Derivatization Yield Research Articles

Application of single-drop microextraction combined with in-microvial derivatization for determination of acidic herbicides in water samples by gas chromatography–mass spectrometry

A single-drop microextraction (SDME) method and gas chromatography with mass spectrometry detection have been developed for the determination of acidic herbicides in water. The analytes were extracted from a 3 mL sample solution using 4 μL of hexyl acetate. After extraction, derivatization was carried out inside a glass microvial (1.1 mm i.d.) using pentafluorobenzyl bromide (PFBBr). Triethylamine (TEA) was used as the reaction catalyst. The influence of derivatization reagent volume, catalyst amount, derivatization time and temperature on the yield of the in-microvial derivatization was investigated. Derivatization reaction was performed using 0.3 μL of PFBBr and 0.4 μL of TEA (10%, v/v in toluene) at 100 °C during 5 min. Also, the effects of different experimental SDME parameters such as selection of organic solvent, sample pH, addition of salt, extraction time and temperature of extraction were studied. Analytical parameters such as enrichment factor, precision, linearity and detection limits were also determined. The enrichment factors were between 83 and 157. The limits of detection (LOD) were in the range 1.2–7 ng/L (S/N = 3). The relative standard deviations obtained were below 10.1% ( n = 5).

Multiresidue analysis of acidic and polar organic contaminants in water samples by stir-bar sorptive extraction–liquid desorption–gas chromatography–mass spectrometry

The feasibility of stir-bar sorptive extraction (SBSE) followed by liquid desorption in combination with large volume injection (LVI)-in port silylation and gas chromatography–mass spectrometry (GC–MS) for the simultaneous determination of a broad range of 46 acidic and polar organic pollutants in water samples has been evaluated. The target analytes included phenols (nitrophenols, chlorophenols, bromophenols and alkylphenols), acidic herbicides (phenoxy acids and dicamba) and several pharmaceuticals. Experimental variables affecting derivatisation yield and peak shape as a function of different experimental PTV parameters [initial injection time, pressure and temperature and the ratio solvent volume/ N-( tert-butyldimethylsilyl)- N-methyltrifluoroacetamide (MTBSTFA) volume] were first optimised by an experimental design approach. Subsequently, SBSE conditions, such as pH, ionic strength, agitation speed and extraction time were investigated. After optimisation, the method failed only for the extraction of most polar phenols and some pharmaceuticals, being suitable for the determination of 37 (out of 46) pollutants, with detection limits for these analytes ranging between 1 and 800 ng/L and being lower than 25 ng/L in most cases. Finally, the developed method was validated and applied to the determination of target analytes in various aqueous environmental matrices, including ground, river and wastewater. Acceptable accuracy (70–130%) and precision values (<20%) were obtained for most analytes independently of the matrix, with the exception of some alkylphenols, where an isotopically labelled internal standard would be required in order to correct for matrix effects. Among the drawbacks of the method, carryover was identified as the main problem even though the Twisters were cleaned repeatedly.

Microwave-accelerated derivatization for the simultaneous gas chromatographic–mass spectrometric analysis of natural and synthetic estrogenic steroids

A rapid microwave-accelerated derivatization process for the GC–MS analysis of steroid estrogens, estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2) and mestranol (MeEE2), was developed. Under microwave irradiation, the five estrogenic hormones studied were simultaneously derivatized with N, O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) + trimethylchlorosilane (TMCS) in pyridine solution. Effects of irradiation time (15–120 s) and power level (240–800 W) on the yield of the derivatization were investigated. The derivatization under the irradiation of 800 W microwave for 60 s produced comparable results when compared with the conventional heating process in a sand bath for 30 min at 80 °C in terms of derivatization yield, linearity and precision for all steroid hormones tested. The calibration curves are linear between 3.00 and 3.00 × 10 2 μg mL −1. The square of the regression coefficients ( R 2) range from 0.979 to 1.000. The applicability of the method was evaluated on spiked river and distilled water samples at two concentrations, 25.0 and 2.00 × 10 2 ng mL −1. The recoveries obtained by using microwave heating (60 s, 800 W) were similar to those by conventional heating. When combined solid-phase extraction (SPE) with the application of the microwave-accelerated derivatization proposed here, the detection limits of 0.02–0.1 ng L −1 for the steroid hormones have been achieved. The results demonstrated that microwave-accelerated derivatization is an efficient and suitable sample preparation method for the GC–MS analysis of estrogenic steroids.

