Levels of Pesticide Residues in Food: Evaluation of Data from Total Diet Studies in Italy

Abstract

Total Diet Studies on pesticide residues in foods carried out in Italy in the last two decades are briefly summarized and data are discussed. Health risk assessment is expressed by the ratio total intake/ADI (%ADI ingested) for each compound and by the sum of the percentages of ADI for each compound within the same class of pesticides.

The total dietary intake of chlorinated pesticides, that was almost 100% of ADI in the years 1970-74, decreased down to 10% in the period 1978-84. This trend was confirmed for DDT in recent years, while data on Lindane and Heptachlor seem to be constant.

As regards the organophosphorus pesticides the sum of the percentages of ADI ingested for each compound, extrapolated from recent data (1990-1991) is about 20% and can be regarded as reasonably acceptable because the study included practically all the mainly used compounds.

Only few data are available for some pesticides like dithiocarbamates, especially EBDCs and their derivatives (e.g. ETU), other carbamates (e.g. aldicarb), paraquat etc. Moreover, analytical methods for these compounds should be improved.

The need for a considerable improvement in the number and organization of monitoring structures, in the use of standardized analytical procedures, in good laboratory practice standards and in the realibility of “monitoring protocols” and their homogeneity is evidenced.     

Diol sep-pak cartridges for enrichment of polychlorobiphenyls and chlorinated pesticides from water samples; determination by GC-ECD

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples has been performed after adsorption from a 20–200-mL sample on to a cartridge containing 100 mg diol-bonded porous silica. The PCBs are desorbed with 500 μL ethyl acetate, which is concentrated and analysed by gas chromatography with electron-capture detection (GC-ECD). The average recovery of 0.1 ng mL⁻¹ PCB congeners from distilled water and from Aniene river water is≥95% (standard deviation≤2.8). Average recoveries of 25 ng mL⁻¹ Aroclor 1254 from distilled water and from Aniene river water were, respectively, 94.4% and 92.5% (standard deviation 5.8). In the separation of PCB congeners from the chlorinated pesticides only the aldrin (40%) was eluted with the PCBs from the diol Sep-Pak cartridge by aqueous methanol. The method described is simple and reproducible.     

Separation of polychlorinated biphenyls from chlorinated pesticides using aminopropyl bonded-phase cartridge and determination by GC-ECD

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples is carried out after adsorption from a 25–500 mL sample, on a cartridge containing 100 mg aminopropyl-bonded porous silica. The clean-up step in which the PCBs and chlorinated pesticides are separated in different eluates is achieved by passing 25 mL of 40% aqueous methanol through the NH₂ Sep-Pak cartridge. The PCBs are desorbed with 500 μL ethylacetate, which is concentrated and analysis by GC-ECD. The average recovery, at 1 ppb is >97% with a standard deviation <2. The limits of detection are 0.1 ng μL⁻¹ and 5 pg μL⁻¹ respectively for Cl₃-PCB and Cl₈-PCB congeners. In the separation of PCBs from the chlorinated pesticides tested in this work, only the Aldrin is adsorbed for 60% with the PCBs by the NH₂ Sep-Pak cartridge. The method described is rapid, simple and reproducible.     

Sequential solid-phase extraction with cyanopropyl bonded-phase cartridges for trace enrichment of PCBs and chlorinated pesticides from water samples

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples has been performed after adsorption from a 50–250 mL sample on to a cartridge containing 100 mg cyanopropyl-bonded porous silica. The PCBs are desorbed with 500 μL ethyl acetate, which is concentrated and analysed by gas chromatography with electron-capture detection (GC-ECD). The average recovery of 1 ppb PCB congeners at from distilled water and from Marta river water is ≥95% (standard deviation ≤2.5). The average recovery of 20 ppb Aroclor 1260 from Marta river water was ≥91% (standard deviation ≤3.5). In the separation of the PCBs from the chlorinated pesticides only aldrin, heptachlor and 4,4′-DDD are adsorbed with the PCBs by the CN Sep-Pak cartridge. The method proposed is rapid, simple and reproducible.     

