[Determination of 1-chloro-2,3-epoxypropane in order to assess the working environment]. / Oznaczanie 1-chloro-2,3-epoksypropanu dla potrzeb oceny srodowiska pracy.

BACKGROUND: 1-Chloro-2,3-epoxypropane, known as epichlorohydrin (ECH), is a colorless liquid used in the production of epoxy resins, synthetic glycerine, elastomers, glycidyl ethers, surfactants, polyamide-epichlorohydrin resins and others. Epichlorohydrin may cause cancer. The aim of this study was to develop a new method for determining concentrations of ECH in workplace air in the range of 1/10-2 values of the maximum admissible concentration (MAC). MATERIAL AND METHODS: The paper presents a method for the determination of ECH in workplace air using a gas chromatograph coupled with a mass spectrometer (GC-MS). The developed method is based on the adsorption of ECH on an activated charcoal, extraction with acetone, and a chromatographic analysis of the resulting solution. RESULTS: The method developed makes it possible to determine ECH in the concentration range of 0.1-2 mg/m3, i.e., 1/10-2 values of MAC established in Poland. The limit of detection (LOD) is 0.24 µg/m3 and the limit of quantification (LOQ) is 0.71 µg/m3. CONCLUSIONS: The method is characterized by good precision and accuracy; it meets the requirements of the European standard PN-EN 482, and can be used by occupational hygiene laboratories to measure concentrations of ECH in workplace air, with a view to assessing workers' exposure to this substance. Med Pr. 2020;71(6):715-23.

Determination of chlorinated volatile organic compounds in polyamine epichlorohydrin solution by headspace gas chromatography.

This study demonstrated a headspace gas chromatographic (HS-GC) method for the determination of residual epichlorohydrin (ECH) and the by-product 1,3-dichloro-2-propanol (DCP) in polyamine epichlorohydrin (PAE) solution. It was based on the vapor-liquid phase equilibrium of these analytes at 60°C for 30min in a closed headspace sample vial before GC measurement. It was found that matrix of the PAE solution had the effect on the headspace equilibrium of these species and therefore a standard addition must be applied in the method validation. The results showed that the present method has a good measurement precision (RSD <2.90%) and accuracy (recoveries from 93.6 to 105%), and the limit of quantitation (LOQ) is 3.75mg/L for ECH and 0.8g/L for DCP. The present method is suitable to be used for analyzing the chlorinated volatile organic compounds in the commercial PAE resin solutions.

[Determination of epichlorohydrin in workplace air by gas chromatograph-electron capture detector].

OBJECTIVE: To develop a method for determining epichlorohydrin in the workplace air by gas chromatograph-electron capture detector (GC-ECD). METHODS: Epichlorohydrin in the workplace air was collected by activated charcoal tubes, desorbed using acetone, and analyzed by GC-ECD. RESULTS: A good linearity was obtained in the range of 1.0-50 µg/mL (r=0.999 7). The detection limit was 0.012 µg/ml, while the recovery rate was 88.1% and relative standard deviation ranged from 1.11% to 3.57%. The samples could be stored for seven days at room temperature. CONCLUSION: This method effectively eliminates the interferences of alkanes on determination of epichlorohydrin and improves the sensitivity by 1 to 2 orders of magnitude, which can solve the problem of detection limit above standard in GBZ/T 160.58-2004.

Controlled drug release from cross-linked κ-carrageenan/hyaluronic acid membranes.

In this work, hydrogel membrane composed of; kappa carrageenan (κC) and hyaluronic acid (HA) crosslinked with epichlorohydrine is produced. The optimum condition has been established based on their water absorption properties. Tensile strength (TS) and elongation (E%) for the formed films are evaluated. The obtained films were characterized by FTIR, scanning electron microscopy (SEM) and thermal analysis. All membranes were loaded with l-carnosine as a drug model. The swelling properties and kinetics of the release of the model drug from the crosslinked hydrogel membrane were monitored in buffer medium at 37°C. The equilibrium swelling of films showed fair dependency on the high presence of HA in the hydrogel. Moreover, the cumulative release profile increased significantly and ranged from 28% to 93%, as HA increases. SEM explored that, the porosity increased by increasing HA content; consequently, drug release into the pores and channels of the membranes is facilitated. In addition, water uptake % increased as well. A slight change in TS occurred by increasing the HA% to κC, while the highest value of strain for κC membrane was 498.38% by using 3% HA. The thermal stability of the κC/HA was higher than that of HA.

