Determination of 77 Multiclass Pesticides and Their Metabolitesin Capsicum and Tomato Using GC-MS/MS and LC-MS/MS

A quick, sensitive, and reproducible analytical method for the determination of 77 multiclass pesticides and their metabolites in Capsicum and tomato by gas and liquid chromatography tandem mass spectrometry was standardized and validated. The limit of detection of 0.19 to 10.91 and limit of quantification of 0.63 to 36.34 µg·kg⁻¹ for Capsicum and 0.10 to 9.55 µg·kg⁻¹ (LOD) and 0.35 to 33.43 µg·kg⁻¹ (LOQ) for tomato. The method involves extraction of sample with acetonitrile, purification by dispersive solid phase extraction using primary secondary amine and graphitized carbon black. The recoveries of all pesticides were in the range of 75 to 110% with a relative standard deviation of less than 20%. Similarly, the method precision was evaluated interms of repeatability (RSDr) and reproducibility (RSD_wR) by spiking of mixed pesticides standards at 100 µg·kg⁻¹ recorded anRSD of less than 20%. The matrix effect was acceptable and no significant variation was observed in both the matrices except for few pesticides. The estimated measurement uncertainty found acceptable for all the pesticides. This method found suitable for analysis of vegetable samples drawn from market and farm gates.     

Simultaneous Analysis of Fenpropimorph and Fenpropimorph Acid in Six Different Livestock Products Using a Single-Sample Preparation Method Followed by Liquid Chromatography–Tandem Mass Spectrometry

Pesticides in livestock products must be measured to ensure food safety. We developed a single-sample preparation method followed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) for simultaneous determination of fenpropimorph and fenpropimorph acid in six different livestock products. The extraction method was a modification of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and was validated according to the CODEX guidelines. The matrix-matched calibration curves for fenpropimorph and fenpropimorph acid exhibited good linearity, with coefficients of determination (R² values) higher than 0.998. The limit of detection (LOD) and the limit of quantitation (LOQ) were 1.25 and 5.0 µg kg⁻¹, respectively. The average recovery values ranged from 61.5% to 97.1% for samples fortified to the LOQ, 2 × LOQ, and 10 × LOQ. The method fully complied with the CODEX guidelines and was successfully applied to real samples obtained from domestic markets.     

Development of One-Step Non-Solvent Extraction and Sensitive UHPLC-MS/MS Method for Assessment of N-(n-Butyl) Thiophosphoric Triamide (NBPT) and N-(n-Butyl) Phosphoric Triamide (NBPTo) in Milk

N-(n-butyl) thiophosphoric triamide (NBPT) is a urease inhibitor utilised in urea-based fertilizers. In Ireland, fertilizer treated with NBPT is applied to pasture to mitigate both ammonia and nitrous oxide emissions, but concerns arise as to the potential for residues in milk products. A quick ultrafiltration extraction and ultra-high performance liquid chromatography coupled with mass spectrometry triple quadrupole (UHPLC-MS/MS) quantitation method was developed and validated in this study. The method was applied in the analysis of samples collected from a field study investigating potential transfer of NBPT residues into milk. NBPT and NBPTo residues, were extracted from fortified milk samples and analysed on a UHPLC-MS/MS with recoveries ranging from 74 to 114%. Validation of the UHPLC-MS/MS method at low (0.0020 mg kg⁻¹) and high (0.0250 mg kg⁻¹) concentration levels in line with SANTE/12682/2019 showed overall trueness in the range of 99 to 104% and precision between 1 and 10%, RSD for both compounds. The limit of quantitation (LOQ) was 0.0020 mg kg⁻¹ and other tested parameters (linearity, sensitivity, specificity, matrix effect, robustness, etc.) satisfied acceptance criteria. Stability assessment using spiked samples revealed the compounds were stable in raw and pasteurised milk for 4 weeks at –80 °C storage temperature. Maintaining samples at pH 8.5–9.0 further improved stability. Analysis of 516 milk samples from the field study found that NBPT and NBPTo concentrations were below the LOQ of 0.0020 mg kg⁻¹, thus suggesting very low risk of residues occurring in the milk. The method developed is quick, robust, and sensitive. The method is deemed fit-for-purpose for the simultaneous determination of NBPT and NBPTo in milk.     

