Residues In Wheat Research Articles

Simultaneous Determination of Foramsulfuron and Orthosulfamuron in Four Common Grains Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

Foramsulfuron and orthosulfamuron are two important sulfonylurea herbicides and have been widely used for the weed control in grain field. But their residues and toxicities have also caused many problems. In this study, the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method and UPLC-MS/MS (ultra-performance liquid chromatography coupled with tandem mass spectrometry) were combined to simultaneously determine them in soybeans, wheat, rice, and maize. The suitable extractants (acetonitrile for soybeans and wheat while acetonitrile containing 1% formic acid for rice and maize) and sorbents (octadecylsilane (C18) for soybeans and wheat while primary secondary amine (PSA) for rice and maize) were tested and selected. In this study, the determinations of the target compounds were achieved in 0.9990) for the target compounds. And the recovery studies of foramsulfuron and orthosulfamuron performed in the four matrices at three spiked levels (5, 10, and 100 μg L−1) showed good average recoveries (75.16~106.45%) and reproducibility (inter-day relative standard deviations (n = 15) ranged from 4.08 to 15.95%). This method will be useful for the quick and simultaneous detection of foramsulfuron and orthosulfamuron residues in soybeans, wheat, rice, and maize.

Wheat preharvest herbicide application, whole‐grain flour properties, yeast activity and the degradation of glyphosate in bread

SummaryThe aim of this study was to determine the effects of wheat preharvest application of a glyphosate‐based herbicide (Roundup WeatherMax® with Transorb® 2 Technology) on whole‐grain flour composition and properties, including yeast activity. The effect of dough fermentation on the degradation of herbicide residues was also estimated. Grain samples from two hard red spring wheat varieties exceeded the maximum residue limits (5 mg kg−1) in Canada. Glyphosate had minor effects on wheat kernels composition and properties, including fructans content and yeast gassing power. No degradation of Roundup® or pure glyphosate was seen after dough fermentation for up to 4 h and baking. These results call for more scientific studies on glyphosate residues in wheat.

Determination of Phosphine Residues in Wheat and Yellow Corn with a New Developed Method Using Headspace and SIM Mode GC-MS.

Phosphine is considered the main fumigant material used for long time for controlling insect pests in stored grains. This research was focused on the determination of phosphine residues in cereal matrixes (mainly wheat and corn) after the fumigation process, using a new procedure developed to reduce the number of analytical steps and improve the chromatographic separation, identification, and quantitation of analyte, thus leading to enhanced total efficiency and sensitivity. This method, using gastight vials for extraction with 5% sulfuric acid, a heating extraction sequence, and injection with headspace and GC-MS in selected-ion monitoring mode, gave clean separation and accurate results. Repeatability was achieved for both wheat and corn after spiking samples at the 0.01 mg/kg level, with RSD values of 7.6 and 6.3%, respectively. The LOD and LOQ values were 0.46 and 1.38 µg/kg, respectively. The mean value of phosphine residue in wheat was 8.43 µg/kg, with an RSD of 8.17%, whereas it was 8.09 µg/kg in corn, with an RSD of 7.75%. All residues detected in all the replicates were below the estimated maximum residue limit for wheat and corn (0.1 mg/kg). The highest residue value for wheat was 9.85 µg/kg and the lowest was 7.70 µg/kg, whereas for corn, the highest value was 9.03 µg/kg and the lowest 7.30 µg/kg.

Detection of Organophosphorus Pesticides in Wheat by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with HPLC.

Food safety issues closely related to human health have always received widespread attention from the world society. As a basic food source, wheat is the fundamental support of human survival; therefore, the detection of pesticide residues in wheat is very necessary. In this work, the ultrasonic-assisted ionic liquid-dispersive liquid-liquid microextraction (DLLME) method was firstly proposed, and the extraction and analysis of three organophosphorus pesticides were carried out by combining high-performance liquid chromatography (HPLC). The extraction efficiencies of three ionic liquids with bis(trifluoromethylsulfonyl)imide (Tf2N) anion were compared by extracting organophosphorus in wheat samples. It was found that the use of 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][Tf2N]) had both high enrichment efficiency and appropriate extraction recovery. Finally, the method was used for the determination of three wheat samples, and the recoveries of them were 74.8–112.5%, 71.8–104.5%, and 83.8–115.5%, respectively. The results show that the method proposed is simple, fast, and efficient, which can be applied to the extraction of organic matters in wheat samples.