Analysis of Some Chlorophenoxy Acids and Carbamate Herbicides in Water and Soil as Amide Derivatives Using Gas Chromatography--Mass Spectrometry

A newly developed method for determining three phenoxy acids and one carbamate herbicide in water and soil samples using gas chromatography with mass spectrometric detection is developed. Phenoxy acids are derivatized through a condensation reaction with a suitable aromatic amine. 1,1-Carbonyldiimidazole is used as a condensation reagent. Derivatization conditions are optimized with respect to the amount of analyte, amine, solvent, and derivatization reagent. The optimum derivatization yield is accomplished in acetonitrile. 4-Methoxy aniline is used as a derivatizing agent. Obtained derivatives are stable indefinitely. Enhancement in sensitivity is achieved by using the single-ion monitoring mass spectrometric mode. The effectiveness of the developed method is tested by determining investigated compounds in water and soil samples. Analytes are concentrated from water samples using liquid-phase extraction and solid-phase extraction. Soil samples are extracted using methanol. Detection limits of 1.00, 50.00, 100.00, and 1.00 ng/mL are obtained for 2-(1-methylethoxy)phenyl methylcarbamate (Baygon), 2-(3-chlorophenoxy)-propionic acid (Cloprop), 2,4,5-trichlorophenoxyacetic acid, and 4-(2,4-dichlorophenoxy)butyric acid, respectively. LPE for spiked water samples yields recoveries in the range of 60.6-95.7%, with relative standard deviation (RSD) values of 1.07-7.85% using single component calibration curves. Recoveries of 44.8-275.5%, with RSD values ranging from 1.43% to 8.61% were obtained using a mixed component calibration curves. SPE from water samples and soil samples showed low recoveries. The reason is attributed to the weak sorption capabilities of soil and Al(2)O(3).

Rapid quantitative and qualitative confirmatory method for the determination of monofluoroacetic acid in foods by liquid chromatography–mass spectrometry

A rapid quantitative method and a qualitative confirmatory method for the determination of monofluoroacetic acid (MFA) in complex food matrices are presented. The quantitative method utilizes a water extraction, solid phase extraction clean-up and liquid chromatography–mass spectrometry (LC–MS) for determination of MFA. This method showed a high degree of specificity, detecting MFA in all of the spiked samples, while none of the unfortified samples tested positive for MFA. Spike recoveries were high in all matrices analyzed, varying from 85 to 110%, and comparable at low (2 mg/L) and high (20 mg/L) spiking levels. Repeatability tests at the low spiking levels yielded RSDs of less than 5% for all matrices analyzed. The qualitative confirmatory method developed is conceptually different from the quantitative method, ensuring that both methods would not be subject to the same interferences. The method uses the formation of the hydrazide of MFA through derivatization with 2-nitrophenylhydrazine. This derivatization is well established for the determination of carboxylic acids, but this is the first application to the determination of MFA. The derivatization yield was matrix dependent, however the limit of detection (LOD) (0.8 μg/L) was sufficient to confirm the presence of MFA in all spiked matrices. Repeatability tests at the low spiking levels yielded RSDs of approximately 7% for all matrices analyzed.

Analysis of 5-hydroxymethylfurfural in foods by gas chromatography–mass spectrometry

A new, simple and selective method for the analysis of 5-hydroxymethylfurfural (HMF) in foods by gas chromatography coupled to mass spectrometry (GC–MS) is proposed. Several derivatising procedures based on the formation of an HMF silylated derivative using different reagents were studied. Among the derivatising reagents examined, N,O- bis-trimethylsilyltrifluoroacetamide (BSTFA) provided the best derivatisation yield. Sample clean-up was also optimised, using either liquid–liquid extraction with dichloromethane or solid-phase extraction (SPE) with several commercially available cartridges, and the best results were obtained using ENV+ cartridges. Quality parameters such as day-to-day and run-to-run precision (RSD < 10%), linearity (between 25 and 700 ng g −1) and detection limit (6 ng g −1) were established. This method was successfully applied to the analysis of HMF content in several Spanish food samples from a local market, such as jam, honey, orange juice and bakery products.

