Determination of multiclass contaminants in chilli powder based on magnetic multiwalled carbon nanotubes and UPLC-QTOF/MS.

A multiclass analysis approach was developed using magnetic multiwalled carbon nanotubes sorbents and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) for the rapid screening and simultaneous determination of 216 contaminants including 15 mycotoxins, 9 synthetic colourants, and 192 pesticides in chilli powder. The sample preparation process was optimized. The optimal preparation procedure utilized NaCl and NaAc as the salting-out agents, and Fe3O4-MWCNTs as the sorbents, resulting in reduced chemical consumption, improved cleaning performance, and facilitated high-throughput analysis. The proposed method was validated, and satisfactory parameters were obtained. Approximately 85.6% of the target analytes exhibited a weak matrix effect, with the matrix effects falling within the range of 0.8 âˆ¼ 1.2. The method demonstrated acceptable recoveries of the analytes, falling within the range of 62.14%∼119.76% at three fortified levels with relative standard deviations (RSDs) of less than 20%. Additionally, the method's limit of quantification (LOQ) ranged from ranged from 0.50 µg·kg-1 to 49.56 µg·kg-1. The method was further applied for analysis of 27 chilli powder samples, demonstrating its potential for screening and quantification of multiclass contaminants for spices.

UPLC-Q-TOF/MS-based metabolomic analysis reveals the effects of asomate on the citrus fruit.

The regulation of the sugar-acid ratio is of great significance to the improvement of citrus fruit quality. The citric acid level in fruit is influenced by many factors. Among them, cultivar selection and production practices are the most important strategies under the grower's control. In recent years, an arsenic-containing preparation called "Tianmisu", with the main ingredient of asomate, has occasionally been reported to be used in citrus cultivation to improve the sweetness of fruits. In order to reveal the effects of the pesticide on citrus fruits, 'Harumi' tangor was treated with "Tianmisu", and the impact of this pesticide on fruit quality and metabolites was investigated through UPLC-Q-TOF/MS-based metabolomic analysis. Compared with the control, the concentration of titratable acidity, in particular citric acid, in the pulp of 'Harumi' tangor treated with the pesticide, was significantly reduced by 60.5%. The differences in metabolites between the pesticide-treated samples and the control were illustrated by Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA). The PLS-DA analysis demonstrated a clear discrimination, with R2Y and Q2 values of 0.982 and 0.933 in the positive mode and 0.984 and 0.900 in the negative mode, respectively. A total of 155 compounds were identified, and 63 characteristic components were screened out from the pesticide-treated samples compared to the control. Aside from the upregulation observed for a few metabolites, the majority of the compounds, including citric acid and various lipids, were down-regulated in the treated citrus fruits compared to the control. This study can serve as a basis for understanding the regulatory mechanism of organic acids in citrus and will be helpful in developing different strategies to improve citrus quality.

Parameter Optimization of a Potted Seedling Tray Prepared from a Mixture of Rice Straw and Fermented Cow Manure Using the Response Surface Methodology.

Biomass is generally regarded as a significant renewable resource, which can be used as the raw material for bioproducts. In the study, a mixture of rice straw and fermented cow manure was utilized to produce potted seedling trays, which are biodegradable and environmentally friendly. The effects of process parameters on the quality of final products were assessed by measuring damage resistance (DR) and expansion ratio (ER). Single-factor experiments and the response surface methodology (RSM) were used to optimize process parameters, including moisture content, forming pressure, mass percentage of straw (the ratio of rice straw to the mixture), and forming temperature as variables, and DR and ER of potted seedling trays as responses. The results showed that moisture content had the largest effect on DR and ER, followed by forming pressure, forming temperature, and mass percentage of straw. The optimal conditions were identified as a moisture content of 13%, forming pressure of 124 kN, mass percentage of straw equal to 8%, and forming temperature of 132 °C. There was a good agreement between the experimental data and the predicted results, indicating the reliability of the optimization process. Under the optimal conditions, the effectiveness of the regression model was further validated by the desirability of 0.97. Our findings shed new light on the perfect utilization of straws and animal manure and provided a reliable reference for the preparation of potted seedling trays from other types of biomass produced by agriculture.

Simultaneous determination of multiclass plant growth regulators in fruits using the quick, easy, cheap, effective, rugged, and safe method and ultra-high performance liquid chromatography-tandem mass spectrometry.

In this study, a modified quick, easy, cheap, effective, rugged, and safe method combined with ultra-high performance liquid chromatography and tandem mass spectrometry was developed for the multiclass determination of 28 plant growth regulators in various fruits. Different extraction solvents and adsorbents, including primary secondary amine, octadecylsilyl, graphitized carbon black, and zirconia-based sorbent, were investigated. Internal calibration and isotope internal standards, chlormequat chloride-d4 , mepiquat chloride-d6 , indole-3-acetic acid-d2 , and forchlorfenuron-d5 were used to improve accuracy. For method validation, good linearity, low limits of detection and quantification were obtained. At three spiked concentrations (10, 50, and 100 µg/kg), satisfactory recoveries with relative standard deviations of 2.4-17.5% were obtained for strawberries (75.2-119.8%), grapes (70.5-114.0%), tangerines (71.7-115.4%), apples (72.7-115.4%), and kiwi fruits (71.7-119.2%). Samples analysis revealed that 15.6% of the samples (n = 96) were contaminated with one or two kinds of plant growth regulators, including chlormequat chloride, forchlorfenuron, paclobutrazol, 2,4-dichlorophenoxyacetic acid, 2-diethylaminoethyl hexanoate, and mepiquat chloride. Similar results were obtained by ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry, indicating the robustness, effectiveness, and suitability of the developed method for routine monitoring of plant growth regulator residues in fruits.

