Optimization of the QuEChERS Method for Determination of Pesticide Residues in Chicken Liver Samples by Gas Chromatography-Mass Spectrometry

The goal of this research was to evaluate the application of Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method for the determination of organochlorine, organophosphate, and carbamate pesticides in fatty animal matrices such as liver of chicken obtained from National Research Institute of Animal Production in Balice (Poland). Pesticides extraction effectiveness was evaluated at two different spiking levels (0.010 and 0.020 mg kg^?1) and efficiency of the dispersive solid-phase extraction (d-SPE) clean-up step was evaluated by comparison adding different d-SPE sorbent combinations (PSA?+?GCB, PSA?+?C₁₈, PSA?+?SAX, and PSA?+?NH₂). The analysis of pesticide residues was performed by gas chromatography ion trap mass spectrometry (GC/IT-MS). The linear relation was observed from 0 to 400 ng mL^?1 and the determination coefficient R ²?>?0.997 in all instances for all target analytes. Better recoveries were obtained in samples at 0.020 mg kg^?1 spiking level. The recoveries were in the range 70–120 %, with relative standard deviation (RSD) values lower than 15 % at 0.020 mg kg^?1 spiking level for most pesticides. Similar recovery ratios were obtained with the four different combinations of sorbents tested in the clean-up step, with better precision when the (PSA?+?SAX) combination was tested. Limits of detection (LODs) ranged from 0.001 to 0.005 mg kg^?1 and limits of quantification (LOQs) ranged from 0.003 to 0.015 mg kg^?1. The proposed method was successfully applied analyzing pesticide residues in real chicken liver samples; detectable pesticide residues were observed, but in all of the cases, the contamination level was lower than the default maximum residue levels (MRLs) set by European Union (EU), Regulation (EC) N 396/2005.     

Antioxidant Activity and Determination of Phenolic Compounds from <Emphasis Type="Italic">Eugenia involucrata</Emphasis> DC. Fruits by UHPLC-MS/MS

Fruits have been the focus of several studies aimed at finding new antioxidant sources for protection against the damage caused by reactive species. In this study, the antioxidant activity and the presence of phenolic compounds in all parts (peel, pulp, and seeds) of Eugenia involucrata DC. fruits were evaluated. DPPH^·, ABTS^·+, and ORAC methods were used to determine the antioxidant activity, and an UHPLC-MS/MS method was developed for determining the phenolic compounds (gallic, chlorogenic, ferulic, p-coumaric and ellagic acids, quercetin, and myricetin). In the determination of both antioxidant activity and phenolic composition, the efficiency of solvents with different polarities—methanol/H₂O (80:20, v/v), ethanol/H₂O (80:20, v/v), methanol/acidified water with phosphoric acid pH 3.00 (80:20, v/v), and ethyl acetate—for the extraction of the phenolic compounds, was also evaluated. All parts of E. involucrata fruits showed antioxidant activity, in the range of 36.68 ± 1.44 to 873.87 ± 18.24 μmol TE g^?1, being the highest values found in the seeds and peel when more polar extraction solvents were used. Six, five, and three phenolic compounds were identified and quantified in the pulp, peel, and seeds, respectively, with the highest abundance as p-coumaric acid (14 ± 2 mg kg^?1) in the pulp, quercetin (47 ± 5 mg kg^?1) in the peel, and gallic acid (74 ± 4 mg kg^?1) in the seeds, also when more polar solvents were used. Although antioxidant activity methods suggested that the peel and seeds have more antioxidant potential, a wider variety of compounds were determined in the pulp.     