Rapid multiplug filtration cleanup method for the determination of 124 pesticide residues in rice, wheat, and corn.

A simple and rapid multiplug filtration cleanup method based on multiwalled carbon nanotubes was developed to determine 124 pesticide residues in rice, wheat, and corn, which could be done in a few seconds without conditioning and elution steps. Various combinations of sorbents were optimized for each matrix with a dispersive solid-phase extraction procedure to get a satisfactory recovery and clean-up performance. Good linearity was obtained for all pesticides with calibration curve coefficients larger than 0.9958. Most recoveries for the majority pesticides were between 70 and 120% (n = 5) with relative standard deviations below 20%. The limit of detection was 0.1-1.3 μg/kg, and the limit of quantification was 0.2-4.3 μg/kg for the pesticides in all matrices. The work suggests that the multiplug filtration cleanup method is better than the dispersive solid-phase extraction method and it could be applied to routinely monitor pesticide residues in market samples.

Phytotoxicity evaluation of 4-chloro-2-methylphenoxyacetic acid based on ionic liquids and their residues in winter wheat

The aim of the study was to evaluate the phytotoxic effects of four new forms of MCPA as a ionic liquids. Herbicidal ionic liquids with MCPA were synthesized at the Chemical Technology Institute of the Poznań University of Technology. As a standard two previously known formulations: potassium-sodium salt and 2-ethylhexyl ester were used. All herbicides were applied at doses of 800 g active substance per ha. The results showed slight injury symptoms. There wasn’t influence on qualitative parameters. No residues of MCPA was found in winter wheat grain. Przedmiotem badań była ocena fitotoksycznego działania czterech nowych form MCPA w postaci cieczy jonowych. Herbicydowe ciecze jonowe (HILs – herbicidal ionic liquids) zsyntezowano w Zakładzie Technologii Chemicznej Politechniki Poznańskiej. Jako standardy zastosowano dostępne w handlu formy MCPA: ester i sól sodowo-potasową. Wszystkie herbicydy zastosowano w dawce 800 g substancji czynnej na ha. Obserwowano niewielkie objawy fitotoksyczności, które nie miały wpływu na parametry jakościowe ziarna. Nie stwierdzono pozostałości MCPA w ziarnie pszenicy ozimej.

살균제 Fludioxonil 및 Metconazole의 밀 부위별 잔류 양상

밀의 재배기간 중 살포된 살균제 fludioxonil 및 metconazole의 부위별 잔류양상을 조사하였다. 밀 부위별 fludioxonil 및 metconazole (cis 및 trans 이성질체의 합)의 잔류분석 회수율은 84.3~113.3%이었으며 변이계수는 0.1~4.7%로 나타나 잔류농약분석 기준을 만족하였다. 두 농약 모두 처리구별 수확된 밀의 짚부위에 가장 많이 잔류되었으며 가식부인 밀알에서 잔류량이 가장 적었다. 밀의 가식부에 잔류하는 농약의 농도는 fludioxonil은 2회 및 3회 살포시 0.01~0.07 mg/kg, metconazole은 0.13~0.17 mg/kg로 나타났다. 침투성 농약인 metconazole은 fludioxonil 보다 더 낮은 농도로 살포되었음에도 불구하고 밀의 가식부로 침투량이 더 많았으며 cis 이성질체가 trans 이성질체 보다 많이 잔류되었다. 밀의 각 부위별 평균무게를 이용하여 밀 한 개체 당 농약의 잔류절대량을 산출하고 밀의 각 부위별 분포율을 산출한 결과, 두 농약 모두 짚 부위에서 68.5~70.7%의 분포율을 나타내었으며 가식부에서 분포율은 0.8% 미만이었다. Residual patterns of fungicides fludioxonil and metconazole applied 2 or 3 times on wheat were investigated with consideration for their distribution rates in each compartment of wheat. Wheat samples collected at harvesting day were divided into three compartments such as grain, hull and straw, and the pesticide residue analysis was individually carried out to such compartments of wheat. The analytical methods of fungicide residues in wheat were acceptable, with recoveries of 84.3 to 113.3% and correlation coefficients of 0.1 to 4.7%. Due to the systemic characteristics, the residual amounts of metconazole in the grain part of wheat were greater as 0.13~0.17 mg/kg than those amounts (0.01-0.03 mg/kg) for fludioxonil. To absolute residue amounts of the fungicides in one wheat plant, their distribution rates in each compartment of wheat were the highest in straws (68.5-70.7%), followed by hulls (29.0-31.0%) and grains (0.2-0.8%).

