Low Temperature Partitioning Research Articles

Development of a new analytical tool for assessing the mutagen 2-methyl-1,4-dinitro-pyrrole in meat products by LC-ESI-MS/MS

The use of sorbate and nitrite in meat processing may lead to the formation of 2-methyl-1,4-dinitro-pyrrole (DNMP), a mutagenic compound. This work was aimed at developing and validating an analytical method for the quantitation of DNMP by liquid chromatography-tandem mass spectrometry. Full validation was performed in accordance to Commission Decision 2002/657/EC and method applicability was checked in several samples of meat products. A simple procedure, with low temperature partitioning solid-liquid extraction, was developed. The nitrosation during the extraction was monitored by the N-nitroso-DL-pipecolic acid content. Chromatographic separation was achieved in 8 min with di-isopropyl-3-aminopropyl silane bound to hydroxylated silica as stationary phase. Samples of bacon and cooked sausage yielded the highest concentrations of DNMP (68 ± 3 and 50 ± 3 μg kg−1, respectively). The developed method proved to be a reliable, selective, and sensitive tool for DNMP measurements in meat products.

Determination of five tetracyclines and their epimers by LC-MS/MS based on a liquid-liquid extraction with low temperature partitioning

ABSTRACTAn LC-MS/MS method is presented for screening five tetracyclines and their epimers in a broad range of food products. The scope of matrices includes meat-, fish-, seafood-based products, various dairy ingredients, infant formulae and fats. The method principle is based on a liquid–liquid extraction with aqueous ethylenediaminetetraacetic acid (EDTA) and acetonitrile followed by a freezing step to promote phase separation at low temperature. After defatting with hexane, sample extracts were evaporated and reconstituted before injection onto the LC-MS/MS system. The addition of oxalic acid in the aqueous mobile phase was mandatory to maintain good peak shape and sensitivity over the run. The screening is based upon a double preparation of each sample, one ‘as such’ and a second one with the analytes spiked in the sample, in order to mitigate the risk of false negative response. The method was validated according to the European Community Reference Laboratories Residues Guidelines. A total of 93 samples were included in the validation by two independent laboratories giving both false-negative and false-positive rates at 0% for all compounds. Over the last two years, 2600 samples were analysed routinely and only one chicken sample was found above the regulatory limit.

Screening of veterinary drug residues in food by LC-MS/MS. Background and challenges

ABSTRACTRegulatory agencies and government authorities have established maximum residue limits (MRL) in various food matrices of animal origin for supporting governments and food operators in the monitoring of veterinary drug residues in the food chain, and ultimately in the consumer’s plate. Today, about 200 veterinary drug residues from several families, mainly with antibiotic, antiparasitic or antiinflammatory activities, are regulated in a variety of food matrices such as milk, meat or egg. This article provides a review of the regulatory framework in milk and muscle including data from Codex Alimentarius, Europe, the U.S.A., Canada and China for about 220 veterinary drugs. The article also provides a comprehensive overview of the challenge for food control, and emphasizes the pivotal role of liquid chromatography-mass spectrometry (LC-MS), either in tandem with quadrupoles (LC-MS/MS) or high resolution MS (LC-HRMS), for ensuring an adequate consumer protection combined with an affordable cost. The capability of a streamlined LC-MS/MS platform for screening 152 veterinary drug residues in a broad range of raw materials and finished products is highlighted in a production line perspective. The rationale for a suite of four methods intended to achieve appropriate performance in terms of scope and sensitivity is presented. Overall, the platform encompasses one stream for the determination of 105 compounds in a run (based on acidic QuEChERS-like), plus two streams for 23 β-lactams (alkaline QuEChERS-like) and 10 tetracyclines (low-temperature partitioning), respectively, and a dedicated stream for 14 aminoglycosides (molecularly-imprinted polymer).