New agar microspheres for the separation and purification of natural products.

A new type of agar chromatography media has been prepared with a yield over 80% using a water-in-oil emulsion technique. These microspheres have regular spherical shapes and particle diameters in the range 40-165 µm (average ∼90 µm). Cross-linking of the resulting agar microspheres with epichlorohydrin and 1,4-butanediol diglycidyl ether enhanced their mechanical and thermal stability. The alkaline conditions used during the cross-linking reaction also decreased the content of ionized sulfate groups of the polysaccharide, thus reducing the nonspecific adsorption of positively charged molecules. The cross-linked agar microspheres were functionalized with (i) branched poly(ethyleneimine) to obtain a stationary phase useful for the separation of proteins in an anion-exchange mode and (ii) with poly-ß-cyclodextrin enabling direct isolation and purification of puerarin from a crude extract of Radix puerariae. Using a 23.5 mL column loaded with 20 mg extract (0.85 mg/mL gel), puerarin with a purity of 96% was recovered with a yield of 86%.

Expression, characterization, and improvement of a newly cloned halohydrin dehalogenase from Agrobacterium tumefaciens and its application in production of epichlorohydrin.

A gene encoding halohydrin dehalogenase (HHDH) from Agrobacterium tumefaciens CCTCC M 87071 was cloned and expressed in Escherichia coli. To increase activity and stability of HHDH, 14 amino acid residues around the active site and substrate-binding pocket based on the structural analysis and molecular docking were selected as targets for site-directed mutagenesis. The studies showed that the mutant HHDH (Mut-HHDH) enzyme had a more accessible substrate-binding pocket than the wild-type HHDH (Wt-HHDH). Molecular docking revealed that the distance between the substrate and active site was closer in mutant which improved the catalytic activity. The expressed Wt-HHDH and Mut-HHDH were purified and characterized using 1,3-dichloro-2-propanol (1,3-DCP) as substrates. The specific activity of the mutant was enhanced 26-fold and the value of k cat was 18.4-fold as compared to the Wt-HHDH, respectively. The Mut-HHDH showed threefold extension of half-life at 45 °C than that of Wt-HHDH. Therefore it is possible to add 1,3-DCP concentration up to 100 mM and epichlorohydrin (ECH) was produced at a relatively high conversion and yield (59.6 %) using Mut-HHDH as catalyst. This Mut-HHDH could be a potential candidate for the upscale production of ECH.

[On the problem of the study of the chemical air pollution with chlororganic hydrocarbons at productions of polyvinyl chloride and epichlorohydrin].

Hygienic assessment of working conditions at the chemical productions of polyvinyl chloride (PVC) and epichlorohydrin (EPCH) in East Siberia has shown that the employees are exposed to the chlororganic hydrocarbons of hazard category 1-2, out of them there were found to be more toxical pollutants such as vinyl chloride, 1.2-dicloroethane in the production of polyvinyl chloride; allyl chloride and epichlorohydrin in the production of epichlorohydrin. Multistageness of the technological processes, the absence of the isolation of main stages of the technological processes as well as the heating microclimate contribute to the chemical pollution of the air environment. In spite of the significant improvement of the hygienic situation at the productions mentioned in the recent 10 years according to the chemical factor due to the introduction of the complex of curative measures, the working conditions of the employees still belonged to the harmful category. According to the content of the harmful chemical substances in the air of the working zone and the parameters of microclimate, the working conditions of the employees working at the production of epichlorohydrin and in the shop of vinyl chloride production must be qualified as the harmful ones of the first category of the hazard and danger (Class 3.1), in the production shop for PVC- as the harmful ones which correspond to the second category of the hazard and danger (Class 3.2).

[Determination of epichlorohydrin in drinking water by isotope dilution gas chromatography-mass spectrometry].