Analysis of a Mixture of Polychlorinated Biphenyls,DDT and its Analogues by High-Performance Liquid Chromatography

Abstract

A simple and rapid method for separation and quantitative analysis of polychlorinated biphenyis (PCBs) and chlorinated pesticides (DDT and its analogues DDE and DDD in their o, o'-and p, p'-isomers) is described. The procedure consists of two steps: a) transformation of DDT and its analogues in o, p'-and p, p'-dichlorobenzophenone (DCBP); b)determination of the amount of PCBs and ∑DDT as DCBP by HPLC. Results obtained confirm that HPLC can be considered as an alternative or a supplementary methodology to conventional methods such as gas chromatography. The method is applied to marine organisms.     

Analysis of PCBs in Biotic Matrices by Two-Dimensional GC-ECD

Abstract

The suitability of three GC-ECD systems for the separation of a model mixture containing various congeners of PCBs together with persistent chlorinated aromatics (pesticides and their metabolites, industrial chemicals) was tested. Analyses were performed on two parallel capillaries, the stationary phase of one of them was always in routine practice very common 5% phenyl-methylpolysiloxane, the second one was either 50% phenylmethylpolysiloxane or 7% phenyl-7% cyanopropyl-methylpolysiloxane. The number of unresolved (coeluted) analytes was significantly reduced in these systems and thus unbiased quantitation of PCBs and other components used for regulation was possible. The utilization of this type of multidimensional chromatography for rapid and reliable analysis of real samples (fish oil, human fat) was documented.     

Analysis of urban particulate standard reference materials for the determination of chlorinated organic contaminants and additional chemical and physical properties

A previously issued National Institute of Standards and Technology (NIST) Standard Reference Material (SRM), SRM 1649, Urban Dust/Organics has been analyzed for chlorinated organic contaminants (polychlorinated biphenyls and chlorinated pesticides) to provide certified values for a new class of compounds relative to the former certification. The material will be reissued as SRM 1649a. Four different analytical techniques were used. Specifically, two different methods of extraction (Soxhlet and pressurized fluid extraction) were used in conjunction with sample analysis by gas chromatography with two different columns (5% phenyl-methyl polysiloxane and 50% methyl C-18 dimethyl polysiloxane) that exhibit distinct selectivity, and with two different modes of detection (electron capture detection and mass spectrometry). The results from these techniques were combined to generate certified concentrations for 35 PCB congeners (some in combination) and 8 chlorinated pesticides. Ancillary assessments of additional chemical and physical properties of SRM 1649a include homogeneity, moisture, total organic carbon, extractable mass, and the particle-size distribution. The approach and the results for the certification of the PCB congeners and chlorinated pesticides in SRM 1649a, and the determination of the additional chemical and physical properties are described. In addition, the determination of PCBs and chlorinated pesticides in SRM 1648, Urban Particulate Matter (a particulate material certified for inorganic constituents), is also discussed although certified values are not presented. Received: 8 June 1998 / Revised: 4 September 1998 / Accepted: 26 September 1998     

Analysis of urban particulate standard reference materials for the determination of chlorinated organic contaminants and additional chemical and physical properties

