Field Incurred Endosulfan Residues in Fresh and Processed Vegetables and Dietary Intake Assessment

Mitigation in endosulfan residues was determined in spinach, cauliflower, potato, brinjal, tomato, and okra by using different techniques. The endosulfan residues were determined in 66 samples of different vegetables, and it was found that the highest endosulfan residues (mg kg^?1) were at the raw stage in okra (1.71), brinjal (1.50), and spinach (1.16), respectively. The residue of endosulfan was lowest in potato (0.130) mg kg^?1. Washing reduced the endosulfan residue from 15 to 28%, peeling reduced it from 60 to 67%, and cooking further lowered it from 18 to 31% in all vegetables. Dietary intake assessment revealed that only samples of okra exceeded the maximum permissible intake value at the raw stage, whereas all the other samples were below maximum permissible intake value, although some were exceeding the maximum residue limits at the raw stage.     

Flavonols (kaempeferol,quercetin, myricetin) contents of selected fruits,vegetables and medicinal plants

The concentrations of flavonols (kaempeferol, quercetin, myricetin) were determined in 22 plant materials (9 vegetables, 5 fruits, and 8 medicinal plant organs). The materials were extracted with acidified methanol (methanol/HCl, 100:1, v/v) and analyzed by reverse phase high-performance liquid chromatographic (RP-HPLC) with UV detection. The total flavonols contents varied significantly (P < 0.05) among vegetables, fruits and medicinal plant organs ranged from 0 to 1720.5, 459.9 to 3575.4, and 2.42 to 6125.6 mg kg⁻¹ of dry matter, respectively. Among vegetables, spinach and cauliflower exhibited the highest amounts of flavonols (1720.5 and 1603.9 mg kg⁻¹, respectively), however, no flavonols were detected in garlic. Within fruits, highest level of flavonols was observed in strawberry (3575.4 mg kg⁻¹), whereas, the lowest in apple fruit (459.9 mg kg⁻¹). Of the medicinal plant organs, moringa and aloe vera leaves contained the highest contents of flavonols (6125.6 and 1636.04 mg kg⁻¹), respectively, whereas, lowest was present in barks (2.42–274.07 mg kg⁻¹). Overall, leafy green vegetables, soft fruits and medicinal plant leaves exhibited higher levels of flavonols.     

Nitrate-N determination in leafy vegetables: Study of the effects of cooking and freezing

Nitrate upon reduction to nitrite can cause methaemoglobinaemia or act as precursor in the endogenous formation of carcinogenic nitrosamines. The leafy vegetables are the major vehicle for the entry of nitrate into the human system. The present study was conducted to establish a flow injection analysis (FIA) technique to investigate the nitrate-N contents of four commonly consumed fresh leafy vegetables (Chinese cabbage, celery, lettuce and English cabbage) from market in Fiji. Two extraction techniques (activated carbon and alkaline extraction) were assessed to extract nitrate-N and the activated carbon extraction was preferred over alkaline extraction and applied. The recoveries of spiked nitrate-N in vegetable matrices ranged from 90.40% to 112.80% in activated carbon extraction with an average of 100.62%. The effects of cooking (boiling, baking and frying) and deep-freezing on the nitrate-N contents were also studied. Nitrate contents in selected leafy vegetables were determined by FIA coupled with Greiss protocol involving sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride as color reagents. Nitrate was determined in the linear range from 1.0 to 20.0 mg L⁻¹ with the method detection limit of 0.042 mg L⁻¹ (0.34 mg kg⁻¹). The results of the study show that nitrate contents in fresh leafy vegetables ranged from 1297 to 5658 mg kg⁻¹. Boiling reduces nitrate content by 47–56% whereas frying in Soya bean oil elevates nitrate content by as much as 159–307%. No significant change was observed in nitrate content after baking. The deep-freezing of the selected leafy vegetables shows that nitrate-N content fluctuates slightly from the original nitrate-N values over the seven day period. The FIA throughput was 38 samples h⁻¹.     

