Derivatization Solution Research Articles

Structural characterization of N-acyl-homoserine lactones from bacterial quorum sensing using LC-MS/MS analyses after Paternò-Büchi derivatization in solution.

Bacterial quorum sensing is a chemical language allowing bacteria to interact through the excretion of molecules called autoinducers, like N-acyl-homoserine lactones (AHLs) produced by Gram-negative Burkholderia and Paraburkholderia bacteria known as opportunistic pathogens. The AHLs differ in their acyl-chain length and may be modified by a 3-oxo or 3-hydroxy substituent, or C = C double bonds at different positions. As the bacterial signal specificity depends on all of these chemical features, their structural characterization is essential to have a better understanding of the population regulation and virulence phenomenon. This study aimed at enabling the localization of the C = C double bond on such specialized metabolites while using significantly lower amounts of biological material. The approach is based on LC-MS/MS analyses of bacterial extracts after in-solution derivatization by a photochemical Paternò-Büchi reaction, leading to the formation of an oxetane ring and subsequently to specific fragmentations when performing MS/MS experiments. The in-solution derivatization of AHLs was optimized on several standards, and then the matrix effect of bacterial extracts on the derivatization was assessed. As a proof of concept, the optimized conditions were applied to a bacterial extract enabling the localization of C = C bonds on unsaturated AHLs.

Towards a better understanding of ethylmercury in the environment: Addressing propylation derivatization artifact and verifying its occurrence in Chinese wetlands

Ethylmercury (EtHg), similar to methylmercury (MeHg), is highly neurotoxic and bioaccumulative. Although recent studies suggested its occurrence in natural soils and sediments, the common propylation derivatization for EtHg analysis might generate EtHg artifacts, potentially leading to its overestimation in environmental samples. Furthermore, the extensive environmental prevalence of EtHg remains unverified, keeping its importance largely uncertain. This study investigated the formation of EtHg artifacts during propylation derivatization, evaluating artifacts formation and recoveries under different extraction methods with real samples, and confirmed the widespread occurrence of EtHg in Chinese wetlands. EtHg artifacts were obviously present during the propylation derivatization and strongly dependent on the levels of Hg2+ (0.1–10 ng) in the derivatization solution (R² = 0.99), accounting for 1.38–2.14% of Hg2+. CuSO4-HNO3CH2Cl2 extraction (effectively removing Hg2+) combined with propylation derivatization offers excellent recovery (81–86%) and low artifacts (< LOD: 1.98 × 10−4 ng/g) for EtHg measurement in soils/sediments, with results aligning with those from online solid phase extraction-high performance liquid chromatography-inductively coupled plasma mass spectrometry (R2 = 0.99). Additionally, we observed the occurrence of EtHg in soil and sediment samples across 14 Chinese wetlands, with concentrations varying from 6.08 to 171 pg/g, similar to MeHg concentrations at some sites. EtHg positively correlates with MeHg, total Hg, and total organic carbon across all samples, indicating a possible biological formation. These findings help better understand and predict the prevalence of EtHg in wetlands and its key role in environmental Hg cycle.

Determination of aliphatic aldehydes C1–C5 with headspace solid phase microextraction in tap water: derivatization in-solution versus on-fiber

Determination of aliphatic aldehydes C1–C5 with headspace solid phase microextraction in tap water: derivatization in-solution versus on-fiber

High-Performance Liquid Chromatography-Tandem Mass Spectrometry Analysis of Carbonyl Emissions from E-Cigarette, or Vaping, Products.