Validated Stability-Indicating GC-MS Method for Characterization of Forced Degradation Products of Trans-Caffeic Acid and Trans-Ferulic Acid

When dealing with simple phenols such as caffeic acid (CA) and ferulic acid (FA), found in a variety of plants, it is very important to have control over the most important factors that accelerate their degradation reactions. This is the first report in which the stabilities of these two compounds have been systematically tested by exposure to various different factors. Forced degradation studies were performed on pure standards (trans-CA and trans-FA), dissolved in different solvents and exposed to different oxidative, photolytic and thermal stress conditions. Additionally, a rapid, sensitive, and selective stability-indicating gas chromatographic-mass spectrometric method was developed and validated for determination of trans-CA and trans-FA in the presence of their degradation products. Cis-CA and cis-FA were confirmed as the only degradation products in all the experiments performed. All the compounds were perfectly separated by gas chromatography (GC) and identified using mass spectrometry (MS), a method that additionally elucidated their structures. In general, more protic solvents, higher temperatures, UV radiation and longer storage times led to more significant degradation (isomerization) of both trans-isomers. The most progressive isomerization of both compounds (up to 43%) was observed when the polar solutions were exposed to daylight at room temperature for 1 month. The method was validated for linearity, precision as repeatability, limit of detection (LOD) and limit of quantitation (LOQ). The method was confirmed as linear over tested concentration ranges from 1−100 mg L⁻¹ (r²s were above 0.999). The LOD and LOQ for trans-FA were 0.15 mg L⁻¹ and 0.50 mg L⁻¹, respectively. The LOD and LOQ for trans-CA were 0.23 mg L⁻¹ and 0.77 mg L⁻¹, respectively.     

Application of HPLC-QQQ-MS/MS and New RP-HPLC-DAD System Utilizing the Chaotropic Effect for Determination of Nicotine and Its Major Metabolites Cotinine,and trans-3′-Hydroxycotinine in Human Plasma Samples

The routine techniques currently applied for the determination of nicotine and its major metabolites, cotinine, and trans-3′-hydroxycotinine, in biological fluids, include spectrophotometric, immunoassays, and chromatographic techniques. The aim of this study was to develop, and compare two new chromatographic methods high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (HPLC-QQQ-MS/MS), and RP-HPLC enriched with chaotropic additives, which would allow reliable confirmation of tobacco smoke exposure in toxicological and epidemiological studies. The concentrations of analytes were determined in human plasma as the sample matrix. The methods were compared in terms of the linearity, accuracy, repeatability, detection and quantification limits (LOD and LOQ), and recovery. The obtained validation parameters met the ICH requirements for both proposed procedures. However, the limits of detection (LOD) were much better for HPLC-QQQ-MS/MS (0.07 ng mL⁻¹ for trans-3′-hydroxcotinine; 0.02 ng mL⁻¹ for cotinine; 0.04 ng mL⁻¹ for nicotine) in comparison to the RP-HPLC-DAD enriched with chaotropic additives (1.47 ng mL⁻¹ for trans-3′-hydroxcotinine; 1.59 ng mL⁻¹ for cotinine; 1.50 ng mL⁻¹ for nicotine). The extraction efficiency (%) was concentration-dependent and ranged between 96.66% and 99.39% for RP-HPLC-DAD and 76.8% to 96.4% for HPLC-QQQ-MS/MS. The usefulness of the elaborated analytical methods was checked on the example of the analysis of a blood sample taken from a tobacco smoker. The nicotine, cotinine, and trans-3′-hydroxycotinine contents in the smoker’s plasma quantified by the RP-HPLC-DAD method differed from the values measured by the HPLC-QQQ-MS/MS. However, the relative errors of measurements were smaller than 10% (6.80%, 6.72%, 2.04% respectively).     

