Decontamination of organochlorine pesticides in Radix codonopsis by supercritical fluid extractions and determination by gas chromatography

A method involving depuration of 12 organochlorine pesticides (OCPs) from Radix codonopsis was developed using supercritical fluid extraction (SFE). The pesticides investigated in the study included alpha-, beta-, gamma- and delta-benzene hexachloride, PCNB (pentachloro-nitrobenzene), PCA (pentachloroaniline), HEPT (heptachlor), MPCPS (methyl-pentachlorophenyl sulfide), pp'-DDE [1,1-dichloro-2, 2-bis(p-chlorophenyl) ethylene], op'-DDT [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane], pp'-DDD [1,1-dichloro-2-2-bis(p-chlorophenyl)ethane] and pp'-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane]. A series of experiments was conducted to optimize the final extraction conditions as follows: pure CO2, extraction pressure 15 MPa, extraction temperature 60 degrees C, extraction time 20 min and flow rate 55 mL/h. A GC method with electron capture detection was employed for the determination of the OCPs in Radix codonopsis. An HPLC method was developed for the quantitative determination of active constituents. SFE was used to remove the organochlorine pesticide from Radix codonopsis. The results showed that at least 93.5% of the organochlorine pesticide residues in the herb sample were removed by SPE, while 95.0% of the active constituent marker (atractylenoide III) remained.     

Supercritical fluid extraction and clean-up of organochlorine pesticides in Chinese herbal medicine

A method involving the simultaneous extraction and clean-up of 13 organochlorine pesticides (OCPs) from Chinese herbal medicines (CHMs) was developed using supercritical fluid extraction (SFE) followed by gas chromatography-electron capture detection and mass spectrometric confirmation. The pesticides in the study consisted of alpha-, beta-, gamma-, and delta-benzene hexachloride, heptachlor, aldrin, heptachlor epoxide, endosulfan I, 4,4'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethene), dieldrin, endrin, 4,4'-DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane), endosulfan II, 4,4'-DDT (2,2-bis(p-chlorophenyl)1,1,1-trichloroethane), endrin aldehyde, and endosulfan sulfate. A series of experiments was conducted to optimize the final extraction conditions [pure CO2, 250 atm extraction pressure (1 atm = 101,325 Pa), 50 degrees C extraction temperature, 5 min static extraction time, 20 min dynamic extraction time, 2.0-g Florisil sorbent on top of 0.1-g samples, 12-ml n-hexane eluting at 1 ml/min, and a 10-ml extraction vessel]. Florisil sorbent was placed with the sample in the SFE vessel to provide a facile and effective clean-up approach. Mean recoveries of 78-121% with reproducibilities of 5-31% were obtained for the pesticides except for endosulfan II, endosulfan sulfate and endrin aldehyde. The simple and rapid method may be used to determine OCPs in CHMs routinely, and in fact, was used to analyze CHMs sold in Taiwan.     

Extraction of DDT [1,1,1,-trichloro-2,2-bis(p-chlorophenyl)ethane] and its metabolites DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene] and DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)-ethane]) from aged contaminated soil

Pressurised liquid extraction (PLE) was used to extract DDT [1,1,1,-trichloro-2,2-bis(p-chlorophenyl)ethane] and its metabolites, DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethane] and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] from an aged, contaminated soil. Using three sequential static phases, PLE removed an equivalent quantity of DDT and its metabolites as Soxhlet extraction, in less time and with less solvent. Recovery was almost quantitative, implying appropriate sample work-up and manipulation.     

Investigation of the feasibility of TiO(2) nanotubes for the enrichment of DDT and its metabolites at trace levels in environmental water samples

TiO(2) nanotubes, novel nanomaterials synthesized from hydrothermal treatment, were investigated for being used as a new solid-phase extraction adsorbent with o,p'-DDT, [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane, p,p'-DDT, [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane] and its principle metabolites p,p'-DDD, [1,1-dichloro-2,2-bis(4-chlorophenyl)ethane] and p,p'-DDE [1,1-(2,2-dichloro-ethanylidene)-bis(4-chlorobenzene)] as the target analytes. Several factors such as eluant and its volume, the sample pH, sample volume and the flow rate of samples, were optimized. The effect of humic acid, which is often present in natural water system, was also investigated. Under the optimal conditions, lower detection limits of 0.0031, 0.0037, 0.0053 and 0.0025 ng mL(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT and p,p'-DDE, respectively, were obtained. The proposed method was successfully applied to the analysis of the target compounds in several environmental water samples. Good recoveries over the range of 81.2-115% were obtained. These results indicated that titanium nanotubes had enormous potential in environmental field as a novel SPE adsorbent material.     