A quantitative method was developed to measure four harmful carbonyls (acetaldehyde, acrolein, crotonaldehyde, and formaldehyde) in aerosol generated from e-cigarette, or vaping, products (EVPs). The method uses a commercially available sorbent bed treated with a derivatization solution to trap and stabilize reactive carbonyls in aerosol emissions from EVPs to reduce reactive analyte losses and improve quantification. Analytes were extracted from the sorbent material using acetonitrile and analyzed via high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). The method was applied to aerosols generated from products obtained from case patients with EVP use-associated lung injury (EVALI). The method accuracy ranged from 93.6 to 105% in the solvent and 99.0 to 112% in the matrix. Limits of detection (LODs) were in the low nanogram range at 0.735–2.10 ng for all analytes, except formaldehyde at 14.7 ng. Intermediate precision, as determined from the replicate measurements of quality-control (QC) samples, showed a relative standard deviation (RSD) of less than 20% for all analytes. The EVALI case-related products delivered aerosol containing the following ranges of carbonyls: acetaldehyde (0.0856–5.59 μg), acrolein (0.00646–1.05 μg), crotonaldehyde (0.00168–0.108 μg), and formaldehyde (0.0533–12.6 μg). At least one carbonyl analyte was detected in every product. Carbonyl deliveries from EVALI-associated products of all types are consistent with the previously published results for e-cigarettes, and levels are lower than those observed in smoke from combustible cigarettes. This method is rugged, has high throughput, and is well suited for quantifying four harmful carbonyls in aerosol emissions produced by a broad spectrum of devices/solvents, ranging from e-cigarette containing polar solvents to vaping products containing nonpolar solvents.

A new approach for the analysis of amino acid neurotransmitters in mouse brain tissues using DESI imaging

Mass spectrometry imaging using desorption electrospray ionization (DESI imaging) is a method with the potential to investigate the distribution of neurotransmitters (biogenic amines and amino acids) in brain tissues. Because of the low ionization efficiency of neurotransmitters in direct tissue analysis by DESI, neurotransmitters can be analyzed using derivatization protocols that insert a known compound into their structures through a chemical reaction due to signal suppression by lipids. In this sense, this work aims to combine a chemical derivatization protocol with DESI imaging in order to improve the analysis sensitivity of the amino acids glycine (Gly), alanine (Ala), dopamine (Dop), and gamma-aminobutyric acid (GABA) in mouse brain tissues, as well as to apply this protocol to analyze mice with Parkinson's disease. Derivatization took place using the reagent 2,4,6-triphenylpyrylium tetrafluoroborate (TPP+) and was first investigated in a solvent to ensure the detection of the expected products. Subsequently, the brain tissue surface was subjected to the derivatization solution through spraying. Then, the tissue was analyzed by DESI, and the derivatized Gly, Ala, Dop, and GABA were detected. DESI imaging analysis demonstrated distinct spatial distributions for these derivatized amino acid neurotransmitters. The application of the protocol in brain sections from mice with Parkinson's disease demonstrated differences in the intensities and anatomical distribution for the derivatized amino acids compared with control tissues (unaffected by Parkinson's). The protocol combining derivatization with DESI imaging described in this work emerges as a potential tool for analyzing Parkinson's disease biomarkers in mouse brain tissues.

Combining the Katritzky Reaction and Paper Spray Ionization Mass Spectrometry for Enhanced Detection of Amino Acid Neurotransmitters in Mouse Brain Sections.

This work describes the development of a system that combines a derivatization protocol based on the Katritzky reaction with paper spray ionization mass spectrometry (PSI-MS) for the analysis of amino acid neurotransmitters in mouse brain tissues. The system is relatively simple, consisting of spraying the derivatization solution onto a mouse brain section mounted on a glass slide, applying a small volume of solvent to moisten the sample, pressing a triangular paper onto the sample surface to transfer the sample constituents to the paper surface, and using the paper as a substrate for PSI-MS analysis. The Katritzky reaction facilitated the ionization of the amino acids by reacting a pyrylium salt with the amino group of the analytes, forming very stable pyridinium cations, which greatly increased the sensitivity of the PSI-MS analysis. Most of the intensities of the amino acids modified by the Katritzky reaction were more than 10 times greater than the nonderivatized ones. The system was applied for the analysis of brain sections obtained from mice with Parkinson's disease, and the amino acids gamma-aminobutyric acid (GABA) and glycine (Gly), two compounds very well-known in studies of Parkinson's disease, were readily detected. The results suggest that the Katritzky reaction combined with PSI-MS might offer a significant advance in the knowledge on protocols that improve the sensitivity of detection of crucial biological compounds.