Fluorimetric Analysis of Five Amino Acids in Chocolate: Development and Validation

Amino acids present ergogenic action, helping to increase, protect, and restore the muscular system of young athletes. Moreover, the encapsulation of five relevant amino acids in chocolate pellet form will appeal to them, facilitating their daily consumption. A reliable HPLC fluorimetric method was developed to detect and quantitatively determine L-Leucine, L-Isoleucine, L-Histidine, L-Valine, and β-Alanine in chocolate using aniline as an internal standard. Experimental design methodology was used to investigate and optimize the clean-up procedure of the samples. Therefore, three extraction techniques (solid-phase extraction (by two different SPE cartridges) and liquid–solid extraction (LSE)) were compared and evaluated. The LOQ values in chocolate varied from 24 to 118 ng/g (recovery 89.7–95.6%, %RSD < 2.5). Amino acids were pre-column derivatized with o-phthalaldehyde (OPA), while derivatization parameters were thoroughly investigated by experimental design methodology. The analysis was performed by HPLC-fluorescence (emission: λ = 455 nm, excitation: λ = 340 nm) method using a C₁₈ column and a mixture of phosphate buffer (pH = 2.8; 20 mM)-methanol as a mobile phase in gradient elution. The method was validated (r² > 0.999, %RSD < 2, LOD: 10 ng mL⁻¹ for histidine and leucine, 2 ng mL⁻¹ for alanine and valine, and 4 ng mL⁻¹ for Isoleucine) according to the International Conference on Harmonization guidelines.     

Determination of trace sulfur in biodiesel and diesel standard reference materials by isotope dilution sector field inductively coupled plasma mass spectrometry

A method is described for quantification of sulfur at low concentrations on the order of mg kg⁻¹ in biodiesel and diesel fuels using isotope dilution and sector field inductively coupled plasma mass spectrometry (ID-SF-ICP-MS). Closed vessel microwave-assisted digestion was employed using a diluted nitric acid and hydrogen peroxide decomposition medium to reduce sample dilution volumes. Medium resolution mode was employed to eliminate isobaric interferences at ³²S and ³⁴S related to polyatomic phosphorus and oxygen species, and sulfur hydride species. The method outlined yielded respective limits of detection (LOD) and limits of quantification (LOQ) of 0.7 mg kg⁻¹ S and 2.5 mg kg⁻¹ S (in the sample). The LOD was constrained by instrument background counts at ³²S but was sufficient to facilitate value assignment of total S mass fraction in NIST SRM 2723b Sulfur in Diesel Fuel Oil at 9.06 ± 0.13 mg kg⁻¹. No statistically significant difference at a 95% confidence level was observed between the measured and certified values for certified reference materials NIST SRM 2773 B100 Biodiesel (Animal-Based), CENAM DRM 272b and NIST SRM 2723a Sulfur in Diesel Fuel Oil, validating method accuracy.     

Simultaneous determination of aflatoxins B2 and G2 in peanuts using spectrofluorescence coupled with parallel factor analysis

In the present study a method for the simultaneous determination of aflatoxins B₂ and G₂ in peanuts has been developed. The method uses second order standard addition method and excitation–emission fluorescence data together with parallel factor analysis (PARAFAC). The aflatoxin analysis was based on extraction with methanol–water and carried out using immunoaffinity clean-up. The results of PARAFAC on a set of spiked and naturally contaminated peanuts indicated that the two aflatoxins could be successfully determined. The method was validated and analytical figures of merit were obtained for both analytes. The limits of detection (LOD) were 0.05 and 0.04 μg kg⁻¹ for aflatoxins B₂ and G₂, respectively. The limits of quantification (LOQ) were 0.16 and 0.12 μg kg⁻¹ for aflatoxins B₂ and G₂, respectively. Coupling of spectrofluorimetry with PARAFAC can be considered as an alternative method for quantification of aflatoxins in the presence of unknown interferences obtained through analysis of highly complex matrix of peanuts samples at a reduced cost per analysis.     