Solid-phase extraction combined with dispersive liquid-liquid microextraction for the determination of pyrethroid pesticides in wheat and maize samples.

A rapid, selective and sensitive sample preparation method based on solid-phase extraction combined with the dispersive liquid-liquid microextration was developed for the determination of pyrethroid pesticides in wheat and maize samples. Initially, the samples were extracted with acetonitrile and water solution followed phase separation with the salt addition. The following sample preparation involves a solid-phase extraction and dispersive liquid-liquid microextraction step, which effectively provide cleanup and enrichment effects. The main experimental factors affecting the performance both of solid-phase extraction and dispersive liquid-liquid microextration were investigated. The validation results indicated the suitability of the proposed method for routine analyze of pyrethroid pesticides in wheat and maize samples. The fortified recoveries at three levels ranged between 76.4 and 109.8% with relative standard deviations of less than 10.7%. The limit of quantification of the proposed method was below 0.0125 mg/kg for the pyrethoroid pesticides. The proposed method was successfully used for the rapid determination of pyrethroid residues in real wheat and maize samples from crop field in Beijing, China.

Organophosphate and pyrethroid residues in stored wheat in Sonora, Mexico

Organophosphate and pyrethroid residues in stored wheat in Sonora, Mexico

Effects of tillage and mulch on the growth, yield and irrigation water productivity of a dry seeded rice-wheat cropping system in north-west India

