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The neurotoxin β-N-methylamino-L-alanine (BMAA) has been widely detected in aquatic environments and got the public's attention due to its potential risk to human neurodegenerative diseases. Three cruises in spring, summer and autumn seasons were carried out in Laizhou Bay (LZB), Sishili Bay (SSLB), Sanggou Bay (SGB), Jiaozhou Bay (JZB) and Haizhou Bay (HZB) in 2023. Results showed that the temporal distribution pattern of BMAA in plankton varied in the survey bays. In LZB, the highest average concentration of BMAA in phytoplankton occurred in spring. The highest average concentration of BMAA in phytoplankton was detected in summer in SSLB, JZB and HZB. However, BMAA was only detected in phytoplankton at the R2 station in SGB in spring. The highest average concentration of BMAA in zooplankton was observed in spring in LZB, SSLB and SGB. Zooplankton accumulated the highest average concentration of BMAA in JZB and HZB in summer and autumn, respectively. The BMAA was widely detected in marine mollusks throughout the investigative period. In addition, Mantel test and RDA analysis results indicated that DIN/DIP strongly impacted on the spatiotemporal distribution of BMAA in phytoplankton, in JZB and SSLB. The spatiotemporal distribution of BMAA in plankton was correlated with temperature and DO in JZB. More field cruises should be conducted to explore the environmental drivers of the neurotoxin BMAA in marine ecosystems in future studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Glufosinate-ammonium (GLAM) can be released into adjacent water bodies with rainfall runoff and return water from farmland irrigation. However, impacts of GLAM on aquatic organisms remain unclear. In this study, changes in water quality, plant physiological parameters and epiphytic microbial community were investigated in wetlands with Hydrilla verticillata exposed to GLAM for 24 days. We found GLAM addition damaged cell and reduced chlorophyll a content in Hydrilla verticillata leaves, and increased ammonium and phosphorus in water (p < 0.001). The α-diversity increased in bacterial community but decreased in eukaryotic community with GLAM exposure. Neutral community models explained 62.3 % and 55.0 % of the variance in bacterial and eukaryotic communities, respectively. Many GLAM micro-biomarkers were obtained, including some clades from Proteobacteria, Bacteroidete, Actinobacteriota, Phragmoplastophyta, Annelida and Arthropoda. Redundancy analysis revealed that GLAM concentration was positively correlated to Flavobacterium, Gomphonema and Closterium but negatively to Methyloglobulus and Methylocystis. Network analysis revealed that 15 mg/L GLAM disturbed the interactions among phytoplankton, protozoa, metazoan and bacteria and reduced the stability of the microbial communities compared to 8 mg/L GLAM. GLAM shaped the nitrogen and phosphorus cycle related bacterial genes. This study highlights that herbicides are non-neglectable factors affecting the efficiency of aquatic ecological restoration in agricultural areas to control agricultural non-point source pollution., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The neurotoxin β-N-methylamino-L-alanine (BMAA), produced by cyanobacteria and diatoms, has been implicated as an environmental risk factor for neurodegenerative diseases. This study first investigated the occurrence and monthly distributions of BMAA and its isomers, 2,4-diaminobutyric acid (DAB) and N-2-aminoethylglycine (AEG), in phytoplankton and mussels from 11 sites along the South Sea Coast of Korea throughout 2021. These toxins were quantified using LC-MS/MS, revealing elevated BMAA concentrations from late autumn to spring, with phase lags observed between phytoplankton and mussels. The highest concentration of BMAA in phytoplankton was detected in November (mean: 1490 ng g -1 dry weight (dw)), while in mussels, it peaked in December (mean: 1240 ng g -1 dw). DAB was detected in phytoplankton but was absent in mussels, indicating limited bioaccumulation potential. In February, the peak mean DAB concentration in phytoplankton was 89 ng g -1 dw. AEG was not detected in any samples. Chlorophyll-a concentrations consistently showed an inverse correlation with BMAA concentrations in mussels throughout the year. Through correlation analysis, four diatom genera, Bacillaria, Hemiaulus, Odontella, and Pleurosigma, were identified as potential causative microalgae of BMAA. This study offers insights into identifying the causative microalgae for BMAA and informs future regulatory efforts regarding unmanaged biotoxins., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Glufosinate is a widely and increasingly used non-selective, broad-spectrum herbicide. Although cases of glufosinate poisoning are frequently reported, they are rarely documented in forensic case reports, particularly in fatal instances. The present study examined six cases of glufosinate poisoning, including a fatal case involving a 25-year-old female found deceased by the roadside, with an empty 1000 mL bottle labeled "glufosinate" by her side. Biological specimens such as plasma or cardiac blood, gastric contents, and liver tissues were collected for quantitative analysis of glufosinate levels using LC-MS/MS. In five cases of acute glufosinate poisoning, glufosinate plasma concentrations ranged from 0.62 to 3.92 μg/mL. In the fatal case, the concentrations of glufosinate in cardiac blood, gastric contents, and liver tissues were 8.41 μg/mL, 31.25 μg/mL, and 66.1 μg/g, respectively. The pathological autopsy concluded that the cause of death was acute cardio-respiratory failure due to glufosinate poisoning, characterized by multi-organ congestion without specific pathological findings. The toxicological data provided in this study aim to serve as a critical reference for future clinical treatment and forensic validation of glufosinate poisoning-related deaths., (Copyright © 2024 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.)