A multi-residue method for pesticide residue analysis in rice grains using matrix solid-phase dispersion extraction and high-performance liquid chromatography–diode array detection

Pesticides are widely used in rice cultivation, often resulting in detection of their residues in rice grains. So far, no analytical method has been available for the simultaneous determination of most rice pesticides in rice grains. This paper reports the development and validation of such a method for the determination of eight rice pesticides (penoxsulam tricyclazole, propanil, azoxystrobin, molinate, profoxydim, cyhalofop-butyl, deltamethrin) and 3,4-dichloroaniline, the main metabolite of propanil. Pesticide extraction and clean-up was performed by an optimized matrix solid-phase dispersion (MSPD) protocol on neutral alumina (5 g) using acetonitrile as the elution solvent. Samples were analyzed in a high-performance liquid chromatography–diode array detection (HPLC-DAD) system. Pesticide separation was achieved with a mobile phase of acetonitrile/water in a linear elution gradient from 30:70% (v/v) to 100:0% (v/v) in 14 min at a flow rate of 0.8 mL min^?1. Method validation was performed by means of linearity, intra-day accuracy, inter-day precision and sensitivity. Linear regression coefficients (R ²) were always above 0.9948. Limits of detection (LOD) and quantification (LOQ) varied from 0.002 to 0.200 mg kg^?1 and 0.006 to 0.600 mg kg^?1, respectively. Recoveries were investigated at three fortification levels and were found to be acceptable (74–127%) with relative standard deviations (RSD) below 12%. Application of the method for the analysis of five commercial rice grain samples showed that the pesticide levels were below the LOD. Overall, the method developed is suitable for the determination of residues of most rice pesticides in rice grains at levels below the established MRLs.     

Determination of Anthelmintic and Antiprotozoal Drug Residues in Fish Using Liquid Chromatography-Tandem Mass Spectrometry

The objective of this study is to develop a comprehensive and simple method for the simultaneous determination of anthelmintic and antiprotozoal drug residues in fish. For sample preparation, we used the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method with a simple modification. The sample was extracted with water and 1% formic acid in acetonitrile/methanol (MeCN/MeOH) (95:5, v/v), followed by phase separation (salting out) with MgSO₄ and NaCl (4:1, w/w). After centrifugation, an aliquot of the extract was purified by dispersive solid-phase extraction (d-SPE) prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The method was validated at three concentration levels for all matrices, in accordance with the Codex guidelines (CAC/GL-71). Quantitative analysis was performed using the method of matrix-matched calibration. The recoveries were between 60.6% and 119.9%, with coefficients of variation (CV) <30% for all matrices. The limit of quantitation (LOQ) of the method ranged from 0.02 μg kg⁻¹ to 4.8 μg kg⁻¹ for all matrices. This comprehensive method can be used for the investigation of both anthelmintic and antiprotozoal drugs belonging to different chemical families in fishery products.     

Simultaneous determination of sex hormones in egg products by ZnCl2 depositing lipid, solid-phase extraction and ultra performance liquid chromatography/electrospray ionization tandem mass spectrometry

A method was developed for simultaneous determination of residues of 17 sex hormones in egg products. Target compounds were extracted from samples with methanol in an ultrasonic bath, effectively separated from lipids in the extracts by ZnCl₂ depositing filtration and purified using a C₁₈ solid-phase extraction (SPE) and followed by NH₂ SPE cartridge. The analytes were quantified by liquid chromatography using a BEH C₁₈ column coupled to an electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS) operating in negative mode for estrogens and in positive multiple reaction monitoring mode for androgens. The parameters of the mass spectrometer and the composition of mobile phase and additives were also optimized to enhance detection sensitivity. Average recoveries of the target compounds varied from 70.0% to 121.0% with relative standard deviations ranging from 2.3% to 11.2% at two fortification levels. The limits of detection (LOD) of the method were from 0.002 μg kg⁻¹ to 0.23 μg kg⁻¹ and the limits of quantification (LOQ) were in the range of 0.007-0.76 μg kg⁻¹.     

