Screening method for phenoxy acid herbicides in ground water by high-performance liquid chromatography of 9-anthryldiazomethane derivatives and fluorescence detection

A high-performance liquid chromatographic (HPLC) method for phenoxy acid herbicides using precolumn derivatization with 9-anthryldiazomethane (ADAM) is presented. The phenoxy acid herbicides investigated were (2,4-dichlorophenoxy)acetic acid, (4-chloro-2-methylphenoxy)acetic acid, 2-(4-chloro-2-methylphenoxy)propionic acid and (4-chloro-2-methylphenoxy)butyric acid. These herbicides reacted with ADAM under mild conditions and were converted into the corresponding fluorescent derivatives. The ADAM derivatives were separated by reversed-phase HPLC and determined using a fluorescence detector. The detection limits were about 500 pg per injection. For the application of ADAM to the determination of these herbicides in ground waters, the recoveries were more than 93% and the average relative standard deviation was 6.0% at 0.5 microgram/l. The procedure is useful as a screening method for phenoxy acid herbicides in ground water samples.     

Separation of ADAM derivatives of carnitine and acyl-carnitines by capillary electrophoresis

 The separation of carnitine, acetylcarnitine and palmitoylcarnitine as ADAM (9-anthryldiazo-methane) derivatives was performed using capillary electrophoresis. A buffer system with 90% methanol and various amounts of phosphoric acid and micelle forming SDS was optimized with respect to the best resolution of the carnitine derivatives. A detection limit of 10 μmol/l or 32 ng carnitine was determined by laser induced fluorescence detection. Under optimized conditions low carnitine contents in acylcarnitine standards have been determined. Received: 30 May 1996/Accepted: 17 June 1996     

Separation of ADAM derivatives of carnitine and acyl-carnitines by capillary electrophoresis

 The separation of carnitine, acetylcarnitine and palmitoylcarnitine as ADAM (9-anthryldiazo-methane) derivatives was performed using capillary electrophoresis. A buffer system with 90% methanol and various amounts of phosphoric acid and micelle forming SDS was optimized with respect to the best resolution of the carnitine derivatives. A detection limit of 10 μmol/l or 32 ng carnitine was determined by laser induced fluorescence detection. Under optimized conditions low carnitine contents in acylcarnitine standards have been determined. Received: 30 May 1996/Accepted: 17 June 1996     

Determination of bisphenol-A in water by semi-micro column high-performance liquid chromatography using 2-methoxy-4-(2-phthalimidinyl)phenylsulfonyl chloride as a fluorescent labeling reagent.

A highly sensitive method for the determination of bisphenol-A in water with semi-micro column high-performance liquid chromatography using 2-methoxy-4-(2-phthalimidinyl)phenylsulfonyl chloride as a fluorescent labeling reagent has been developed. The labeling reaction was carried out at 70 degrees C for 20 min in borate buffer (pH 9.5). The derivative eluted at 11.6 min on a reversed-phase column with methanol-water (78:22, v/v) at a flow-rate of 0.2 ml/min. The fluorescence was monitored at 308 nm for excitation and 410 nm for emission. The detection limit (S/N = 3) was 10 fmol per injection. The labeling yield was about 95%.     

Determination of jasmonic acid in <Emphasis Type="Italic">Lemna minor</Emphasis> (L.) by liquid chromatography with fluorescence detection

A new method is described for the determination of endogenous jasmonic acid (JA) in Lemna minor plant extracts using liquid chromatography (LC) with fluorescence detection. Plant tissues were extracted and derivatised using 9-anthryldiazomethane (ADAM reagent) prepared in situ. Accuracy and precision were improved by using the internal standard dihydrojasmonic acid (dh-JA) for the correction of JA losses during sample preparation steps. Liquid chromatography–mass spectrometry (LC/MS) analysis of ADAM derivatives of JA and dh-JA confirmed that a single molecule of JA and dh-JA was coupled with one molecule of reagent. Derivatives of JA and dh-JA were separated with gradient elution on a C₁₈ reversed-phase column using acetonitrile/water as a mobile phase and detected by a fluorescence detector at excitation and emission wavelengths of 254 and 412 nm, respectively. The detection limits of JA and dh-JA were 2.9 ng mL⁻¹ and 3.7 ng mL⁻¹ per 50-μL injection. The method is reproducible and selective and yields single peaks for each compound regardless of isomer. The specificity and accuracy of the proposed LC/FD method was confirmed by liquid chromatography–TurboIon Spray tandem mass spectrometric (LC/MS/MS) analysis of free JA in Lemna minor samples under multiple reaction monitoring conditions.     