Fatty acids,tocopherols, phenolic and antioxidant properties of six citrus fruit species: a comparative study

Citrus fruit is a rich source of bioactive phytochemicals. Information on the fatty acid and tocopherol composition of locally grown citrus fruits in Korea is elusive. This work was aimed to study fatty acid, tocopherols, ascorbic acid, antioxidant potential, and selected phenolics from peel and pulp of six citrus species. The most dominant fatty acid was linoleic acid (15–45%), followed by linolenic, palmitic, and oleic acid. Stearic acid was highly abundant in yuzu peel (14.45%) and pulp (15.88%) compared to the other fruits. Unsaturated fatty acids (54–74%) contributed higher composition than saturated fatty acids (25–46%). Peel exhibited better antioxidant potential and contained higher phytochemicals than pulp. The concentrations of α-tocopherol and γ-tocopherol were ranged from 22.96 (yuzu) to 86.93 (cheonhyeyang) and 38.59 (yuzu) ~83.03 (tangerine) μg/g DW, respectively. J-Redhyeyang peel exhibited highest total flavonoids (4.17?±?0.10 mgQE/g DW) and DPPH radical scavenging activity (6.17?±?0.03 mgTE/g DW). FRAP values were highest (20.05?±?0.64 mgTE/g DW) in yuzu peel, while peel of cheonhyeyang was superior in total phenolic contents. Tangerine (3.02?±?0.05 mg/g DW) and yuzu (7.49?±?0.38 mg/g DW) had higher hesperidin concentrations in pulp and peel, respectively. Naringin was found in an appreciable amount in yuzu pulp (2.04?±?0.09 mg/g DW) and peel (6.30?±?0.19 mg/g DW) but not detected in all other fruit species. Our results indicate that citrus fruit peel is the rich source of antioxidant compounds, which can be used to prepare antioxidant rich food product.     

The content of chlorogenic acids in tropical fruits

This work investigates the content of feruloylquinic (FQA), caffeoylquinic (CQA) and dicaffeoylquinic (diCQA) acids in the peel, pulp and seed of 22 tropical fruits from Brazil. 3‐CQA, 4,5‐diCQA and 4‐ and 5‐FQA were not detected in any of the fruits analysed. Relatively small amounts of 4‐CQA (4.0–48.7 mg kg^?1) were found in the peel and/or pulp of seven of the fruits; only the peel of Artocarpus heterophyllus was significantly (p < 0.05) richer in this acid (1000 mg kg^?1). The distribution of 3,4‐ and 3,5‐diCQA in different parts of the fruits was relatively poor, only reaching levels of up to 16.4 mg kg^?1. The peel of A heterophyllus also showed the highest amount of 5‐CQA (13 000 mg kg^?1), while the seed of most fruits generally contained a lower amount of this acid than the peel or pulp. On the basis of the 5‐CQA content found in the pulp, 15 of the fruits were classified as follows: very low concentration (4.4–15.8 mg kg^?1), low concentration (28.9–66.4 mg kg^?1), medium concentration (132 mg kg^?1), high concentration (473–474 mg kg^?1) or very high concentration (1730 mg kg^?1); however, no 5‐CQA was detected in the pulp of the other seven fruits. Thus 5‐CQA was the major chlorogenic acid present in most of the tropical fruits studied and was generally accompanied by small amounts of 4‐CQA and 3,4‐ and 3,5‐diCQA. © 2002 Society of Chemical Industry     

Modification of Multiresidue QuEChERS Protocol to Minimize Matrix Effect and Improve Recoveries for Determination of Pesticide Residues in Dried Herbs Followed by GC-MS/MS

An accurate, rapid, and reliable multiresidue QuEChERS method based on gas chromatography coupled with tandem mass spectrometry was developed for the determination of 235 pesticides in challenging, dry, complex herb matrices (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.). Sample mass and the type of cleanup sorbent used to estimate the procedure’s effectiveness were optimized. Purification steps with ChloroFiltr, ENVI-Carb, GCB, octadecyl, PSA, and Z-Sep as cleanup sorbents and a step without purification were compared. To minimize the matrix effect and obtain acceptable recoveries for pesticides, 2 g of herb sample and 10 mL acetonitrile, followed by d-SPE cleanup step with a combination of 150 mg PSA/45 mg ENVI-Carb/900 mg MgSO₄, and additionally 50 μL of 5% formic acid and some droplets of dodecane, were needed. Matrix effects for the vast majority of pesticides were reduced (>?20%), showing suppression or enhancement. Most recoveries were in the range of 70–120% (RSD < 18%), reaching the quantification limit of 0.001 to 0.002 mg kg^?1. There was excellent linearity within the range from 0.001 to 2.00 μg mL^?1, and a correlation coefficient higher than 0.999 was obtained. Expanded measurement uncertainty was estimated to be between 4 and 43%. Finally, the developed method was successfully employed to identify and quantify pesticide residues in the analysis of 46 real herb samples.     