A new sensitive and selective analytical methodology to quantify glyphosate (GLY), aminomethylphosphonic acid (AMPA), and glufosinate (GLU) in both soil and earthworms (Allolobophora chlorotica) was developed. The extraction and purification methods were optimized. The samples were extracted with various aqueous solutions (HNO 3 , H 2 O, KOH and borate buffer) and derivatized with 9-Fluorenylmethyl chloroformate (FMOCCl). To optimize the extraction step, a method to remove the excess FMOCCl was applied based on liquid-liquid extraction with diethyl ether. The purification of derivatized extracts was carried out using XLB solid phase extraction (SPE) cartridges before internal standard quantification by liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS). The elution step was optimized to obtain the best recoveries possible, which was with acidic methanol (1% formic acid) (67% for GLY, 70% for GLU and 65% for AMPA). The extraction and purification method followed by analysis of the two herbicides and AMPA in soils using LC/MS/MS determined limit of quantification (LOQ) values of 0.030 μg g  -   1 for GLY, 0.025 μg g  -   1 for AMPA and 0.020 µg g  -   1 for GLU . For earthworms, LOQ were 0.23 μg g  -   1 for GLY, 0.20 μg g  -   1 for AMPA and 0.12 μg g  -   1 for GLU. . The developed method was applied to determine these compounds in natural soils and earthworms., Competing Interests: Declaration of Competing Interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A new green method for trace level quantification of four herbicides, glyphosate (GLYP), glufosinate (GLUF), and their main metabolites, aminomethylphosphonic acid (AMPA) and 3-(methyl-phosphinico)-propionic acid (MPPA), was developed. The purification step without any derivatization was conducted by solid-phase extraction using Chelex-100 resin in the Fe (III) form, followed by elution with 5% NH 4 OH. The four analytes were quantified by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The developed extraction method was validated on five fresh and sea water matrices with mean recoveries ranging from 80.1% to 109.4% (relative standard deviation < 20%). The extraction conditions were evaluated and certified for the high applicability of the extraction method too. The limits of detection (ng/L) in the five water matrices were in ranges 0.70 - 4.0, 2.4 - 3.9, 1.8 - 4.7, and 1.6 - 4.0 for GLYP, AMPA, GLUF, and MPPA, respectively. The method was successfully applied to detect the four compounds in surface waters sampled along the Red River Delta region in July 2019. The highest concentrations were detected at 565, 1,330, 234, and 871 ng/L for GLYP, AMPA, GLUF, and MPPA, respectively. These results showed the potential capacity of this new method for convenient monitoring of herbicides and their metabolites in the diverse natural water system., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Glyphosate and other polar and acidic pesticides have been particularly studied due to the concerns over widespread and intensive use. The chemical properties of these compounds necessitate use of customised methods, such as derivatisation or ion exchange chromatography. These approaches present a compatibility problem with ESI-MS due to presence of salts and non-volatile compounds. For that reason, a simple procedure has been developed for the extraction, pre-column derivatisation with dansyl chloride (5-(dimethylamino)naphthalene-1-sulfonyl chloride), and mass spectrometric detection of glyphosate, AMPA, and glufosinate after the separation on a C 18 stationary phase. The dansyl derivatives were characterised with ESI-MS and their separation from derivatisation reagent byproducts was demonstrated with UV absorption detection. Reagent byproducts eluted before the analytes and were separated from the analytes completely, thus the proposed procedure did not contaminate the mass spectrometers. The proposed procedure was evaluated with respect to the matrix effects and extraction efficiency, and was validated with different mass spectrometers for milk, cucumber, honey, porridge formula, bovine kidney and liver matrix. The LOQ was 10 μg kg -1 for AMPA and glufosinate, and 10-25 μg kg -1 for glyphosate, depending on matrix. Measurement uncertainties ranged from 4 to 44%. Method performance was compared to the QuPPe (Quick Polar Pesticides) procedure in combination with a diethylamino-based column from Waters™. In the case of Orbitrap™ detection, the proposed procedure had a comparable performance to the QuPPe procedure. Although, improved peak shape, higher absolute peak intensity, and lower standard deviation of the calibration curve slope was observed with the proposed procedure. This could be explained by the superior electrospray stability and lower extent of ion suppression., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A three-dimensional (3D) HPLC system in combination with fluorescence derivatization has been developed for the highly sensitive and selective analysis of chiral amino acids in extraterrestrial samples. As the targets, alanine (Ala), 2-aminobutyric acid (2AB), valine (Val), norvaline (nVal) and isovaline (iVal), frequently found chiral amino acids in the carbonaceous chondrites, were selected. These amino acids were pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), and the target analytes were separated from other amino acids and organic compounds by a reversed-phase column in the first dimension. The targets were further separated from interferences by an anion-exchange column in the second dimension, and their enantiomers were separated and determined in the third dimension by a Pirkle-type enantioselective column. The present 3D-HPLC system was validated and applied to the Murchison meteorite and the Antarctic meteorites, and all of the target amino acid enantiomers were clearly observed (0.78-22.33 nmol/g in the Murchison meteorite and 1.79-78.84 nmol/g in the Antarctic meteorites) without severe interferences. The %L values of the non-proteinogenic amino acids were almost 50% in both meteorites, and even the proteinogenic amino acids were almost racemic in the Antarctic meteorites., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Glyphosate (Glyp) and glufosinate (Gluf) are widely used herbicides around the world, and their effects on human health and detection of levels have drawn increasing attention. The present study was to establish a method to determine the contents of Glyp and Gluf from corn using multi-walled carbon nanotubes (MWCNTs) followed by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The corn samples were purified by MWCNTs, then the analytes reacted with 9-fluorenylmethylchloroformate (FMOCCl) of acetonitrile solution (20.0 g/L) at 50 °C water bath in a borate buffer solution (50.0 g/L, pH=9) to generate FMOC derivative products. After the derivatization, HSS T3 was used as the separation column, with acetonitrile and 0.05% ammonia as the mobile phase, and multiple reaction monitoring (MRM) mode with negative electrospray ionization (ESI-) was adopted. The validation parameters showed good verification results, with both of their quantitative limits (LOQ) as 0.005 mg/kg, recoveries between 90.3% and 95.4%, intra-day relative standard deviations (RSDs) in the ranges of 1.24% and 3.35%, and inter-day RSDs between 3.56% and 6.06%. The analytical method, developed in this study, has high accuracy and sensitivity, and is suitable for the simultaneous detection of Glyp and Gluf in corn., Competing Interests: Declaration of Competing Interest The authors declared that they have no conflicts of interest to this work. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted, (Copyright © 2020 Elsevier B.V. All rights reserved.)

