Solid-phase microextraction for organochlorine pesticide residues analysis in Chinese herbal formulations

Review of scientific literature on available methods of assessing organochlorine pesticides in the environment

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) widely used in agriculture and industry, causing serious health and ecological consequences upon exposure. This review offers a thorough overview of OCPs analysis emphasizing the necessity of ongoing work to enhance the identification and monitoring of these POPs in environmental and human samples. The benefits and drawbacks of the various OCPs analysis techniques including gas chromatography-mass spectrometry (GC-MS), gas chromatography-electron capture detector (GC-ECD), and liquid chromatography-mass spectrometry (LC-MS) are discussed. Challenges associated with validation and optimization criteria, including accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ), must be met for a method to be regarded as accurate and reliable. Suitable quality control measures, such as method blanks and procedural blanks, are emphasized. The LOD and LOQ are critical quality control measure for efficient quantification of these compounds, and researchers have explored various techniques for their calculation. Matrix interference, solubility, volatility, and partition coefficient influence OCPs occurrences and are discussed in this review. Validation experiments, as stated by European Commission in document SANTE/11813/2017, showed that the acceptance criteria for method validation of OCP analytes include ≤20 % for high precision, and 70-120 % for recovery. This may ultimately be vital for determining the human health risk effects of exposure to OCP and for formulating sensible environmental and public health regulations.

Simultaneous Determination of 26 Pesticide Residues in Traditional Chinese Medicinal Leeches by Modified QuEChERS Coupled with HPLC-MS/MS

A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) pretreatment technique combined with HPLC-MS/MS was established to detect 26 pesticides in traditional Chinese medicinal leeches. The sample was extracted by acetonitrile solution with sodium acetate-0.1% (v/v) acetic acid as a buffer system, then cleaned up by a mixture of 750 mg of MgSO₄, 150 mg of C₁₈, and 150 mg of PSA, separated by an ACQUITY BEH C₁₈ column, and determined in the dynamic multiple reaction mode. Under the optimized conditions, the peak areas of the 26 pesticides in leeches showed good linearity (r > 0.99) between their mass concentrations from 1 to 100 μg/L. At the spike levels of 10, 20, and 100 μg/kg, the recoveries of 26 pesticides in leeches were 72.9-101.6% with an RSD of 1.1-12.8%, an LOQ of 10 μg/kg, and an LOD of 0.1-5.4 μg/kg. This method is easy, rapid, sensitive, and practical and meets the requirements of pesticide residue detection standards.

Preparation of a new three-component deep eutectic solvent and its use as an extraction solvent in dispersive liquid-liquid microextraction of pesticides in green tea and herbal distillates

BACKGROUND

A new solvent, deep eutectic solvent, in which there is growing interest, has been prepared and used as an extraction solvent in the dispersive liquid-liquid method of microextraction. To prepare the solvent, dichloroacetic acid, l-menthol, and n-butanol are mixed at a molar ratio of 4:1:1 and the deep eutectic solvent is formed after heating. Then a dispersive liquid-liquid microextraction method using the prepared solvent is used for the extraction and preconcentration of some pesticides from an aqueous sample. To carry out the procedure, the deep eutectic solvent is mixed with methanol and rapidly injected by a syringe into the aqueous sample containing the analytes. After centrifuging, an aliquot of the sedimented phase is injected into the gas chromatograph. The influence of several variables on the extraction efficiency was investigated and optimized.

RESULTS

Extraction recoveries and enrichment factors were obtained in the ranges of 53-86% and 1760-2853, respectively. The intra- (n = 6) and inter-day (n = 5) precision of the method was satisfactory, with relative standard deviations ≤ 7% obtained at two concentrations of 10 and 50 μg L^-1 of each analyte. Moreover, detection and quantification limits for the target analytes were obtained in the ranges of 0.11-0.23 and 0.38-0.74 μg L^-1 , respectively.

CONCLUSION

Different samples, including green tea, rose water, lemon balm, mint, and pussy willow distillates were analyzed successfully using the method that was developed, and chlorpyrifos was found in rose water at a concentration of 17 ± 1 μg L^-1 (n = 3). © 2019 Society of Chemical Industry.