In-solution derivatization and detection of glyoxal and methylglyoxal in alcoholic beverages and fermented foods by headspace solid-phase microextraction and gas chromatography–mass spectrometry

A simple and sensitive method for the simultaneous determination of glyoxal and methylglyoxal in alcoholic beverages and fermented foods was developed. This method involved simultaneous derivatization in solution with 2,2,2-trifluoroethyl hydrazine (TFEH) and headspace solid phase microextraction, followed by detection via gas chromatography-mass spectrometry (GC–MS). The method established herein can be summarized as follows. The sample was adjusted to pH 6.0 in a headspace vial, saturated with sodium chloride, and allowed to react with TFEH at 85 °C for 20 min. The formed derivatives were vaporized and adsorbed on divinylbenzene/carboxy/polydimethylsiloxane fibers. The TFEH derivatives were subsequently desorbed and analyzed by GC–MS, where the spectrum showed a single sharp peak. Under the established conditions, the quantification limits of glyoxal and methylglyoxal were 3.6 and 2.1 μg kg−1, respectively, and the relative standard deviations were under 8% at concentrations of 20, 100 and 2000 μg kg−1. All samples were detectable at typical glyoxal (62–4116 μg kg−1) and methylglyoxal (11–2342 μg kg−1) concentrations in beverages and foods.

HPLC Method for Determination and Optimization of 2,4-DNPH PreColumn Derivatization Effect of Reaction Conditions for Muscone in Natural Musk

To establish a method for the determination of muscone in natural musk by pre-column derivatization HPLC with 2, 4-Dinitrophenyl hydrazine (DNPH) and the reaction conditions were optimized. The influencing factors of derivatization reaction were investigated by single factor, and the main influencing factors were optimized by orthogonal test. Under the optimum reaction conditions, muscone-DNPH derivatives were obtained and detected by 365 nm following the Alltima C18 column (5 μm, 150 mm × 4.6 mm) separation. Single factor investigation revealed: the suitable reaction medium and catalyst were ethanol and hydrochloric acid, respectively; the molar ratio of muscone to DNPH should not be less than 300 times, the appropriate reaction time was 20 min or more; the effect of reaction temperature on derivatization reaction was obvious and needs to be optimized. Furthermore, the orthogonal test of acid concentration, reaction time and temperature showed that the effect of temperature on reaction was significant (p 0.05); The optimum reaction conditions were: reaction temperature was 65°C, hydrochloric acid be added to derivatization solution was (1.25:98.75) (mL/mL) and the reaction time was 30 min. Under this conditions, there was good linearity in range of 0.04 μg•mL-1-30.00 μg•mL-1 for muscone (r=0.999 9), the average spiked recoveries were 98.37%-100.32% and their RSD were 0.57%-1.32%. All the RSD of repeatability of sample and standard treatment were less than 4.12%; the limits of detection (S/N=3) and quantitation (S/N=15) were 0.005 μg•mL-1 and 0.04 μg•mL-1 respectively. The established method for detecting is accurate with good reproducibility and can be used for determination of muscone in natural musk.