苯甲酰化展青霉素和青霉酸的高效液相色谱紫外吸收测定法

建立了一种快速、灵敏检测痕量展青霉素（ｐａｔｕｌｉｎ）和青霉酸（ｐｅｎｉｃｉｌｌｉｃａｃｉｄ）的新方法。对酞内酰胺苯甲酰氯（４（２－ｐｈｔｈａｌｉｎｕｄｙｌ）ｂｅｎｚｏｙｌｃｈｌｏｒｉｄｅ,简称ＰＩＢ－Ｃｌ］为柱前衍生试剂同展青霉素和青霉酸衍生反应,衍生物用ＯＤＳ柱分离,乙腈－水（４７：５３,Ｖ／Ｖ）作流动相,紫外检测器检测（λ＝３００ｎｍ）。以２倍信噪比计算最低检出限,展青霉素２．０ｐｍｏｌ,青霉酸１０ｐｍｏｌ。     

Determination of mercury ion by MEKC with on-column derivatisation and LIF detection

A simple and automatic method for the determination of mercury ion by MEKC with on-column derivatisation and LIF detection is described in the present paper. In this method, solutions of a nonfluorescent rhodamine derivative and mercury ion were injected individually and mixed by applying a short voltage. Subsequently, the mercury ions reacted with the nonfluorescent rhodamine derivative to produce strongly fluorescent product. The resulting product was then removed by EOF and micelles towards the detection window and detected by LIF detector. The experimental conditions in terms of the concentration and injection volume ratios between mercury ion and derivatisation reagent, the mixing time and waiting time for the on-column reaction were optimised. The optimal conditions were determined as follows: the concentration and injection volume ratios between mercury ion and derivatisation reagent were 1:20 and 10:1, respectively; the mixing time was 40 s under the applied voltage of 5 kV; the waiting time was proved unnecessary. The detection limit for mercury ion was 5 x 10(-8) M, and the total analysis time was less than 10 min.     

A flow injection analysis technique for the determination of chloride using reflectance detection

A flow injection (FI) determination for chloride has been developed using the light reflectance of the precipitate formed by the reaction of chloride with silver(I) as the method of detection rather than turbidimetry, as in the previous FI method using this reaction. The dynamic range of the analysis is increased to 0-10 mM chloride with a 10 mM silver(I) reagent and to 0-50 mM chloride with a 50 mM silver(I) reagent by using this mode of detection. The ability to select the injected reagent from an option of two concentrations via the control program is incorporated into the FI system, enhancing the versatility of the analysis. The dynamic range is further extended to 100 mM chloride by measuring the signal levels at the trailing portion of the response curve. The consumption of reagent is kept to a minimum by merging injected zones of sample and reagent instead of using a constant reagent stream.     

Sphingosine determination at the picomole level using dimethylaminoazobenzene sulphonyl chloride

A sensitive method (lower detection limit 5 picomoles) is proposed for the determination of sphingoid bases liberated from mammalian glycosphingolipids by acid hydrolysis. The azo dye 4-dimethylaminoazobenzene-4'-sulfonyl chloride reacts with the primary amino group of the sphingosine bases, forming a stable derivative. Excess reagent, which is degraded during the derivatization, and free amino sugars as common hydrolysis products of glycosphingolipids are completely separated by reversed-phase high-performance liquid chromatography. This method was applied to the determination of the glycosphingolipid content of mouse spleen and thymus.     

Fluorimetric sequential injection determination of magnesium using 8-hydroxiquinoline-5-sulfonic acid in a micellar medium

A fluorimetric sequential injection method for the determination of magnesium is proposed. The system is based on the complex formation between Mg(II) and 8-hydroxyquinoline-5-sulfonic acid (HQS). The reaction was carried out in the presence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) as a masking agent. Cetyltrimethylammonium chloride (HTAC) was employed as a fluorescence enhancer. The influence of several variables, such as reagent concentration, volumes and pH has been investigated. The reagent was prepared in a 0.1 M Tris-HCl buffer solution (pH 9). A detection limit of 12 mug l(-1) magnesium was obtained. The proposed method was applied to the determination of magnesium in natural waters.     

Determination of catecholamines and indoleamines in human urine based on intramolecular excimer-forming derivatization and fluorescence detection.

A liquid chromatographic (LC) determination of catecholamines and indoleamines is described. This is based on intramolecular excimer-forming fluorescence derivatization with 4-(1-pyrene)butanoyl chloride, followed by reversed-phase LC. The analytes, containing an amino moiety and phenolic hydroxyl moieties in a molecule, were converted to the corresponding polypyrene-labeled derivatives by one-step derivatization. They afforded intramolecular excimer fluorescence, which can clearly be discriminated from the normal fluorescence emitted from reagent blanks. The detection limits (S/N = 3) for catecholamines and indoleamines were femto-mole levels per 20-microL injection. Furthermore, this method was applied to a urine assay.     