Depletion and/or degradation of natural resources, increasing farm labour scarcity, and high production cost are major threats to the rice-wheat cropping system of north-west India. Conservation agriculture (CA) is a potential solution which can be achieved by switching from puddling then transplanting of rice to dry seeding (DSR), together with changing from conventional tillage (CT) to zero tillage (ZT) for wheat with surface retention of rice residues. Whether the use of ZT for both crops confers additional benefits to either crop is not known. The effects of surface retention of rice residues in wheat on the subsequent DSR crop are also unknown, nor how this is affected by tillage for DSR. Therefore, a field study was conducted during 2012-14 to investigate the interactions between tillage for rice and wheat (CT, ZT), and rice residue management (removed, retained on the soil surface), on the performance of a dry seeded rice-wheat system.There were no significant interaction or main treatment effects on wheat grain yield in the first two years, but in the third year, yield of ZT wheat (5.5tha−1) was significantly lower than yield of CT wheat (6.0tha−1). Yield of wheat decreased significantly over the three years, for example from 7.7 to 6.3 to 5.8tha−1 in the control system (CT for both crops, no rice straw mulch). Weather data analysis and simulation modelling suggested that this was entirely due to differences in seasonal weather conditions. Growth of non-mulched ZT wheat was inferior to that of mulched ZT wheat, and that of CT wheat with and without mulch, regardless of tillage for rice, although this was not reflected in wheat grain yield. Mulch delayed wheat crop development and the time of irrigation to varying degrees depending on seasonal conditions, and reduced irrigation amount by 50–100mm in two of the three years.Tillage and rice residue management treatments did not affect the yield of DSR in the first year (mean yield 6.0tha−1). However, in the second year, growth and grain yield of ZTDSR (3.2tha−1) were inferior to that of CTDSR (3.8tha−1), regardless of tillage treatment for wheat. There was a consistent trend for poorer growth of DSR following wheat mulched with rice straw (significant in the first year), suggesting the need to examine the possibility of allelopathic effects of surface rice straw retention in dry seeded rice-wheat systems. There was a decline in rice growth and grain yield over the two years in all treatments. For example, yield of rice in the control declined from 5.9tha−1 in 2012 to 4.3tha−1 in 2013. Seasonal conditions and simulated growth and yield were similar each year; the poorer observed rice growth and yield in 2013 were due to disease during grain filling, greater weed infestation during the early vegetative stage, and unexplained factors during the middle of the season.Total system rice equivalent yield (REY) was not affected by tillage or mulch treatments nor their interactions in 2012 (mean REY 13.3tha−1), but was significantly lower in systems with ZTDSR (9.4tha−1) than CTDSR (10.0tha−1) in 2013. Treatment effects on irrigation input to rice and the total system were small. The net result was no treatment effects on total cropping system irrigation water productivity (WPi) in 2012 (mean 0.83kgm−3), and significantly higher system WPi in 2013 in systems with CTDSR (0.69kgm−3) than ZTDSR (0.63kgm−3).The results suggest that in a dry seeded rice-wheat cropping system, surface retention of rice residues can improve the growth of ZT wheat right from the first crop, although this did not affect yield in the first three years. However, whether there is an adverse carry over effect of the rice residues on DSR requires further investigation.

Simultaneous determination of penflufen and one metabolite in vegetables and cereals using a modified quick, easy, cheap, effective, rugged, and safe method and liquid chromatography coupled to tandem mass spectrometry

The present study attempts to investigate a rapid, effective and sensitive analytical method to determine a new fungicide penflufen and its metabolite residues in potato, cowpea, corn, wheat and rice using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC–MS/MS). The compounds were extracted using acetonitrile and cleaned up by primary secondary amine (PSA) and octadecylsilane (C18). Both compounds were determined in less than 5.0min using an electrospray ionization source in positive mode (ESI+). The calculated limits of detection and quantification were below 0.018μgkg−1 and 0.060μgkg−1 in different matrices. The method revealed excellent linearity (R2>0.9957) for both compounds. The recoveries ranged from 76.1 to 101.0% for both compounds with RSD values lower than 9.8% in all matrices. The results demonstrated that the method is reliable and effective enough for the routine detecting penflufen and its metabolite residues in vegetables and cereals.

Dissipation and Residues of Dichlorprop-P and Bentazone in Wheat-Field Ecosystem.

Dichlorprop-P and bentazone have been widely used in the prevention and control of weeds in wheat field ecosystems. There is a concern that pesticide residues and metabolites remain on or in the wheat. Thus, the study of the determination and monitoring of their residues in wheat has important significance. A rapid, simple and reliable QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was modified, developed and validated for the determination of dichlorprop-P, bentazone and its metabolites (6-hydroxy-bentazone and 8-hydroxy-bentazone) in wheat (wheat plants, wheat straw and grains of wheat) using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The average recoveries of this method ranged from 72.9% to 108.7%, and the limits of quantification (LOQs) were 2.5–12 μg/kg. The dissipation and final residue of four compounds in three provinces (Shandong, Jiangsu and Heilongjiang) in China were studied. The trial results showed that the half-lives of dichlorprop-P and bentazone were 1.9–2.5 days and 0.5–2.4 days in wheat plants, respectively. The terminal residues in grains of wheat and wheat straw at harvest were all much below the maximum residue limit (MRL) of 0.2 mg/kg for dichlorprop-P and 0.1 mg/kg for bentazone established by the European Union (EU, Regulation No. 396/2005).