A Simple Method for On-Gel Detection of Myrosinase Activity

Myrosinase is an enzyme present in many functional foods and spices, particularly in Cruciferous vegetables. It hydrolyses glucosinolates which thereafter rearrange into bioactive volatile constituents (isothiocyanates, nitriles). We aimed to develop a simple reversible method for on-gel detection of myrosinase. Reagent composition and application parameters for native PAGE and SDS-PAGE gels were optimized. The proposed method was successfully applied to detect myrosinase (or sulfatase) on-gel: the detection solution contains methyl red which gives intensive red bands where the HSO4− is enzymatically released from the glucosinolates. Subsequently, myrosinase was successfully distinguished from sulfatase by incubating gel bands in a derivatization solution and examination by LC-ESI-MS: myrosinase produced allyl isothiocyanate (detected in conjugate form) while desulfo-sinigrin was released by sulfatase, as expected. After separation of 80 µg protein of crude extracts of Cruciferous vegetables, intensive color develops within 10 min. On-gel detection was found to be linear between 0.031–0.25 U (pure Sinapis alba myrosinase, R2 = 0.997). The method was successfully applied to detection of myrosinase isoenzymes from horseradish, Cruciferous vegetables and endophytic fungi of horseradish as well. The method was shown to be very simple, rapid and efficient. It enables detection and partial characterization of glucosinolate decomposing enzymes without protein purification.

Stability of Isocyanates Sampled in Fire Smokes.

Inhalation of airborne isocyanates is associated with acute asthma attacks and inflammation in the respiratory tract as well as cancer. These highly reactive compounds are used as monomers in various applications such as foams for insulation materials and upholstery furniture and are therefore commonly found in fire smoke from insulation materials, such as rigid polyisocyanurate (PIR) foams. Consequently, there is an increasing concern regarding the potential adverse health effects they may cause during this type of exposure.The aim of this study was to investigate the stability of generated isocyanates from aerobic pyrolysis of PIR after sampling in the derivatization solution as well as after sample preparation to establish the optimal storage conditions and rate of degradation. Both airborne and particle-bound isocyanates were collected, using dibutylamine as derivatization agent in a midget impinger and impregnated filter after the impinger. The rapid degradation of the generated isocyanates after sampling emphasizes the need for a prompt sample preparation and analysis, in particular for the collected mono-isocyanates, as the concentration decreased by 50% within 4-8 h.

Optimization of a Precolumn OPA Derivatization HPLC Assay for Monitoring of l-Asparagine Depletion in Serum during l-Asparaginase Therapy.

A method for monitoring l-asparagine (ASN) depletion in patients' serum using reversed-phase high-performance liquid chromatography with precolumn o-phthalaldehyde and ethanethiol (ET) derivatization is described. In order to improve the signal and stability of analytes, several important factors including precipitant reagent, derivatization conditions and detection wavelengths were optimized. The recovery of the analytes in biological matrix was the highest when 4% sulfosalicylic acid (1:1, v/v) was used as a precipitant reagent. Optimal fluorescence detection parameters were determined as λex = 340 nm and λem = 444 nm for maximal signal. The signal of analytes was the highest when the reagent ET and borate buffer of pH 9.9 were used in the derivatization solution. And the corresponding derivative products were stable up to 19 h. The validated method had been successfully applied to monitor ASN depletion and l-aspartic acid, l-glutamine, l-glutamic acid levels in pediatric patients during l-asparaginase therapy.

Molecular level investigation of the role of peptide interactions in the glyphosate analytics

The detection of the herbicide glyphosate (GLP) in environmental samples is most often conducted after derivatizing the target molecule with the chromophore 9-fluorenylmethyloxycarbonyl chloride (FMOC-Cl). However, this method is sensitive to all primary and secondary amines, which can occur in the sample matrix as well. In order to quantify the interference of primary and secondary amines on GLP detection, we have used well-defined peptides such as pentaglycine (PG) and albumin as well as mixtures of peptides such as peptone. These peptides have been added to the derivatization solution of GLP at different constant concentration levels and UV extinction coefficients have been determined. Data analysis supported by quantum chemical modeling of the GLP–peptide, FMOC–GLP, and FMOC–peptide complexation reactions facilitated the identification of two interfering impacts of peptide on GLP derivatization: (i) increase of the signal due to reaction with FMOC-Cl leading to an overestimation of GLP concentration and (ii) decrease of GLP recovery due to complex formation and therefore inhibition of GLP derivatization, which leads to an underestimation. Specifically, our results indicated that the GLP-peptide- and peptide-FMOC-interactions are mainly affected by type of interfering peptides as well as concentration of each peptide and GLP in the environmental samples.