ANALYSIS OF ALDICARB IN SURFACE WATER FROM THE PARANÁIBA RIVER

The pesticide aldicarb is the most toxic active ingredient registered in all national territory, standing out for its extreme acute toxicity. In the environment, mainly in the water resources, several studies have demonstrated the potential of contamination of aldicarbe. The Paranaíba River cuts off the municipality of Itumbiara-GO, a region considered an important economic center in the south of the state. Along the Paranaíba River Basin there is a wide range of crops, such as sugarcane, corn, soy, cotton. This work aimed to quantitatively analyze the occurrence of aldicarb contamination in surface waters of the Paranaíba River, in addition to conducting a theoretical study of the river. For this purpose, the liquidliquid extraction with low temperature partitioning (LLE-LTP) and high-performance liquid chromatography (HPLC-UV) analysis were used. In the surface water samples of the river analyzed, no aldicarb contamination levels were found or the concentrations were below the detection limit of the LLE-LTP and HPLC-UV method.

Determination of 6-benzylaminopurine in edible mushrooms by solid liquid extraction with low-temperature partition and high performance liquid chromatography-mass spectrometry

A simple method based on solid liquid extraction with low-temperature partition (SLE-LTP) coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed for the determination of 6-benzylaminopurine (6-BA) in edible mushrooms. The samples were extracted with acetonitrile followed by low-temperature partition at -30℃ for 4 h. The separation was performed on a Hitachi LaChrom C18 column (250 mm×4.6 mm, 5 μm) with 0.02 mol/L ammonium acetate (containing 0.1% (v/v) glacial acetic acid)-methanol (6:4, v/v) as the mobile phases with isocratic elution. The compound was detected in positive electrospray ionization mode, and quantified by external standard method. The results showed that the limit of detection (LOD, S/N>3) for the analyte was 0.006 mg/kg, and the limit of quantification (LOQ, S/N>10) was 0.02 mg/kg. The calibration curve showed good linear in the range of 0.05-2.0 mg/L, and the correlation coefficient (r2) was 1.0000. The spiked recoveries were between 81.3% and 93.7% with the relative standard deviations (RSDs, n=6) of 0.7%-2.4% at the spiked levels of 0.1 mg/kg and 0.5 mg/kg. The developed method is simple, reliable and can be applied for the accurate determination of 6-BA residue in edible mushrooms.

Pesticide residue removal in classic domestic processing of tomato and its effects on product quality

ABSTRACTThis study was undertaken to evaluate the effectiveness of several household practices (washing with water or acidic, alkaline, and oxidizing solutions, and peeling) in minimizing pesticide residue contamination of tomatoes, as well as the impact on the quality of the treated fruit. Tests were performed using two systemic fungicides (azoxystrobin and difenoconazole) and one contact fungicide (chlorothalonil). Solid-liquid extraction with low temperature partition (SLE/LTP) and liquid-liquid extraction with low temperature partition (LLE/LTP) were used to prepare the samples for pesticides determination by gas chromatography. Washing the tomatoes with water removed approximately 44% of chlorothalonil, 26% of difenoconazole, and 17% of azoxystrobin. Sodium bicarbonate (5%) and acetic acid (5%) solutions were more efficient, removing between 32 and 83% of the residues, while peeling removed from 68 to 88% of the pesticides. The washing solutions altered some fruit quality parameters, including acidity and chroma, and also caused weight loss. Acetic acid (0.15 and 5%) and hypochlorite (1%) solutions had the greatest effect on these parameters.

Ozone as degradation agent of pesticide residues in stored rice grains.

This work aimed to study the kinetics of bifenthrin and deltamethrin residues degradation in rice grains under exposure to ozone and evaluate the effect of ozonization on rice grains marketing standards. The grains sprayed with pesticides were exposed to ozone at a concentration of 3mgL-1 and continuous flow of 1.0Lmin-1 for defined periods of up to 10h. Residues of pesticides were extracted from grains using solid liquid extraction method with low-temperature partition analyzed by gas chromatography with electron capture detection (SLE/LTP-GC/ECD). Data from residual concentrations of bifenthrin and deltamethrin, due to the ozone exposure period, were adjusted to kinetic models of zero order, first order and second order. It was observed that ozone was effective in the degradation bifenthrin and deltamethrin residues, removing 91.9% of bifenthrin and 92.7% of deltamethrin. The kinetic model that best fitted deltamethrin and bifenthrin residues degradation data by ozone, was the one of first order. The marketing standards evaluated were the water content and yield. It was observed the ozone did not alter the rice grains water content and yield.