Electronic structure and biological activity of chosen DDT-type insecticides studied by 35Cl-NQR

A correlation between the electronic structure and biological activity of chosen dichlorodiphenyltrichloroethane (DDT)-type insecticides: 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane, 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene, 2,2-bis(4-chlorophenyl)ethanoic acid and 4,4'-dichlorobenzophenone (used in agriculture) has been analysed on the basis of the (35)Cl-nuclear quadrupole resonance (NQR) spectroscopy. The (35)Cl-NQR resonance frequencies measured at 77 K have been correlated with the lethal dose (LD(50)) parameter that characterises the biological activity of these insecticides.     

Determination of organochlorine pesticides and their metabolites in radish after headspace solid-phase microextraction using calix[4]arene fiber

A novel laboratory-made sol-gel calix[4]arene/hydroxy-terminated silicone oil coated fiber has been applied for headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC) with electron capture detection (ECD) to determine 12 organochlorine pesticides (OCPs) and their metabolites in radish sample. The analytes in the study consisted of α-, β-, γ- and δ-hexachlorocyclohexane (BHC), 1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane (o,p′-DDT), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p′-DDT), 2,4-dichlorobenzophenone (o,p′-DBP), 4,4-dichlorobenzophenone (p,p′-DBP), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p′-DDE), bis(4-chlorophenyl)methane (p,p′-DDM), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (p,p′-DDD) and endrin. The following parameters were adjusted to optimize HS-SPME in order to obtain the maximum sensitivity: extraction temperature, extraction time, the addition of salt, desorption temperature and time. Especially, the effect of the complex radish matrix on quantitative extraction of pesticides was discussed in detail. Detection limits of the developed method for radish matrices were below 174 ng/kg for all pesticides. Relative standard deviations for quintuplicate analyses of radish samples fortified each analytes were not higher than 13.1%. The results demonstrate the suitability of the HS-SPME/GC-ECD approach for the analysis of multi-residue OCPs and metabolites in radish.     

Rapid method for the determination of organochlorine pesticides in milk

This method involved one step solvent extraction of milk with ethyl acetate-acetone-methanol by ultrasonication. The supernatants were further cleaned-up and enriched by solid-phase extraction using octadecyl (C18)-bonded silica cartridges, then assayed by capillary gas-liquid chromatography with electron capture detection. The recoveries of eleven organochlorine pesticides (OCPs) from raw milks were quantitative, ranging from 90-110% at 10 times the limit of detection (LOD). The LOD ranged from 0.5 micrograms/l whole milk for alpha-hexachlorocyclohexane to 2.5 micrograms/l whole milk for 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane. The day-to-day variation of the method was evaluated over 7 days using 3 different pools of spiked cow milks (at the LOD, 5 and 10 times the LOD). The coefficient of variations (C.V.s) were 16 +/- 6, 10 +/- 2 and 9 +/- 3% (mean S.D.), respectively. The method showed no emulsion problems common with conventional non-polar solvent extraction, and the use of solid-phase extraction considerably reduced the sample clean-up process compared with the existing methods. The method also showed that OCPs in milk could be extracted quantitatively without extraction of total fat, and that OCPs spiked into cows milk could be used to construct calibration curves for human milk determinations.     

Facile and catalytic degradation method of DDT using Pd/C-Et3N system under ambient pressure and temperature

The catalytic degradation method of p,p′-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] and its regioisomer o,p′-DDT [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane] using the Pd/C-Et₃N system under ambient hydrogen pressure and temperature was established. The presence of Et₃N was necessary for the quick and complete breakdown of DDT. The independent degradation study of two intermediates, p,p′-DDD [2,2-bis(p-chlorophenyl)-1,1-dichloroethane] and p,p′-DDE [2,2-bis(p-chlorophenyl)-1,1-dichloroethylene] using GC-MS let us to speculate the degradation pathway of p,p′-DDT. In the initial phase of the reaction, p,p′-DDT degradation splits into two ways: a dehydrochlorination pathway and a hydrodechlorination pathway. In each pathway, reaction starts from an aliphatic moiety and subsequent hydrodechlorination from the benzene moieties takes place in a stepwise manner. The former pathway leads to the formation of 1,1-diphenylethane and the latter leads to the formation of 1,1-dichloro-2,2-diphenylethane. These diphenylethane analogs, which are less toxic compared with p,p′-DDT, are terminal degradation products in our system. The distinctive features of our catalytic degradation method of DDTs are reliability, simplicity, efficiency, and inexpensiveness.     

