.Thesesideef- fectsareoftensevereenoughtolimitthe…     

Determination of Amino Acids in Single Human Lymphocytes after On-capillary Derivatization by Capillary Zone Electrophoresis with Electrochemical Detection

Sensitive and selective methods for the detection of amino acids (AAs) in single cells are of increasing importance. Capillary zone electrophoresis (CZE) with electrochemical detection (ED) is suitable for analysis of electroactive contents in single cells. However, most native AAs have no electroactivity. Derivatization with an electroactive tag is an attractive method. An on-capillary derivatization scheme was reported1. Naphtha- lene-2, 3-dicarboxaldehyde (NDA) can react with pri…     

Quantitative Analysis of Terbutaline (Bricanyl®) in Human Plasma with Liquid Chromatography and Electrochemical Detection Using On-Line Enrichment

Abstract

A liquid chromatographic method with electrochemical detection (LC-EC) has been developed for the quantitative analysis of terbuta-line in the range 5–50 pmole ml^?1 of human plasma. Terbutaline is isolated from 2 ml of plasma on an ion-exchange column and the eluate is concentrated on a hydrophobic precolumn on-line in the chromatographic system. The precolumn is then back-flushed for further separation onto a hydrophobic analytical column. The mobile phase is a methanol-aqueous buffer to which sodium perchlorate is added to achieve resolution from interfering peaks. A glassy carbon electrode is used for detection. Comparison has been made with gas chromatography-mass spectrometry (GC-MS) to examine the accuracy of the method.     

Simultaneous Determination of 6β-Hydroxycortisol and 6β-Hydroxycortisone in Human Urine by LC with UV Absorbance Detection

A liquid chromatographic method for the simultaneous determination of 6β-hydroxycortisol and 6β-hydroxycortisone using dexamethasone as internal standard in human urine is described. Separation was achieved on a reversed-phase C18 column by a gradient elution of acetonitrile and water containing 0.1% formic acid. 6β-Hydroxycortisol and 6β-hydroxycortisone were monitored by UV absorption at 244 nm. The lower limits of quantitation were 5 ng mL^?1 for both analytes. The intra-day and inter-day relative standard deviations were less than 7.4%. Accuracy determined at three concentrations ranged between 92.16 and 109.77%. The sensitivity, specificity and accuracy of this method were demonstrated to be satisfactory for measuring both metabolites in human urine.     

Direct detection of Δ9-tetrahydrocannabinol in saliva using a novel homogeneous competitive immunoassay with fluorescence quenching

For the detection of the major active component of cannabis, Δ9-tetrahydrocannabinol (THC) in aqueous samples, a homogeneous competitive immunoassay based on fluorescence quenching induced by fluorescence resonance energy transfer (FRET) has been developed. The fluorescence of anti-THC-antibody, labeled with fluorescence dye DY-481XL, can be quenched after its binding to THC-BSA-quencher conjugate (bovine serum albumin coupled with THC and another fluorescence dye, DYQ-661, as quencher). This quenching effect is inhibited when the antibodies bind to free THC in aqueous sample, thus competing for binding sites with the THC-BSA-quencher conjugate. The extent of the inhibition corresponds to the concentration of THC in the samples. The assay principle is simple and the test duration is within 10 min. The detection limit for THC in buffer was 2 ng mL⁻¹. In pooled saliva samples a detection limit of 50 ng mL⁻¹ was achieved.     

Real-time Quantitative RT-PCR for CT9 Level in Human Cancer

Introduction Malignantdiseasesarecharacterizedbytheunreg ulatedgrowthoftransformedcells.Inrecentyears,dramaticinsightsintothemolecularmechanismsofthis phenomenonhavebeenachievedfrombasiccancerre search.Manycellularfunctionsareregulatedbychan gesingeneexpr…     

Simultaneous determination of Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol in oral fluid using isotope dilution liquid chromatography tandem mass spectrometry

The detection and confirmation of cannabinoids in oral fluid are important in forensic toxicology. Currently, the presence of Δ⁹-tetrahydrocannabinol (THC) is used for the detection of cannabis in oral fluid. A low concentration of 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH) is found in oral fluid, which suggested a convenient and low-sensitivity confirmation assay can be used in a routine forensic laboratory. In this study, a highly sensitive isotope dilution liquid chromatography–tandem mass spectrometry method following dansylation was successfully developed for simultaneous determination of THC and THC-COOH in oral fluid. The dansylated derivatives dramatically demonstrated and enhanced the sensitivity of THC and THC-COOH. To avoid signal influenced by the matrix, a 5-min liquid chromatography gradient program was evaluated and optimized, which reduced the sample diffusion and caused sharp peaks (less than 12 s) and thus helped to achieve detection at a low level. The sensitivity, accuracy, and precision were also evaluated, and high quantitative accuracy and precision were obtained. The limit of quantitation of this approach was 25 pg/mL for THC and 10 pg/mL for THC-COOH in oral fluid. Finally, the method was successfully applied to eight suspected cannabis users. Among them, in six oral fluid samples THC-COOH was determined at a concentration from 13.1 to 47.2 pg/mL.     

A New Glucuronidated Metabolite of Andrographolide in Human

A new andrographolide metabolite 1 was isolated from human urine samples after oral administration. The structure was determined to be 3-carbonylandrographolide-19-O-β-D-glucuronide on the basis of chemical evidences and spectral analysis, especially by 2D-NMR techniques.     

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.