Degradation kinetics of pirimiphos-methyl residues in maize grains exposed to ozone gas

This work investigates the kinetics of degradation of pirimiphos-methyl residues in maize grains exposed to ozone gas and evaluates the effect of ozonation on grain quality. The assays employed maize grains treated with the insecticide, namely Actellic 500 CE® (pirimiphos-methyl), which were exposed for different periods to ozone gas at a concentration of 0.86 mg L−1, provided at a continuous flow rate of 1.0 L min−1. The insecticide residues were extracted from the grains using solid-liquid extraction with low temperature partitioning. The extracts were analyzed by gas chromatography with electron capture detection. Ozone effectively degraded more than 91% of the pirimiphos-methyl residues, with the degradation efficiency increasing in direct proportion to the duration of exposure to the gas. A first order kinetic model provided the best fit to the degradation data. The use of ozone gas did not alter the qualitative characteristics of the maize.

A multi-purpose tool for food inspection: Simultaneous determination of various classes of preservatives and biogenic amines in meat and fish products by LC-MS

This paper describes an innovative fast and multipurpose method for the chemical inspection of meat and fish products by liquid chromatography-tandem mass spectrometry. Solid-liquid extraction and low temperature partitioning were applied to 17 analytes, which included large bacteriocins (3.5kDa) and small molecules (organic acids, heterocyclic compounds, polyene macrolides, alkyl esters of the p-hydroxybenzoic acid, aromatic, and aliphatic biogenic amines and polyamines). Chromatographic separation was achieved in 10min, using stationary phase of di-isopropyl-3-aminopropyl silane bound to hydroxylated silica. Method validation was in accordance to Commission Decision 657/2002/CE. Linear ranges were among 1.25–10.0mgkg−1 (natamycin and parabens), 2.50–10.0mgkg−1 (sorbate and nisin), 25.0–200mgkg−1 (biogenic amines, hexamethylenetetramine, benzoic and lactic acids), and 50.0–400mgkg−1 (citric acid). Expanded measurement uncertainty (U) was estimated by single laboratory validation combined to modeling in two calculation approaches: internal (U = 5%) and external standardization (U = 24%). Method applicability was checked on 89 real samples among raw, cooked, dry fermented and cured products, yielding acceptable recoveries. Many regulatory issues were revealed, corroborating the need for enhancement of the current analytical methods. This simple execution method dispenses the use of additional procedures of extraction and, therefore, reduces costs over time. It is suitable for routine analysis as a screening or confirmatory tool for both qualitative and quantitative results, replacing many time consuming analytical procedures.

OPTIMIZATION OF SOLID-LIQUID EXTRACTION WITH THE LOW TEMPERATURE PARTITION FOR THE DETERMINATION OF CARBOFURAN IN SUGAR CANE

The broad application of cabofuran pesticide in sugar-cane cultures and its high toxicity makes it essential a search for new methods of preparing the samples to analysis of this pesticide in this culture. This work tried to optimize the solid-liquid extraction technique with low temperature partitioning (SLE/LTP) to determine the carbofuran in samples of sugar cane. The SLE/LTP technique, is a simple technique that shows advantages regarding other extraction techniques. Being so, a factorial experimental design 23 was created to study the simultaneous behavior of three factors in two levels. After this stage of split, to split, identification and qualification of carbofuran was analyzed the supernatant using the high efficiency of liquid chromatography with ultraviolet detector (HPLC/UV). The method ´s efficient to the extraction of carbofuran from sugar cane with percentages of recovery over the 73,0 %. After optimizing, the technique was applied in real samples of sugar cane in the region of Itumbiara-GO, Brazil. No carbofuran residues were found in the analyzed samples or they were below the detection limit. The SLE/LTP technique optimized to sugar cane, showed to be simple and efficient, being a economic method, consuming a little amount of sample and solvent extractor.