Oxidation of N-(1-Hydroxypolychloroethyl)sulfonamides

N-(2,2,2-Trichloro-1-hydroxyethyl)- and N-(2,2-dichloro-1-hydroxy-2-phenylethyl)arenesulfonamides are oxidized with chromium(VI) oxide to give, respectively, N-(arylsulfonyl)trichloroacetamides and N-(arylsulfonyl)dichloro(phenyl)acetamides. Under analogous conditions N-(2,2,2-trichloro-1-hydroxyethyl)trifluoromethanesulfonamide is converted into 1,1,1-trichloro-2,2-bis(trifluoromethylsulfonylamino)ethane.     

Development of dispersive liquid-phase microextraction based on new ionic liquid 1,3-diisooctylimidazolium hexafluorophosphate as solvent for the extraction and determination of dicofol and its degradation products in water samples

In the current paper we describe a novel sample preparation technique termed dispersive liquid-phase microextraction for the preconcentration and determination of 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol) and its degradation products in water samples that includes 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene(2,4′-DDE), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane(4,4′-DDE) and 1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane (2,4′-DDT) coupled with gas chromatography mass spectrometry (GC-MS), in which a new ionic liquid 1,3-diisooctylimidazolium hexafluorophosphate abbreviated as [D(i-C₈)IM][PF₆] was used as extraction solvent. For each one extraction, 1.00 mL of the methanol solution containing 40 µL of the ionic liquid was sprayed into 25.00 mL of water sample. In the meantime the ionic liquid was finely dispersed into the aqueous phase and analytes were rapidly migrated into the ionic liquid. After the solution was centrifuged for 2 min at 5000 rpm, the droplets of the ionic liquid are subsided in the bottom of the conical test tube (30.0 ± 0.2 µL). Moreover, the factors relevant to extraction efficiencies were investigated and optimised including the volume of the ionic liquid, disperser solvent, extraction time, sample pH and ionic strength. Under optimal conditions, the enrichment factors of the extraction were between 550 and 725 with an extraction efficiency ranging from 66% to 87% for each different analyte. Finally, 1.0 µL of the ionic liquid collected from above extraction was injected into the injector block of GC-MS instrument for analysis. The detection limit (S/N = 3), the relative standard deviations for 2.0 µg L^?1 of the standard analyte (n = 5) and linearity in a calibration range were found to be 3–8 ng L^?1, 1.0–2.7% and 10–3000 ng L^?1, respectively. Good spiked recoveries over the range of 92.0–13.5% were obtained. The proposed method offers the advantages of simplicity of operation, rapidity, good extraction efficiency and enrichment factor; it has been successfully applied to determination of dicofol and its degradation products in environmental water samples.     

Electrochemical ELISA for the screening of DDT related compounds: analysis in waste waters

An electrochemical enzyme-linked immunosorbent assay (ELISA) for the detection of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DTT), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p′-DDE), 1,1-dichloro-2,2-bis-(4-chlorophenyl)ethane (p,p′-DDD) and o,p-DDT was developed. Optimization of the ELISA competition conditions, led to similar response for the p,p′-isomers. The activity of the label enzyme (horseradish peroxidase) was measured electrochemically using 3,3′,5,5′-tetramethylbenzidine as substrate. The use of purified antiserum for p,p′-DDT resulted in a sensitive assay with a detection limit of 40 pg ml⁻¹ and R.S.D. ranging from 1 to 3% intra-day and 3 to 6% inter-day. No matrix effect for waste water samples of different origin has been evidenced. The ELISA was used to detect DDTs in 20 samples after extraction in diethylether. This method appears suitable for routine screening of DDTs without sample pre-treatment other than dilution in PBS or after organic solvent extraction if high sensitivity is required.     