Argentina, together with the USA and Brazil, produces approximately 80% of the total worldwide glyphosate loadings. The development of a simplified ultra-high performance liquid chromatographic tandem mass spectrometric method (UHPLC-MS/MS) for the determination of glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate in water is described, including studies of several alternatives of 9-fluorenylmethylchloroformate (FMOC-Cl) derivatization and pretreatment steps. The proposed method includes acidification and neutralization of a low sample volume (3 mL), 2 hours derivatization step, cleanup with dichloromethane, followed by reverse phase UHPLC-MS/MS determination of the analytes. Figures of merit were satisfactory in terms of linearity, selectivity, accuracy and intermediate precision (%REC 70-105% with RSD < 15%). Limits of quantification (LOQ) were suitable for monitoring purposes (0.6, 0.2, 0.1 μg/L for glyphosate, AMPA and glufosinate respectively). The validated methodology was applied for the analysis of livestock wells waters from 40 dairy farms located in the central region of Argentina. Glyphosate and AMPA were quantified in 15% and 53% of the analyzed samples with concentrations ranging from 0.6-11.3 μg/L and 0.2-6.5 μg/L respectively. Greater concentrations of glyphosate were also verified in waters from open-reservoir tanks, which are directly exposed to the farm environment. In these cases glyphosate and AMPA occurrence increased, being quantified in the 33% and 61% of the samples with values ranging 0.6-21.2 μg/L and 0.2-4.2 μg/L respectively. Also in this case glufosinate was found in 52% samples at