Study on the simultaneous degradation of five pesticides by Paenibacillus polymyxa from Panax ginseng and the characteristics of their products

The quality and safety of ginseng products were seriously affected due to the slow metabolism and long-term residual pesticides in ginseng. Microbial degradation is an effective method to degrade pesticide residues. In this study, ginseng endophytic Paenibacillus polymyxa was used to degrade pesticide residues. A method of simultaneous determination of fluazinam, BHC, PCNB, chlorpyrifos and DDT in ginseng roots and ginseng stems and leaves by GC was established. The sample was extracted with n-hexane and purified by Florisil solid phase extraction column. The limit of quantitation was 0.01 μg mL^-1, the linear relationship was good (r ≥ 0.9901). 7 days after inoculated with P. polymyxa, the degradation rates of fluazinam, BHC, PCNB, chlorpyrifos, and DDT in the medium were 94.77%, 70.34%, 77.92%, 78.30%, 66.70%, respectively (P < 0.05). The safety of 5 pesticide degradation products was investigated by GC-MS. The results showed that after 7 days degradation, the main degradation products were alkanes, which are non-toxic and can't cause secondary pollution to the environment. The actual degradation results were verified by field experiments. The results indicated that after sprayed 5 times with P. polymyxa, the degradation rates of fluazinam, BHC, PCNB, chlorpyrifos and DDT in the ginseng roots were 66.07%, 46.24%, 21.05%, 72.40%, 54.21%, respectively (P < 0.05). The degradation rates in ginseng stems and leaves were 74.18%, 55.61%, 73.65%, 58.13%, 46.91%, respectively (P < 0.05). The results indicated that Paenibacillus polymyxa was an effective degradation strain of 5 pesticides.

Simultaneous determination of organochlorine and pyrethriod pesticide residues in the Chinese patent medicines by gas chromatography-tandem mass spectrometry

A simple, sensitive, reliable method was developed for the simultaneous determination of organochlorine and pyrethriod pesticide residues in Chinese patent medicines Six ingredient rehmannia pills and Xiaoyao pills. These pesticides were extracted by ethyl acetate. The extraction time and volume of ethyl acetate were optimized. Cleanup of extracts was performed with dispersive-solid phase extraction using graphitized carbon black as the sorbent. The determination of pesticides in the final extracts was carried out by gas chromatography-tandem mass spectrometry in multiple reaction monitoring mode (GC-MS/MS, MRM). The linearity of the calibration curves is good in matrix-matched standard and yields the coefficients of determination (R²) ≥0.99 for all of the target analytes. Under optimized conditions, the average recoveries (five replicates) for most pesticides range from 75.5% to 114.6%, and RSDs are less than 10.0%. The LODs of 18 pesticides in Six ingredient rehmannia pill and Xiaoyao pills are in the range of 0.01-8.82 μg kg^-1. The developed method meets the requirements of pesticide residue analysis and could be effectively used for routine analysis of the organochlorine and pyrethriod pesticide residues in Six ingredient rehmannia pills and Xiaoyao pills.

Employing Solid Phase Microextraction as Extraction Tool for Pesticide Residues in Traditional Medicinal Plants

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58 ± 7.20 to 113 ± 15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R² > 0.9900) in the range of 2 to 100 ng g^-1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48 ± 0.16 to 1.50 ± 0.50 ng g^-1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants.

Zebrafish: A Versatile Animal Model for Fertility Research

The utilization of zebrafish in biomedical research is very common in the research world nowadays. Today, it has emerged as a favored vertebrate organism for the research in science of reproduction. There is a significant growth in amount numbers of scientific literature pertaining to research discoveries in reproductive sciences in zebrafish. It has implied the importance of zebrafish in this particular field of research. In essence, the current available literature has covered from the very specific brain region or neurons of zebrafish, which are responsible for reproductive regulation, until the gonadal level of the animal. The discoveries and findings have proven that this small animal is sharing a very close/similar reproductive system with mammals. More interestingly, the behavioral characteristics and along with the establishment of animal courtship behavior categorization in zebrafish have laid an even stronger foundation and firmer reason on the suitability of zebrafish utilization in research of reproductive sciences. In view of the immense importance of this small animal for the development of reproductive sciences, this review aimed at compiling and describing the proximate close similarity of reproductive regulation on zebrafish and human along with factors contributing to the infertility, showing its versatility and its potential usage for fertility research.