Determination of formaldehyde in bovine milk using a high sensitivity HPLC-UV method

A method of high performance liquid chromatography with UV detection (HPLC-UV) was implemented and validated for formaldehyde determination in bovine milk. A formaldehyde derivatization reaction with 2,4-dinitrophenylhydrazine, at pH4.0, enabled its detection in milk at 360nm. The clean up treatment of milk samples by liquid-liquid extraction with low temperature partitioning (LLE-LTP) was thoroughly optimized. The linearity of the method was shown by analytical curves ranging from 10.0 to 400.0μgL−1 in aqueous solutions and milk samples that were characterized by R2>0.99. The limit of quantification of 20.0μgL−1 demonstrated the high sensitivity of the method to determinate formaldehyde residues in milk. Extracts of milk samples fortified with formaldehyde at three concentration levels, led to a mean overall recovery of 102.2±1.3% (n=9), which satisfies the performance criteria established by the Codex Alimentarius for analytical methods suitable for determination of food residues. The accuracy was evaluated by comparison with a well-established procedure using the Student t-test. Comparable results were obtained at a 95% confidence level, demonstrating the usefulness and effectiveness of the proposed method.

Validation of a new high-throughput method to determine urinary S-phenylmercapturic acid using low-temperature partitioning extraction and ultra high performance liquid chromatography-mass spectrometry.

A new highly sensitive and environmentally friendly analytical method, using low-temperature partition extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry, without the use of a labeled analyte, was developed and validated to determine and quantify urinary S-phenylmercapturic acid in urine samples. The World Health Organization, in its guidelines for air quality in Europe, recognizes that benzene is carcinogenic to humans and there is no safe level of exposure. Urinary S-phenylmercapturic acid is a sensitive and specific biological marker of exposure to benzene. The new analytical method, extraction, and analysis, were linear in the working range between 0.1 and 200.0μg/L, precise (relative standard deviation lower than 6.0%), accurate (97.0-105.0%), and sensitive. The method's limits of detection and quantification were 0.02 and 0.084μg/L, respectively. The recovery with the low-temperature partition extraction was 96.1%, with relative standard deviation less than 3.8%. The method is simple, accurate, and reproducible, and has been successfully applied in the evaluation of nonoccupational exposure to benzene, by urinary S-phenylmercapturic acid in urine samples.

Study of Analytical Techniques to Determine Chlorpyrifos in the Surface Waterways of the Rural Zone of Ouro Branco, Brazil: A Case Study

The presence of insecticides in the waterways of the municipality of Ouro Branco, MG, Southeastern Brazil, has become a public health problem. Recent research correlates the presence of these toxins in the water to the high indexes for hypertension and abortions occurring in the rural area. These insecticide residues are only slightly concentrated in the water, and as such, it is necessary to search for and optimize analytic methods that are capable of detecting these very low concentrations. To define the method that presents the best detectability for the organochlorine chlorpyrifos, one of the most used pesticides in the area, sample extraction techniques such as liquid–liquid extraction with low temperature partition (LLE-LTP) and headspace solid-phase microextraction (HS-SPME) were used, followed by gas chromatography analysis with electron capture detection (GC-ECD). Full factorial design 24 and the Doehlert matrix were used to optimize both extraction techniques. The results displayed that HS-SPME-GC-ECD was the method that presented the best performance for determining the presence of chlorpyrifos in the water. The optimum condition was defined at the extraction time and temperature of 60 min and 85 °C, respectively, with a sample volume of 11 mL and Na2HPO4 concentration of 0.04 mol/L. The optimized method was validated for the principal figures of merit. The method displayed linearity with R 2 equal to 0.992 and detection limit (LOD) and quantification limit (LOQ) of 0.50 and 1.67 μg/L, respectively. The results indicate that the HS-SPME-GC-ECD technique proposed is efficient for determining the presence of chlorpyrifos in water, and analyses of the collected sample indicated the presence of chlorpyrifos in water bodies in the rural zone of Ouro Branco in concentrations within detection and quantification limits.