A reliable and sensitive method was developed for simultaneous determination of glyphosate and glufosinate in various food products by liquid chromatography-tandem mass spectrometry. Based on extraction, derivatization with 9-fluorenylmethylchloroformate and purification on solid phase extraction column, quantification was done by using isotopic-labeled analytes as internal standard and calibration in matrix. Good selectivity and sensitivity were achieved with a limit of quantification of 5 μg/kg. The recoveries of these two pesticides ranged from 91% to 114% with inter-day and relative standard deviation of 3.8-6.1% in five matrices of cereal group spiked at 5, 10, and 20 μg/kg. An accuracy profile was performed for method validation, demonstrating the accuracy and precision of the method for the studied food groups. The verification results in expanded food groups indicated extensive applicability for the analysis of glyphosate and glufosinate. Finally, the developed method was applied to analyze 136 food samples including milk-based baby foods from the French Agency for Food, Environmental and Occupational Health & Safety. Glyphosate residues were detected in two breakfast cereal samples (6.0 and 34 μg/kg). Glufosinate residues were found in a sample of boiled potatoes (9.8 μg/kg). No residues were detected in the other samples, including milk-based baby foods with limits of detection ranging from 1 to 2 μg/kg. The method has been applied for routine national monitoring of glyphosate and glufosinate in various foods., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Different innovative spectrophotometric methods were introduced for the first time for simultaneous quantification of sacubitril/valsartan in their binary mixture and in their combined dosage form without prior separation through two manipulation approaches. These approaches were developed and based either on two wavelength selection in zero-order absorption spectra namely; dual wavelength method (DWL) at 226nm and 275nm for valsartan, induced dual wavelength method (IDW) at 226nm and 254nm for sacubitril and advanced absorbance subtraction (AAS) based on their iso-absorptive point at 246nm (λ iso ) and 261nm (sacubitril shows equal absorbance values at the two selected wavelengths) or on ratio spectra using their normalized spectra namely; ratio difference spectrophotometric method (RD) at 225nm and 264nm for both of them in their ratio spectra, first derivative of ratio spectra (DR 1 ) at 232nm for valsartan and 239nm for sacubitril and mean centering of ratio spectra (MCR) at 260nm for both of them. Both sacubitril and valsartan showed linearity upon application of these methods in the range of 2.5-25.0μg/mL. The developed spectrophotmetric methods were successfully applied to the analysis of their combined tablet dosage form ENTRESTO™. The adopted spectrophotometric methods were also validated according to ICH guidelines. The results obtained from the proposed methods were statistically compared to a reported HPLC method using Student t-test, F-test and a comparative study was also developed with one-way ANOVA, showing no statistical difference in accordance to precision and accuracy., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography-heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI-MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na + , K + ) or trivalent (Al 3+ , Fe 3+ ) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu 2+ , Co 2+ , Zn 2+ , and Mn 2+ prevented glyphosate detection whereas Ca 2+ , Mg 2+ , and Sr 2+ altered the retention time. At certain tested concentrations of Ca 2+ and Sr 2+ glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca 2+ , Mg 2+ , and Sr 2+ can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI-MS/MS analysis., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The resistance to glufosinate of two lines-genetically modified (GM) and unmodified (T-590 and T-549, respectively)-of Triticum aestivum has been studied. In the GM line, the bar gene was introduced to increase the resistance to glufosinate. Experiments in a controlled growth chamber showed that line T-590 presented a high resistance to glufosinate with an ED50 value of 478.59 g active ingredient per hectare (g ai ha(-1)) versus 32.65 g ai ha(-1) for line T-549. The activity of glutamine synthetase (GS) in leaf extracts from both lines was investigated. The I50 for line T-590 was 694.10 μM glufosinate versus 55.46 μM for line T-549, with a resistance factor of 12.51. Metabolism studies showed a higher and faster penetration of glufosinate in line T-549 than in line T-590. LC-TOF/MS analysis of glufosinate metabolism at 48 h after herbicide treatment (300 g ai ha(-1)) revealed an 83.4% conversion of the herbicide (66.5% in N-acetyl-glufosinate metabolite), while in line T-549 conversion of the herbicide was about 40% (0% to N-acetyl-glufosinate). These results suggest that metabolism of glufosinate by the bar gene is a key mechanism of resistance in line T-590 that explains such high levels of herbicide tolerated by the plant, together with other mechanisms due to unmodified pathway, absorption and loss of glufosinate affinity for its target site., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

With an increasing concern on food safety, fast screening of residues of widespread herbicides becomes necessary. Herein we report a microchip electrophoresis system with laser induced fluorescence (LIF) detection for rapid and sensitive analysis of glyphosate (GLYP) and glufosinate (GLUF) residues. Disposable cyclic olefin copolymer microchips and a low-cost LIF detector were employed to minimize the cost of the analysis. Systematic optimization of experimental conditions was performed to achieve highly efficient analysis. Under the selected condition, GLYP and GLUF were efficiently resolved from sample matrices with a buffer containing 10 mmol/L borax and 2.0% (m/v) hydroxypropyl cellulose at pH 9.0. The number of theoretical plates of 1.0×10(6) m(-1) was attained for both analytes. Derivatization at lower concentrations (<10 μg/L) was also examined, successful detection of 0.34 μg/L GLYP and 0.18 μg/L GLUF was confirmed. The system was applied for the determination of both analytes in real samples without any preconcentration involved. Recoveries of GLYP and GLUF spiked in these samples were 84.0-101.0% and 90.0-103.0%, respectively., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this work, a novel method combining constant pressure-assisted head-column field-amplified sample injection (PA-HC-FASI) with in-capillary derivatization was developed for enhancing the sensitivity of capillary electrophoresis. PA-HC-FASI uses an appropriate positive pressure to counterbalance the electroosmotic flow in the capillary column during electrokinetic injection, while taking advantage of the field amplification in the sample matrix and the water of the "head column". Accordingly, the analytes were stacked at the stationary boundary between water and background electrolyte. After 600s PA-HC-FASI, 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatization reagent was injected, followed by an electrokinetic step (5kV, 45s) to enhance the mixing efficiency of analytes and reagent plugs. Standing a specified time of 10min for derivatization reaction under 35 degrees C, then the capillary temperature was cooled to 25 degrees C and the derivatives were immediately separated and determined under 25 degrees C. By investigating the variables of the presented approach in detail, on-line preconcentration, derivatization and separation could be automatically operated in one run and required no modification of current CE commercial instrument. Moreover, the sensitivity enhancement factor of 520 and 800 together with the detection limits of 16.32 and 6.34pg/mL was achieved for model compounds: glufosinate and aminomethylphosphonic acid, demonstrating the high detection sensitivity of the presented method.

