Multiresidue methods

Pubhc concerns about pesticides in the diet of infants and children resulted in an expert committee convened by the U.S. National Academy of Sciences which devoted four years to the review of all available data. A consensus report was issued in 1993 (80). A number of recommendations for further work to more precisely define what constitutes the diet of infants and children were made. No risk could be estimated. The residue data reviewed by the panel were mainly from monitoring studies conducted by the PDA using multiresidue methods to analyze fresh produce and market basket samples collected from various geographic areas (81,82). These and other rehable scientific studies have demonstrated that relatively few food samples contain detectable residues. Most residues are far below estabhshed tolerances which are set above the maximum residue found in treated raw agricultural... 

Pesticide Analytical Manual, Food and Dmg Administration, Rockville, Md., Vol. I, 1990, and Vol. II, 1989. Includes multiresidue methods used by U.S. FDA to routinely check foods for pesticide residues, and single residue methods for certain pesticides not detected by any of the multiresidue methods. 

The U.S. FDA monitors foods for half of the approximately 300 pesticides having official EPA tolerances as weU as a number of other pesticides that have no official tolerances. Multiresidue methods, most of which are based on chromatography protocols, are employed (7). Not aU pesticides are monitored on aU foods and sampling (qv) is purposely biased to catch possible problems. The overaU iacidence of iUegal pesticide residue is, however, quite smaU 1% for domestic surveiUance samples and 3% for imported foods. The methods employed can usuaUy quantify residues present at 0.01 ppm. Quantitation limits range from 0.005 to 1 ppm. 

The applieation range of eoupled-eolumn teehnology is determined by the separation power of the first eolumn. In general, it ean be said that low resolution favours multiresidue methods (MRMs), while high resolution leads to methods for a single analyte or for a group of analytes with similar properties. 

When a first column of a very short length (and therefore a low selectivity) is used (this is especially suitable for multiresidue methods), we talk about an on-line precolumn (PC) switching technique coupled to LC (PC-LC or solid-phase extraction (SPE)-LC). This is particulary useful for the enrichment of analytes, and enables a higher sample volume to be injected into the analytical column and a higher sensitivity to be reached. The sample is passed through the precolumn and analytes are retained, while water is eliminated then, by switching the valve, the analytes retained in the precolumn are transferred to the analytical column by the mobile phase, and with not just a fraction, as in the previous cases. 

Chlorophenoxy acids are relatively polar pesticides which are usually determined by LC because volatile derivatives have to be prepared for GC analysis. This group of herbicides can be detected by multiresidue methods combined with automated procedures for sample clean-up, although selectivity and sensitivity can be enhanced by coupled-column chromatographic techniques (52). The experimental conditions for Such analyses are shown in Table 13.1. 

Kasprzyk-Hordern B, Dinsdale RM, Guwy AJ (2008) Multiresidue methods for the analysis of pharmaceuticals, personal care products and illicit drugs in surface water and wastewater by solid-phase extraction and ultra performance liquid chromatography-electrospray tandem mass spectrometry. Anal Bioanal Chem 391(4) 1293-1308... 

Numerous methods have also been reported for foods, including milk (Bennett et al. 1997), chili fruits (Pokharkar and Dethe 1981), fruits and vegetables (Mitchell 1976), and the multiresidue methods for fatty and non-fatty foods (fruits, vegetables, seeds, dairy, eggs, meats) published by FDA (FDA 1994). Limits of detection are generally in the sub-ppm to ppb range. 

Bennett DA, Chung AC, Lee SM. 1997. Multiresidue method for analysis of pesticides in liquid whole milk. JAOACInt 80(5) 1065-1077. 

FDA. 1994. Pesticide analytical manual, Vol. 1, 3rd edition, Multiresidue methods. Method 302 Method for Nonfatty Foods Method 303 Method II for Nonfatty Foods, Method 304 Method for Fatty Foods. FDA, US Department of Health and Human Services. 