A previously issued National Institute of Standards and Technology (NIST) Standard Reference Material (SRM), SRM 1649, Urban Dust/Organics has been analyzed for chlorinated organic contaminants (polychlorinated biphenyls and chlorinated pesticides) to provide certified values for a new class of compounds relative to the former certification. The material will be reissued as SRM 1649a. Four different analytical techniques were used. Specifically, two different methods of extraction (Soxhlet and pressurized fluid extraction) were used in conjunction with sample analysis by gas chromatography with two different columns (5% phenyl-methyl polysiloxane and 50% methyl C-18 dimethyl polysiloxane) that exhibit distinct selectivity, and with two different modes of detection (electron capture detection and mass spectrometry). The results from these techniques were combined to generate certified concentrations for 35 PCB congeners (some in combination) and 8 chlorinated pesticides. Ancillary assessments of additional chemical and physical properties of SRM 1649a include homogeneity, moisture, total organic carbon, extractable mass, and the particle-size distribution. The approach and the results for the certification of the PCB congeners and chlorinated pesticides in SRM 1649a, and the determination of the additional chemical and physical properties are described. In addition, the determination of PCBs and chlorinated pesticides in SRM 1648, Urban Particulate Matter (a particulate material certified for inorganic constituents), is also discussed although certified values are not presented. Received: 8 June 1998 / Revised: 4 September 1998 / Accepted: 26 September 1998     

Separation of polychlorobiphenyls from chlorinated pesticides in sediment and oyster samples for analysis by gas chromatography.

Polychlorobiphenyls (PCBs) have been separated from DDT and its analogs and from the other common chlorinated pesticides by adsorption chromatography on columns of alumina and charcoal. Elution from alumina columns with increasing fractional amounts of hexane first isolates dieldrin and heptachlor epoxide from a mixture of chlorinated pesticides and PCBs. The remaining fraction, when added to a charcoal column, can be separated into two fractions, one containing the chlorinated pesticides, the other containing the PCBs, by eluting with acetone-diethyl ether (25:75) and benzene, respectively. The PCBs and the pesticides are then determined by gas chromatography on the separate column eluates without cross interference. The method is applicable to sample extracts prepared for gas chromatography. Recoveries of the PCBs (Aroclors) and the chlorinated pesticides are good and the method is applicable to sediment and marine biota samples.     

Evaluation of a Novel Dechlorination Reaction as an Analytically Useful Derivatization Reaction Part 1. Stoichiometry,Mechanism and Yield Optimization

Abstract

A novel reaction for the dechlorination of polychlorinated biphenyls (PCBs) as well as most other chlorinated aromatic and aliphatic compounds is evaluated and discussed in terms of its potential for analytical purposes. The active dechlorinating agent is prepared through the reaction of molten sodium or potassium with polyethylene glycols (MW >200), in the absence of oxygen, to form the corresponding alkali metal glycolate, a powerful nucleophilic agent. Special emphasis is given to the mechanistic aspects of the reaction and their importance in terms of achieving high and reproducible yields with analytical quantities of substrate, in short periods of time. The contribution of the techniques: ESR, NMR, IR, UV, MS, GC-ECD, LC-EC, CIDNP-NMR, conductimetry and chloride analysis (amperometric) in elucidating the reaction mechanism and providing valuable kinetic data is illustrated. This reaction can potentially be applied to the determination of PCBs in waste oils.     

Monitoring of di-(2-ethylhexyl)phthalate,nonylphenol, nonylphenol ethoxylates,and polychlorinated biphenyls in anaerobic and aerobic sewage sludge by gas chromatography–mass spectrometry

The occurrence of di-(2-ethyhexyl)phthalate (DEHP), nonylphenol and nonyphenol mono- and diethoxylates (NPEs) and seven polychlorinated biphenyl (PCB) congeners in different types of sludge samples is reported. The analysis of these compounds was carried out by sonication-assisted extraction and analytical determination by gas chromatography coupled with a mass spectrometry detector, following a previously described method. The applicability of the method was tested by monitoring the organic pollutants in primary, secondary, mixed, and digested-dehydrated sludge samples from two wastewater treatment plants (WWTPs) based on aerobic and on anaerobic biological stabilization. The occurrence of these compounds in sewage sludge and the influence of sludge stabilization process on the further farmland application of the sludge were evaluated. DEHP and NPEs were detected in all analysed sludge samples from both WWTPs at concentration levels in the range of 22.3–601?mg?kg^?1 and 136–2357?mg?kg^?1 dm (dry matter), respectively. PCBs were detected in all types of sludge analysed from the anaerobic WWTP but was not detected in any sludge sample from the aerobic WWTP. Concentration levels of the sum of the seven PCBs congeners were up to 1.5?mg?kg^?1 dm. The concentration of DEHP, sum of NPEs, and sum of the seven PCB congeners were higher than the limits fixed in the third draft of the future Sludge Directive for land application of sludge in the 67%, 100%, and 11% of samples from the anaerobic WWTP and in the 83%, 92%, and 0% of samples from the aerobic WWTP, respectively.     