Flow injection analysis of nitrate-N determination in root vegetables: Study of the effects of cooking

Vegetables are the major vehicles for the entry of nitrate into the human system. Ever-increasing concern over nitrate toxicity has directed a number of countries to lay down maximum allowable threshold concentrations with regards to nitrate-N in vegetables. Fiji is an independent island nation, located in the southern Pacific Ocean, has a tropical oceanic climate and hence expected to have high nitrate-N levels in vegetables. Thus, the present study was devoted to establish a flow injection analysis (FIA) technique for nitrate-N determination in Fiji’s commonly consumed fresh and cooked root vegetables such as potato (Solanum tuberosum), dalo (Colocasia esculenta), sweet potato (Ipomoea batatas) and carrot (Daucus carota L.). Activated carbon extraction technique was applied to extract nitrate-N. FIA with colorimetric detection technique having linear dynamic range of determination 1.0–20.0 mg L⁻¹ and detection limit of 0.042 mg L⁻¹ (0.34 mg kg⁻¹), using sulphanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride as colour reagents, was used to determine nitrate-N contents in selected fresh and cooked root vegetables. The samples throughput was 38 h⁻¹. The effects of various cooking (boiling, baking and frying) methods on nitrate-N contents in root vegetables have also been studied. The study shows that the nitrate content of fresh root vegetables ranges from 53.76–258.00 mg kg⁻¹ whereas boiling reduces nitrate content by 23.30–42.62%. The frying in soya bean oil elevates nitrate contents from 204.53–299.12% but after baking nitrate contents remains almost constant with slight increasing trend from 2.80–8.43%. A comparison of the nitrate obtained by standardised method and the nitrate contents in vegetables of other countries are also presented.     

Nitrate and nitrite content in organically cultivated vegetables

The nitrate and nitrite content of leaf vegetables (Swiss chard, sea beet, spinach and cabbage), “inflorescence” vegetables (cauliflower) and fruit vegetables (eggplant and vegetable marrow) grown with organic fertilizers have been determined by a modified cadmium–Griess method. Samples were purchased from organic food stores as well as collected directly from an organic farm in Madrid (Spain). Nitrate levels were much higher in the leaf vegetables (especially Swiss chard species; average over the different samples and species of 2778.6 ± 1474.7 mg kg^{? 1}) than in inflorescence or fruit products (mean values between 50.2 ± 52.6 and 183.9 ± 233.6 mg kg^{? 1}). Following Swiss chard species, spinach (1349.8 ± 1045.5 mg kg^{? 1}) showed the highest nitrate content, and nitrite was found above the limit of detection in some samples only (spinach, 4.6 ± 1.0 mg kg^{? 1}; sea beet, 4.2 ± 0.7 mg kg^{? 1} and Swiss chard, 1.2 ± 0.4 mg kg^{? 1}). Some vegetables (spinach, cabbage and eggplant) had lower nitrate content in the samples harvested in summer, showing the influence of climatic conditions on the nitrate levels in a plant. The samples taken directly from the organic farm, with the exception of eggplant, had higher or slightly higher average nitrate values than samples purchased in the organic food stores, ranging from 117 to 1077%.     

Study of flavonoids in aqueous spinach extract using positive electrospray ionisation tandem quadrupole mass spectrometry

The presence of three flavonols (quercetin, kaempferol, myricetin) and two flavones (apigenin, luteolin) were investigated in the extract of fresh spinach leaves. Aqueous spinach extracts were prepared with a leaf/water ratio of 1:2 at 80 °C for 30 min stirring. Ferric ammonium sulphate method was used for measuring total polyphenols in the extracts and expressed as catechins and tannic acid equivalents. The flavonoids glycosides in the extract were hydrolysed to their aglycons with 1.2 M HCl in boiling 50% water methanol solution. The resulting aglycons were identified and quantified by a C18 reverse phase high-performance liquid chromatography (RP-HPLC). Furthermore, the results were confirmed by HPLC coupled to an electrospray ionisation tandem triple-quadrupole mass spectrometer ESI-MS performing low-energy collision induced dissociation (CID-MS/MS) in the collision cell (HPLC-ESI-MS/MS). Analyses were made in the multiple reaction monitory (MRM) mode. Results showed that total polyphenols contents in fresh spinach leaves were 270 mg kg⁻¹ and 390 mg kg⁻¹ as tannic acid and catechin equivalents, respectively, in which, major flavonoids aglycons were apigenin (170 mg kg⁻¹), quercetin (50 mg kg⁻¹) and kaempferol (30 mg kg⁻¹).     