Determination of Prometryne in water and soil by HPLC-UV using cloud-point extraction

A CPE-HPLC (UV) method has been developed for the determination of Prometryne. In this method, non-ionic surfactant Triton X-114 was first used to extract and pre-concentrate Prometryne from water and soil samples. The separation and determination of Prometryne were then carried out in an HPLC-UV system with isocratic elution using a detector set at 254 nm wavelength. The parameters and variables that affected the extraction were also investigated and the optimal conditions were found to be 0.5% of Triton X-114 (w/v), 3% of NaCl (w/v) and heat-assisted at 50 °C for 30 min. Using these conditions, the recovery rates of Prometryne ranged from 92.84% to 99.23% in water and 85.48% to 93.67% in soil, respectively, with all the relative standard deviations less than 3.05%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.5 μg L⁻¹ and 11.0 μg L⁻¹ in water and 4.0 μg kg⁻¹ and 13.0 μg kg⁻¹ in soil, respectively. Thus, we developed a method that has proven to be an efficient, green, rapid and inexpensive approach for extraction and determination of Prometryne from soil samples.     

Immunosensor for estrone with an equal limit of detection as common analytical methods

Immunoanalytical methods at a very low limit of detection (LOD) and a low limit of quantification (LOQ) are becoming more and more important for environmental analysis and especially for monitoring drinking water quality. Biosensors have suitable characteristics such as efficiency in allowing very fast, sensitive, and cost-effective detection. Here we describe a fully automated immunoassay for estrone with a LOD below 0.20 ng L^–1 and a LOQ below 1.40 ng L^–1. In contrast to common analytical methods such as GC-MS or HPLC-MS, the biosensor used requires no sample pre-treatment and pre-concentration. The basis of our sensitive assay is the antibody with a high affinity constant towards estrone. The very low amount of antibody per sample results in low validation parameters (LOD, LOQ, and IC50), but this assay for estrone represents the current device-related limitation of the River Analyser (RIANA).     

QuEChERS method combined to liquid chromatography high-resolution mass spectrometry for the accurate and sensitive simultaneous determination of pyrrolizidine and tropane alkaloids in cereals and spices

Within the last decades, in the EU, there has been an increasing interest in toxic plant alkaloids as food contaminants, especially after the continuous and growing consumption of plant-based foods compared with food of animal origin. In this regard, the once neglected presence of these tropane alkaloids (TAs) and pyrrolizidine alkaloids (PAs) has recently been reconsidered by the European Food Safety Authority, highlighting the lack of data and the need to develop risk assessment strategies. For this reason, the emphasis has been placed on detecting their occurrence in food through the development of accurate and sensitive analytical methods to achieve the determination of these compounds. The present study aims to elaborate and validate an analytical method based on QuEChERS sample preparation approach, exploiting the UHPLC coupled to the HRMS to simultaneously identify and quantify 21 PAs and two TAs in cereals and spices. For TAs, the obtained limit of detection (LOD) is 0.1 μg·kg⁻¹ and the limit of quantification (LOQ) is 0.4 μg·kg⁻¹, while for PAs, the LODs values ranging between 0.2 to 0.3 μg·kg⁻¹ and the LOQ, between 0.4 and 0.8 μg·kg⁻¹, ensuring compliance with the recently established European Regulations. Several commercial samples were analysed to further verify the applicability of this comprehensive analytical approach.     