The methods EN 1528 1996 and EN 12393 1998 comprise a range of old multiresidue methods of equal status, which are widely accepted throughout Europe. These are, e.g., the Luke method and the German Deutsche Forschungsgemeinschaft (DFG) methods S8 and S19 ° (all based on extraction with acetone), the Association of Official Analytical Chemists (AOAC) method 970.52 (using acetonitrile extraction and liquid-liquid partition combined with Horisil column cleanup) and the Dutch ethyl acetate extraction combined with GPC. All methods have been subjected to inter-laboratory studies, although not with all pesticide/matrix combinations, which would be impossible to achieve. 

The integration of analytical methods in European standards requires their acceptance by several national experts within special working groups and in a final weighted vote of National Standards Bodies. Therefore, there needs to be very high confidence in the performance of methods. Consequently, methods should be tested in inter-laboratory method validation studies, with the exception of those multiresidue methods which are widely used throughout Europe. In the case of CEN methods there is no doubt about residue definition but detailed requirements about the number of matrices and concentration levels in validation experiments do not exist. Eor this reason it may be that CEN methods are validated for important crops only. 

Pesticide Analytical Manual. Volume 1, Multiresidue Methods, third edition, US Food and Drug Administration Washington, DC, Sect. 302 (1994). 

OPPTS 860.1000 Background OPPTS 860.1100 Chemical Identity OPPTS 860.1200 Directions for Use OPPTS 860.1300 Nature of Residue - Plants, Livestock OPPTS 860.1340 Residue Analytical Method OPPTS 860.1360 Multiresidue Method OPPTS 860.1380 Storage Stability Data OPPTS 860.1400 Water, Fish, Irrigated Crops OPPTS 860.1460 Food Handling OPPTS 860.1480 Meat/Milk/Poultry/Eggs OPPTS 860.1500 Crop Field Trials OPPTS 860.1520 Processed Food/Feed OPPTS 860.1550 Proposed Tolerances... 

For example, in order to meet the demanding requirements of legislation such as the European Union (EU) Baby Food Directive (Directive 95/5/EC and subsequent revisions), analysts must improve on the scope and sensitivity of multiresidue methods of analysis. This Baby Food Directive, which became effective on 1 July 2002, limits residues of all pesticides to a maximum level of 0.01 mgkg There will also be a banned list of pesticides, annexed to the Directive, which will not permit the use of certain pesticides on crops intended for use in baby food production. As a consequence, food manufacturers often require residue results for raw or primary ingredients within 24 8 h of sample receipt at the laboratory. 

In another example, a multiresidue method using HPLC/ESI-MS was developed to determine six imidazolinone herbicides in five different soil types. Good recoveries (80-120%) and adequate sensitivity at the 2.0 ngg level were obtained for the compounds investigated. In the method, a 50-g soil sample was extracted for 1 h in 0.5N NaOH solution. A portion of the extract was acidified, to precipitate the humic acids, and the supernatant was then loaded on to a preconditioned trifunctional Cig SPE cartridge and eluted with ethyl acetate. Further cleanup was achieved using a tandem strong anion-exchange (SAX)-SCX SPE combination. Analytes were eluted... 

The analytical methods summarized in this article are generally multiresidue methods for the determination of oxime carbamates in different sample matrices (crops, animal tissues, soil, and water). These methods include HPLC with fluorescence, MS, and MS/MS detection. 

Crops, food, and feed. The first recommended method is based on the Dutch Multiresidue Method 2 for A-methylcarbamates, which was originally developed by de Kok et The method has recently been validated by DuPont Crop Protection and Batelle, Geneva Research Centres, for the analysis of methomyl and oxamyl in dry, high-water, high-fat, and high-acid content crops and in various grape processed products. The limit of detection for each analyte is 0.003-0.005 mg kg . ... 

The European drinking water guidelines set a maximum admissible concentration of 0.10 pgL for individual pesticides and their related compounds in drinking water. The recommended methods for oxime carbamates and their metabolites in groundwater and surface water are suitable for detection limits below 0.10 pgL. The first method is the HPLC/lluorescence multiresidue method of de Kok et al The second method is an HPLC/MS/MS method of DuPont Crop Protection which is specific for oxamyl and may be applicable for the analysis of other oxime carbamates in heavily polluted waters. 