OBJECTIVE: To establish a method for determination of the epichlorohydrin in drinking water by isotope dilution gas chromatography-mass spectrometry (GC-MS). METHODS: The internal standard solution D5-epichlorohydrin was added in drinking water sample. The epichlorohydrin was firstly collected by active carbon, and the adsorbent was then centrifuged at 2739 × g for 10 min to remove water. Finally, the epichlorohydrin was desorbed by dipping the active carbon in 1.0 ml acetone for 1 h. The desorbed solution was tested by GC-MS and quantified with isotopic internal standards. The detection limit, precision and accuracy of the assay were evaluated. This method was adopted to detect the epichlorohydrin in drinking water for 25 batches in a city. RESULTS: The determination method of epichlorohydrin represented a good linear relationship in the range of 0.0645-3.8700 µg/L, the linear regression equation was Y = 2.828X + 4.91 × 10(-2) (r > 0.999). When the epichlorohydrin concentration were 0.0806, 0.3230 and 3.2300 µg/L, the relative standard deviations (RSD) were 7.9%, 4.7% and 3.1%, respectively. The average recoveries were from 95.7% to 98.7%. The limit of detection (LOD) was 0.015 µg/L, limit of quantification (LOQ) was 0.052 µg/L. The content of epichlorohydrin in the 25 cases of drinking water was under the limit of detection. CONCLUSION: The method is more simple than the national standard method, with high sensitivity, accuracy and good reproducibility, which is suitable for detection of the trace amounts of epichlorohydrin in drinking water.

Determination of epichlorohydrin and 1,3-dichloro-2-propanol in synthesis of cationic etherifying reagent by headspace gas chromatography.

This study demonstrates a headspace gas chromatographic(HS-GC) technique for the determination of residual epichlorohydrin (ECH) and generated 1,3-dichloro-2-propanol (DCP) in synthesis process of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHTAC). By a weight-based sampling method, coupled with significant dilution in 15.8% sodium sulfate and 0.1% silver nitrate mixed solution rapidly, the sample for HS-GC analysis is prepared. Based on the reaction stoichiometry, the conversion (R) of CHTAC during the synthesis process can be calculated from sampling weight and GC peak area. The results showed that the method has a good measurement precision (RSD<2.5%) and accuracy (recovery=101-104%) for the quantification of both ECH and DCP in the process samples. The present method is simple and accurate, which can be used for the efficient determination of the CHTAC conversion in the synthesis research.

A convenient method for epichlorohydrin determination in water using headspace-solid-phase microextraction and gas chromatography.

A simple procedure for epychlorohydrin determination in water is presented. In order to optimize the epichlorohydrin extraction conditions in water using headspace (HS)-solid-phase microextraction (SPME), followed by gas chromatography, an experimental design in two steps is performed. Firstly, a 2(5-2) fractional factorial design for screening the significant variables is used. Secondly, a central composite design for optimizing them is carried out. The best experimental conditions are the followings: poly(dimethysiloxane)-divinylbenzene coating fiber; 20 min extraction time; 5 degrees C extraction temperature; 300 g/L sodium chloride; and 20 mL HS volume in a 40-mL vial. Using the previous extraction conditions with gas chromatography (GC)-flame ionization detection equipment, a limit of detection (LOD) of 1.8 microg/L and a relative standard deviation (RSD) of 3.8% (for 25 microg/L) are obtained. With a GC electron capture detection equipment the RSD is 6.6% (for 5 microg/L), and the LOD found is lower (0.08 microg/L). The method is applied to the analysis of water from four treatment plants at the entrance and effluent stream. The standard addition method is used to quantitate the epichlorohydrin that is found in the raw water of the three wastewater treatment plants.

Aqueous-phase aminolysis: approach for the analysis of epoxides in water.

Trace concentrations of small soluble epoxides are suspected byproducts of drinking water ozonation. However, adequate characterization of epoxide formation is currently limited by the lack of suitable analytical methods to target these chemicals in dilute, but complex aqueous solutions. One potential approach is presented here based on aqueous-phase aminolysis. The method also employs solid-phase extraction, silylation of the solvent extract, and analysis by gas chromatography-mass spectrometry. This approach is demonstrated to be effective for the selective analysis of the epoxides 1,2-epoxybutane, epichlorohydrin, and epifluorohydrin in water with optimized method detection limits of 5-10 ng/L.

Analysis of liquid-phase chemical detection using guided shear horizontal-surface acoustic wave sensors.

Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36 degrees rotated Y-cut LiTaO3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the four-layer model. Contributions from mass loading and coating viscoelasticity changes to the sensor response are evaluated, taking into account the added mass, swelling, and plasticization. Chemically sensitive polymers are investigated in the detection of low concentrations (1-60 ppm) of toluene, ethylbenzene, and xylenes in water. A low-ppb level detection limit is estimated from the present experimental measurements. Sensor properties are investigated by varying the sensor geometries, coating thickness combinations, coating properties, and curing temperature for operation in liquid environments. Partition coefficients for polymer-aqueous analyte pairs are used to explain the observed trend in sensitivity for the polymers PMMA, poly(isobutylene), poly(epichlorohydrin), and poly(ethyl acrylate) used in this work.

Determination of epichlorohydrin by sulfite derivatization and ion chromatography: characterization of the sulfite derivatives by ion chromatography-mass spectrometry.

This work is an upgrade of a previously developed method (J. Chromatogr. A 884 (2000) 251] for epichlorohydrin determination by ion chromatography (IC) and conductivity detection. Here, an ion chromatography-mass spectrometry (IC-MS) coupling has been employed for the separation and the identification of products of epichlorohydrin when reacted with the nucleophilic agent SO3(2-). The high capacity column (IonPac AS11-HC) used for separation provided good resolution. This allowed evaluation of the IC behavior and mass spectrometric identification of epichlorohydrin sulfite derivatives. By using atmospheric pressure interfaces (ESI and APCI) the following species were tentatively identified: 2,3-dihydroxy-1-propanesulfonic, 2,3-epoxy-1-propanesulfonic,1,3-dihydroxy-2-propanesulfonic and 3-oxetanesulfonic acids and 2-hydroxy-1,3-propanedisulfonic acid (or its isomer 3-hydroxy-1,2-propanedisulfonic acid). The study showed that chlorine atoms are displaced from epichlorohydrin during the reaction, while mass spectrometry confirmed that none of the products formed contains chlorine atoms.

[Determination of residual epichlorohydrin and sym-dichloroisopropyl alcohol in cationic etherified reagent by gas chromatography].

A method for the determination of the residual epichlorohydrin and sym-dichloroisopropyl alcohol in cationic etherified reagent by gas chromatography has been established. Methyl benzoate, which has high extraction efficiency for the two components, was used as extractant. With an HP-5 capillary column, the two components were baseline separated and they eluted before the extractant. The linear ranges achieved were 5 - 590 mg/kg for epichlorohydrin and 21 - 480 mg/kg for sym-dichloroisopropyl alcohol. The limits of detection were 1.2 mg/kg for epichlorohydrin and 2.2 mg/kg for sym-dichloroisopropyl alcohol. Recoveries for epichlorohydrin were 95.93% - 103.42% with relative standard deviations of 2.4% - 10.6% and those for sym-dichloroisopropyl alcohol were 98.54% - 107.40% with relative standard deviations of 6.6% -11.1%. The method is simple, fast, and convenient.

[Studies on the analytical method for epichlorohydrin from internal can coatings].

An improved migration test was developed for determination of trace amounts of epichlorohydrin from internal can coatings. Eight kinds of sample cans, coated mainly with epoxy resin, for foods and beverages were prepared, and both their bodies and lids were tested for migration as follows. A body was filled with n-pentane and soaked for 2 hours at 25 degrees C. A lid was soaked in n-pentane (2 mL/cm2) for 2 hours at 25 degrees C. The test solution was analyzed by GC-FID and GC/MS using two DB-WAX capillary columns with different inside diameters. The limits of quantitation were 0.05 microgram/mL by GC-FID and 0.02 microgram/mL by GC/MS with selected ion monitoring. Recoveries of spiked epichlorohydrin were 99.9-104.5% at the level of 0.05 microgram/mL and 0.5 microgram/mL, with high precision. In this study, no epichlorohydrin was found to have migrated from any of the bodies and lids.

[Preparation and quality control of cross-linked agarose coated activated charcoal (CAAC-II) used as adsorbents for hemoperfusion in artificial liver support].