Persistence and dissipation of fluopicolide and propamocarb on cabbage and soil under semi-arid climatic conditions

Persistence and dissipation of fluopicolide and propamocarb were studied on cabbage and soil as per good agricultural practices over a period of 2 years. A modified QuEChERS analytical method in conjunction with gas chromatography (GC) and GC–mass spectrometry was used for analysis of fluopicolide and its metabolite, 2,6-dichlorobenzamide, and propamocarb in cabbage and soil. The results of the method validation were satisfactory with recoveries within 74.5–100.81% and relative standard deviations 4.8–13.9% (n = 6). The limit of detection (LOD) and limit of quantification (LOQ) of both fluopicolide and 2,6-dichlorobenzamide were 0.003 µg mL^?1 and 0.01 mg kg^?1, respectively. The LOD and LOQ of propamocarb were 0.03 µg mL^?1 and 0.1 mg kg^?1, respectively. During 2013, the initial residue deposits of fluopicolide on cabbage were 0.60 and 1.48 mg kg^?1 from treatments at the standard and double doses of 100 and 200 g a.i. ha^?1 which dissipated with the half-life of 3.4 and 3.7 days. During 2014, the residues were 0.49 and 1.13 mg kg^?1 which dissipated with the half-life of 4.2 and 5.1 days. Propamocarb residues on cabbage were 5.36 and 12.58 mg kg^?1 in the first study (2013) and 4.85 and 10.26 mg kg^?1 in the second study (2014) from treatments at the standard and double doses of 1000 and 2000 g a.i. ha^?1, respectively. The residues dissipated with the half-life of 4–5.5 days. The preharvest interval, the time required for fluopicolide + propamocarb residues to dissipate below the maximum residue limits (notified by EU) at the standard dose, was 11.8 and 14 days during 2013 and 2014. Residue of 2,6-dichlorobenzamide was always <LOQ in cabbage. Residues of fluopicolide, 2,6-dichlorobenzamide and propamocarb were <LOQ in field soil at harvest.     

Complex Activity and Sensor Potential toward Metal Ions in Environmental Water Samples of N-Phthalimide Azo-Azomethine Dyes

Herein, the spectral and electrochemical characterizations of three different substituted N-phthalimide azo-azomethine (NAA) dyes (L) containing an o-hydroxy group and their NAA-M(II) chelates [M(II): Cu, Ni, Co, Pb] were reported by using UV–Vis and fluorescence spectroscopy and potentiometric and voltamperometric techniques. The pK value of the dyes as well as the stoichiometry and stability of the NAA-metal chelates were studied, and the stoichiometry was found to be mostly 1:2 (ML₂) with high complex stability constant values. The sensor activity of N-phthalimide azo-azomethine derivatives toward pH and metal ions has been also investigated and tested for indicator application in acid–base analysis and detection of Cu(II) ions in real samples of surface river water using voltamperometric detection. The results showed that one of the ligands possesses the highest electrochemical response upon binding to copper ions and could be successfully used in the analysis of copper in water at a concentration range of the analyte from 3.7 × 10⁻⁷ to 5.0 × 10⁻⁶ mol L⁻¹, with analytical characteristics of the method being Sr = 1.5%, LOD = 3.58 µg L⁻¹ and LOQ =11.9 µg L⁻¹     

Quantification of 2-acetyl-1-pyrroline in rice by stable isotope dilution assay through headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry

A new and convenient synthesis of 2-acetyl-1-pyrroline (2AP), a potent flavor compound in rice, and its ring-deuterated analog, 2-acetyl-1-d₂-pyrroline (2AP-d₂), was reported. A stable isotope dilution assay (SIDA), involving headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-positive chemical ionization-ion trap-tandem mass spectrometry (GC-PCI-IT-MS-MS), was developed for 2AP quantification. A divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used for HS-SPME procedure and parameters affecting analytes recovery, such as extraction time and temperature, pH and salt, were studied. The repeatability of the method (n = 10) expressed as relative standard deviation (RSD) was 11.6%. A good linearity was observed from 5.9 to 779 ng of 2AP (r² = 0.9989). Limits of detection (LOD) and quantification (LOQ) for 2AP were 0.1 and 0.4 ng g⁻¹ of rice, respectively. The recovery of spiked 2AP from rice matrix was almost complete. The developed method was applied to the quantification of 2AP in aerial parts and grains of scented and non-scented rice cultivars.     