Influence of herbal combinations on the extraction efficiencies of chemical compounds from Cinnamomum cassia, Paeonia lactiflora, and Glycyrrhiza uralensis, the herbal components of Gyeji-tang, evaluated by HPLC method

During decoction process, the ingredients of herbal formula interact with each other, such that therapeutic properties and chemical extraction characteristics are altered. The crude drugs, Cinnamomum cassia (CC), Paeonia lactiflora (PL), and Glycyrrhiza uralensis (GU), are the main herbal constituents of Gyeji-tang, a traditional herbal formula. To evaluate the chemical interaction between CC, PL, and GU during the course of decoction, quantification of 16 marker compounds in the herbal decoction, performed using a Box-Behnken experimental design, was carried out by HPLC-diode array detection using validated method. Correlations between the amounts of marker compounds from CC, PL, and GU were assessed by multiple regression analysis. The results obtained showed that amounts of single herb marker compounds significantly changed (usually decreased) by decoction in the presence of other herbs and that these changes depended on the chemical natures of the markers and the herbal medicines present. Results also demonstrated that the extraction efficiencies of marker compounds increased when the proportion of the herb containing them was increased and decreased in proportion to amounts of herbs added. In conclusion, chemical interactions between compositional herbal medicines may occur when herbs are co-decocted. This study provides insight of understanding the herbal interactions in herbal formulae.

Preparation of porous aromatic framework/ionic liquid hybrid composite coated solid-phase microextraction fibers and their application in the determination of organochlorine pesticides combined with GC-ECD detection

Novel porous aromatic framework/ionic liquid hybrid composite coated SPME fibers were prepared for the preconcentration of OCPs coupled with GC-ECD.

Chemical interaction between Paeonia lactiflora and Glycyrrhiza uralensis, the components of Jakyakgamcho-tang, using a validated high-performance liquid chromatography method: herbal combination and chemical interaction in a decoction

The herbal combination is the basic unit of a herbal formula that affects the chemical characteristics of individual herbs. In the present study, a method of simultaneous determination of the 11 marker compounds in Jakyakgamcho-tang was developed using high-performance liquid chromatography with photodiode array detection. The validated analytical method was successfully applied to approach the chemical interaction between Paeonia lactiflora and Glycyrrhiza uralensis in co-decoction. In P. lactiflora, the contents of gallic acid, oxypaeoniflorin, (+)-catechin, paeoniflorin, and benzoylpaeoniflorin were decreased, while those of albiflorin and benzoic acid were increased; in G. uralensis, the contents of liquiritin, isoliquiritin, ononin, and glycyrrhizin were decreased, when decocting two herbs together. Moreover, as the ratio between P. lactiflora and G. uralensis was increased, the contents of chemical contents from each herb were proportionally increased. However, each content of marker compound per the gram of herbal medicine was decreased as the ratio of combinative herbs increased. The results showed that P. lactiflora and G. uralensis affect the extraction efficiency of chemical compounds in a Jakyakgamcho-tang decoction. Overall, the method established in this study was simple, rapid, and accurate, and would be useful for the determination of marker compounds and for the investigation of the chemical interaction between herbal medicines.

