FaPEx® Multipesticide Residues Extraction Kit for Minimizing Sample Preparation Time in Agricultural Produce.

Background: The quick, easy, cheap, effective, rugged, and safe method, generally applied to the determination of pesticide residues in food, has been recently modified and adopted for the analysis of pesticide residues worldwide, including Taiwan. Objective: The method still needs to be improved, particularly in efficiency and normalization, because the time costs 20-30 min for extraction and cleanup of multiple pesticides in every food. Methods: In this study, we present a highly efficient and simple sample preparation method that was developed for the determination of 380 pesticide residues in food, including mangoes, scallions, bok choy, apples, carrots, and pea seedlings. The homogenized 1 g samples mixed with 5 mL 1.0% acetic acid in acetonitrile were pushed through the FaPEx® (fast pesticide extraction) kits in a dropwise manner to obtain sample extracts. The total processing time was less than 15 min. The extracts were subject to chromatographic separation followed by GC-tandem MS (MS/MS) and LC-MS/MS analysis. Results: For more than 270 pesticide residues in these foods, the test gave acceptable mean recoveries, ranging between 70 and 120%, and relative SDs below 20%. The LOQ was at least 0.01 mg/kg for 380 pesticides. Conclusions: The developed method can greatly reduce the time needed for multiple pesticide residues analysis. Highlights: FaPEx is used for the extraction of pesticide residues that relies on single-use pre-filled sealed cartridges. FaPEx diminishes operation time, glassware demand, and laboratory space requirement. It also significantly decreases the amount of chemical solvents.

A simple approach for the ultrasensitive detection of paraquat residue in adzuki beans by surface-enhanced Raman scattering.

Paraquat (PQ), a broad-spectrum contact herbicide, has been used in many countries for controlling weed growth in agriculture because of its quick-acting and nonselective contact with green plant tissue. PQ is also toxic to humans, and even contributes to the development of neurodegenerative diseases. However, PQ is generally excluded from pesticide residue monitoring programs due to the lack of suitable determination methods. Thus, this study developed a detection method combined with simple extraction and surface-enhanced Raman spectroscopy (SERS) to rapidly determine and quantify the PQ residue on legumes without destructive procedures and high-cost instruments. Following the extraction procedure of the QuPPe-method, however, we took whole adzuki beans (Vigna angularis) extracted via a mixture of methanol and 1% formic acid at room temperature and followed by a 1 min cleanup by SPE. The PQ values for adzuki beans determined by LC/MSMS showed that regardless of whether extraction was followed by the QuPPe-method or the method we proposed, a consistent and low relative standard deviation (RSD) below <22% was found. In this study, we proposed to extract PQ on the surface of the beans by shaking briefly with solvent, and then the PQ molecules were detected and quantified by depositing Ag nanoparticles (AgNPs) and performing SERS within 10 min. Using a coating of deposited Ag nanoparticles, SERS can achieve a limit of detection (LOD) for PQ on the order of 1 µg L-1 (∼4 × 10-9 M) and a method detection limit (MDL) for adzuki beans of 0.8 µg kg-1 (∼3.3 × 10-9 M). This sensitivity at the ppb level absolutely met the maximum residue limit (MRL) for PQ in dried beans as declared by most countries, including the US (0.3 mg kg-1), Australia (1.0 mg kg-1) and Taiwan (0.2 mg kg-1). Taiwan will ban the use of PQ as a defoliating agent for harvest in adzuki bean fields in 2019; therefore, developing a method for detecting PQ residues in the field or in import markets is necessary for consumer health and for authorities. This study provided an opportunity to utilize SERS in the field of on-site pesticide residue screening.

Modified QuEChERS method for 24 plant growth regulators in grapes using LC-MS/MS.

A multiresidue analytical method was developed for grapes for the following 24 plant growth regulators: 1-naphthylacetamide, 2,3,5-triiodobenzoic acid, 2,4,5-T, 2-naphthoxyacetic acid, 3-indolylacetic acid, 4-(3-indolyl)-butyric acid, 4-chlorophenoxyacetic acid, 4-nitrophenol, 6-benzylaminopurine, N6-isopentenyladenine, butralin, chlormequat chloride, chlorphonim-Cl, cloprop, forchlorfenuron, gibberellic acid 3, gibberellic acid 4, gibberellic acid 7, inabenfide, mepiquat chloride, paclobutrazol, prohydrojasmon, thidiazuron and uniconizole-P. The compounds were extracted from grape samples using an extraction method modified from the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method. Liquid chromatography - tandem mass spectrometry was used for the detection and quantification of the compounds. Validation of the method was performed by using recovery studies at both intra-day and inter-day intervals, as well as by evaluation of the matrix effect, limit of quantification, trueness and precision. We used matrix-matched calibrations for the quantification of the compounds, which all resulted in determination coefficients (r2) higher than 0.995. The limit of quantification ranged from 0.1 to 5 ng/mL. Recovery studies using three spiking concentrations at varying levels showed recoveries of 70.2-112.6% and 67.5-101.8% at intra-day and inter-day intervals, respectively. Relative standard deviations were below 20% for the recovery studies. The extraction method were further validated by performing recovery study and matrix effect test in six different grape varieties from Taiwan and the United States and all resulted in comparable results. Application of the established method to 50 grape samples, resulted in the detection of chlormequat chloride and forchlorfenuron residues in the tested grapes. The results of the method validation and real sample analysis shows the extraction method is therefore suitable for routine monitoring of residue in grapes.