An Innovative Rapid Method for Analysis of 10 Organophosphorus Pesticide Residues in Wheat by HS-SPME-GC-FPD/MSD.

The rapid detection of pesticide residues in wheat has become a top food security priority. A solvent-free headspace solid-phase microextraction (HS-SPME) has been evaluated for rapid screening of organophosphorus pesticide (OPP) residues in wheat with high sensitivity. Individual wheat samples (1.7 g), spiked with 10 OPPs, were placed in a 4 mL sealed amber glass vial and heated at 60°C for 45 min. During this time, the OPP residues were extracted with a 50 μm/30 μm divinylbenzene (DVB)/carboxen (CAR)/plasma desorption mass spectroscopy polydimethylsiloxane (PDMS) fiber from the headspace above the sample. The fiber was then removed and injected into the GC injection port at 250°C for desorption of the extracted chemicals. The multiple residues were identified by a GC mass spectrometer detector (GC-MSD) and quantified with a GC flame photometric detector (GC-FPD). Seven spiked levels of 10 OPPs on wheat were analyzed. The GC responses for a 50 μm/30 μm DVB/CAR/PDMS fiber increased with increasing spiking levels, yielding significant (R(2) > 0.98) linear regressions. The lowest LODs of the multiple pesticide standards were evaluated under the conditions of the validation study in a range of levels from 0 (control) to 100 ng of pesticide residue per g of wheat that separated on a low-polar GC capillary column (Agilent DB-35UI). The results of the HS-SPME method were compared with the QuEChERS AOAC 2007.01 method and they showed several advantages over the latter. These included improved sensitivity, selectivity, and simplicity.

Use of Factorial Design in the Development of Multiresidue Method for Determination of Pesticide Residues in Wheat by Liquid Chromatography-Tandem Mass Spectrometry

The evaluation of analytical methods for determining the level of residues and contaminants in food samples is a continuing need. To improve this evaluation, it is necessary to investigate different extraction procedures and conditions. A 23 factorial design was applied to establish an analytical method for determining pesticide residues in wheat by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Factors that influence the recovery of compounds, such as agitation and different processes of partition and cleanup, were investigated. Extracts were analyzed by LC-MS/MS with electrospray ionization in a triple quadrupole system. The use of ultrasonic agitation in the extraction step, deep freezing for the partition step, and C18 cleanup provided significantly better recoveries for most of the compounds evaluated. Assessment of each factor as well as interactions between factors allowed for a more effective evaluation of the parameters involved in the development of analytical methods. The validation results were satisfactory, since the method presented linearity (r 2) >0.99 for all compounds, the matrix effect ranged from 3 to 97 % and was corrected by matrix-matched standards, and recoveries ranged from 70 to 120 % with RSD ≤20 % for the spike levels of 10 and 100 μg kg−1. The method limit of detection and limit of quantification ranged from 3.3 to 6.7 μg kg−1 and from 10 to 20 μg kg−1, respectively, and the expanded uncertainty ranged from 15 to 32 %. The proposed method met the criteria for determination of 42 pesticides in wheat samples and was successfully tested in real samples.

Accumulation of Residual Antibiotics in the Vegetables Irrigated by Pharmaceutical Wastewater

Soil and vegetables are the most integral environmental segments for human and animal life. Day by day both of these segments are becoming polluted by anthropogenic resources, and one of the major sources of contamination is pharmaceutical wastewater entering environment. Contamination levels of antibiotics namely ofloxacin (OFL), ciprofloxacin, levofloxacin (LEV), oxytetracycline (OTC), and doxycycline were determined (found) in soil and vegetables samples in surrounding areas of pharmaceutical industry. HPLC with DAD detector, C-18 column and solid-phase cartridges were used to extract and analyze antibiotic residues in soil, carrot, wheat, and spinach samples. In wheat samples, LEV and OFL in spinach and carrot samples were accumulated highest. OFL, in soil of wheat and spinach samples, and OTC, in soil of carrot samples, were determined as highest level contaminant. In all types of vegetable samples, the contamination of each antibiotic was highest in leaves and lowest in fruits. The order of accumulation was leaves > stem/shoot > root > fruit. The contamination level was higher in soil samples than vegetable samples. Plants and vegetables directly or indirectly are part of human food. From soil, antibiotics accumulates to plants and vegetables, and leach to groundwater.