Characterization and transformation of the <Emphasis Type="Italic">Opuntia ficus indica</Emphasis> fruits

Opuntia ficus indica fruits have been associated with health effects, due to their protective actions against oxidation. Nevertheless, few studies about processing of Opuntia fruits are available’; therefore, we studied the pulp characteristics and processing of a local variety, for producing beverage nectars. The pulp had an average pH of 5.64, 13.47 °Brix, with total sugars (106 g L^?1), K (1180 mg L^?1), 503.3 µg L^?1 of β carotene, 120 mg L^?1 of total phenolic compounds, 4.9 mg and 46.9 mg L^?1 respectively for betacyanins and betaxanthins and 243.4 mg L^?1 of vitamin C. The formulated nectars with 35% of pulp (N35) and 45% of pulp (N45) had respectively 14 and 15 °Brix. Minor components represent 1109 and 1112 mg L^?1 of K for N35 and N45 respectively, β carotene (318.6 µg and 362.8 µg L^?1), and vitamin C 227 and 231 mg L^?1. We confirmed the stability and acceptability of these beverages after a month of storage, after stability and panel tests. Therefore, we suggest that the pulp processing can be used as a new form of agro industrial utilization of this underutilized fruit.     

Simple and fast spectrophotometric determination of low levels of thiabendazole residues in fruit and vegetables after pre-concentration with ionic liquid phase microextraction

There is a great importance of monitoring thiabendazole (TBZ) residues in fruits and vegetables to ensure food safety. Therefore, a new ionic liquid (IL) phase microextraction method using IL, 1-butyl-3-methylimidazoliumhexafluorophosphate [C₄mim][PF₆], as extracting solvent is proposed for simple and fast determination of low levels of TBZ in fruits and vegetables by spectrophotometry. The method is based on selective complex formation of TBZ with Cu(II) ions in presence of PF₆^– as counter ion at pH 5.5, and then microextraction of the complex into the fine micro-drops of IL phase. After optimisation of variables affecting microextraction efficiency, the analytical parameters of the method were determined by calibration curves. The method exhibits a linear relationship (0.3–280 μg L^?1), low detection limit (0.1 μg L^?1), good intra- and inter-day precision (2.4–4.5% as RSD_r%, 2.1–5.6% as RSD_R%), good recovery (≥95.1–98.2%) and high sensitivity enhancement factor (150) by solvent-based calibration curve. It allows a detection limit of 0.24 μg L^?1 and a range of 0.8–250 μg L^?1 by the matrix-matched calibration curve. After validation, the method was successfully applied to the determination of TBZ residues with method quantification limits in fruit and vegetables of 2.0 and 2.5 µg kg^?1 with and without adding polyvinylpyrrolidone (PVP-15) solution. Recoveries range from 85.5% to 98.2% after spiking (10, 50 and 100 µg kg^?1, n: 3).     

Heavy metals in vegetables sold in the local market in Jordan

Heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) in various vegetables (cabbage, green onion, lettuce, parsley, rocket, spinach, carrot, onion, potato and cauliflower) from the market in Jordan were measured using inductively coupled plasma-mass spectrometry. As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn ranged from 0.009–0.275 mg kg^?1 wet weight, 0.004–0.060 mg kg^?1, 0.003–0.401 mg kg^?1, 0.105–3.51 mg kg^?1, 0.15–1.15 mg kg^?1, 0.93–14.39 mg kg^?1, 0.044–0.702 mg kg^?1, 0.072–0.289 mg kg^?1 and 2.23–6.65 mg kg^?1, respectively. Parsley, followed by spinach, contained the highest concentration of heavy metals. Onion contained high levels of toxic heavy metals. The content of Cu in parsley and spinach and Pb in onion exceeded the Codex limits. However, the daily intake of heavy metals from the tested vegetables was lower than the maximum limits for allowable intake.     