Rapid profiling method for mammalian feces short chain fatty acids by GC-MS

Short chain fatty acids (SCFAs) are key feces metabolites generated by gut bacteria fermentation.Despite the importance of profiling feces SCFAs, technical difficulties in analysis remain due to their volatility and hydrophilicity. We improve previous protocols to profile SCFAs and optimize the metabolite profiling platform for mammalian feces samples.In this study, we investigated feces as biological samples using gas chromatography-mass spectrometry (GC-MS). Isobutyl chloroformate was used for a derivatization in aqueous solution without drying out the samples.Ultimately, we envisage being able to determine the way in which gut bacteria fermentation influences host gut condition by using our rapid metabolite profiling methods.

Simultaneous analysis of free amino acids and taurine-related compounds in deep-sea mussel tissues using reversed-phase HPLC

Taurine and hypotaurine are abundantly present in molluskan tissues; however, the pathways for their biosynthesis have not yet been well investigated. In this study, we established a method for simultaneous detection of taurine-related compounds, including taurine, hypotaurine, cysteic acid, cysteine sulfinic acid (CSA), cystathionine, γ-aminobutyric acid, and β-alanine along with 17 free amino acids, using phenylthiocarbamyl derivatization in ammonia-containing solution, followed by injection into reversed-phase high-performance liquid chromatography. Using this method, we analyzed the major tissues (gill, mantle, adductor muscle, foot, and digestive gland) of the hydrothermal-vent-specific mussel Bathymodiolus septemdierum. The gill and digestive gland were suggested to be the major organs for taurine/hypotaurine biosynthesis because taurine and hypotaurine levels tended to be high, and their precursors, i.e., cysteine, cysteic acid, and CSA (only in digestive gland), were detected in these two tissues. Cystathionine was detected at relatively high level in digestive gland and in other tissues at low levels, suggesting its role as storage material for taurine/hypotaurine biosynthesis. Adductor muscle was found to be rich in free amino acids, mainly due to abundance of non-sulfur-containing amino acids.

High sensitivity HPLC method for analysis of in vivo extracellular GABA using optimized fluorescence parameters for o-phthalaldehyde (OPA)/sulfite derivatives.

Reversed-phase HPLC with derivatization using o-phthalaldehyde (OPA) and sulfite allows electrochemical detection of γ-aminobutyric acid (GABA) in microdialysis samples. However, OPA/sulfite derivatives have been reported to produce lower fluorescent yield than OPA derivatives using organic thiols as the nucleophile. To overcome this limitation we examined excitation and emission spectra, reaction time, pH, and concentration of reagents in the derivatization solution. Optimal detection parameters were determined as λex=220nm and λem=385nm for maximal fluorescence. The derivatization reaction occurred immediately and the product was stable up to 24 h [corrected]. A pH of 10.4 for the borate buffer used in the derivatization solution was significantly better than lower pH. Increasing the amount of sulfite combined with diluting the derivatization solution in borate buffer resulted in complete separation of the GABA peak from contaminants without any loss in signal. Controlling the temperature of the detector at 15°C significantly improved sensitivity with a detection limit of approximately 1nM. To validate this assay, we performed microdialysis in the dorsal striatum and ventral tegmental area (VTA) of adult Long Evans rats. GABA concentrations in dialysates were determined using external standards and standard additions, in order to further confirm interfering peaks were not present in biological samples. Within the dorsal striatum (n=4), basal GABA concentrations were 12.9±2.2 and 14.5±2.2nM (external and additions, respectively). Respective basal GABA concentrations in the VTA (n=3) were 4.6±1.1 and 5.1±0.6nM. Thus, we have developed a novel, sensitive fluorescence method to determine GABA in microdialysates using HPLC of an OPA/sulfite derivative.