Determination of Free Fatty Acids from Soil and Bryophyte by HPLC with Fluorescence Detection and Identification with Mass Spectrometry

A simple and sensitive method for the determination of free fatty acids using acridone-9-ethyl- p-toluenesulfonate (AETS) as tagging reagent by reversed-phase high-performance liquid chromatography with fluorescence detection has been developed. Studies on derivatization conditions indicate that free fatty acids react rapidly and smoothly with AETS in the presence of K 2CO 3 catalyst in N, N-dimethylformamide (DMF) solvent at 85°C to give the corresponding sensitive fluorescence derivatives. The maximal derivatization yields are close to 100% with a six fold molar reagent excess. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography. Separation of the derivatized fatty acids exhibits a good baseline resolution in combination with a gradient elution on a reversed-phase Eclipse XDB-C 8 column. The identification of 19 fatty acid derivatives was carried out by online post-column mass spectrometry with atmospheric pressure chemical ionization (APCI) source in positive-ion mode. The contents of 19 free fatty acids in soil and three kinds of bryophytes ( Tree Moss, Entodon macropodus, Dicranum caesium) were determined. The results indicate that the bryophyte plants enrich an abundance of free fatty acids from soil. The fluorescence excitation and emission wavelengths of derivatives were 404nm of λ ex and 440 nm of λ em, respectively. Excellent linear responses were observed with the linear correlation coefficients over 0.9996, and detection limits (at signal-to-noise of 3:1) are 12.3–43.7 fmol. The proposed method is sensitive and reproducible for the determination of free fatty acids from real samples with satisfactory results.

Aracyl triflates for preparing fluorescent and UV absorbing derivatives of unreactive carboxylates, amines and other metabolites

Aracyl trifluoromethanesulfonate (triflate) reagents alkylate the unreactive carboxyl groups of betaines. The reagents also derivatise tertiary amines, amine oxides, phosphates and thioethers. A general derivatisation procedure is to dilute the sample with a polar aprotic organic solvent containing a trace of water, followed by adding an appropriate base and the aracyl triflate reagent. Limits of detection were 40 nM for glycine betaine (GB) and carnitine, 0.14 μM for N, N-dimethylglycine, 70 nM for trimethylamine (TMA), and 5.9 μM trimethylamine- N-oxide (TMAO). Limits of detection were improved when derivatisation yield was optimised for different analytes by changing solvent, base and water content of the reaction mixture. Solvents used include acetonitrile, acetone, butanone, dimethoxyethane and dimethoxyethyl ether, with the presence of some water or alcohol tolerated. Suitable bases include the inorganic bases magnesium hydroxide, silver oxide and lithium phosphate. These bases are sparingly soluble in the reaction solvent so sustain weakly basic conditions during derivatisation and can be removed by centrifugation to stop the reaction. This is particularly important for betaine assays since the derivatives are base-sensitive. The information presented here can be used to develop assays for many metabolites using these versatile reagents.

A rapid method for determination and confirmation of the thyreostats in milk and urine by matrix solid-phase dispersion and gas chromatography–mass spectrometry

A rapid and simple method for determination and confirmation of the thyreostats in milk and urine has been developed. The samples were extracted and purified by matrix solid-phase dispersion (MSPD) with silica gel as the solid support, and the thyreostats including tapazole, 2-thiouracil, 6-methyl-2-thiouracil, 6-propyl-2-thiouracil and 6-phenyl-2-thiouracil have been separated and detected by gas chromatography–mass spectrometry in selected ion mode with dimethylthiouracil as internal standard after derivatization with pentafluorobenzylbromide and N-methyl- N-(trimethylsilyl)-trifluoroacetamide. The derivatization reaction was conducted in a strong basic condition, which can improve the derivatization yields of the thyreostats in the presence of the matrix. The relative abundances of the selected ions in the chromatograms of the derivatives were stable and consistent, and can be used for the confirmatory purpose. The average recoveries of the five thyreostatic compounds in milk and urine were above 70% in most cases with the relative standard deviations between 2.1 and 7.9%. The limit of detection was 0.0016 μg g −1 for the thyreostats except for that of tapazole, which was 0.004 μg g −1.