Influence of high temperature during grain filling on the accumulation of storage proteins and grain quality in rice (Oryza sativa L.).

The present study was performed to understand the effects of high temperature (HT) during filling on the expression of storage proteins and the quality of rice grains. HT (35/30 °C day/night) reduced the weight, amylose content, and flour gel consistency of grains. It increased the accumulation of all classes of storage proteins at early filling stage but decreased the accumulation of prolamins at maturation. For albumins, the expressions of cyclophilin 2, peroxiredoxin, and HSP16.9 were differentially enhanced by HT. For globulins, HT decreased the accumulation of globulin but increased that of glyoxalase I and peroxiredoxin. HT enhanced the transcription of genes for glutelins, prolamins, globulins, and protein disulfide isomerase at early filling stage but decreased the expression of these genes at a later stage. Low amounts of prolamins and globulins, as well as low pH value, were found in sound, immature, and dead kernels grown under HT. The relationships among HT, storage proteins, and grain quality are discussed.

Agrobacterium-produced and exogenous cytokinin-modulated Agrobacterium-mediated plant transformation.

Agrobacterium tumefaciens is a plant pathogenic bacterium that causes neoplastic growths, called 'crown gall', via the transfer and integration of transferred DNA (T-DNA) from the bacterium into the plant genome. We characterized an acetosyringone (AS)-induced tumour-inducing (Ti) plasmid gene, tzs (trans-zeatin synthesizing), that is responsible for the synthesis of the plant hormone cytokinin in nopaline-type A. tumefaciens strains. The loss of Tzs protein expression and trans-zeatin secretions by the tzs frameshift (tzs-fs) mutant is associated with reduced tumorigenesis efficiency on white radish stems and reduced transformation efficiencies on Arabidopsis roots. Complementation of the tzs-fs mutant with a wild-type tzs gene restored wild-type levels of trans-zeatin secretions and transformation efficiencies. Exogenous application of cytokinin during infection increased the transient transformation efficiency of Arabidopsis roots infected by strains lacking Tzs, which suggests that the lower transformation efficiency resulted from the lack of Agrobacterium-produced cytokinin. Interestingly, although the tzs-fs mutant displayed reduced tumorigenesis efficiency on several tested plants, the loss of Tzs enhanced tumorigenesis efficiencies on green pepper and cowpea. These data strongly suggest that Tzs, by synthesizing trans-zeatin at early stage(s) of the infection process, modulates plant transformation efficiency by A. tumefaciens.

Proteomic analysis of the expression of proteins related to rice quality during caryopsis development and the effect of high temperature on expression.

Proteins are essential to rice caryopsis development and quality formation. High temperature is an important environmental factor, which may decrease grain quality. In the present study rice caryopsis proteins were profiled by two-dimensional polyacrylamide gel electrophoresis, and differentially expressed proteins were analyzed by liquid chromatography/tandem mass spectrometry. Expressions of more than 400 polypeptide spots during caryopsis development, in response to temperature treatments or between varieties were monitored. Among them, more than 70 differentially expressed polypeptides were analyzed by liquid chromatography/tandem mass spectrometry. We identified 54 proteins with known functions. Of these, 21 were involved with carbohydrate metabolism, 14 with protein synthesis and sorting, and 9 with stress responses. Waxy (Wx) proteins and glutelins were the most significant spots, which increased significantly during development. Allergen-like proteins, PPDK and NADH-SDH, also were expressed during development, implying their physiological roles in caryopsis. Expression of large isoforms of Wx proteins was correlated with the amylose content of rice caryopses. One protein with high GC content in its DNA sequence was correlated with the chalky trait of kernels. High temperature (35/30 degrees C) decreased the expression of Wx proteins, allergen-like proteins, and elongation factor 1beta, but increased the expression of small heat shock proteins (sHSP), glyceraldehyde-3-phosphate dehydrogenase, and prolamin. sHSP was positively correlated with the appearance of chalky kernels. During development, glutelins were phosphorylated and glycosylated, indicating that these molecules were post-translationally modified. Possible functions of the expression of candidate proteins on the grain quality are discussed.

Evaluation of two stool antigen tests for the detection of Helicobacter pylori infection in the Chinese population.

BACKGROUND AND AIM: The stool antigen test, the HpSA test, has been validated mainly in Western countries, but not properly in the Chinese population. Recently, another stool antigen test, the Apollo test, was developed, but its accuracy has rarely been validated. The aim of this study is to compare the accuracy of these two tests in the diagnosis of Helicobacter pylori infection in the Chinese population. METHODS: Consecutive dyspeptic patients referred for upper endoscopy were recruited. During endoscopy, biopsies were taken for the rapid urease test and histological examination as the gold standard. Stool specimens were collected and used for the HpSA and Apollo tests. RESULTS: Overall, 86 patients (39 males and 47 females, with a mean age of 55.8 years) were recruited. Helicobacter pylori infection was present in 44 (51%) patients as determined by the gold standard. The sensitivity, specificity and accuracy were 86.4, 100, and 93.0%, respectively, for the HpSA, and 90.9, 97.6, and 94.2%, respectively, for the Apollo test when cases with equivocal results were considered as positive. In addition, agreement was achieved in 81 (94.2%) cases between the two tests, with a Kappa value of 0.887. CONCLUSION: Both the HpSA and Apollo tests achieve acceptable sensitivity and excellent specificity, with accuracies of over 90% for the detection of H. pylori infection in the Chinese population.