The preparation and the quality control of cross-linked agarose coated activated (CAAC-II) were described. The crosslinking reagent epichlorohydrin was removed. Investigations indicate that the trace elements such as Pb, Cd, As, Cr, Fe and heavy metals, the pH, NH4+, SO4(2-), and ultraviolet absorbance in sample have met the requirements in Chinese Pharmacopeia and some other relevant standard promulgated by the Ministry of Health. No epichlorohydrin was detected in CAAC-II.

Determination of epichlorohydrin by ion chromatography.

In this work we developed a new method for epichlorohydrin determination with suppressed ion chromatography. The technique is based on a reaction between the analyte and sulfur(IV) to form a product with a terminal sulfonate group that can be analyzed by anion-exchange chromatography. The reaction conditions were optimized as a function of temperature, type and concentrations of reagents and pH. Due to the characteristics of the product formed, the columns used were an lonPac AS 11 and AS II-HC with a NaOH eluent. The eluent concentration was optimized in order to achieve a complete separation of epichlorohydrin, chloride and nitrate ions, commonly occurring in drinking waters. In order to improve the detection limits, a preconcentration step, using reversed-phase materials, has been optimized. The method developed was suitable for epichlorohydrin determination in drinking water.

Exposure to solvents in a synthetic leather manufacturing plant.

The objective of this study was to evaluate the exposure of synthetic leather workers to dimethylformamide (DMF), epichlorohydrin (ECH) and toluene, in a manufacturing plant. The correlation between biological and environmental monitoring for DMF was also investigated. Environmental monitoring of the three solvents included personal and area sampling based on time of day (morning and afternoon). Urine samples were taken at the end of the shift and urinary N-methylformamide (NMF) was then used to biologically monitor DMF levels. Results for solvent concentrations based on air sampling were considerably higher in area than in personal sampling. Of 41 area samples, 15 (36.6%) and five (12.2%) exceeded permissible exposure levels for DMF and ECH, respectively, compared with 22 (28.6%) and three (3.9%) based on 77 personal samples. Overall, urinary NMF concentrations were lower than the Biological Exposure Index (BEI) suggested by the American Conference of Governmental Industrial Hygienists (ACGIH). A significant correlation (r = 0.32; P < 0.05) was found between environmental and biological monitoring. Even though urinary NMF concentration was within permissible levels for Taiwan, the authors recommend that immediate measures be taken to decrease DMF and ECH concentrations in synthetic leather manufacturing plants.

On-line coupling of equilibrium-sorptive enrichment to gas chromatography to determine low-molecular-mass pollutants in environmental water samples.

On-line combination of equilibrium sorptive enrichment and gas chromatography is used for the analysis of a group of pollutants varying widely in polarity and volatility in aqueous samples at trace levels. For the ESE process open-tubular traps were used. The newly developed hyphenated method shows a high sensitivity for all the compounds under study. The detection limits were typically between 0.1 and 1 microg/l. The sample volumes required for the compounds to reach equilibrium with the stationary phase are in the range of 20 ml for the aromatic hydrocarbons included in the study (benzene, toluene and p-xylene), to 200 ml for epichlorohydrin and dichlorohydrin. Within- and between-day precision of the absolute peak areas varied between 3 and 16%. The performance of the new method was tested by the analysis of different environmental water samples.

Biomonitoring of epichlorohydrin by hemoglobin adducts.

A gas chromatographic mass spectrometric method for monitoring exposure to epichlorohydrin (ECH) by means of quantitative analysis of N-(2,3-dihydroxypropyl)valine in hemoglobin has been developed. The analysis is based on the modified Edman method for measurement of adducts to the N-terminal valine, one of the reactive sites of the globin chains. The presence of two hydroxyl groups in the adduct to be analyzed required special precautions to be introduced into the method, such as acetylation of the Edman derivative. An in vitro treated globin with [2H5]N-2,3-dihydroxypropyl adducts was used as internal standard. The limit of detection achieved is 4 fmol in analysis by tandem mass spectrometry. Adduct levels found in smokers (15 to 20 cigarettes per day) were between 6.5 and 11.2 pmol/g globin and for nonsmokers the adduct levels were close to the detection limit (about 2 pmol/g globin). In two rats, treated ip with 40 mg ECH/kg body wt and sacrificed after 30 days, the average adduct level was 44 pmol/g globin and that for two nonexposed rats was close to the detection level. The method will be useful for monitoring of exposure and for cancer risk estimation of ECH.