Behaviour of spirotetramat residues and its four metabolites in citrus marmalade during home processing

The effect of home processing on the residues of spirotetramat and its four metabolites (B-enol, B-glu, B-mono and B-keto) in citrus marmalade is comprehensively investigated in this paper by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). A five-fold recommended dose of spirotetramat was applied to citrus fruit under field conditions and the processing included five steps: washing, peeling, pre-treatment for peel, mixing and boiling. The results showed that spirotetramat was the predominant component detected in unprocessed citrus, accounting for 64%. All the detected residues were primarily deposited on citrus peel, except for B-enol which was also present in the citrus pulp. Washing reduced spirotetramat, B-enol, B-glu and B-keto by 83%, 56%, 41% and 16%, respectively, and pre-treatment of the peel removed between 42% and 68% of the residues. Four compounds were all below the limit of detection after the mixing step. In the final product, only B-keto was detected at the concentration of 0.010 mg kg^–1. After the whole process, the processing factors for spirotetramat, B-enol, B-glu and B-keto were < 0.041, < 0.125, < 0.294 and 0.313, respectively, which indicated that home processing can significantly reduce residues of spirotetramat and its metabolites in citrus marmalade.     

Analysis of Fluopicolide and Propamocarb Residues on Tomato and Soil Using QuEChERS Sample Preparation Method in Combination with GLC and GCMS

Persistence of fluopicolide and propamocarb in tomato was studied following three applications of a combination formulation of Infinito 68.75 SC (fluopicolide 6.25 %?+?propamocarb 62.5 %) at 1500 and 3000 mL ha^?1 by 7 days interval, starting the spray at fruit development stage. QuEChERS method included extraction of sample with ethyl acetate and cleanup of dispersive solid-phase extraction was used for the determination of fluopicolide and propamocarb residues on tomato and soil. Residues of fluopicolide and propamocarb in tomato were estimated by gas–liquid chromatography and gas chromatograph–mass spectrometry, respectively. Half-lives for fluopicolide were found to be 2.58 and 2.31 days, whereas for propamocarb these values were observed to be 1.49 and 2.08 days at single and double the application rates, respectively. Residues of fluopicolide dissipated below its limit of quantification (LOQ) of 0.01 mg kg^?1 after 7 and 10 days at single and double the application dosage, respectively. Similarly, residues of propamocarb took 5 and 7 days to reach LOQ of 0.10 mg kg^?1, at single and double dosages, respectively. Soil samples collected after 15 days of the last application did not show the presence of fluopicolide and propamocarb at their detection limit of 0.01 and 0.10 mg kg^?1, respectively. The initial deposit of residues of propamocarb and fluopicolide for both the dosages were below the prescribed codex maximum residue limit values of 2 and 1 mg kg^?1, respectively. Therefore, a 1-day waiting period was suggested to reduce human health risks before consumption of tomato fruits.     

Cadmium and lead in female cattle livers and kidneys from Vojvodina,northern Serbia

ABSTRACT

Concentrations of cadmium (Cd) and lead (Pb) were determined in livers (n = 52) and kidneys (n = 52) of female cattle (345–2717 days old) from dairy farms in the region Vojvodina. Cd and Pb were analysed by inductively coupled plasma-optical emission spectrometry, after microwave digestion. Cd and Pb concentrations did not exceed the Serbian and European maximum set limits in any sample. The Cd concentrations in the livers and kidneys ranged from 0.033 to 0.151 mg kg^?1 wet weight and from 0.055 to 0.510 mg kg^?1 wet weight, respectively. The corresponding Pb concentrations were 0.015-0.159 mg kg^?1 wet weight and 0.021-0.196 mg kg^?1 wet weight, respectively. Mean Cd and Pb concentrations were significantly lower (p < 0.001) in the liver (0.072 and 0.053 mg kg^?1 wet weight) than in the kidney (0.190 and 0.075 mg kg^?1 wet weight). There were good correlations between Cd in liver and Cd in kidney, Pb in liver and Pb in kidney, Cd level and age and Pb level and age in both tissues.     