A sensitive and selective determination method of histamine by HPLC with intramolecular excimer-forming derivatization and fluorescence detection

A highly sensitive, selective and simple method is described for the determination of histamine by high-performance liquid chromatography (HPLC) with fluorescence detection. The method is based on an intramolecular excimer-forming fluorescence derivatization of histamine with 4-(1-pyrene)butyric acid N-hydroxysuccinimide ester (PSE), followed by reversed-phase HPLC. Histamine, having two amino moieties in a molecule, was converted to the dipyrene-labeled derivative by reaction with PSE. The derivative afforded intramolecular excimer fluorescence (450-540 nm), which can clearly be discriminated from the monomer fluorescence (370-420 nm) emitted from PSE. Typically, a 10 micro L sample solution was mixed with 100 micro L of derivatization reagent solution, which was a mixture of 0.5 mm PSE in acetonitrile and 0.5 mm potassium carbonate in water (8:2, v/v). The derivatization was carried out at 100 degrees C for 90 min. The PSE derivative of histamine could be separated by reversed-phase ODS column with isocratic elution using acetonitrile:water (82:18, v/v) containing 0.03% triethylamine. The detection limit (singnal-to-noise ratio = 3) of histamine was 0.5 fmol for a 30 micro L injection. The method was successfully applied to the determination of histamine in human urine, and had enough selectivity and sensitivity for urinary histamine quantification.     

Peroxyoxalate chemiluminescence detection of condensates of malondialdehyde with thiobarbituric acids using a flow system.

The peroxyoxalate chemiluminescence(CL) detection method for the evaluation of the CL intensity of malondialdehyde(MDA) condensates with seven 2-thiobarbituric acid derivatives is described. The method consists of a flow injection technique together with a CL detection system using bis(2,4,6-trichlorophenyl) oxalate(TCPO) and hydrogen peroxide as chemiluminogenic reagents. Linear correlations between CL intensity and concentration are obtained for pmol levels of condensates. Among the condensates, 1,3-diethyl-2-thiobarbituric acid(DETBA)-MDA shows the largest CL intensity. High performance liquid chromatography (HPLC)/CL detection of DETBA-MDA and 1,3-diphenyl-2-thiobarbituric acid(DPTBA)-MDA using a mixture of TCPO and hydrogen peroxide in acetonitrile as a postcolumn reagent solution is also described. The detection limits for DETBA-MDA and DPTBA-MDA are 20 and 200 fmol, respectively, per 20 microL injection at a signal-to-noise ratio of 2. This HPLC/CL detection system was applied to the determination of MDA in rat brains by using DETBA as a fluorescent derivatizing reagent.     

An ionizable chromophoric reagent for the analysis of primary amine-containing drugs by capillary electrophoresis

We found that ofloxacin acyl chloride is a potential chromophoric reagent for labeling amino analytes for capillary electrophoresis. Ofloxacin acyl chloride has a tertiary amino function in its structure and the derivatives from ofloxacin acyl chloride reacting with amino analytes can be ionized by an acid treatment and analyzed by simple capillary zone electrophoresis. Ofloxacin acyl chloride was used to derivatize model analytes (without chromophore) of amantadine (amino drug), tranexamic acid (non-protein amino carboxylic acid), glycine, and methionine (protein amino acids). The resulting derivatives were analyzed by capillary zone electrophoresis with ultraviolet detection (300 nm). The detection limits of the analytes studied were in the range of 1.0-2.5 microM (S/N = 3, injection 3 s). The precision (relative standard deviation) and accuracy (relative error) of the method for intra- and inter-day analyses of the analytes were respectively below 4.5% and 3.9%. Application of the method to the analysis of tranexamic acid in plasma proved feasible.     