Application of a multiclass screening method for veterinary drugs and pesticides using HPLC-QTOF-MS in egg samples.

A multi-class screening method for the determination of veterinary drugs and pesticides in eggs was developed by high performance liquid chromatography quadrupole-time-of-flight mass spectrometry (HPLC-QTOF-MS). A single-injection workflow was developed for qualitative analysis, and method validation was conducted in terms of retention time deviation (ΔRt), exact mass error (Δm), selectivity, specificity, precision and trueness. The characteristic fragment ions in information dependent acquisition (IDA) mode were summarized for retrospective and non-target screening. Five of 70 samples were found positive with sulfachloropyridazine, sulfamonomethoxine and fipronil sulfone. Compared with triple-quadrupole (QqQ) MS method, the obtained results showed that QTOF-MS gave comparable results to QqQ-MS with residue concentrations higher than 10 µg·kg-1, whereas QqQ-MS was more powerful at lower concentrations (<1 µg·kg-1). Moreover, the amount of fragment ions acquired by HPLC-QTOF-MS decreased substantially at trace levels, which may be a potential cause of reduced reliability of identification.

Development of a modified QuEChERS method based on magnetic multiwalled carbon nanotubes for the simultaneous determination of veterinary drugs, pesticides and mycotoxins in eggs by UPLC-MS/MS.

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was developed for the simultaneous determination of veterinary drugs, pesticides and mycotoxins in eggs by ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Several extraction conditions were tested and optimized, and the obtained extraction efficiency of all the targeted compounds (particularly macrolides) could fulfill the requirements. In the purification procedure, magnetic multiwalled carbon nanotubes (Fe3O4-MWCNTs) were used as adsorbents, and an external magnet was utilized to achieve a faster adsorbent separation, compared to the traditional centrifugation process. The recoveries of all analytes were in the range of 60.5%-114.6% at three fortified levels with relative standard deviations (RSDs) of less than 20%, and the LOQs ranged from 0.1 µg·kg-1 to 17.3 µg·kg-1. This method was successfully applied to the analysis of egg samples, demonstrating its applicability and suitability for the routine analysis of multiclass residues in egg samples.

Optimization of a multi-residue method for 101 pesticides in green tea leaves using gas chromatography–tandem mass spectrometry

ABSTRACT A method for analysis of 101 pesticide residues in tea leaves was developed and validated for the first time. Pure acetonitrile was used as extraction solvent rather than acetonitrile after matrix hydration based on the amount of co-extracts and recoveries performance. During clean-up procedure, primary-secondary amine/graphitized carbon black (500 mg) was selected, which exhibited outstanding properties in clean-up capabilities and recoveries of pesticides comparing to primary-secondary amine/graphitized carbon black (250 mg), NH2-Carbon and TPT absorbents. The method was validated employing gas chromatography coupled to tandem mass spectrometry at the spiked concentration levels of 0.050 and 0.100 mg kg−1. For most of the targeted pesticides, the percent recoveries range from 70 to 120%, with relative standard deviations <20%. The linear correlation coefficients (r 2) were higher than 0.99 at concentration levels of 0.025–0.250 mg kg−1. Limits of quantification ranged from 1.1 to 25.3 µg kg−1 for all pesticides. The developed method was successfully applied to the determination of pesticides in tea leaf samples.

A multi-residue method for the determination of pesticides in tea using multi-walled carbon nanotubes as a dispersive solid phase extraction absorbent.

A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method using multi-walled carbon nanotubes (MWCNTs) as a dispersive solid phase extraction (d-SPE) absorbent was established for analysis of 78 pesticide residues in tea. A 6 mg MWCNT sample was selected as the optimised amount based on the distribution of pesticide recoveries and clean-up efficiency from 6 mL acetonitrile extracts. The matrix effects of the method were evaluated and matrix-matched calibration was recommended. The method was validated employing gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) at the spiked concentration levels of 0.05, 0.1 and 0.15 mg kg(-1). For most of the targeted pesticides, the percent recoveries range from 70% to 120%, with relative standard deviations (RSDs) <20%. The linear correlation coefficients (r(2)) were higher than 0.99 at concentration levels of 0.025-0.500 mg kg(-1). In this study, MWCNTs were proved to be a promising d-SPE absorbent with excellent cleanup efficiency, which could be widely applied for the analysis of pesticide residues.

Development and validation of an rp-hplc method for simultaneous determination of Ramipril and Amlodipine in tablets.

An rp-hplc method for the simultaneous determination of Ramipril (RP) and Amlodipine (AL) in tablets was developed and validated by Chinese Pharmacopoeia 2010. The linearity of the proposed method was investigated in the range of 0.01-0.25 mg/mL (r2=0.9998) for RP and 0.014-0.36 mg/mL (r2=0.9997) for AL. The limits of detection (LOD) were 0.06 µg/mL and 0.02 µg/mL for RP and AL, and the limits of quantitation (LOQ) were 0.2 µg/mL and 0.07 µg/mL, respectively. Some major impurities and degradation products did not disturb the detection of RP and AL and the assay can thus be considered stability-indicating.