Gln-tRNAGln Formation from Glu-tRNAGln Requires Cooperation of an Asparaginase and a Glu-tRNAGln Kinase

Gln-tRNA(Gln) is synthesized from Glu-tRNA(Gln) in most microorganisms by a tRNA-dependent amidotransferase in a reaction requiring ATP and an amide donor such as glutamine. GatDE is a heterodimeric amidotransferase that is ubiquitous in Archaea. GatD resembles bacterial asparaginases and is expected to function in amide donor hydrolysis. We show here that Methanothermobacter thermautotrophicus GatD acts as a glutaminase but only in the presence of both Glu-tRNA(Gln) and the other subunit, GatE. The fact that only Glu-tRNA(Gln) but not tRNA(Gln) could activate the glutaminase activity of GatD suggests that glutamine hydrolysis is coupled tightly to transamidation. M. thermautotrophicus GatDE enzymes that were mutated in GatD at each of the four critical asparaginase-active site residues lost the ability to hydrolyze glutamine and were unable to convert Glu-tRNA(Gln) to Gln-tRNA(Gln) when glutamine was the amide donor. However, ammonium chloride rescued the activities of these mutants, suggesting that the integrity of the ATPase and the transferase activities in the mutant GatDE enzymes was maintained. In addition, pyroglutamyl-tRNA(Gln) accumulated during the reaction catalyzed by the glutaminase-deficient mutants or by GatE alone. The pyroglutamyl-tRNA is most likely a cyclized by-product derived from gamma-phosphoryl-Glu-tRNA(Gln), the proposed high energy intermediate in Glu-tRNA(Gln) transamidation. That GatE alone could form the intermediate indicates that GatE is a Glu-tRNA(Gln) kinase. The activation of Glu-tRNA(Gln) via gamma-phosphorylation bears a similarity to the mechanism used by glutamine synthetase, which may point to an ancient link between glutamine synthesized for metabolism and translation.

Wisdom from a medical elder

This study is a reply to a paper in this journal reporting on the chemical instability of ifosfamide (IF) (<i>Drug Metab. Dispos.</i> 23, 433–437, 1995). The authors describe chloroethylamine as a major degradation product of IF in both the powder and aqueous solutions. In the present study, we show that:<i>i</i>) IF powder remains pure up to 3–5 years after its expiration date; <i>ii</i>) solutions of IF at pH 7 are stable for at least 12 hr at 40°C; and <i>iii</i>) solutions of IF at pH 4 or pH 10 are only slightly degraded (≈1%) after standing for 6 hr at 37°C. We also demonstrate that the reported IF instability depends on the analytical procedure used. The trifluoroacetylation procedure used by the authors, which is conducted in dichloromethane, led to low derivatization yields and to the formation of several degradation compounds of IF, among them chloroethylamine. In contrast, when the trifluoroacetylation reaction is conducted in ethyl acetate, there is high yield of trifluoroacetylated IF, and degradation compounds are minor. In conclusion, we believe that the large amounts of chloroethylamine reported by the authors in both powder and aqueous solutions of IF stemmed from degradation linked to the method of derivatization. Because IF is not readily derivatized by trifluoroacetic anhydride in dichloromethane, the combination of heating with possible uncontrolled evaporation of solvent and the presence of trifluoroacetic acid in the medium lead to degradation of IF and formation of chloroethylamine.

Derivatization of Acidic Herbicides with Selected Tetraalkyl Ammonium and Trimethyl Sulfonium Hydroxides for Their GC Analysis