Pressurised hot water extraction followed by simultaneous derivatization and headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry for the determination of aliphatic primary amines in sewage sludge

In this paper we describe an environmentally friendly and sensitive method for the determination of ten primary amines in sewage sludge. The method is based on pressurised hot water extraction (PHWE) followed by simultaneous derivatization with pentafluorobenzaldehyde (PFBAY) and headspace solid-phase microextraction (HS-SPME) and subsequent gas-chromatography ion-trap tandem mass spectrometry (GC-IT-MS-MS) analysis. The influence of the main factors on the PHWE of sludge was optimized by a central composite design. For all species the optimal conditions were water at pH 4 as the extracting solvent, an extraction temperature of 100 °C and an extraction time of 15 min. The separation and detection of the ten amines by GC-IT-MS-MS took just 10 min and the entire process took approximately 1 h. Repeatability and reproducibility between days, expressed as RSD (%) (n = 5), were less than 19 and 24%, respectively. The average limit of detection (LOD) was of 65 μg kg⁻¹ s (range found 9-135) and the average limit of quantification (LOQ) was of 230 μg kg⁻¹ (range found 50-450) of dry weight (d.w.). Under optimized conditions we used this method to determine the compounds in industrial and municipal sewage sludge samples and in sludge from a potable water treatment plant. Methylamine and isobutylamine showed the highest levels in one of the industrial sewage sludge samples (404 and 543 mg kg⁻¹ (d.w.), respectively). To our knowledge, this paper presents for the first time the determination of ten primary amines in sewage sludge samples using PHWE.     

Simultaneous determination of thiamethoxam and its metabolite clothianidin by LC-MS/MS in goji berry and soil

In this study, an effective analytical method for simultaneous determination of thiamethoxam and its metabolite clothianidin in goji berry and soil was developed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The recoveries of the compounds in goji berry and soil at the levels of 0.005, 0.02, and 0.1 μg kg^?1 were 84.7–98.9% and the relative standard deviations (RSDs) were 0.9–3.2%. The limits of detection (LOD) for both compounds in goji berry and soil matrices were 0.001 mg kg^?1; the limits of quantification (LOQ) were 0.005 mg kg^?1 for both compounds in two matrices. The dissipation and final residual experiments in 2016 with the commercial formulation of dinotefuran ? thiamethoxam 30% suspension concentrate (SC) was conducted in goji berries in northwest China (Qinghai, Gansu, Inner Mongolia, and Ningxia). Thiamethoxam was dissipated fast in goji plant ecosystem with half-lives were 1.08–1.01 and 2.04–4.25 days in goji berry and soil. The final residues of thiamethoxam were <0.005–0.382 and <0.005–1.120 mg kg^?1 in goji berry and soil, respectively.     

Determination of Aniline in Soil by ASE/GC-MS

In this study, a rapid and simple method based on accelerated solvent extraction (ASE) combined with gas chromatography-mass spectrometry (GC-MS) was established to determine the levels of aniline in soil. The matrix spike recovery rates of aniline were investigated by changing several experimental parameters such as vacuum freeze-drying, accelerated solvent extraction, sample transfer, nitrogen-blowing concentration and solvent exchange. Under optimized pretreatment conditions, the linearity of the method ranged from 0.5 to 20 μg mL⁻¹ for aniline, and the correlation coefficient was 0.999. Recoveries of aniline from quartz sand and soil ranged from 76% to 98%, while the precision was excellent with average inter-day and intraday values ranging (n = 6) from 3.1% to 7.5% and 2.0% to 6.9%, respectively. The limits of quantification of the method were 0.04 mg kg⁻¹. Notably, the results show that the method we developed is simple, fast, low cost and can meet the requirements for the determination of aniline in soil samples, sewage sludge, river and pond sediments.