Abstract: A gas chromatographic (GC) method is presented for determining residues of chloramphenicol (CAP), florfenicol (FF), florfenicol amine (FFa), and thiamphenicol (TAP) in shrimp tissues, with meta-nitrochloramphenicol (mCAP) as the internal standard. The composited shrimp is extracted with basic ethyl acetate, followed by an acetonitrile-basic ethyl acetate mixture. This extract is centrifuged, filtered, evaporated, and reconstituted in water; the reconstituted extract is acidified, defatted with hexane, and passed through a propylsulfonic acid (PRS) and C 18 solid-phase extraction (SPE) system. The C 18 SPE column is eluted with methanol, and the PRS SPE column is eluted with basic MeOH plus counter ion. The combined eluates are evaporated, reconstituted in acetonitrile, and derivatized with Sylon BFT. After derivatization, the addition of toluene directly to the sample, followed by the addition of basic water, quenches the derivatization process. After centrifugation, the organic layer is carefully removed, and the analytes are determined by GC with electron capture detection. Shrimp tissues were fortified with fenicols (i.e., CAP, FF, FFa, and TAP) at 5, 10, 20, 40, and 80 ng/mL. Overall recoveries were 88, 101, 91, and 84% with overall interassay (between-day) variabilities (i.e., relative standard deviations) of 5.3, 9.4, 12.8, and 7.4% for CAP, FF, FFa, and TAP, respectively. The method detection limits were calculated as 0.7, 1.4, 2.4, and 1.3 ng/g (ppb) for CAP, FF, FFa, and TAP, respectively, based on a 10 g sample. The quantitation limit as determined empirically by this method is the lower limit of the standard curve, which is about 5 ng/g (ppb) for each analyte.

Abstract: In the analysis of organotin compounds, derivatization is required in order to achieve more volatile compounds prior to the use of techniques based on GC separation. Derivatization can be considered as one of the main critical steps in organotin analysis, since low yields of derivatization and losses of analytes can easily occur at this stage, and lead to an underestimation of their content in environmental samples. Furthermore, experimental conditions which are not perfectly under control may induce degradations, and alter the original speciation in the sample. Hydride generation, and alkylation by Grignard reagents or by NaBEt 4, are the derivatization methods usually applied for organotins. The advantages and disadvantages of these methods are reported. z2000 Elsevier Science B.V. All rights reserved.

Abstract: Amino Acid Analysis: An Overview, Margaret I. Tyler. Amino Acid Analysis, Using Postcolumn Ninhydrin Detection, in a Biotechnology Laboratory, Frank D. Macchi, Felicity J. Shen, Rodney G. Keck, and Reed J. Harris. Purification of Proteins Using UltraMacro Spin Columns or ProSorb Sample Preparation Cartridges for Amino Acid Analysis, Li Zhang and Nancy Denslow. Amino Acid Analysis Using Precolumn Derivatization with 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate Steven A. Cohen. Amino Acid Analysis by High-Performance Liquid Chromatography after Derivatization with 1-Fluoro-2,4-Dinitrophenyl-5-l-Alanine Amide (Marfey's Reagent), Sunil Kochhar, Barbara Mouratou, and Philipp Christen. The Analysis of Amino Acids Using Precolumn Derivatization, HPLC, and Electrochemical Detection, C. David Forster and Charles A. Marsden. Anion Exchange Chromatography and Intergrated Amperometric Detection of Amino Acids, Petr Jandik, Christopher Pohl, Victor Barreto, and Nebojsa Avdalovic. Ion-Pair Chromatography for Identification of Picomolar-Order Protein on a PVDF Membrane, Noriko Shindo, Tsutomu Fujimura, Saiko Kazuno, and Kimie Murayama. Capillary Gas Chromatographic Analysis of Protein and Nonprotein Amino Acids in Biological Samples, Hiroyuki Kataoka, Sayuri Matsumura, Shigeo Yamamoto, and Masami Makita. Measurement of Blood Plasma Amino Acids in Ultrafiltrates by High-Performance Liquid Chromatography with Automatic Precolumn O-Phthaldialdehyde Derivatization, Hua Liu. Determination of Amino Acids in Foods by Reversed-Phase High-Performance Liquid Chromatography with New Precolumn Derivatives, Butylthiocarbamyl, and Benzylthiocarbamyl Derivatives Compared to the Phenylthiocarbamyl Derivative and Ion Exchange Chromatography, Kang-Lyung Woo. Amino Acid Measurement in Body Fluids Using PITC Derivatives, Roy A. Sherwood. Determination of Proteins, Phosphatidylethanolamine, and Phosphatidylserine in Lipid-Rich Materials by Analysis. of Phenylthiocarbamyl Derivatives, Margareta Stark and Jan Johansson. Analysis of O-Phosphoamino Acids in Biological Samples by Gas Chromatography with Flame Photometric Detection, Hiroyuki Kataoka, Norihisa Sakiyama, Yukizo Ueno, Kiyohiko Nakai, and Masami Makita. Determination of Sulfur Amino Acids, Glutathione, and Related Aminothiols in Biological Samples by Gas Chromatography with Flame Photometric Detection, Hiroyuki Kataoka, Kiyomi Takagi, Hirofumi Tanaka, and Masami Makita. Capillary Electrophoretic Determination of 4-Hydroxyproline, Qingyi Chu and Michael Zeece. Total Plasma Homocysteine Analysis by HPLC with SBD-F Precolumn Derivatization, Isabella Fermo and Rita Paroni. Determination of Early Glycation Products by Mass Spectrometry and Quantification of Glycation Mediated Protein Crosslinks by the Incorporation of [14C]lysine into Proteins, Malladi Prabhakaram, Beryl J. Ortwerth, and Jean B. Smith. Index.