Stimulants are banned by the World Anti-Doping Agency (WADA) if used "in competition". Being the analysis of stimulants presently carried out on urine samples only, it might be useful, for a better interpretation of analytical data, to discriminate between an early intake of the substance and an administration specifically aimed to improve the sport performance. The purpose of the study was to investigate the differences, in terms of excretion/disappearance of drugs, between urine and oral fluid, a sample that can reflect plasmatic concentrations. Oral fluid and urine samples were collected following oral administration of the following stimulants: modafinil (100 mg), selegiline (10 mg), crotetamide/cropropamide (50 mg each), pentetrazol (100 mg), ephedrine (12 mg), sibutramine (10 mg), mate de coca (a dose containing about 3mg of cocaine); analysis of drugs/metabolites was carried out by gas chromatography/mass spectrometry (GC/MS) in both body fluids. Our results show that both the absolute concentrations and their variation as a function of time, in urine and in oral fluid, are generally markedly different, being the drugs eliminated from urine much more slowly than from oral fluid. Our results also suggest that the analysis of oral fluid could be used to successfully complement the data obtained from urine for "in competition" anti-doping tests; in all those cases in which the metabolite(s) concentration of a substance in urine is very low and the parent compound is not detected, it is indeed impossible, relying on urinary data only, to discriminate between recent administrations of small doses and remote administrations of higher doses.

This paper describes a method for the sensitive and selective determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) residues in water and soil samples. The method involves a derivatization step with 9-fluorenylmethylchloroformate (FMOC) in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS). In the case of water samples a volume of 10 mL was derivatized and then 4.3 mL of the derivatized mixture was directly injected in an on-line solid phase extraction (SPE)-LC-MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column. Soil samples were firstly extracted with potassium hydroxide. After that, the aqueous extract was 10-fold diluted with water and 2 mL were derivatized. Then, 50 microL of the derivatized 10-fold diluted extract were injected into the LC-MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at 50 and 500 ng/L, and also in soil samples, spiked at 0.05 and 0.5 mg/kg. In water samples, the mean recovery values ranged from 89 to 106% for glyphosate (RSD <9%), from 97 to 116% for AMPA (RSD < 10%), and from 72 to 88% in the case of glufosinate (RSD < 12%). Regarding soil samples, the mean recovery values ranged from 90 to 92% for glyphosate (RSD <7%), from 88 to 89% for AMPA (RSD <5%) and from 83 to 86% for glufosinate (RSD <6%). Limits of quantification for all the three compounds were 50 ng/L and 0.05 mg/kg in water and soil, respectively, with limits of detection as low as 5 ng/L, in water, and 5 microg/kg, in soil. The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA, while it was not efficient for glufosinate, that was quantified by external standards calibration. The method developed has been applied to the determination of these compounds in real water and soil samples from different areas. All the detections were confirmed by acquiring two transitions for each compound.

A reversed phase ion-pairing high performance liquid chromatographic (RPIP-HPLC) method is developed for the separation of two phosphorus herbicides, Glufosinate and Glyphosate as well as Aminomethylphosphonic acid (AMPA), the major metabolite of Glyphosate. Tetrabutylammonium hydroxide is used as the ion-pairing reagent in conjunction with an ammonium acetate/acetic acid buffering system at pH 4.7. An inductively coupled plasma mass spectrometer (ICP-MS) is coupled to the chromatographic system to detect the herbicides at m/z = 31P. Historically, phosphorus has been recognized as one of the elements difficult to analyze in argon plasma. This is due to its relatively high ionization potential (10.5 eV) as well as the inherent presence of the polyatomic interferences 14N16O1H+ and 15N16O+ overlapping its only isotope at m/z = 31. An octapole reaction cell is utilized to minimize the isobaric polyatomic interferences and to obtain the highest signal-to-background ratio. Detection limits were found to be in the low ppt range (25-32 ng/l). The developed method is successfully applied to the analysis of water samples collected from the Ohio River and spiked with a standard compounds at a level of 20 microg/l.