Mixed liquids for single-drop microextraction of organochlorine pesticides in vegetables

A new approach for the extraction of nine kinds of organochlorine pesticides (OCPs) from vegetable samples coupling single-drop microextraction with gas chromatography-mass spectrometry was presented. Experimental parameters, such as organic solvent, exposure time, agitation and organic drop volume were controlled and optimized. An effective extraction was achieved by suspending a 1.00microL mixed drop of p-xylene and acetone (8:2, v/v) to the tip of a microsyringe immersed in a 2mL donor aqueous solution and stirred at 400rpm. The approach was applied to the determination of OCPs in vegetable samples with a linearity range of 0.05-20ng mL(-1) for alpha-, beta-, gamma-, delta-hexachlorobenzene (BHC) and dicofol, 0.5-20ng mL(-1) for dieldrin and 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (DDD) or 0.5-50ng mL(-1) for 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE) and 2-(2-chlorophenyl)-2 (4-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT). Correspondingly, the determination limit at an S/N of 3 ranged from 0.05ng mL(-1) for alpha-, beta-, gamma-, delta-BHC to 0.2ng mL(-1) for dicofol, dieldrin or p,p'-DDT. The relative recoveries were from 63.3 to 100%, with repeatability ranging from 8.74 to 18.9% (relative standard deviation, R.S.D.). The single-drop microextraction was proved to be a fast and simple approach for the pre-concentration of organochlorine pesticides in vegetable samples.     

Chlorine isotope fractionation of a semi-volatile organochlorine compound during preparative megabore-column capillary gas chromatography

Chlorine isotope fractionation during preparative capillary gas chromatography (pcGC) was investigated using 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) as a model compound for semi-volatile organochlorine (OCl) molecules. Chlorine isotope analysis by thermal ionization mass spectrometry revealed no significant alteration of the chlorine isotope composition when the whole peaks were collected in pcGC (delta37Cl -3.2 per thousand versus -3.6 per thousand for the unprocessed DDT, +/-0.5 per thousand SD). However, distinct isotope fractionations were measured for the front (delta37Cl -5.1 per thousand) and tail (delta37Cl -1.8 per thousand) segments of partially collected samples. Isolation of individual OCls by pcGC enables accurate off-line chlorine isotope analysis, and thus facilitates the investigation of naturally occurring OCls.     

Synthesis of 1,1-dichloro-2,2-bis(4-hydroxyphenyl)-ethylene via ammonia or methylamine dehydrochlorination. A bisphenol for the preparation of highly flame-resistant polycarbonates

Ammonia used as both reactant and solvent has been shown to dehydrochlorinate 1,1,1-tri-chloro-2,2-bis(4-hydroxyphenyl)ethane smoothly to 1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene. The reaction is complete in 1 hr at 100°C, and after two crystallizations from methanol/water affords polymerizable quality monomer for the synthesis of highly flame-resistant polycarbonates. The use of organic solvents in combination with ammonia does not offer any rate advantages over pure ammonia. Primary and secondary amines also can be used to effect the dehydrochlorination but, except for the methylamine, are significantly less reactive and lead to less pure product than amonia.     

气相色谱-串联质谱法测定土壤中的有机氯农药

建立了气相色谱-串联质谱测定土壤中有机氯农药的方法,同时测定了上海郊区的20个农业土壤。样品前处理包括加速溶剂萃取(弗罗里硅土池内净化)和凝胶渗透色谱净化在线浓缩。采用多反应监测模式的气相色谱-串联质谱分析有机氯农药,降低了背景干扰,提高了分析的灵敏度。在0.001～2 mg/L的质量浓度范围内,各种农药标准溶液的线性相关系数均大于0.995。分别向3种实际土壤样品中添加农药的混合标准溶液,所测定的有机氯农药的平均回收率为65.9%～140.0%,相对标准偏差为1.5%～20.3%(n=5)。有机氯农药的检出限（S/N=3）为0.1～3.0 μg/kg,定量限（S/N=10）为0.3～8.0 μg/kg。实际土壤样品的测定结果表明：六六六(1.82～3.70 μg/kg)和六氯苯(0.94～9.8 μg/kg)有少量检出,滴滴涕的检出率高达100%,其含量范围较宽(1.08～308.76 μg/kg),平均值为53.28 μg/kg,其中85%的样品中滴滴涕含量/(滴滴伊+滴滴滴)含量的比值小于1,表明滴滴涕主要来自于早期的使用     

Preparation and characterization of organic calibration solutions for development of certified reference materials at the National Metrology Institute of Japan