Pesticide residues in apples grown under a conventional and integrated pest management system

This paper describes method validation for determination of more than 40 pesticides in apples using a GC technique. Target compounds belonged to the organochlorine, organophosphorus, carbamates, pyrethroids, triazoles, dicarboximides and strobilurins groups, among others. Sample preparation consisted of acetone extraction and subsequent cleanup/concentration by SPE with a polymer-based sorbent. Single quadrupole GC–MS operating in SIM mode and electron impact ionization was used for identification and quantification of the pesticides. Average recoveries for analytes ranged between 70 and 110% at three fortification levels – 0.01, 0.1 and 0.2 mg kg^?1. Relative standard deviations were lower than 20% for all tested compounds. Calculated limits of detection and limits of quantification were below 0.01 mg kg^?1, which were sufficiently low compared to the maximum residue levels (MRLs) established by European legislation. The proposed method was applied for determination of pesticide residue in four selected apple varieties after harvesting. Whole and processed fruits (peel and peeled fruits) were analyzed from different treatment systems: two conventional, one based on integrated pest management (IPM) and two variants based on organic production (controls). Higher levels of pesticide residues were found in apple fruits under conventional conditions. Fenitrothion and chlorpyrifos residues were detected frequently in apple peel at concentrations up to 0.45 and 0.77 mg kg^?1, respectively. The levels found in the whole fruits of the same samples were much lower than in peel and below the respective MRLs (0.5 mg kg^?1 for both pesticides). Measurable residues of triadimenol only, up to 0.05 mg kg^?1, concentrated in the peel, were found in the apples from IPM.     

Validation and quantification of neonicotinoid insecticide residues in rice whole grain and rice straw using LC-MS/MS

An efficient analytical method was developed and validated using a modified QuEChERS method and LC-MS/MS for the detection and quantification of neonicotinoid insecticide residues in rice whole grain and rice straw. The samples were extracted using acetonitrile and cleaned up by dispersive solid-phase extraction. Validation based on five fortification levels showed good recoveries of neonicotinoids ranging from 75% to 116 % and 60% to 105 % for rice whole grain and straw, respectively. The precision ranged between 3% and 17 %, and 2% and 10 % for grain and straw, respectively. The limit of detection was from 0.007 to 0.0084 mg kg^?1 and 0.005 to 0.15 mg kg^?1 and the limit of quantification was in the range of 0.024–0.028 mg kg^?1 and 0.016–0.051 mg kg^?1 for rice whole grain and rice straw, respectively. Monitoring of farm gate samples indicated that, out of 24 samples, 1 rice whole grain sample was contaminated with thiamethoxam residues (0.07 mg kg^?1).     

Assessment of the dietary intake of propylene glycol in the Korean population

An improved method for the analysis of propylene glycol (PG) in foods using a gas chromatography-flame ionisation detector (GC-FID), with confirmation by GC-MS, was validated by measuring several analytical parameters. The PG concentrations in 1073 products available in Korean markets were determined. PG was detected in 74.1% of the samples, in a concentration range from the limit of detection (n.d., 0.39 μg ml^?1) to 12,819.9 mg kg^?1. The Korea National Health and Nutrition Examination Survey (KNHANES) 2011–2013 reported the mean intake levels of PG from all sources by the general population and consumers were 26.3 mg day^?1 (0.52 mg kg^?1 day^?1) and 34.3 mg day^?1 (0.67 mg kg^?1 day^?1), respectively. The 95th percentile intake levels of the general population and consumers were 123.6 mg day^?1 (2.39 mg kg^?1 day^?1) and 146.3 mg day^?1 (2.86 mg kg^?1 day^?1), respectively. In all groups of the general population, breads were the main contributors to the total PG intake. These reports provide a current perspective on the daily intake of PG in the Korean population.     