Nitrogen management for zero till wheat with surface retention of rice residues in north-west India

In intensive rice–wheat systems of north-west (NW) India, surface retention of rice residues in wheat has been recommended instead of burning. Optimum nitrogen (N) management for zero till (ZT) wheat sown into rice residues may to differ from that of conventional practice (in-situ burning of residues followed by intensive tillage prior to sowing). Therefore, we conducted several on-farm and on-station field experiments in 2007–2008 to 2012–2013 to evaluate N management practices for ZT wheat sown into rice residues using the Happy Seeder. The optimum N rate for wheat planted into rice residues in fields with no or only a short history of rice residue retention was 120kgNha−1, the current recommendation for conventional practice. Short-term (up to 20 d) soil N mineralization was lower in undisturbed soil than disturbed soil, while the total amount of N mineralization was similar after 40d, suggesting that over the crop season, total soil N mineralization may be similar in tilled and non-tilled soil. Ammonia volatilization loss from urea broadcast over the residue covered surface, followed by irrigation, was low (<2kgha−1) regardless of time of urea application. Band placement of 20% of the fertilizer N as diammonium phosphate at seeding, and topdressing of the remaining 80% as urea in two equal doses before first and second irrigations produced higher grain yield and N use efficiency than other treatments. However, surface residue retention reduces the rate of soil drying and in some situations this delays the time of the second irrigation and thus N fertilizer application beyond the optimum time. Therefore, the effect of banding various proportions of the urea N between the rows at sowing was investigated. The results showed that, on a loam soil, up to 75% of the recommended N fertilizer can be applied at sowing, 24kgNha−1 as DAP with the seed and 66kgNha−1 as urea drilled between every second wheat row, without loss of yield. In conclusion, a better applied N management strategy for ZT wheat than currently practiced is drilling of 24kgNha−1 as diammonimum phosphate into the soil at seeding followed by two top-dressings of 48kgNha−1 each just prior to first and second irrigations.

Simultaneous determination of three herbicides in wheat, wheat straw, and soil using a quick, easy, cheap, effective, rugged, and safe method with ultra high performance liquid chromatography and tandem mass spectrometry

In this study, a sensitive and effective analytical method for the extraction and detection of three herbicide residues (florasulam, fluroxypyr, and halauxifen-methyl) in wheat and soil was developed. Samples were extracted with acetonitrile/water followed by salting out, dispersive solid-phase extraction cleanup, and detection using ultra high performance liquid chromatography coupled with tandem mass spectrometry. The target analytes were detected within a 5 min runtime using an ultra high performance liquid chromatography high-strength silica trifunctional column connected to an electrospray ionization source in positive mode. The method was validated in five replicates at three fortification concentrations in each matrix. Adequate pesticide quantification and identity confirmation were attained, even at the lowest concentration levels. The method showed very good accuracy and precision. Good recoveries were observed for the three herbicides and mostly ranged between 75.8 and 114.6%, with intraday relative standard deviations <6.01% and interday relative standard deviations <4.02%. The limits of quantification ranged between 0.14 and 7.68 μg/kg for each herbicide. The method was successfully applied for the simultaneous analysis of the three herbicides in actual trial samples, and the results proved that the proposed method was effective in detecting these three herbicides.