Certified reference materials (CRMs) are playing an increasingly important role in environmental monitoring in Japan. The National Metrology Institute of Japan (NMIJ)/National Institute of Advanced Industrial Science and Technology (AIST) has been developing CRMs of organic calibration solutions since 2003, and has issued several NMIJ CRMs. The development of these materials was conducted at the NMIJ in cooperation with candidate material producers. The freezing-point depression method was principally adopted for assessment of the purity of starting materials to give reliable certified values. Gas chromatography with flame ionization detection (GC–FID) and/or high-performance liquid chromatography (HPLC), which are based on independent principles and whose levels of accuracy are well evaluated, were applied in combination with other methods to avoid any possible analytical bias. Purity assessment is outlined for two typical examples, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DDD) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DDT), which were used as starting materials for a CRM under development. Methods adopted for gravimetric preparation and ampouling of solutions were qualified and optimized to reduce the uncertainties of certified values due to these factors. Furthermore, a new experimental scheme for assessment of stability and preparation variation is proposed for the proper estimation of uncertainties. Presented at BERM-11, October 2007, Tsukuba, Japan.     

Contamination by Organochlorine Pesticides in the Estuaries of Southeast China* 06 A

Persistent organic pollutants(POPs) such as organochlorine pesticides are of global concern due to their widespread occurrence and persistence. This paper reports recent research studying the distribution and fate of organochlorine pesticides in the Jiulong River, the Minjiang River and the Pearl River estuaries in Southeast China. Eighteen organochlorine pesticides were extracted from water, pore water and sediment samples, followed by analysis by GC-ECD. The results showed that the contamination levels were similar in these three estuaries.The levels of the total organochlorine pesticides in porewater were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. Among the hexachlorocyclohexane (HCH) compounds, β-HCH was found to be the most important isomer. The analysis of 1, 1,1-trichloro-2,2-bis-chlorophenyl-ethane(DDT) and its metabolites showed that 1, 1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group.Koywords Organochlorine insecticides, DDT, Lindane, Jiulong River Estuary, Minjiang River Estuary, Pearl River Estuary, Water, Sediment     

Preparation and certification of a fish oil natural matrix reference material for organochlorine pesticides

The mass fractions of six organochlorine pesticides in a fish oil certified reference material (CRM) have been determined using multiple methods of analysis. Fish oil was extracted from the filet of Tilapia fish collected from the River Nile, and this CRM was recently issued by the National Institute of Standards (NIS). It can be used as natural matrix CRM for organochlorine pesticides determination in fish and for marine environmental measurement purposes. The analytical methods used are described, and the obtained results were combined to calculate the mass fractions of the six detected organochlorine pesticides and their associated uncertainty values. It has been concluded that mass fractions of four pesticides are certified values. These are 1,1-(dichloroethylidene)bis[4-chlorobenzene](4,4′-DDE), 1,1-(2,2,-dichloroethylidene)bis[4-chlorobenzene] (4,4′-DDD), 1-chloro-2-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene (2,4′-DDT) and 1,1-(2,2,2-trichloroethylidene)bis[4-chlorobenzene] (4,4′-DDT). Meanwhile, mass fractions of two pesticides were reference values. These are heptachlor and 1-chloro-2-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene (2,4′-DDD).     

Determination of organochlorine pesticide residues in medicinal plants sold in Coimbra, Portugal.

Levels of 14 organochlorine pesticide residues--1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) group (p,p'-DDT, o,p'-DDT, p,p'-DDD, and p,p'-DDE), HCH isomers (alpha-, beta-, and gamma-HCH), hexachlorobenzene (HCB), aldrin, dieldrin, endrin, heptachlor, alpha-endosulfan, and endosulfan sulfate--were evaluated in 127 samples of medicinal plants collected in pharmacies (78 samples) and herb stores (49 samples) in 1996. Samples were divided between 15 national brands and 7 foreign brands. Most samples sold in pharmacies contained residues of gamma-HCH (51.3%). All residues were detected in analyzed samples, with exception of endrin in herb store samples. Detection frequency varied between 51.3% for gamma-HCH and 1.3% for endrin in pharmacy samples, and between 34.7% for HCB and 4.1% for endosulfan sulfate in herb store samples. Maximum residue levels were exceeded in 38 (48.7%) pharmacy samples and in 26 (53.1%) medicinal herb store samples.     

β-Elimination in 1,1,1-Trichloro-2,2-bis(4-nitrophenyl)ethane by the Action of Sodium Nitrite in Dipolar Aprotic Solvents

The kinetics of dehydrochlorination of 1,1,1-trichloro-2,2-bis(4-nitrophenyl)ethane with sodium nitrite in dipolar aprotic solvents have been studied. Quantum chemical simulation of the process has been performed, and its thermodynamic parameters have been determined. The effects of dissociation and solvation on the rate constant have been considered. The reaction mechanism has been identified as E2H.