Optimization and Validation of a Method Without Alkaline Clean-Up for Patulin Analysis on Apple Puree Agar Medium (APAM) and Apple Products

A sensitive high-performance liquid chromatography-UV (HPLC-UV) method, based on the Association of Analytical Communities (AOAC) Official method 2000.02, was developed and validated for the high-throughput analysis of patulin in in vitro experiments on apple puree agar medium (APAM). The importance of repeating the ethyl acetate extraction step at liquid-liquid extraction (LLE) was examined, as well as the extent of patulin degradation during the sodium carbonate clean-up. In addition to this alkaline clean-up, the efficiency of using an Oasis HLB or C₁₈ cartridge as solid-phase extraction (SPE) clean-up was compared. This resulted in a two-step ethyl acetate LLE, followed by an Oasis HLB SPE clean-up, without alkaline clean-up conditions. The method was fully validated for APAM, cloudy apple juice, and apple puree. Average patulin recoveries at levels of 100, 500, and 1000 μg kg^?1 of APAM varied between 95 and 113 % over 3 independent days, with an interday precision (RSD_R) of 5 to 10 %. Recovery experiments carried out with the spiked apple juice (at 50 μg kg^?1) and apple puree (10 μg kg^?1) showed average recovery rates laying between 80–101 % (RSD_R?=?12 %) and 77–100 % (RSD_R?=?9 %), respectively. This method offered a detection limit of 3–4 μg kg^?1 and a quantification limit of 5–8 μg kg^?1 for APAM, apple juice, and puree.     

Comparison of fruit characteristics,oil properties and fatty acid composition of local Syrian Kaissy cv olive (<Emphasis Type="Italic">Olea europaea</Emphasis>)

Characterization of Syrian (Kaissy cultivar) olive fruits and evaluation of physic-chemical properties of oils were carried out during 3 years of production. The mean values of data for both measured and calculated variables of fruits were: grain length (21.89 mm), grain width (17.92 mm), length/width (1.22), weight of grain (3.79 g), weight of pulp (flesh) (3.19 g), weight of pit (0.60 g), pulp/pit ratio (5.35), crude oil (17.13%), water content (moisture) (51.34%). The 3 year average values of chemical properties of Syrian Kaissy cultivar olive oils (SKOO) including acid value, peroxide vale, Thiobarbituric acid value, iodine value(IV), saponification value, and phenolic content were 0.58%, 4.33 mEq O₂ kg^??1, 0.028 mg MDA kg^??1 oil, 90.77 g I₂, 100 g^??1, 194.91 mg KOH g^??1, and 218.08 g gallic acid kg^??1, respectively. Pefractive index (RI), and viscosity were 1.4666 nD at 25?°C and 139.56 mPa.s, respectively. However, the 2 years average values of Hunter’s color parameters of SKOO were; the lightness (L*= 66.91), redness (a* = 18.80), yellowness (b* = 29.08) and the color differences (?E?=?65.49). FA analysis of the SKOO used showed a high content of monounsaturated fatty acids (oleic acid 70.82% and palmitic acid 1.01%) and low polyunsaturated fatty acids (Linoleic acid 10.72% and Linolenic 0.82%) and saturated fatty acids (Palmitic 14.10% and stearic 2.57%). Results for 3 years production of Syrian Kaissy cultivar olive fruit and oil are discussed in detail.     