Indirect Enantioseparation of Amino Acids by CE Using Automated In-Capillary Derivatization with ortho-Phthalaldehyde and N-Acetyl-l-Cysteine

A simple CE method for the assessment of enantiomeric purity of individual amino acids (AAs) is presented. The AAs were derivatized with ortho-phthalaldehyde and a thiol in the capillary by means of successive hydrodynamic injections (5 s, 0.5 psi) of derivatization solution, sample and derivatization solution. A voltage of 1 kV was applied to blend the solutions and to start the reaction. Subsequently, the derivatives were separated using a background electrolyte (BGE) composed of 50 mM borate buffer (pH = 9.25) and 7.5 mM of a cyclodextrin (CD). To find the optimal derivatization reagent and CD, the impact of the thiols 3-mercaptopropionic acid (MPA), N-acetyl-l-cysteine (NAC) and N-isobutyryl-l-cysteine (NIBLC), and various neutral and negatively charged CDs on the resolution were assessed. The use of NAC and γ-CD enabled the best indirect enantioseparation of 16 AAs. Serine could be separated with β-CD, and proline and cysteine are not suitable for automated OPA-derivatization. The resolutions were ranging from 2.3 to 16.6. A method was validated representative for the AAs methionine, aspartic acid, tryptophan and phenylalanine. The recovery (n = 3) of the minor enantiomers was found to be within 95.1 and 107.5 %. The relative standard deviation (RSD) was ranging from 1.2 to 6.4 %. The method is accurate, precise, linear, and robust. For methionine it could be demonstrated that the ratio of l- and d-AA ranging from 1 to 99 % can be evaluated by direct comparison of the corrected peak areas with satisfactory accuracy ranging between 92.1 and 115.9 %.

Determination of amphetamines in hair by integrating sample disruption, clean-up and solid phase derivatization

The utility of matrix solid phase dispersion (MSPD) for the direct analysis of amphetamines in hair samples has been evaluated, using liquid chromatography (LC) with fluorescence detection and precolumn derivatization. The proposed approach is based on the employment of MSPD for matrix disruption and clean-up, followed by the derivatization of the analytes onto the dispersant-sample blend. The fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC) has been used for derivatization. Different conditions for MSPD, analyte purification and solid phase derivatization have been tested, using amphetamine (AMP), methamphetamine (MET), ephedrine (EPE) and 3,4-methylenedioxymethamphetamine (MDMA) as model compounds. The results have been compared with those achieved by using ultrasound-assisted alkaline digestion and by MSPD combined with conventional solution derivatization. On the basis of the results obtained, a methodology is proposed for the analysis of amphetamines in hair which integrates sample disruption, clean-up and derivatization using a C18 phase. Improved sensitivity is achieved with respect to that obtained by the alkaline digestion or by the MSPD followed by solution derivatization methods. The method can be used for the quantification of the tested amphetamines within the 2.0–20.0ng/mg concentration interval, with limits of detection (LODs) of 0.25–0.75ng/mg. The methodology is very simple and rapid (the preparation of the sample takes less than 15min).

No Quantifiable Carbonyls, Including Formaldehyde, Detected in Voke® Inhaler

Carbonyls such as formaldehyde, acetaldehyde, and acrolein have been detected in e-cigarette vapors, with one study (albeit at a higher than the typical voltage) reporting formaldehyde-releasing agents in quantities sufficient to increase the risk of cancer by 5–15 fold when compared with long-term smoking. This study examines the Voke® Inhaler for traces of carbonyls and aims to quantify any that are detected in its aerosol. Three batches of five Voke® devices each were charged with formulation and allowed to rest for 0, 1, and 24 hr respectively, before being sampled. Aerosol from each device was extracted using a linear smoking machine and collected by dissolution into DNPH derivatization solution. Samples of the extract solution were analyzed for carbonyls using UHPLC. Results were reported as µg/8 puffs. Samples were analyzed for the presence of formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, butan-2-one, and butyraldehyde. At the given LOD, no carbonyls were detected in 13 of the 15 samples tested. Acetaldehyde was detected in two samples, one tested immediately after charging and the other tested 1 hr after sampling; however, both samples contained the analyte in quantities below its LOQ (3.18 µg/mL). Among various carbonyls, formaldehyde, in particular, has been identified as a known carcinogen by the IARC and as a probable human carcinogen by the US EPA. The absence of measurable quantities of carbonyls in the Voke® Inhaler establishes its clear distinction from e-cigarettes and reflects on a significant advantage of not having a heating element.