Development of high-throughput multi-residue method for non-steroidal anti-inflammatory drugs monitoring in swine muscle by LC-MS/MS

ABSTRACTA reliable and simple method for the detection and quantification of residues of 14 non-steroidal anti-inflammatory drugs and a metamizole metabolite in swine muscle was developed using liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). The samples were extracted with acetonitrile (ACN) in solid–liquid extraction followed by a low-temperature partitioning (LLE-LTP) process at –20 ± 2°C. After evaporation to dryness, the residue was reconstituted with hexane and a mixture of water:acetonitrile (1:1). LC separation was achieved on a reversed-phase (RP18) column with gradient elution using water (phase A) and ACN (phase B) both containing 1 mmol l–1 ammonium acetate (NH4COO) with 0.025% acetic acid. Analysis was carried out on a triple-quadrupole tandem mass spectrometer (LC-MS/MS) in multiple reaction monitoring mode using an electrospray interface in negative and positive mode in a single run. Method validation was performed according to the criteria of Commission Decision No. 2002/657/EC. The matrix effect and linearity were evaluated. Decision limit (CCα), detection capability (CCβ), accuracy and repeatability of the method are also reported. The proposed method proved to be simple, easy and adequate for high-throughput analysis and was applied to routine analysis by the Brazilian Ministry of Agriculture, Livestock and Food Supply.

Determination of oxadiazon residues in the field treated soil with and without organic matter incorporated

The behavior of oxadiazon (5-tert-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2 (3H)-one) in the soil may be influenced by organic material content. The objective of this study was to chromatographically determine soil oxadiazon residue content as a function of organic material and soil depth. A randomized block design was used, with treatments arranged in a scheme comprising 2 × 4 × 8 + 1 sub-subdivided plots with four repetitions. Plots were comprised of soil with (8 t ha−1) and without organic material incorporated, together with a control (0 t ha−1 and 0 g ha−1 of oxadiazon). Subplots were based on soil depth (0.00–0.05; 0.05–0.10; 0.10–0.15 and 0.15–0.20 m) and sub-subplots on soil collection time (0, 2, 4, 8, 16, 32, 64 and 128 days after application—DAA). Oxadiazon was applied at 1 kg ha−1. For residue determination, samples were quantified via high performance liquid chromatography (HPLC) using the solid–liquid extraction with low temperature partitioning (SLE-LTP) technique. In the superficial layer at 0.00–0.05 m, dissipation t 1/2 of oxadiazon took between 56 and 51 days in soil with and without organic material incorporated, respectively. Oxadiazon was found in the upper layer (0.00–0.10 m) of soil until 64 DAA and did not occur at any other depth, demonstrating low soil mobility potential. In soils containing incorporated organic material, higher concentrations of oxadiazon were observed over different depths and evaluation periods.

Determination of Haloxyfop-Methyl, Linuron, and Procymidone Pesticides in Carrot Using SLE-LTP Extraction and GC-MS

This study aimed to optimize and validate an analytical method for extraction, detection, and quantification of haloxyfop-methyl, procymidone, and linuron pesticides in carrot samples using solid–liquid extraction methods and low temperature partition (SLE-LTP), accompanied by gas chromatography coupled to mass spectrometry (GC-MS). For SLE-LTP technical optimization, we utilized a complete factorial planning, which had as its variables, agitation time, freezing time, and the correct sample mass/extracting solution volume ratio. The organic extract obtained was analyzed by GC-MS. To test the performance of this procedure, the method was validated and applied to the monitoring of pesticide residues in 20 samples of carrot produced in Alto Paranaíba, Minas Gerais, Brazil. The proposed method showed linearity between 0.5 and 3.5 mg·kg−1 with correlation coefficients greater than 0.99. The quantification limits were 0.48 mg·kg−1 for haloxyfop-methyl, 0.69 mg·kg−1 for linuron, and 0.65 mg·kg−1 for procymidone, values below the maximum residue limit provided by international legislation of 1.0 mg·kg−1 for linuron and procymidone. The use of haloxyfop-methyl is not approved in the cultivation of carrot. The recovery percentages were between 90 and 110 %, with a coefficient of variation of less than 12 %. Ten percent of the carrot samples monitored showed residues of linuron and procymidone in concentrations exceeding those permitted by Brazilian law.