Fish and food safety: Determination of formaldehyde in 12 fish species by SPME extraction and GC–MS analysis

The formaldehyde (FA) content in different fish products was evaluated using a solid phase microextraction (SPME)-GC–MS method based on fiber derivatisation with pentafluorobenzyl-hydroxyl-amine hydrochloride. LOD and LOQ values of 17 and 28 μg kg⁻¹, respectively were calculated. Fish quality was assessed by the analysis of 12 species (sea-fish, freshwater-fish and crustaceans), revealing variable FA levels. Fresh, deep frozen, canned, boiled and roasted fish were analysed; cooking always produced a decrease in the analyte content. Fish belonging to the Gadidae family were the samples with the highest FA concentration (from 6.4 ± 1.2 mg kg⁻¹ to 293 ± 26 mg kg⁻¹), in four cases out of 14 exceeding the value of 60 mg kg⁻¹ proposed by the Italian Ministry of Health. Storage on ice was also investigated, showing moderate FA production also at temperature around 0 °C. FA contents lower than 22 mg kg⁻¹ were finally found in all the other samples.     

Quantification of organophosphate insecticides and herbicides in vegetable samples using the “Quick Easy Cheap Effective Rugged and Safe” (QuEChERS) method and a high-performance liquid chromatography-electrospray ionisation-mass spectrometry (LC-MS/MS) technique

A Quick Easy Cheap Effective Rugged and Safe (QuEchERS) extraction was developed and followed by selective analysis using a liquid chromatography-mass spectrometry method for the quantification of eighteen pesticides in vegetable samples. This method was accurate (?99.5%), and it exhibited limits of detection and quantification values in the 0.006-0.091 and 0.020-0.314 μg kg⁻¹ ranges, respectively. Furthermore, the coefficients of variations (?0.9999) were less than 1% at the low μg kg⁻¹ end of the method. Mean recoveries ranged between 94% and 102%, and relative standard deviations were below 10%. Based on these results, the methodology was proven to be highly efficient, robust, and suitable for monitoring the maximum residue limits (MRL) compliance of a wide range of commodity/pesticide combination. This method was successfully applied to the analysis of vegetable samples that were collected from different government farmers’ markets and street shops in urban areas. The presence of target pesticides was found in the range of 0.016 and 50.85 μg kg⁻¹.     

Determination of volatile nitrosamines in grilled lamb and vegetables using comprehensive gas chromatography – Nitrogen chemiluminescence detection

The grilling of meat may generate dangerous levels of mutagenic and carcinogenic nitrosamines (NAs). Meat and vegetable samples underwent a two-step solid-phase extraction before analysis by comprehensive gas chromatography with a nitrogen chemiluminescence detection system (GCxGC-NCD). The GCxGC-NCD method showed high selectivity, sensitivity and equimolarity in its response to six specific NAs. NA contamination of charcoal-grilled lamb at various stages of cooking and with various fat contents and also charcoal-grilled vegetables were investigated. The grilling of lamb on unready charcoal resulted in the formation of considerable quantities of NAs. Grilling lamb on properly prepared, ready charcoal resulted in an increase in total concentrations of six NAs from 0 to 4.51 μg kg⁻¹ over a period of 16 min. Increasing the fat content of the grilled lamb from 5% to 20% caused a modest increase in total concentrations of the six investigated NAs from 4.51 to 5.30 μg kg⁻¹.     