This work presents studies on phenoxy acid [MCPP—2‐(4‐chloro‐2‐methylphenoxy)propanoic acid; MCPA—(4‐chloro‐2‐methylphenoxy)acetic acid; 2,4‐D‐2,4‐dichlorophenoxyaceticacid; 2,4,5‐T‐(2,4,5‐trichlorophenoxy)acetic acid] and phenolic [PCP—pentachlorophenol, dinoterb‐2‐(1,1‐dimethylethyl)‐4,6‐dinitrophenol, dinoseb‐2‐(1‐methylpropyl)‐4,6‐dinitrophenol] herbicides with derivatization aimed at their gas chromatographic determination. The derivatization was performed in an injection port of a gas chromatograph with trimethylphenylammonium hydroxide (TMPH), trimethylsulfonium hydroxide (TMSH), and tetramethylammonium hydroxide (TMAH). The effects of temperature of the injection port, reaction medium (solvent), and reagent excess on derivatization yield were investigated. TMPH in 20‐fold excess in methanol was selected for analysis. Dichloromethane was also found to be an appropriate solvent. Repeatability of the results was poor when tert‐butyl methyl ether (MTBE) was used as reaction medium.

Determination of abscisic acid by capillary electrophoresis with laser-induced fluorescence detection

A novel method based on capillary electrophoresis coupled to laser-induced fluorescence detection (CE–LIF) was developed for the determination of abscisic acid (ABA), which is an essential phytohormone during plant growth and development. ABA was labeled with 8-aminopyrene-1,3,6-trisulfonate via reductive amination in presence of acetic acid and sodium cyanoborohydride. The derivatization yield was maximized by optimizing several derivatization parameters including derivatization reagent concentration, reaction temperature and time. The conjugate was separated and quantitated by CE–LIF. The linearity of ABA was determined in the range from 0.1 to 10 μmol l −1 with a correlation of 0.9979. The derivatization limit of detection for ABA was found to be 56 fmol (corresponding to the concentration of 2.8×10 −8 mol l −1). The detection limit for ABA was 5.5 amol for an injection volume of 5 nl. As a preliminary application, the proposed method was successfully applied to determining trace amount of ABA in the crude extracts of tobacco without extra purification and enrichment procedure and showed a better selectivity and sensitivity than those conventional methods used in determination of ABA.

Comparison of different chloroformates for the derivatisation of seleno amino acids for gas chromatographic analysis

Three chloroformate reagents, ethyl chloroformate (ECF), methyl chloroformate (MCF) and menthyl chloroformate (MenCF), have been used for the derivatisation of seleno amino acids and their performance was compared. Chromatographic parameters and the inertness of the different instrumental configurations used (gas chromatography–atomic emission detection (GC–AED), and GC–MS) were shown to have a significant influence on the detection of various seleno amino acids (selenomethione, selenoethione and selenocysteine) and some sulphur-containing amino acids (methionine, cysteine, cystine and methylcysteine) which were included in the experiments for comparison. Methyl chloroformate was the preferred derivatisation reagent, since it generally performed best in terms of derivatisation yield and reproducibility and also showed less significant conditioning effects than ethyl chloroformate. Methyl and ethyl chloroformate derivatives of selenomethionine, selenoethionine, cysteine and methionine were detectable, while the detection of the menthyl chloroformate derivatives of selenocystine and cystine was not reproducible. Overall efficiencies for the determination of selenomethionine and selenoethionine from aqueous extracts ranged from 40 to 100% for methyl chloroformate, over 30–75% for ethyl chloroformate to 15–70% for menthyl chloroformate for different series measured over a period of months. The relative standard deviation of the method for the methyl and menthyl chloroformate derivatisation ranged from 7 to 13% without internal standard and was improved to 2% for the determination of selenomethionine using selenoethionine as internal standard. This indicates that, despite the limited reproducibility of the method, its repeatability is good enough to allow accurate determination of seleno amino acids, which was also demonstrated by the analysis of selenium supplementation tablets for human diet that contained selenomethionine.

Derivatisation in gas chromatographic determination of acidic herbicides in aqueous environmental samples.