Determination of Dicarboxylic Acids in Fine Atmospheric Particles by Micro-Pressurized Liquid Extraction Coupled with Gas Chromatography-Mass Spectrometer

Abstract The method of micro-pressurized liquid extraction (μ-PLE) coupled with gas chromatography-mass spectrometer (GC-MS) for analysis of 4 dicarboxylic acids (DCAs, including malonic acid, succinic acid, glutaric acid, and adipic acid) in fine atmospheric particles was developed. PM2.5 filter sample was extracted by μ-PLE at a pressure of 8 MPa and temperature of 80 °C using methanol as extraction solution. After two static 5-min extractions and a rinsing step with 100 μL methanol, about 500 μL of extraction solution was obtained. The extraction solution was then blown to dry with high purity nitrogen and submitted to a silylation reaction at 60 °C for 30 min. After internal standard (IS) was added, the derivatization solution was directly injected for GC-MS analysis. For quantification of 4 normally DCAs in fine atmospheric particles, the calibration curve was obtained with a good linear relationship in the range of 0.2–20 ng μL−1. The limits of quantification (LOQs, S/N = 10) were in the range of 0.15–0.47 ng m−3. The relative recoveries were between 92% and 122% with the RSDs between 2.6% and 11.8% for spiked filter samples. The method developed here was used to determine malonic acid, succinic acid, glutaric acid, and adipic acid in real PM2.5 samples collected from Xinghai Bay of Dalian city, and the results were determined to be 64.6, 50.0, 41.8 and 20.2 ng m−3, respectively.

Determination of Water- and Methanol-Extractable Pentachlorophenol in Soils Using Vortex-assisted Liquid-Liquid Extraction and Gas Chromatography

Abstract An analytical procedure for determination of water- and methanol-extractable pentachlorophenol (PCP) in soils was developed using vortex-assisted liquid-liquid extraction (VALLE) and gas chromatography (GC). Significant extraction parameters such as vortex speed and liquid-liquid volume ratio were optimized for extracting PCP from solution. The recovery of PCP was the highest (97.4%) with good reproducibility and a small relative standard deviation (RSD, 0.5%) when the vortex speed was at 2000 rpm. Meanwhile, when the volume ratio of derivatization solution to n-hexane was at 10:4, the recovery of PCP was 103% with a RSD of 0.7%. The linearity of the calibration curve for PCP determination ranged from 1.25 μg L−1 to 4000 μg L−1, with a correlation coefficient (R2) of 0.9999. The detection limit of PCP in water samples was below 0.2 μg L−1 and the measuring range was relatively wide, and suitable for trace- and micro-analysis of PCP. Compared with traditional extraction methods (liquid-liquid and solid-phase), VALLE consumes less extractant, requires fewer steps, and achieves higher recovery (96.8%) and smaller RSD (3.7%). The reliability of VALLE was verified in four distinct types (paddy, red, black and alluvial) of soil samples spiked with 1 and 10 mg kg−1 PCP. The total recoveries of PCP in the soil samples were in the range of 89.5%–98.9% by water extraction and 88.7%–98.4% by 3 consecutive extractions with methanol in a sequential procedure. The results indicated that VALLE-GC satisfied the requirements for extracting and determining water- and methanol-extractable PCP in soils polluted by PCP at varying levels.