The potential of capillary electrophoresis combined with mass spectrometry for the simultaneous determination of two herbicides (glyphosate and glufosinate) and their metabolites (aminomethylphosphonic acid and methylphosphinicopropionic acid) as the native species is demonstrated utilising a simple microelectrospray interface. The interface uses the voltage applied to the CE capillary to drive separation and generate the electrospray, avoiding sample dilution associated with the use of a sheath liquid interface. The chemistry of the internal walls of the capillary has a marked influence on peak shape, and appropriate choice is essential to successful operation of the interface. A linear polyacrylamide coated capillary, which has no electroosmotic flow, gave best reproducibility, with precision of migration time and peak area in the range 1-2 and 7-12% RSD, respectively, for the four analytes. Limits of detection, low-pg on-column, are substantially better than for previous methods and calibration curves over the range 1-100 microM have R2 values greater than 0.97. The observed concentration limit of detection for glyphosate in water is 1 microM and for a water-acetone extract of wheat is 2.5 microM, allowing the underivatised herbicide to be detected at 10% of the maximum residue limit in wheat.

We have developed a new analytical method to quantify the DL-homoalanine-4-yl(methyl)phosphinate (DL-GLUF) enantiomers in biological specimens using a reversed-phase high-performance liquid chromatography system with a fluorescence detection system. The derivatization of DL-GLUF enantiomers with (+)-1-(9-fluorenyl)ethyl chloroformate was carried out under mild conditions (40 degrees C for 30 min) without inducing racemization. The lower limit of quantitation was 0.01 microg/ml for both D-GLUF and L-GLUF, and the detection limit was 5 ng/ml. When DL-GLUF enantiomers were added to serum to produce concentrations between 0.1 and 100 microg/ml, the mean recovery rate was at least 93.8%. The recovery rate from urine was also satisfactory., (Copyright 2002 Elsevier Science B.V.)

A capillary electrophoresis (CE)-indirect fluorescence detection method is described for the simultaneous determination of glufosinate, glyphosate and aminomethylphosphonic acid. The three analytes were separated by CE in 5 min with a 1 mM fluorescein solution at pH 9.5. Fluorescein also functioned as a background fluorophore for the indirect detection of these nonfluorescent species. Linearity of more than two orders of magnitudes was generally obtained. The concentration limits of detection were in the microM range. Precisions of migration times and peak areas were less than 1.7% and 7.4%, respectively. Quantitation of glyphosate and glufosinate in commercial herbicides is demonstrated. In addition, the applicability of the method for the analysis of ground water was examined.

We have established a new HPLC method for derivatizing and quantifying glufosinate (GLUF) in human serum and urine using p-nitrobenzoyl chloride (PNBC). The p-nitrobenzoyl derivative of GLUF (PNB-GLUF) was produced quantitatively over 10 min at room temperature. PNB-GLUF possesses the property of ultraviolet (UV) light absorption with a lambda(max) of 272.8 nm, and was isolated from biological specimens by reversed-phase chromatography using Inertsil Ph-3. In experiments at a UV wavelength of 273 nm, GLUF has a quantitative detection limit of 0.005 microg/ml, and when it was added to both serum and urine to yield concentrations of 0.1-1000 microg/ml, its recovery rate was quite satisfactory: at least 93.8% in all cases. Further, the measured amounts of GLUF in 23 serum samples from patients intoxicated by ingestion of GLUF compared favorably with those obtained by fluorescence derivatization-HPLC using 9-fluorenylmethyl chloroformate (R=0.998). This technique of analysis is, in addition, applicable for Glyphosat, which possesses a chemical structure resembling that of GLUF, and it will be of great use in the determination of these two compounds.

A rapid and practical method for direct detection of the herbicides (glufosinate, bialaphos and glyphosate) in anion-exchange chromatography has been developed with integrated pulsed amperometric detection (IPAD). The electrochemical behavior of these herbicides showed catalytic currents based on the oxidation of amines in their structures. Waveform in IPAD was similar to that for amino acids, which exhibited adsorption/desorption catalytic features at gold electrode surface in alkaline solution. Under optimized conditions, detection limits (signal-to-noise ratio of 3) for glufosinate, bialaphos and glyphosate were 20, 65 and 50 ng ml(-1), respectively, with correlation coefficients of 0.995, 0.997 and 0.996 over concentration ranges of 0.1-45, 0.3-32 and 0.1-50 microg ml(-1), respectively. The relative standard deviations (n=5) were 1.7-3.0%. The present method was successfully applied to the determination of glyphosate in urine and serum.

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed to obtain pure erythro[2S3S, 2R3R]- and threo[2S3R, 2R3S]-beta-methylphenylalanine. These amino acids were incorporated into an enkephalin, H-Tyr-D-Ala-Gly-beta-MePhe-Val-Val-Gly-NH2, and into a deltorphin C, H-Tyr-D-Ala-beta-MePhe-Asp-Val-Val-Gly-NH2, analogue, which yielded four diastereoisomers of the peptides. The diastereoisomers were separated on different columns and with different eluent systems. The sequence of elution of the peptide diastereoisomers was determined after hydrolysis of the peptides. For identification of the beta-methylphenylalanine enantiomers, enzymatic degradation and an RP-HPLC method were used, with application of 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide as derivatizing reagent.