This paper reviews derivatisation processes applied in chromatographic determination of acidic herbicides (with carboxyl and phenol groups), mainly in aqueous environmental samples. The discussion focuses on the basic derivatisation reactions used to convert herbicides to derivatives to make them analysable by gas chromatography, and possibly to reduce detection limits and/or increase extraction recovery from aqueous samples. The reactions are transesterification, esterification, silylation, alkylation, and extractive and pyrolytic alkylation. The reagents used to conduct the reactions are numerous. Diazomethane is a very efficient methylation reagent but explosive and toxic. Methyl iodide also ensures rapid and efficient methylation. Benzyl bromide can be used directly in water but derivatisation yield is low and reproducibility is poor. Butyl chloroformate and dimethyl sulfite can also be used for derivatisation in water, and acetic anhydride can be used for in-situ derivatisation of phenolic herbicides. For increasing selectivity of GC detection pentafluorobenzyl bromide (for ECD) and (2-cyanethyl)dimethyl(diethylamino)silane (for NPD) have been applied. Very characteristic ions are produced in mass spectra if silyl groups are introduced, e.g. by using bis(trimethylsilyl)trifluoroacetamide. Tetramethylammonium, trimethylphenylammonium, tetraalkylammonium, and trimethylsulfonium hydroxides and salts can by used for derivatisation at elevated temperature in the GC injection port. Extractive alkylation is relatively efficient if tetraalkylammonium salts with long chain alkyl groups are used.

On-line derivatization utilizing solid-phase microextraction (SPME) for determination of busulphan in plasma using gas chromatography-mass spectrometry (GC-MS).

Busulphan (Bu) is an alkylating agent used in preparative regimen before stem cell transplantation (SCT). Bu has a narrow therapeutic window, and underdosing or overdosing may have a fatal outcome for the patient. Therapeutic drug monitoring (TDM) combined with dose adjustment is currently used to optimize and individualize therapy with Bu. However, this approach is limited to centers with laboratory facilities. An automated and easy method for measurement of Bu plasma concentrations may facilitate TDM for Bu and thus improve the clinical outcome. A solid-phase microextraction (SPME) on line with gas chromatography (GC) and mass-spectrometric detection to quantify Bu in human plasma samples was developed using in-vial derivatization. Bu was mixed with reagent in a 2-mL vial and shaken for 15 minutes at 80 degrees C; subsequently, the SPME fiber was immersed into the vial for 15 minutes. The fiber was washed in water for 10 seconds before injection. Several parameters influencing the extraction and recovery were studied, such as absorption and desorption times, the effects of the temperature on the reaction, and the shaking time on the derivatization yield. Carbowax-divinylbenzene, polyacrylate, and polydimethylsiloxane fibers were tested. The carbowax-divinylbenzene fiber resulted in the highest recovery in plasma samples. The validation of the method showed a high chromatographic selectivity and a good sensitivity (LOQ = 20 ng/mL). Coefficient of variation for SPME was less than 15%. The results showed good correlation between Bu concentrations and response within the range of 40 to 2500 ng/mL (R2 = 0.999). The accuracy ranged from 94% to 106%. This is well in line with the international criteria for validation. The present method was applied to patient plasma. The obtained results were comparable with the results obtained from GC with electron capture detection. The authors conclude that this method has shortened the analysis time considerably and is fully automated, which benefits TDM of Bu in SCT patients.

Phase-transfer catalytic determination of phenols as methylated derivatives by gas chromatography with flame ionization and mass-selective detection

A convenient method for the GC determination of phenols as methylated derivatives is proposed, taking advantage of the beneficial features of phase-transfer catalysis (PTC). The optimal experimental conditions of pH, temperature, organic solvent, time of extraction–derivatization and amounts of the participating reactants and catalysts, were properly established. Several catalysts in soluble or polymer-bound form were tested. Most of them demonstrated appreciably high-performance characteristics but the polymer-bound catalyst is most favourable due to its facile separation from the rest of the reaction system after the extraction–derivatization. Interferences with the extraction and derivatization yield were not noticed. The chromatographic separation of 11 methylated derivatives of phenols was complete within 23 min. The detection limits of the method, which range from 0.005 to 0.120 μg, are inadequate for drinking water analysis. However, the method was successfully applied to the analysis of fortified composite lake water samples using GC–flame ionization detection and GC–MS in the single ion monitoring mode with the most abundant characteristic ions. Spiked recoveries of phenolics were in the range 94–102%, on the basis of distilled water calibration graph, signifying that PTC determination of phenols is not affected by the composition of such matrices.

Derivatization procedures for the detection of estrogenic chemicals by gas chromatography/mass spectrometry.