Abstract: This survey gives an overview of recent derivatization protocols, starting from 1996, in combination with capillary electrophoresis (CE). Derivatization is mainly used for enhancing the detection sensitivity of CE, especially in combination with laser-induced fluorescence. Derivatization procedures are classified in tables in pre-, on- and postcapillary arrangements and, more specifically, arranged into functional groups being derivatized. The amine and reducing ends of saccharides are reported most frequently, but examples are also given for derivatization of thiols, hydroxyl, carboxylic, and carbonyl groups, and inorganic ions. Other reasons for derivatization concern indirect chiral separations, enhancing electrospray characteristics, or incorporation of a suitable charge into the analytes. Special attention is paid to the increasing field of research using on-line precapillary derivatization with CE and microdialysis for in vivo monitoring of neurotransmitter concentrations. The on-capillary derivatization can be divided in several approaches, such as the at-inlet, zone-passing and throughout method. The postcapillary mode is represented by gap designs, and membrane reactors, but especially the combination of separation, derivatization and detection on a chip is a new emerging field of research. This review, which can be seen as a sequel to our earlier reported review covering the years 1991-1995, gives an impression of current derivatization applications and highlights new developments in this field.

Abstract: An analytical method for the determination of glyphosate and its principal metabolite, aminomethylphosphonic acid (AMPA), in water of different hardnesses (5, 20, and 30 °DH, french hardness) has been developed. Samples were fortified at different levels (0.05, 0.1, 1, and 5 μg/L) and were purified by column chromatography on ion-exchange resins. After derivatization with TFAA/HFB mixture, the derivatives were quantified by using capillary gas chromatography with an ion-trap tandem mass spectrometric detector. Analytical conditions for MS/MS detection were optimized, and the quantification was carried out on the sum of areas of the three most representative ions: m/z 283, 223, and 181 for AMPA and m/z 440, 321, and 261 for glyphosate. The limit of quantification was demonstrated to be at 0.05 μg/L for each compound. The mean recovery value and the relative standard deviation (n = 65) were 93 and 12% for AMPA and 95 and 13% for glyphosate.

Abstract: A rapid, sensitive, and solvent-free procedure for the simultaneous determination of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethamphetamine (MDMA) in urine was developed using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode. A headspace vial containing the urine sample, NaOH, NaCl, and amphetamine-d3 as the internal standard was heated at 100 degrees C for 20 min. A polydimethylsiloxane fiber was maintained in the vial headspace for 10 min in order to adsorb the amphetaminic compounds, which were subsequently derivatized by exposing the fiber to trifluoroacetic anhydride for 20 min in the headspace of another vial maintained at 60 degrees C for 20 min. The trifluoroacetyl derivatives were desorbed in the GC injection port for 5 min. Several parameters were considered during the method optimization process. These included a comparison of SPME with or without headspace, the required derivatization procedure, and the influence of temperature on the headspace extraction and derivatization methods. The optimized method was validated for the four compounds tested. Calibration curves showed linearity in the range 50-1000 ng/mL (r = 0.9946-0.9999). Recovery data were 71.89-103.24%. The quantitation limits were 10 ng/mL for amphetamine and methamphetamine and 20 ng/mL for MDA and MDMA. All of these data recommend the applicability of the method for use in the analytical routine of a forensic laboratory.

Abstract: An in situ derivatization solid-phase microextraction method has been developed for the determination of haloacetic acids (HAAs) in water. The analytical procedure involves derivatization of HAAs to their methyl esters with dimethyl sulfate, headspace sampling using solid-phase microextraction (SPME), and gas chromatography-ion trap mass spectrometry (GC/ITMS) determination. Parameters affecting both derivatization efficiency and headspace SPME procedure, such as the selection of the SPME coating, derivatization−extraction time and temperature, and ionic strength, were optimized. The commercially available Carboxen-poly(dimethylsiloxane) (CAR-PDMS) fiber appears to be the most suitable for the determination of HAAs. Moreover, the formation of HAA methyl esters was dramatically improved (up to 90-fold) by the addition of tetrabutylammonium hydrogen sulfate (4.7 μmol) to the sample as ion-pairing agent in the derivatization step. The precision of the in situ derivatization/HS-SPME/GC/ITMS method evaluated u...