The use of 13C and 15N based isotopic techniques for assessing soil C and N changes under conservation agriculture

A four years experiment was conducted to investigate the effect of tillage and addition of crop residues in wheat–faba bean rotation. The soil was fertilized with a total of 150kgnitrogen (N)ha−1 enriched with 9.96 percent nitrogen-15 (15N) atom excess, in four applications. The first crop was corn, a C4 plant cropped under till (T) and no-till (NT) conditions. Percent N derived from fertilizer (Ndff) by corn was 37.12–48.62. The leaves had the lowest delta carbon-13 (δ13C) values of −12.7 and the seeds the highest (−11.8). Soil δ13C was affected by addition of C4 plant residues. Soil under residue and till treatment (RT) had the highest percent 15N values. Residues and no-till (RNT) had the lower percent 15N values. At the end of the corn crop soil percent 15N was 0.211, 0.26, and 0.253 in the three soil depths. Residues and tillage increased significantly the Ndff of wheat: from 6.43 to 6.46kgNha−1 for no residues no-till (NRNT) and no-residues and till (NRT) and from 11.1 to 13kgNha−1 in RNT and RT treatments. In wheat nitrogen derived from residues (Ndfr) was 4.68 and 1.53kgNha−1 in grain and residues, respectively. Residues and tillage affected significantly soil C, N, 15N, and δ13C from seeding to two months after and have no effect at harvest. The interaction was always significant. After four years the 15N fertilizer contributed only with 1.5–2.85kgNha−1 in NRNT and NRT, respectively, and 3.3–5.63kgNha−1 in RNT and RT, respectively. Cumulated N recovered during the three growing seasons following corn was 8.59–11.07kgNha−1 for NRNT and NRT; 20.24–15.6kgNha−1 for RT and RNT, respectively. Residues increased N mineralization by 50 percent and the quantity of 15N available to plants increased with tillage.

Determination of halosulfuron-methyl residues and dissipation in wheat by QuEChERS and LC-MS/MS

A sensitive and rapid analytical method based on QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation and LC-MS/MS detection was developed for the analysis of halosulfuron-methyl residues in wheat. The recoveries of halosulfuron-methyl in both the wheat plant and grain ranged from 87% to 119% and from 75% to 97%, respectively, with relative standard deviations (RSDs) of 3–9%. The limit of quantification (LOQ) was 0.005 mg kg−1 for wheat plant and 0.001 mg kg−1 for wheat grain. The half-life of halosulfuron-methyl in the wheat plant was 0.9–9.5 days. The terminal residue levels of halosulfuron-methyl in wheat grain were below 0.01 mg kg−1 at harvest.

Rapid method based on immunoassay for determination of paraquat residues in wheat, barley and potato

The detection of bipyridine herbicides residues in food samples is hampered due to their particular physico-chemical features, which requires the application of specific extraction and analytical procedures, which disqualifies them from being incorporated into the multi-residue methods (MRMs). There is a need for alternative robust and efficient analytical screening methods, and in this respect, we present here a fast and reliable immunochemical analytical procedure for the detection of paraquat (PQ) residues in food samples, particularly potato, barley and wheat. The procedure involves the extraction with 1 N HCl:MeOH at 80 °C, followed by centrifugation and filtration, and the extracts can be directly measured by a microplate-based ELISA without any other sample treatment or clean-up, except from buffering the solution and adjusting the pH. Selective polyclonal antibodies, were raised against N-(4-carboxypent-1-yl)-N′-methyl bipyridilium acid (hapten PQ1), and used to establish a high sensitive immunochemical analytical assay, able to measure simultaneously many samples. Under these conditions the accuracy is very good, with almost quantitative recoveries. The non-specific interferences caused by the matrix are negligible for the case of potato and wheat, while for barley it is necessary to further dilute the extract or using a negative certified extract to build the standard calibration curve. The method of extraction consisted in acidic extraction and after a dilution is able to be measured. The analysis method results simply, achieving good detectabilities. The limits of detection (LODs) achieved were between 0.037 ± 0.01 μg kg−1 in wheat, 0.71 ± 0.3 μg kg−1 in barley and 0.56 ± 0.10 μg kg−1 in potatoes, values that are far below the Maximum Residue Level (20 μg kg−1) established by the EU policies for paraquat residues in these foodstuff products. The results demonstrate the high potential of these methods as screening tools for food safety and inspection controls.