This work evaluated derivatization procedures for detecting both natural and synthetic estrogenic chemicals by gas chromatography/mass spectrometry (GC/MS). Different silylating agents, mainly trimethylsilylating (TMS) agents, were compared, and the roles of various content of trimethylchlorosilane (TMCS, as a stimulator) were investigated. The difference in the abundances of the derivatives was caused by the steric hindrance of multiple hydroxyl groups and ethynyl groups in the structures of estrogenic chemicals. The use of TMCS produces an increase in the derivatization yield, especially for the compounds with multiple hydroxyl groups (i.e., 17beta-estradiol (E(2)) and estriol (E(3))). Mass spectra of O-TMS derivatives and tentative fragmentation profiles are proposed. Molecular ions were the base peaks for all the derivatives, and were used as the quantitation ions to obtain maximum detection sensitivity and specificity. Sample enrichment was achieved by Oasis HLB solid-phase extraction cartridges. The quantitation limits of these compounds ranged from 5 to 10 ng/L in 1000-mL water samples. Recovery of the estrogenic chemicals in spiked various water samples ranged from 78 to 102% while relative standard deviation (RSD) ranged from 1 to 15%.

Analysis of organotin compounds by grignard derivatization and gas chromatography–ion trap tandem mass spectrometry

The determination of organotin compounds in water using gas chromatography–tandem mass spectrometry (GC–MS–MS) is described. Several organotin derivatives were synthesized by the reaction of organotin chlorides with Grignard reagents such as methyl-, propyl- and pentylmagnesium halides. After the optimization of the GC–MS–MS conditions, several derivatizations with the Grignard reagents were compared by evaluating the molar responses and volatilities of the derivatives and derivatization yields. As a result, the derivatizing reagent of choice is pentylmagnesium bromide. Calibration curves for the mono-, di- and tributyltins and mono-, di- and triphenyltins with pentylmagnesium bromide were linear in the range of 0.5–100 pg of Sn. The instrumental detection limits of six organotins ranged from 0.20 to 0.35 pg of Sn. The recovery tests from water samples (500 ml) were performed by using sodium diethyldithiocarbamate (DDTC) as a complexing reagent. Except for monophenyltin, the absolute recoveries of organotins from pure water at 200 ng of Sn/l were satisfactory. The recoveries calibrated by surrogate compounds (perdeuterated organotin chlorides) ranged from 71 to 109%. The method detection limits ranged from 0.26 to 0.84 pg of Sn (500-ml sample). This method was applied to the recovery of organotins from river water and seawater. The calibrated recoveries were between 90 and 122%.

陰イオン性毒物のペンタフルオロベンジル誘導体化ＧＣ‐ＭＳ法を用いた同時検出

A method for the simultaneous detection of anionic toxic substances and related compounds (azide, cyanide, thiocyanate, sulfide, ethyl methylphosphonate, isopropyl methylphosphonate, pinacoryl methylphosphonate (PMPA), methylphosphonate (MPA), nitrate, nitrite) has been developed using gas chromatography-mass spectrometry after pentafluorobenzyl (PFB) derivatization. The PFB derivatives of the analyte anions separated on a HP-5 capillary column were identified by the characteristic electron impact ionization mass spectra (EI-MS). Cyanide gave three kinds of derivatives, and two PMPA diastereomers were separated. The PFB derivative of nitrite could be clearly identified because of the poor resolution from that of nitrate and the absence of distinctive fragmentation ions on EI-MS. The effect of reaction conditions on the yield of the PFB derivatives was investigated. As catalysts, tetradecyldimethylbenzylammonium chloride (TDMBA) and polymer bound tributylmethylphosphonium chloride (TC) were examined. The effect of phosphate (pH 7.0) and borate (pH 9.3) buffer were examined. The pentafluorobenzylation with TC in borate buffer gave the best degree of efficiency except for thiocyanate. The highest yields of PFB derivatives in beverages and blood samples were also given using TC and borate buffer just the same as when tested in water. The derivatization values were 75-100% in the tea sample and 12-100% in the canned coffee sample. For the blood sample, five fold dilution was proved to be necessary in order to avoid coagulation. The derivatization efficiency values were 6-93% in the blood sample. The derivatization yield of MPA was considerably low in the coffee and blood samples.