The fractional contributions (FC) of threonine to glycine and 2-ketobutyrate (KB) fluxes in fed pigs have been assessed by the constant infusion of L-[1-13C]-threonine. The analysis of the enantiomeric purity of labeled threonine by gas chromatography/mass spectrometric (GC/MS) analysis is reported as the N-TFA isopropyl ester derivative. The commercially available [1-13C]threonine comprised 98.7% of the L-enantiomer, enriched at 99 atom percentage excess (APE), and 1.3% of L-allo-threonine contaminant, also enriched at 99 APE. The enantiomeric purity of threonine in plasma of pigs infused for 10 h with [1-13C]threonine showed that the L-allo contaminant did not accumulate. The t-butyl dimethylsilyl derivatives of threonine, glycine, and 2-aminobutyrate (ABA) were used to measure the enrichment of these compounds in plasma and liver samples by GC/MS/selected ion monitoring analysis. Analyses were performed on between 1 and 5 nmol of each amino acid extracted from biological fluids and a 1:10 split injection. GC/MS parameters were assessed with standards at similar quantities and found to be satisfactory; e.g., injection of 1-10 nmol of glycine did not significantly alter the slope and the precision of the standard curve. The coefficient of variation of enrichment determination was less than 10% for standards enriched at 0.4 APE or more and biological samples enriched at 0.6 APE or greater. Within-animal coefficients of variation for four plasma samples obtained at equal intervals between 8 and 10 h of [1-13C]threonine infusion were 4, 21, and 24% for threonine, ABA, and glycine, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

A gas chromatographic method for the determination of gamma-aminobutyric acid (GABA) in brain tissue is described. After microwave fixation, the brains were dissected and homogenized in 0.1 N formic acid; delta-amino-n-valeric acid (AVA), a homologue of GABA, was then added as an internal standard. After centrifugation, aliquots of the supernatant were treated with cation-exchange paper to adsorb the amino acids. The eluates of this paper were dried and the residues subjected to reaction with trifluoroacetic anhydride and hexafluoroisopropanol. After removal of the derivatization reagents by evaporation, the residues were dissolved in ethyl acetate and an aliquot was analysed by gas chromatography with electron-capture or mass fragmentographic detection. Quantitation can be carried out by either peak-height or peak-area measurements. The specificity of this method has been demonstrated with brain tissue by simultaneous mass fragmentographic analysis. The sensitivity is comparable to that of mass fragmentographic methods and is in the femtomole range. The method is simple and readily automated.

Transfer of labeled glucose and alpha-amino isobutyric acid from the maternal circulation into the fetus was studied in the rat at various times during gestation and the results were correlated with placental and fetal growth. It was found that the rate of transfer of both substances per gram of placental tissue increase markedly near term in coincidence with a simultaneous fetal growth spurt. The data suggest a bimodal sequence of growth of the conceptus with a first phase of rapid placental growth and reduced placental transfer and a second phase of slow placental growth, increased transfer, and rapid fetal growth.

The xylem sap of nitrogen-fixing Pisum Sativum cv Homesteader has been examined by capillary gas chromatography and by gas chromatography mass spectrometry in both electron-impact and chemical ionization modes following the formation of N-heptafluorobutyryl isobutyl ester derivatives. One of the compounds thus detected had a mass of 389 and contained chlorine, one carboxylic acid group and a nitrogen atom. High-resolution mass spectrometry indicated that there were no other hetero atoms present in the molecule. The composition was determined to be C4H8NO2Cl. This composition can be explained only in terms of a chloroamino butyric acid.

The separation of diastereoisomeric pentafluoropropionyl-D, L-amino acid (+)-3-methyl-2-butyl esters, including those derived from histidine, arginine and tryptophan, is achieved on glass capillaries. Separation factors of between 1.03 and 1.09 are observed for the derivatives of protein amino acids. The gas chromatographic separation of a mixture of common amino acids usually takes less than 1 h.

Mice which had been housed in groups were introduced into the home cages of isolated mice and the aggressive defensive behaviour assessed. The grouped mice were chronically treated with testosterone, cyproterone acetate or arachis oil. The concentration of GABA was determined in 10 regions following the last behavioural assessment. The grouped mice which were treated with testosterone or with the anti-androgen, cyproterone acetate, were subjected to fewer aggressive attacks by the isolated mice thatn the grouped controls. The concentration of GABA in particular brain areas appears to depend on the degree of aggressive behaviour exhibited, the type of environment into which the mouse is introduced, the hormone treatment, and the housing conditions.