Comparison of different sample pre-treatments for multi-residue analysis of organochlorine and pyrethroid pesticides in chrysanthemum by gas chromatography with electron capture detection

The widespread use of insecticides in Chinese herbal medicines has created a compelling need for the development of a multiresidue analytical method to help assure herbs safety. The operating variables affecting the performance of the multiresidue analysis of 34 organochlorine and 12 pyrethroid pesticides in chrysanthemum, a widely used kind of Chinese herbal medicines, were evaluated. Three different extraction solvents including n-hexane and its mixtures with acetone and petroleum ether were compared, and n-hexane was found to be an appropriate option. A combination of gel permeation chromatography and SPE was selected as the optimum cleanup, in comparison with dispersive SPE, or the two former methods alone. The determination of the 46 pesticide residues in the spiked chrysanthemum samples was performed by GC with electron capture detection. The average recoveries ranged from 71.3 to 102.6% with RSDs of 1.4-15.7% for all of the pesticides. The LOQs were in the range of 0.0015-0.2 mg/kg, while the LODs were between 0.0005 and 0.1 mg/kg. The satisfactory accuracy, and precision, in combination with a good separation and few interferences, have demonstrated the strong potential of this technique for its application in chrysanthemum analysis.

A multiresidue method for 20 pesticides in Radix paeoniae Alba of Chinese herb by gas chromatography with electron-capture detection

A rapid multiresidue method was developed for the determination of 20 pesticides in Radix paeoniae Alba of Chinese herb by ultrasonic wave extraction, silica gel column chromatography and gas chromatography (GC) with electron-capture detection (ECD) in this study, Mean recoveries of the method ranged from 74.45 to 115.14%. The validation of the proposed approach was verified on Isatis indigotica Fort, Pltycodon grandiflorum, Cotex mouta and Poria cocos of Chinese herbs; good recoveries were also obtained in the range of 72.51-113.47%, respectively.

Simultaneous determination of organophosphorus and organonitrogen pesticides residues in Angelica sinensis

Gas chromatography with nitrogen phosphorus detector (GC-NPD) was applied to the simultaneous determination of 15 organophosphorus and 6 organonitrogen pesticides residues in Angelica sinensis. The pesticides were extracted by microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) techniques, respectively. The experimental variables were optimized through orthogonal array experimental design. Cleanup of extracts was performed with column chromatography using florisil and neutral aluminum as the sorbents. The determination of pesticides in the final extracts was carried out by GC-NPD. Under optimized conditions, the average recoveries obtained from MAE and UAE are in the range of 75.1-129% and 70.6-129%, respectively, and the relative standard deviations of MAE and UAE were 3.1-10.6% and 1.0-17.8%, respectively.

Study on the performance of the headspace liquid-phase microextraction, gas chromatography-mass spectrometry in the determination of sorbic and benzoic acids in soft drinks and environmental water samples

A simple, efficient and virtually solventless headspace liquid-phase microextraction (HS-LPME) technique, combined with gas chromatography-mass spectrometry (GC-MS), was developed for the analysis of sorbic acid (SA) and benzoic acid (BA) in soft drinks and environmental water samples. A microdrop of organic solvent was suspended from the tip of a microsyringe needle over the headspace of the stirred sample solution, containing the analytes for a desired time. The microdrop was then retracted into the microsyringe and directly injected into the GC-MS, without any further pretreatment. Initially, microextraction efficiency factors were optimized, and the optimum experimental conditions found were as follows: 2.5 microL toluene microdrop exposed for 20 min over the headspace of a 6.5 mL aqueous sample (45 degrees C), containing 3 M of NaCl with pH of 1.5 and stirred at 1000 rpm. Under the optimized extraction conditions, preconcentration factors of 154 and 198, limits of detection of 0.3 and 0.1 microg L(-1) (S/N=3) with dynamic linear ranges of 1-500 and 0.5-500 microg L(-1), were obtained for SA and BA respectively. A good repeatability (RSD<10.3%, n=8) and satisfactory linearity (r(2) >or= 0.99) of results were achieved. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 90 to 113%. The method proved to be rapid and cost-effective and is a green procedure for screening purposes.