Multiresidue determination of pesticides in honey by matrix solid-phase dispersion and gas chromatography with electron-capture detection

A multiresidue method was developed for the determination of 15 pesticides (organochlorines, organophosphorus compounds, pyrethroids, and other acaricides) in various commercial honeys (eucalyptus, lavender, orange, rosemary, and multifloral). The analytical procedure is based on the matrix solid-phase dispersion of honey in a mixture of Florisil and anhydrous sodium sulfate; the mixture is placed in small plastic columns and extracted with hexane-ethyl acetate (90 + 10, v/v). The pesticide residues are determined by capillary gas chromatography with electron-capture detection. Recoveries with the method at concentrations between 0.15 and 1.5 microg/g ranged from 80 to 113%, and relative standard deviations were <10% for all the pesticides studied. The pesticide detection limits were within the range 0.5-5 microg/kg for organochlorines, around 3 microg/kg for the chlorinated organophosphorus pesticides studied, near 15 microg/kg for fluvalinate, and about 3 microg/kg for the other pyrethroids.     

Quantitative determination of toxic mono- and non-ortho polychlorinated biphenyls in cod liver oil after selective liquid chromatographic separation

Summary By application of chromatographic column filled with Supelclean ENVI-Carb/Celite and elution with three solvents of different polarity three PCB fractions were obtained. Fraction A contained poly-ortho PCBs, Fraction B mono-ortho PCBs, and Fraction C non-ortho PCBs. The Supelclean ENVI-Carb/Celite column was used in combination with a sample preparation procedure for pre-cleaning of acid-stable chlorinated hydrocarbons such as DDT and its metabolites, HCH isomers, and regulation-relevant PCB congeners. The method was optimized using standard solutions of 55 PCB congeners, 8 chlorinated pesticides and contaminated cod liver oil samples. The influence of traces of remaining matrix on the elution profile of the organochlorine compounds on Supelclean ENVI-Carb/Celite was observed. Quantitation was carried out by GC-ECD with fused silica capillary columns of different polarity.     

Fast solid phase extraction of polychlorobiphenyls and chlorinated pesticide residues from mussels using sep-pak cartridges

Summary A rapid method for the determination of chlorinated pesticides and polychlorinated biphenyls in mussels (Mytilus sp.) is reported. The mussel sample is homogenized and extracted with acetonitrile. The organic solution is concentrated and successively diluted with distilled water solution (12 g L⁻¹ NaCl). The organic compounds from water solution are adsorbed onto a NH₂ Sep-Pak cartridge. The clean-up step, in which the polychlorobiphenyls and chiorinated pesticides are separated in different eluates, is achieved by passing 25 mL of a 40% methanol aqueous solution through the NH₂ Sep-Pak and the C₁₈ Sep-Pak cartridges connected in series. The polychloroblphenyls are desorbed from the NH₂ Sep-Pak cartridge whilst the chlorinated peslicides are recovered from the C₁₈ Sep-Pak cartridge. In the separation of polychlorobiphenyls from the chlorinated pesticides tested in this work, only aldrin, hepatachlor and 4,4′-DDD are partially adsorbed with the polychlorobiphenyls onto the NH₂ Sep-Pak cartridge. The average recovery is ≥95.0% with a relative standard deviation ≤5.0%. The limits of detection for different pesticides and polychlorobiphenyl congeners are 0.01 and 0.008 μg Kg⁻¹. The final determination is carried out by capillary gas chromatography with ECD.     