In vitro binding of bile acids by okra,beets, asparagus,eggplant, turnips,green beans,carrots, and cauliflower

The in vitro binding of bile acids by okra (Abelmoschus esculentus), beets (Beta vulgaris), asparagus (Asparagus officinalis), eggplant (Solanum malongena), turnips (Brassica rapa rapifera), green beans (Phaseolus vulgaris), carrots (Daucus carota), and cauliflower (Brassica oleracea botrytis) was determined using a mixture of bile acids secreted in human bile at a duodenal physiological pH of 6.3. Six treatments and two blank incubations were conducted, testing various fresh raw vegetables on an equal dry matter basis. Considering cholestyramine (bile acid-binding, cholesterol-lowering drug) as 100% bound, the relative in vitro bile acid binding on dry matter (DM) and total dietary fibre (TDF) basis was 1–16% and 2–54%, respectively. Bile acid binding for okra was significantly higher than for all the other vegetables tested. For beets, binding values were significantly higher than for asparagus. Binding values for asparagus were significantly higher than for eggplant, turnips, beans green, carrots and cauliflower. These results point to the health promoting potential of okra > beets > asparagus > eggplant = turnips = green beans = carrots = cauliflower, as indicated by their bile acid binding, on a dry matter basis.     

Chemical composition of cultivated seaweed Ulva clathrata (Roth) C. Agardh

Samples of cultivated Ulva clathrata were collected from a medium scale system (MSS, 1.5 × 1.5 m tank), or from a large scale system (LSS, 0.8 ha earthen pond). MSS samples were dried directly while the LSS sample was washed in freshwater and pressed before drying. Crude protein content ranged 20–26%, essential amino acids accounting for 32–36% of crude protein. The main analysed monosaccharides were rhamnose (36–40%), uronic acids (27–29%), xylose (10–13%) and glucose (10–16%). Some notable variations between MSS and LSS samples were observed for total dietary fibre (26% vs 41%), saturated fatty acids (31% vs 51%), PUFAS (33% vs 13%), carotenoids (358 vs 169 mg kg⁻¹ dw) and for Ca (9 vs 19 g kg⁻¹), Fe (0.6 vs 4.2 g kg⁻¹), Cu (44 vs 14 mg kg⁻¹), Zn (93 vs 17 mg kg⁻¹) and As (2 vs 9 mg kg⁻¹). The chemical composition of U. clathrata indicates that it has a good potential for its use in human and animal food.     

Multicommuted fluorescence based optosensor for the screening of bitertanol residues in banana samples

A multicommuted flow through optosensor is developed in order to determine bitertanol in banana samples, by measuring the pesticide native fluorescence at 261/326 nm. The solid support used in the flow-through cell, C₁₈, allows both high selectivity and sensitivity necessary for the screening of the pesticide at residue levels. These characteristics of optosensing are implemented with low sample consumption and automation intrinsic properties of multicommutation, providing a useful tool for pesticide residue routine determination in foods. An acetonitrile extraction/partitioning and dispersive solid-phase extraction clean-up procedure proved to be useful; an additional cleaning step with C₁₈ solid phase extraction (SPE) cartridges was carried out, eliminating all matrix limitations. Recovery experiments performed on banana samples at different concentrations provided recoveries between 81% and 115%. A detection limit of 0.014 mg kg⁻¹ was obtained. This makes the method suitable for screening bitertanol in banana samples, fulfilling the maximum residue levels of 3 mg kg⁻¹ established by the European Union.     

A rapid multi-residue method for the determination of pesticide residues in choi sum, yardlong beans and aubergines

A rapid multi-residue modified QuEChERS method has been developed to analyse 20 pesticide residues in choi sum, yardlong beans and aubergines by gas chromatography with flame photometric and electron capture detectors. Primary secondary amine in dispersive form was omitted in the extraction step but instead packed in a Pasteur glass pipette for column cleanup. The recoveries for all 20 pesticides except chlorothalonil at 10-500 μg kg⁻¹ fortification levels ranged from 74.0% to 117%. Similar recoveries of 81.7-117% were obtained for all organochlorine and pyrethroid pesticides including chlorothalonil using silica gel cleanup. The relative standard deviation obtained was below 14.9%. The limit of quantification was in the range 1-10 μg kg⁻¹. The method has high selectivity for pesticides in vegetables containing high amount of chlorophyll, pigment and coloured compounds such as in choi sum and aubergines. The method was used to analyse 132 vegetable samples from residue survey.     