Determination of pesticides in lettuce using solid–liquid extraction with low temperature partitioning

This work describes the optimization and validation of a method employing solid–liquid extraction with low temperature partitioning (SLE/LTP) together with analysis by gas chromatography with electron capture detection (GC/ECD) for the determination of nine pesticides (chlorothalonil, methyl parathion, procymidone, endosulfan, iprodione, λ-cyhalothrin, permethrin, cypermethrin, and deltamethrin) in lettuce. The method was found to be selective, accurate, and precise, with means recovery values in the range of 72.3–103.2%, coefficients of variation ⩽12%, and detection limits in the range 0.4–37μgkg−1. The matrix components significantly influence the chromatographic response of the analytes (above 10%). The optimized and validated method was applied to determine the residual concentrations of the fungicides iprodione and procymidone that had been applied to field crops of lettuce. The maximum residual concentrations of the pesticides in the lettuce samples were 13.6±0.4mgkg−1 (iprodione) and 1.00±0.01mgkg−1 (procymidone), on the day after application of the products.

Leaching of sulfentrazone in soils of reforestation in Brazil

This study determined the mobility of sulfentrazone in soils used for reforestation (Haplic Planosol, Ultisol, Humic Cambisol, and Regolithic Neosol) in the south of Brazil. To form the soil columns, previously prepared PVC tubes (10-cm diameter and 50-cm long) were filled with soil samples. Sulfentrazone was applied on top of the columns, which contained soil with moisture close to the field capacity. Subsequently, simulated 60-mm rainfall was applied to the columns. After draining the water, the columns were opened, and soil samples of each segment of 5.0 cm of the columns were taken for analysis of sulfentrazone by high-performance liquid chromatography. The herbicide was extracted from the soils by the solid–liquid extraction method with low temperature partition (SLE-LTP), which was adapted and validated. Sulfentrazone showed high mobility in the four soils analyzed, but presented lower mobility in the Humic Cambisol due to its lower rate of desorption. In this soil, the herbicide remained in the upper layers of the column, while in the other soils the herbicide was distributed throughout the columns. The soil that held the highest concentration of the compound in the first two segments of the column (0–5 and 5–10 cm) was the one with the highest clay content. Thus, it was concluded that the sulfentrazone leaching process in the soils analyzed is dependent on the chemical and physical characteristics of the soils, particularly, the contents of clay, sand, and organic matter.

The validation of a new high throughput method for determination of chloramphenicol in milk using liquid–liquid extraction with low temperature partitioning (LLE-LTP) and isotope-dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS)

The first application of LLE-PBT for determination of chloramphenicol in milk.

Paclobutrazol Residue Determination in Potato and Soil Using Low Temperature Partition Extraction and Ultrahigh Performance Liquid Chromatography Tandem Mass Spectrometry.

A simple, accurate, and highly sensitive analytical method was developed for determining the paclobutrazol residue in potato and soil, the dynamics dissipation in soil. Extraction was carried out by low temperature partitioning and analyzed by ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). For a favor extraction yield, the parameters such as temperature and solvent were optimized. The result showed that sample would be easily frozen and separated using acetonitrile under −20°C for 10 min. The limit of detection (LOD) was 0.5 μg/kg, and the limit of quantification (LOQ) was 2 and 5 μg/kg for potato and soil, respectively. The influence of paclobutrazol residue in potato was evaluated. The possible contamination of paclobutrazol from surface can be rinsed by distilled water or peeled off, but the paclobutrazol in potato harvest comes mainly from absorption and transport, which could not be removed by peeling. The half-life of paclobutrazol in soil was 20.64 days, and the residue was below 0.22 mg/kg on 50th day after spraying. According to the risk assessment with Need Maximum Daily Intake (NEDI) and Acceptable Daily Intake (ADI), a Maximum Residue Limit (MRL) of paclobutrazol in potato was recommended as 1.0 mg/kg.