Determination of polychlorinated biphenyl congeners and chlorinated pesticides in a fish tissue standard reference material

The concentrations of a wide range of polychlorinated biphenyl congeners (PCBs) and chlorinated pesticides in a fish tissue Standard Reference Material (SRM) have been determined using multiple methods of analysis. This material, SRM 1946, Lake Superior Fish Tissue, was recently issued by the National Institute of Standards and Technology (NIST) and complements a suite of marine environmental natural-matrix SRMs that are currently available from NIST for the determination of organic contaminants such as aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), PCBs, and chlorinated pesticides. SRM 1946 is a fresh tissue homogenate (frozen) prepared from filleted adult lake trout (Salvelinus namaycush namaycush) collected from the Apostle Islands region of Lake Superior. SRM 1946 has certified and reference concentrations for PCB congeners, including the three non- ortho PCB congeners, and chlorinated pesticides. Certified concentrations are available for 30 PCB congeners and 15 chlorinated pesticides. Reference concentrations are available for 12 PCB congeners and 2 chlorinated pesticides. In addition, SRM 1946 is characterized for additional chemical constituents and properties: fatty acids, extractable fat, methylmercury, total mercury, selected trace elements, proximates, and caloric content. The characterization of chlorinated compounds is described in this paper with an emphasis on the approach used for the certification of the concentrations of PCB congeners and chlorinated pesticides. The PCB congener and chlorinated pesticide data are also compared to concentrations in other marine natural-matrix reference materials available from NIST (fish oil, mussel tissue, whale blubber, and a second fresh frozen fish tissue homogenate prepared from filleted adult lake trout collected from Lake Michigan) and from other organizations such as the National Research Council Canada (ground whole carp), the International Atomic Energy Agency (fish homogenate), and the European Commission Joint Research Centre [fish oils (cod and mackerel) and mussel tissue].     

Cyanopropyl Bonded-Phase Cartridges for Trace Enrichment of Dioxins and Chlorinated Pesticides from Water Samples

Gas chromatography of dioxins and chlorinated pesticides in water samples has been performed after adsorption from 50 to 100 mL sample on to a cartridge containing 100 mg cyanopropyl-bonded porous silica. The dioxins and chlorinated pesticides were desorbed with 2 mL carbon disulfide, which is concentrated and analysed by gas chromatography coupled with an electron-capture detector. The average recovery of 0.20 ng mL^?1 of each chlorinated pesticide and of 0.50 ng mL^?1 of each dioxin from distilled water and river water samples (50 mL) is ≥97.2% with a standard deviation (SD) ≤ 2.6. In the dioxin separation from chlorinated pesticides the recovery of dioxins at levels of 0.1–0.5 ng mL^?1 is ≥97.9% with a SD ≤ 1.3, with traces of aldrin, heptachlorepoxide and 4,4′-DDD (≤1.7%) by the CN-Sep-Pak cartridge, while the recovery of chlorinated pesticides at levels of 0.05–0.2 ng mL^?1 is ≥97.4% with a SD ≤ 1.5, with traces of hep-dioxin (2.4%) and penta-dioxin (1.0%) by the C₁₈-Sep-Pak cartridge connected “in series” to the CN-Sep-Pak cartridge.     

Derivatization of Humic Compounds: An Analytical Approach for Bound Organic Residues

Abstract

Bound residues of pesticides and their metabolites are defined as being nonextractable with organic solvents, but partly extractable together with the humic matrix by NaOH or other solvents suitable to extract humic compounds. Recently, an improvement in humus extraction from soils was achieved upon derivatization of the organic matter with silylating reagents at room temperature. By this method 70–90% of the organic carbon or nitrogen either from soil or from humin became soluble in organic solvents. The extracts were analyzed by means of ¹³C NMR-spectroscopy. The spectra were well resolved with signal-separation of less than 1 ppm. The extracted humic compounds were of rather low molecular weight, ranging from 300 to 4000 to 6000 d or more.