The ability to withstand a fasting stress as related to glucose homeostasis was studied in malnourished rats. Young male Wistar rats were fed a low-protein (D), or a low-protein, low-energy diet (M) containing, respectively, 4% protein with 70% carbohydrate (D) and 4% protein and 45% carbohydrate (M). They were compared with rats fed a control diet with 18% protein and 70% carbohydrate (C). All diets contained 8% fat. After consuming the respective diets for 4 weeks, the rats were either killed or fasted for 24 or 48 hours. Hypoglycemia developed in the malnourished rats upon fasting, but not in those receiving a complete diet. Malnourished rats had a higher blood glycine level after 4 weeks of dietary treatment. There was a marked decrease of circulating alanine and glutamate-glutamine after 48 hours of fasting in all rats. There were no differences in lysine, histidine, glycine and serine-valine. Protein malnutrition produced an increase in brain lysine, gamma-aminobutyric acid, glycine and alanine, and of glycine and alanine in liver. In contrast, D and M rats showed a depletion in muscle lysine, alanine, serine-valine and glutamate-glutamine. The fasting stress produced no changes in brain or muscle glycogen. However, liver glycogen of rats fed the D and M diets was below that of rats fed the C diet for 4 weeks. In addition, after 48 hours of fasting the C rats mobilized more exhaustively their glycogen stores that the M rats. These data suggest that in chronic malnutrition, rats may maintain their glucose homeostasis by mobilization of muscular gluconeogenic amino acids through proteolysis or de novo synthesis. Rats which were fed protein and protein-energy-deficient diets lacked adequate liver glycogen stores and their overall gluconeogenic capacity was exceeded during fasting with resultant hypoglycemia.

Amino acids have been separated by gas-liquid chromatography as their N-heptafluorobutyryl isobutyl esters. Complete resolution of derivatives of all the common amino acids has been achieved using a high-performance support-coated open-tubular capillary column. The analysis time was 30 min. Modifications to the derivatization procedure of MacKenzie and Tenaschuk have been introduced. Acylation by heating at 150 degrees was shown to be destructive; 110 degrees has been selected for routine preparation. To obtain a volatile histidine derivative it has been found necessary to add an antioxidant and to heat samples with ethoxyformic anhydride prior to injection. Amino acid analysis of beta-lactoglobulin after 6 N HCl digestion yielded results in good agreement with those obtained by the conventional ion-exchange method. The method has also been successfully applied to estimation of the different caseins in whole casein and in purified fractions by amino acid analysis of residues liberated by carboxy-peptidase digestion.

Baclofen and the internal standard are isolated from biological samples by adsorption on charcoal. After elution, the compounds are converted into butyl esters and purified by base-specific solvent extraction. The butyl esters are then N-acylated with heptafluorobutyrylimidazole, and the neutral derivatives are isolated by solvent extraction and subjected to gas-liquid chromarography, with use of an electron-capture detector. Baclofen can be determined in concentrations down to about 30 ng per sample.

A procedure is available for the production of DL-[carboxy-14C]canaline from [14C]cyanide by reaction of ethyl N-hydroxyacetimidate and acrolein to form ethyl N-[3-oxopropoxy]acetimidate. The reaction product is converted to the nitrile and then to the hydantoin derivative of DL-canaline; alkaline hydrolysis produces the free amino acid (2-amino-4-aminooxypropionic acid). This procedure can be extended to the production of DL-[carboxy-14C]canavanine by guanidination of C-1-labeled DL-canaline with O-methylisourea. A markedly improved colorimetric assay for canaline has been achieved by a procedure involving carbamylation of canaline with cyanate to form O-ureidohomoserine (2-amino-4-ureidooxybutyric acid). Colorimetric analysis of the latter amino acid markedly enhances the sensitivity, reproducibility, and accuracy of the analysis of L-canaline from biological materials.

The quantitative gas--liquid chromatographic analysis of non-protein amino acids, in the presence of protein amino acids, is described. The amino acids were determined as their N-trifluoroacetyl n-butyl esters on an ethylene glycol adipate column. The relative molar responses of 38 amino acids are reported.

A method for the simultaneous quantitation of glutamic acid and gamma-aminobutyric acid (GABA) in tissue by mass fragmentography has been developed. The amino and carboxylic groups of the two amino acids were in a convenient one-step reaction derivatized with pentafluoropropionic anhydride and hexafluoroisopropanol. Deuterium-labeled glutamic acid and GABA and a homologue of GABA have been used as internal standards. The usefulness of the technique has been demonstrated by measurements in parts of rat cerebellum and in the superior cervical ganglion.

Cysteinesulfinate, hypotaurine and taurine, which are key metabolites of cysteine, can be separated from each other and other closely eluting amino acids in biological samples by reversed-phase high-performance liquid chromatography on a Waters Nova-Pak C18 column. Samples were derivatized with o-phthalaldehyde-2-mercaptoethanol prior to injection. The elution system consisted of 100 mM potassium phosphate buffer, pH 7.0, with 3% (v/v) tetrahydrofuran with an initial isocratic phase at 1.2% acetonitrile and a gradient from 1.2 to 12.8% acetonitrile. This method is suitable for measurement of the production of metabolites from cysteine by isolated cells and for analysis of plasma and tissue extracts. Low levels of hypotaurine in rat tissues were easily measured with this method and are reported here for the first time.