Detection of 5-hydroxymethyl-2-furfural Levels in Selected Chinese Foods by Ultra-High-Performance Liquid Chromatograph Analytical Method

In this study, an ultra-high-performance liquid chromatography method was developed to detection the levels of 5-hydroxymethyl-2-furfural (HMF) in 227 selected food products obtained from the Chinese markets. The performance of the analysis method was evaluated by some quality parameters such as limit of detection (LOD), limit of quantification (LOQ), linearity, recovery, and run-to-run (n?=?6) and day-to-day (n?=?18) precisions. The LOD and the LOQ of the method in different food matrices ranged from 0.15 to 0.50 and from 0.35 to 1.20 mg kg^?1, respectively. The results from this study showed that HMF was mostly detected in all samples selected. HMF contents in different samples varied greatly according to the raw materials and processing conditions. The highest level of HMF was found in preserved fruits and ground coffee, with average levels of 409.6 and 409.9 mg kg^?1, respectively. Preliminary estimates of HMF exposure from foods in the Chinese population was estimated to be 0.12 mg kg^?1 body weight day^?1, which is relatively low compared with the result reported by JECFA and European Food Safety Authority.     

Multi-Residue Determination of Pesticides in Açai Tropical Fruit (Euterpe oleracea) by Matrix Solid-Phase Dispersion Combined with Liquid Chromatography

An extraction method based on matrix solid phase dispersion was developed to determine bromuconazole, fenbuconazole, parathion-methyl, kresoxim-methyl, and teflubenzuron in açai using liquid chromatography with ultraviolet diode array detector. The best results were obtained using 1.0 g of açai, 3.0 g of neutral alumina as the dispersant sorbent, and cyclohexane/ethyl acetate (1:1, v/v, 20 mL) as an eluting solvent. The method was validated using açai samples fortified with pesticides at three concentration levels (0.25, 0.5, and 1.0 mg kg^?1). Average recoveries (seven replicates) ranged from 66 to 119 %, with relative standard deviations between 1.4 and 20 %. The detection and quantification limits for açai ranged from 0.02 to 0.05 mg kg^?1 and from 0.05 to 0.1 mg kg^?1, respectively.     

Biogenic amines in commercially produced Yulu,a Chinese fermented fish sauce

Seven biogenic amines were determined in 35 commercially produced Yulu samples from three provinces of China by pre-column derivatisation with dansyl chloride (Dns-Cl) and high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Putrescine, cadaverine, histamine and tyramine were the major biogenic amines (more than 100 mg kg^?1), while tryptamine, spermidine and spermine were regarded as minor biogenic amines (less than 25 mg kg^?1). Twenty samples contained more than 50 mg kg^?1 histamine (the limit for histamine in seafood products as suggested by the Food and Drug Administration). Twenty-one samples contained more than 100 mg kg^?1 tyramine and 10 contained more than 1000 mg kg^?1 total biogenic amines. This study provided data on biogenic amine levels in Chinese fermented fish sauce. The results suggested that biogenic amine content should be monitored in commercially produced Yulu.     

Validation of the procedure for the determination of maduramicin in concentrates,premixes, and feeds by liquid chromatography

A single laboratory validation was carried out for the determination of maduramicin in concentrates, premixes, and feed. The method comprised sample extraction of maduramicin, derivatization with dansylhydrazine and liquid chromatography with ultraviolet light detection. The limit of detection (LOD) and limit of quantification (LOQ) were 0.4 and 1.0 mg kg^?1, respectively. The repeatability expressed as the average difference between the results of duplicate measurements was 5.9% at the concentration level of 1% (concentrate), 7.1% at the concentration level of 1 g kg^?1 (premix), and 11% with the feed containing maduramicin with the nominal concentration of 5 mg kg^?1 and feed spiked at the concentration level of 1 mg kg^?1. The relative standard deviations for the within-laboratory reproducibility (RSD_W) were 9.2%, 16%, 18%, and 17% at the concentration levels of 1%, 1 g kg^?1, 5 mg kg^?1, and 1 mg kg^?1, respectively. The measurement uncertainties were ±0.2%, ±0.3 g kg^?1, ±1.9 mg kg^?1, and ±0.3 mg kg^?1 at the same concentration levels, respectively.