¹⁴C-labeled residues of pesticides or other xenobiotics found to be nonextractable after exhaustive organic solvent extraction became readily dissolved along with most of the humic matrix using this derivatization procedure. Between 60–80% of ¹⁴C anilazine residues or of ¹⁴C-labeled chlorinated phenols or anilines originating from both previously solvent extracted soil samples or from humin became solubilized in organic solvents.     

Simultaneous determination of two serine proteinases by hydrophobic interaction chromatography

Summary An LC clean-up procedure based upon a complexation between polycyclic aromatic hydrocarbons (PAHs) and silica with chemically bonded 2,4-dinitroaniline has been combined with GC/MS. The LC pre-separation makes it possible to obtain a relatively clean fraction of PAHs free from alkanes, alkylbenzenes and naphthalenes, PCBs, chlorinated pesticides and many other interfering compounds. This fraction has been analyzed using capillary GC and mass selective detector (MSD). Substantial improvement of the MS spectra of PAHs with three or more fused benzene rings is achieved.     

Rapid multiresidue determination of organochlorine and organophosphorus compounds in human serum by solid-phase extraction and gas chromatography coupled to tandem mass spectrometry

A rapid analytical method for the multiresidue determination of several organochlorine and organophosphorus pesticides and polychlorinated biphenyls in human serum samples has been developed. Analytes were isolated by solid-phase extraction using C18 cartridges with subsequent analysis by GC-MS/MS using a glass liner packed with CarboFrit in the GC injection port. Labelled surrogate internal standards (fenitrothion D6, HCB (13)C6, p, p'-DDE D8 and PCB 138 (13)C12) were added to the samples before the extraction and were used for quantitation and for quality control in the analysis of real-world samples. Accuracy and precision were evaluated by using serum samples fortified at two concentration levels for the three families of compounds, with satisfactory results in the majority of cases. The high selectivity and sensitivity of GC-MS/MS allowed low detection limits of 0.05-0.5 ng mL(-1) for most of the analytes investigated. The developed procedure improves other current methodologies for the analysis of pesticides and PCBs in biological fluids, especially as regards to analysis time and simplicity of sample treatment. The method was applied to several serum samples obtained from farmers devoted to citrus crop production. Chlorpyrifos, HCB, p, p'-DDE and the higher chlorinated PCBs (153, 138 and 180) were the most frequently detected compounds.     

Halocarbons in Aqueous matrices from the Rennick Glacier and the Ross Sea (Antarctica)

Aqueous matrices from Antarctica were analysed for three volatile chlorinated hydrocarbons (VCHCs): tetrachloromethane (CCl₄), trichloroethylene (C₂HCl₃) and tetrachloroethylene (C₂Cl₄). The matrices analysed were snow from Rennick Nèvè and Rennick Glacier sampled during the Italian Expeditions of 1995/96 and 1996/97, respectively, and seawater, pack ice, sea-microlayer, subsuperficial water and freshwater, collected during the Italian Expedition of 1997/98. Extractions from the aqueous matrices were carried out in Antarctica (the laboratories of the Italian Base, Terra Nova Bay). Because of the critical space–time conditions in these laboratories, an extraction procedure was developed, suitable for large volumes of water (10?L), in order to combine the extraction of other classes of organic compounds (polychlorinated biphenyls, polycyclic aromatic hydrocarbons and chlorinated pesticides) with those of our direct interest. The VCHC organic extracts were analysed in Italy by GC-ECD and GC-MS. The analyses confirmed the presence of the three halocarbons in Antarctica in quantities ranging from units to some dozens of nanograms per kilogram. The results were evaluated with respect to the local distribution of these compounds and their diffusion on a global scale.