Trace element content of Boletus tomentipes mushroom collected from Yunnan,China

The contents of As, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, and Zn in eleven fruiting bodies of Boletus tomentipes were determined. The results showed the values of the studied elements decreased in the order: Mg (208–279 mg kg⁻¹) > Fe (106–137 mg kg⁻¹) > Mn (29.5–46.8. mg kg⁻¹) > Zn (18.7–23.1 mg kg⁻¹), > Cu (11.4–15.8 mg kg⁻¹) > Cr (3.36–4.78 mg kg⁻¹) > Pb (1.38–3.88 mg kg⁻¹) > Ni (1.68–3.01 mg kg⁻¹) > Cd (0.16–0.32 mg kg⁻¹) > As (0.10–0.24 mg kg⁻¹) > Hg (<0.06 mg kg⁻¹).     

HPLC–MS identification and quantification of flavonol glycosides in 28 wild and cultivated berry species

Berries and red fruits are rich dietary sources of polyphenols with reported health benefits. More than 50 different flavonols (glycosides of quercetin, myricetin, kaempferol, isorhamnetin, syringetin and laricitrin) have been detected and quantified with HPLC–MSⁿ in fruits of blueberry, bilberry, cranberry, lingonberry, eastern shadbush, Japanese wineberry, black mulberry, chokeberry, red, black and white currants, jostaberry, red and white gooseberry, hardy kiwifruit, goji berry, rowan, dog rose, Chinese and midland hawthorn, wild and cultivated species of blackberry, raspberry, strawberry and elderberry. The phenolic constituents and contents varied considerably among the analyzed berry species. Elderberry contained the highest amount of total flavonols (450–568 mg kg⁻¹ FW), followed by berry species, containing more than 200 mg kg⁻¹ FW of total: chokeberry (267 mg kg⁻¹), eastern shadbush (261 mg kg⁻¹), wild grown blackberry (260 mg kg⁻¹), rowanberry (232 mg kg⁻¹), american cranberry (213 mg kg⁻¹) and blackcurrants (204 mg kg⁻¹). Strawberry (10.5 mg kg⁻¹) and white currants (4.5 mg kg⁻¹) contained the lowest amount of total flavonols. Quercetins represent the highest percentage (46–100%) among flavonols in most analyzed berries. In wild strawberry and gooseberry the prevailing flavonols belong to the group of isorhamnetins (50–62%) and kaempferols, which represent the major part of flavonols in currants (49–66%). Myricetin glycosides could only be detected in chokeberry, rowanberry and species from the Grossulariaceae, and Adoxaceae family and Vaccinium genus. Wild strawberry and blackberry contained from 3- to 5-fold higher total flavonols than the cultivated one.     

A novel method for pesticide analysis in refined sugar samples using a gas chromatography–mass spectrometer (GC–MS/MS) and simple solvent extraction method

A sensitive method for the quantification of 11 pesticides in sugar samples to the μg kg⁻¹ level has been developed. These pesticides are often used in an agricultural context. A simple solvent extraction followed by selective analysis using a gas chromatography–mass spectrometric method was used. This method was accurate (?99%) as it possesses limits of detection in the 0.1-μg kg⁻¹ range, and the coefficients of variations are less than 15% at the low μg kg⁻¹ end of the method’s linear range. The percent recovery of all the pesticides at the lowest levels of detection ranges from 82% to 104%. This method was used for the quantification of pesticides in sugar samples collected from different factory outlets from different parts of India. In this study, 27 refined sugar samples were analysed in which one sample showed a detectable level of the chlorpyrifos pesticide. This study showed that Indian sugar is free from the commonly-used pesticides at the low μg kg⁻¹ levels.     

Simplified pesticide multiresidues analysis in fish by low-temperature cleanup and solid-phase extraction coupled with gas chromatography/mass spectrometry

A simple and fast method for the simultaneous analysis of thiobencarb, deltamethrin and 19 organochlorine pesticide residues in fish by gas chromatography–mass spectrometry was investigated in this study. Samples are extracted with acetonitrile. Most of lipids in the extract are eliminated by low-temperature cleanup, prior to solid-phase extraction cleanup. The lipids extracted from the fish samples were easily removed without any significant losses of the pesticides. Aminopropyl (NH₂) cartridge was effective to eliminate the remaining interference. Spiked experiments were carried out to determine the recovery, precision and limits of detection (LODs) of the method. The method detection limits ranged from 0.5 μg kg⁻¹ to 20 μg kg⁻¹, whilst recoveries of the pesticides were in the range of 81.3–113.7% with relative standard deviations ?13.5% at a spiked concentration of 0.05 mg kg⁻¹, 0.02 mg kg⁻¹ and 0.1 mg kg⁻¹. The newly developed method is demonstrated to give efficient recoveries and LODs for detecting pesticide multiresidues in fish.     