Development of pressurized subcritical water extraction combined with stir bar sorptive extraction for the analysis of organochlorine pesticides and chlorobenzenes in soils

An analytical method for the determination of several organochlorine pesticides (OCPs) like hexachlorocyclohexanes (HCHs), cyclodiene derivates (dieldrin, aldrin, endrin, heptachlor, heptachlor epoxide, endrin aldehyde, endosulfan and ensodulfan sulphate) and DDX compounds (p,p'-DDE, p,p'-DDD and p,p'-DDT) as well as chlorobenzenes in soils has been developed. The procedure is based on pressurized subcritical water extraction (PSWE) followed by stir bar sorptive extraction (SBSE) and subsequent thermodesorption-gas chromatography/mass spectrometry analysis. Significant PSWE and SBSE parameters were optimized using spiked soil and water samples. For the PSWE of the organochlorine compounds, water modified with acetonitrile as the extraction solvent, at an extraction temperature of 120 degrees C, and three cycles of 10 min extraction proved to be optimal. Under optimized conditions, the figures of merit, such as precision, accuracy and detection limits were evaluated. The detection limits obtained for soil samples were in the range 0.002-4.7 ng/g. Recoveries between 4.1 and 85.2% were achieved from samples spiked at a concentration level of 25-155 ng/g. The main advantages of this method are the avoidance of clean-up and concentration procedures as well as the significant reduction of the required volume of organic solvents. The described method was applied to the determination of the pollutants in soil samples collected from a polluted area, the Bitterfeld region (Germany). The results obtained by PSWE-SBSE were in a good agreement with those obtained by a reference method, a conventional pressurized liquid extraction (PLE).

Development and validation of a novel method for the analysis of chlorinated pesticides in soils using microwave-assisted extraction–headspace solid phase microextraction and gas chromatography–tandem mass spectrometry

A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, alpha- and gamma-chlordane, p,p'-DDT, heptachlor, heptachlor epoxide isomer A, gamma-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.

Transport and fate of dieldrin in poplar and willow trees analyzed by SPME

Dieldrin is a hydrophobic organochlorine insecticide that is persistent in the environment. The fate and transport of dieldrin in trees is important both in the context of potential remediation, as well as food chain impacts through dieldrin transport to shoots and leaves. Experiments were conducted to measure the degree of dieldrin partitioning to plant tissue and the potential for biodegradation of dieldrin in the microbe rich tree rhizosphere. Dieldrin was analyzed in water and plant tissue using headspace solid-phase microextraction (SPME) coupled with gas chromatography. Poplar and willow saplings planted in soil and watered with 10 microgl(-1) dieldrin for up to 9 months showed no adverse effects due to dieldrin exposure and no dieldrin was observed in plant shoots with a method detection limit (MDL) of 7 ngg(-1). One-week hydroponic tests of poplar saplings exposed to aqueous dieldrin also showed no detection of dieldrin in shoots, with an average of 66% of the dieldrin partitioned to the plant roots and an overall mass balance recovery of 76% in the plant-water system. The root concentration factor (RCF) was found to be 30+/-3 ml water g(-1) root. Biodegradation of dieldrin was not observed in an aqueous batch bioreactor containing 8 microgl(-1) dieldrin, nutrients and bacteria from the root zone of a poplar sapling that had been exposed to dieldrin for 9 months. These results show that planting trees is likely to be safe and potentially useful at sites containing low-levels of dieldrin in groundwater.

Identification of volatile basic components in tobacco by headspace liquid-phase microextraction coupled to matrix-assisted laser desorption/ionization with Fourier transform mass spectrometry

A method incorporating headspace liquid-phase microextraction (HS-LPME) coupled to matrix-assisted laser desorption/ionization (MALDI) with Fourier transform mass spectrometry (FTMS) was established to analyze volatile basic components in tobacco. The sample preparation volume for MALDI-MS was compatible with the volume of the solvent microdrop in the HS-LPME procedure. The pH and the polarity of the solvent for HS-LPME were adjusted by choice of the MALDI matrix and matrix additive. Based on the elemental composition and tandem mass spectrometry information, 25 volatile nitrogenous compounds in tobacco were detected and identified. The approach is fast and sensitive, and has the potential for automation for high-throughput analysis. This approach offers an alternative method for analysis of trace volatile organic compounds in complex samples.