Abstract: A thorough review of the application of solid-phase microextraction (SPME) combined with gas chromatography for the analysis of forensic specimens is presented, including experimental results for several recent applications. The SPME applications covered in this comprehensive review include ignitable liquid residues (also referred to as accelerants), explosive traces, drugs and poisons from biological specimens, and other forensic applications. Recently developed SPME methods are also presented, including the analysis of ignitable liquid residues on human skin, odor signatures, and several drug applications such as free-fraction antipsychotic drug levels, blood alcohol casework, drink-tampering analysis, and gamma-hydroxybutyrate identification without the need for derivatization. SPME is shown to be an inexpensive, rapid, and sensitive method for the analysis of a variety of forensic specimens.

Abstract: A sensitive method was developed to determine 16 amino acids, including all the neurotransmitter amino acids and neuromodulators, in physiological samples. Samples were derivatized with o-phthalaldehyde/tert-butyl thiol followed by two scavenging reactions that reduced the chemical background caused by excess derivatization reagent by ∼90%. A total of 250 nL of the derivatized sample was injected and concentrated onto a 50-μm-inner diameter capillary column packed with 5-μm reversed-phase particles and separated using gradient elution. Analytes were detected amperometrically at a cylindrical 9-μm carbon fiber microelectrode. The combination of on-column concentration, scavenging reactions after derivatization, high sensitivity electrochemical detection, and protocols to minimize amine contamination allowed detection limits of 90−350 pM (20−80 amol) for all the amino acids tested. This method was used to analyze in vivo microdialysate samples from probes implanted in the striatum of anesthetized rats. Prob...

Abstract: Capillary electrophoresis (CE) is becoming an established method for the determination of chiral trace impurities. This paper provides an overview of the state of the art of CE for such determinations. Detection limits of 0.1% impurity is widely accepted as a minimum requirement for chiral trace impurity determinations. This can be relatively easily achieved with CE. However, determination of lower concentrations requires careful optimization of the separation system. Four factors that are of particular significance for trace enantiomeric determinations: resolution, limit of detection, linear range and type of detection, are discussed. Further, the advantages and disadvantages of derivatization in this context are treated as well as the separation approach, ie., direct chiral separation or separation after the formation of diastereomers. It is concluded that the limit of impurity detection can be about 0.05% when UV detection is employed. Using laser-induced fluorescence detection, a quantitative determination at the 0.005% level is often possible.

Abstract: Key words: Capillary electrophoresis, sugars, amino acids,nitrate, ammonium.Amino acids and sugars are probably the most com-monly measured solutes in plant fluids and tissueextracts. Chromatographic techniques used for the Introductionmeasurement of such solutes require complex derivat- A number of techniques have been used to quantifyization procedures, analysis times are long and separ-sugars and amino acids. For free amino acids, chromato-ate analyses are required for sugars and amino acids.graphic methods including gas chromatography (GC) orTwo methods were developed for the analysis ofgas chromatography-mass spectrometry (GC-MS) andunderivatized sugars and amino acids by capillaryhigh performance liquid chromatography (HPLC) areelectrophoresis (CE). Separation of a range of sugarsand amino acids was achieved in under 30 min, with most common. These methods frequently rely on a varietygood reproducibility and linearity. In general, there of derivatization procedures (Fan

Abstract: A novel interface design for coupling gas chromatography and inductively coupled plasma mass spectrometry (GC/ICP-MS) was used to perform mercury speciation in biological tissues. Three derivatization approaches were optimized and compared for this purpose: anhydrous butylation using a Grignard reagent, aqueous ethylation by means of NaEt(4)B and aqueous propylation with NaPr(4)B. The last reagent was synthesized in the laboratory as it is not commercially available. Detection limits obtained by GC/ICP-MS ranged between 100 and 200 fg (as absolute mass) for methylmercury and between 500 and 600 fg for inorganic mercury using a 1 microl injection. Quantification of methyl- and inorganic mercury was carried out by resorting to aqueous calibration, using ethylmercury as internal standard for both propylation and butylation derivatization techniques. For ethylation procedures, a methylpropylmercury solution was used as internal standard. The absence of transmethylation during sample preparation was checked using a 97% enriched (202)Hg inorganic standard. The accuracy of the three derivatization approaches was evaluated by the analysis of the certified reference material DOLT-2 (dogfish liver) from the National Research Council of Canada and certified for methylmercury, with satisfactory results.

Abstract: A method for full speciation and determination of alkyllead and inorganic lead(II) in aqueous samples was developed. This was accomplished by in situ derivatization with deuterium-labeled sodium tetraethylborate NaB(C2D5)4 (DSTEB). The derivatization was carried out directly in the aqueous sample and the derivatives were extracted from the headspace by a solid-phase microextraction (SPME) fiber. The extracted analytes were then transferred to a GC/MS or a GC/FID for separation and detection. The research presented demonstrates that SPME and the derivatization reagent DSTEB can be used successfully for the speciation of Pb2+, Pb(CH3)3+, Pb(C2H5)3+, and Pb(C2H5)4 in water samples. All derivatives, Pb(C2D5)4, (CH3)3Pb(C2D5), (C2H5)3Pb(C2D5), and Pb(C2H5)4, are separated using an SBP-5 column. This method was applied to monitor degradation of tetraethyllead in water. This is the first report of ethylation by DSTEB for full speciation of methyllead, ethyllead, and inorganic lead compounds. This approach can be...