Determination of organochlorine pesticide residues in rice and human and fish fat by simplified two-dimensional gas chromatography

The residue levels of four hexachlorocyclohexane (HCH) isomers (α-HCH, β-HCH, γ-HCH and δ-HCH), 4 dichloro-diphenyl-trichloroethane (DDT) congeners (p,p-DDE, o,p-DDT, p,p-DDD, and p,p-DDT), heptachlor, heptachlor epoxide, aldrin, dieldrin and endrin in rice and its bran from Jiangsu Province, PR China, were investigated by simplified two-dimensional gas chromatography, coupled with micro-electronic capture detector (μECD). Concentrations of organochlorine pesticides (OCPs) for ∑HCH ranged from 0 to 0.039 mg kg⁻¹ in the rice and 0 to 0.057 mg kg⁻¹ in its bran. For ∑DDT, the concentrations ranged from 0 to 0.053 mg kg⁻¹ in the rice and 0 to 0.051 mg kg⁻¹ in its bran. The five other OCPs, except HCH and DDT, were not detected. The major HCH isomers and DDT, congeners detected, both in the rice and its bran, were β-HCH and p,p′-DDE. Compared with the residue levels in the rice, the OCPs levels in fish and human fat were detected at higher residue levels. It is necessary to investigate the OCP residues in foodstuffs of the food chain in order to evaluate the potential health risk to humans.     

Elemental composition of cephalopods from Portuguese continental waters

Essential and contaminant elements concentrations were determined in the muscle tissue of octopus (Octopus vulgaris), squid (Loligo vulgaris) and cuttlefish (Sepia officinalis), caught off the Portuguese coast in 2004–2005. As expected, the largest concentrations found correspond to Cl, S, K, Na, P and Mg (average values between 629 mg (100 g)⁻¹, for Cl, and 435 mg kg⁻¹, for Mg, in octopus and squid, respectively). Above average concentrations of Zn, Cu, Fe and Sr were also found. The highest total Hg concentration was found in cuttlefish (0.36 mg kg⁻¹); however, this value did not exceed the recommended limit proposed by EU (0.5 mg kg⁻¹). Lead levels observed in all samples were always significantly lower than the EU limit (1.0 mg kg⁻¹). Regarding Cd, the 1.0 mg kg⁻¹ limit was only exceeded in two octopus samples. It may be concluded that the cephalopods studied do not constitute cause for concern, in terms of toxic elements, and could be safely used for daily intake of essential elements. Nevertheless, the squid contribution for elemental DI is minor in comparison to the other two species.     

Determination of metal contaminations in sea foods from Marmara,Aegean and Mediterranean seas: Twelve fish species

The concentrations of cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc were determined by ICP-AES in muscles and livers of 12 fish species sampled from the Marmara, Aegean and Mediterranean seas of Turkey. Iron showed the highest levels in examined tissues of all fish species. Following Fe, Zn generally showed the second highest levels. Metal concentrations in edible parts of fish species were 0.02–0.37 mg kg⁻¹ for cadmium, 0.04–0.41 mg kg⁻¹ for cobalt, 0.04–1.75 mg kg⁻¹ for chromium, 0.32–6.48  mg kg⁻¹ for copper, 7.46–40.1 mg kg⁻¹ for iron, 0.10–0.99  mg kg⁻¹ for manganese, 0.02–3.97 mg kg⁻¹ for nickel, 0.33–0.86 mg kg⁻¹ for lead, 4.49–11.2 mg kg⁻¹ for zinc, respectively. All metal concentrations in livers were higher than those in muscles. In some stations, cadmium and chromium concentrations in both muscles and livers, and lead levels in livers of the examined species were higher than permissible safety levels for human uses.