Indirect enantioseparation of alpha-amino acids by reversed-phase liquid chromatography using new chiral derivatizing reagents synthesized from s-triazine chloride

Ten chiral dichloro- and monochloro-s-triazines were prepared by the nucleophilic displacement of chlorine atom(s) in s-triazine chloride and its 6-methoxy derivative with different amino acid amides. Dichloro-s-triazines (DCTs) were used as CDRs for derivatization of alpha-amino acids under basic conditions at room temperature (30 degrees C) while derivatization with monochloro-s-triazine (MCT) reagents was carried out at 80 degrees C. The resultant diastereomers were separated on a reversed-phase C(18) column using mixtures of acetonitrile and aqueous-trifluoroacetic acid (TFA). The separation results for the two were compared. One DCT reagent was optimized for derivatization kinetics with respect to the effects of pH, reagent excess, temperature and reaction time on derivatization yield. In most of the cases, DCT reagents provided better separation of diastereomers in comparison to MCT reagents. One DCT reagent was also validated for limit of detection, linearity, recovery and robustness. Effects of structural modifications in reagents on chromatographic properties were investigated. Separation mechanism of diastereomers was proposed in light of both MCT and DCT reagents.     

流动相离子色谱法同时测定植物中残留的矮壮素和缩节胺

以离子对试剂作流动相,采用离子对抑制电导检测法同时测定植物中残留的矮壮素和缩节胺。简单处理后的样品经过Dionex　IonPac NG1保护柱和NS1分离柱,在流速为1.00 mL/min、淋洗液为1.00 mmol/L九氟戊酸(作为离子对试剂)-7%(体积分数,下同)乙腈时等度洗脱分离,能够快速稳定出峰,且被测物与其他干扰离子充分分离。矮壮素和缩节胺的检出限分别为0.1546和0.1714 mg/L,在1～100 mg/L范围内具有良好的线性关系和重现性。对实际样品进行测定,矮壮素和缩节胺的回收率范围分别为96.06%～104.6%和98.53%～103.7%,相对标准偏差小于3%。该方法分析结果令人满意,可以满足矮壮素和缩节胺常规的定性、定量分析需求。     

Ultratrace analysis for trans,trans-muconic acid by electrophoric derivatization and capillary gas chromatography

A highly sensitive method is described for the determination of trans,trans-muconic acid (MA), a biomarker of benzene exposure. The method is based on the derivatization of MA with an electrophoric reagent, 2-(pentafluorophenoxy)ethyl-2-(piperidino)ethanesulfonate, using potassium carbonate and 18-crown-6 ether as reaction activators. The resulting pentafluorophenoxy derivative of MA was analyzed by capillary GC with an electron-capture detector (ECD). The lower quantitation limit of the method is attainable at 0.3 μM of MA with a detection limit of about 60 nM (S/N=3) (60 fmol per 1.0 μl injection). Application of the method to the analysis of MA in urine proved feasible.     

Sensitive analysis of amino acids in injection liquor by reversed-phase HPLC

A convenient derivatization method of amino acids with l-fluoro-2,4-dimtrobenzene as reaction reagent and a separation system were described. The derivative amino acids were separated on a specific chemically bonded phase column with a simple linear gradient elution consisting of aqueous buffer and methanol. The eluate was detected by common ultraviolet absorption detector at 360 nm. The detection limits of amino acids were as low as 10 picomole. This method has been successfully applied to assay amino acid injection liquor used in hospital. It has good repro-ducibility and precision. The procedures avoid the requirements of particular derivative equipment and analyzer employed in conventional amino acid analysis.     

Extraction of Copper(II) and Zinc(II) from Chloride Media with Mixed Extractants

Extraction of copper(II) and zinc(II) from acidic chloride solutions with mixtures of two extractants: a basic or solvating one and a chelating extractant was discussed. Processes for recovery and separation of Cu(II) from Zn(II) were proposed, which consist of the following steps: extraction from chloride media with the formation of metal chlorocomplex ion pair or solvate, scrubbing of chloride ions with an aqueous solution of appropriate pH with simultaneous transfer of the metal ion to the chelate, traditional stripping with sulphuric acid and conditioning of the basic extractant. Both effective recovery and separation of metal ions with simultaneous change of the system from the chloride to the sulphate state can be achieved. A bifunctional reagent, such as alkyl derivative of 8-hydroxyquinoline, can be also used instead of the extractant mixture.     

High Performance Liquid Chromatographic Analysis for Free Valine in Plasma

Abstract

A precolumn derivatization method is presented with the use of a fluorescent derivative, 1-dimethylaminonaphhalene-5-sulfonyl-chloride, dansyl chloride, for the detection of free valine in plasma. Dansylated amino acids were determined in deproteinized samples by reverse-phase liquid chromatography. The level of detection is 100 femtoraoles (10^?15). Sample preparation required precipitation of proteins with trichoroacetic acid and removing the excess acid with water saturated ether. The deproteinized sample was adjusted to pH 9.0 and reacted with dansyl chloride. The dansylated products were detected by ultraviolet and fluorescence spectrometry. Elution time for valine subsequent to injection is 25 minutes, while the total assay requires less than 50 minutes.