The author thanks the following scientists at DuPont Crop Protection and Battelle, Geneva Research Centres, for developing and validating some of the methods summarized in this article C.R. Powley for the soil method by HPLC/MS/MS J. J. Stry, SJ. Hill and PR Maliszewski for the water method by HPLC/MS/MS and K.M. Jernberg, B. Francon, M. Jetzer, C. Steiner, L. Dubey and H. Mattou for the independent laboratory validations of the Multiresidue Method 2 for crop samples. 

FDA. 1994b. 302 and 303 Methods for nonfatty foods. In Pesticides Analytical Manual, 3rd edition, vol. 1 Multiresidue methods. US. Department of Health and Human Services, Food and Drug Administration. 

Krause RT. 1973. Detemiination of several chlorinated pesticides by the AOAC multiresidue method with additional quantitation of perthane after dehydrochlorination Collaborative study. J Assoc Off Anal Chern 56(3)721-727. 

Recent trends in pesticide analysis in food aims for reduced sample pretreatments or simplified methodologies (as QuEChERS approaches), the use of online purification processes, the use of new adsorbents (such as molecular imprinted polymers (MIPs) and nanomaterials) for the extraction and clean-up processes, and focused on the development of large multiresidue methods, most of them based on LC-MS/ MS. In spite of the relevant role of LC-MS/MS, GC-MS-based methods still play an important role in pesticide analysis in food. Despite the development achieved in the immunochemical approaches, the need for multi-residue methods has supported the development and use of instrumental techniques. 

Carvalho JJ, Jeronimo PCA, Goncalves C et al (2008) Evaluation of a multiresidue method for measuring fourteen chemical groups of pesticides in water by use of LC-MS-MS. Anal Bioanal Chem 392 955-968... 

The determination of diazinon in foods is important because this chemical is used as a pesticide on plant crops and, at least in some cases, in pesticide dips for the control of parasitic infestations in animals (Brown et al. 1987 Miyahara et al. 1992). Because animals are exposed to this compound, both via pesticide dips and by ingestion of crops to which diazinon has been applied, some methods have been reported for animal products. The majority of methods, however, deal with the determination of residues in plant products. Most of the analytical methods found that describe the extraction from, and determination of, diazinon residues in various crops (plant materials) were developed as part of multiresidue methods. They are based on homogenization of the sample with an organic solvent (polar or non-polar) the isolation of the residues from this initial extract and, usually, some additional cleanup prior to the analysis of the extract by GC. The most common non-MS modes of detection exploit the... 

Leoni V, Caricchia AM, Chiavarini S. 1992. Multiresidue method for quantitation of organophosphorus pesticides in vegetable and animal foods. J AOAC International 75(3) 511-518. 

Miyahara M, Suzuki T, Saito Y. 1992. Multiresidue method for some pesticides in lanolin by capillary gas chromatography with detection by electron capture, flame photometric, mass spectrometric, and atomic emission techniques. J Agric Fd Chem 40 64-69. 

Seiber JN, Glotfelty DW, Lucas AD, et al. 1990. A multiresidue method by high performance liquid chromatography-based fractionation and gas chromatographic determination of trace levels of pesticides in air and water. Arch Environ Contam Toxicol 19 583-592. 

Jansson B, Andersson R, Asplund L, et al. 1991. Multiresidue method for the gas-chromatographic analysis of some polychlorinated and polybrominated polutants in biological samples. Fresenius Z Anal Chem 340 439-445. 

Tlie demand for reliable, sensitive, automated, fast, low-cost methods for residue analysis that are also applicable to a wide range of drugs and matrices is growing fast, especially in the field of food inspection. A universal analytical scheme that could simultaneously quantify all compounds of interest in the edible animal products, correctly identify the molecular structure of the analytes, and, at the same time, produce very few false-negative and -positive results to protect the consumer, producer and international trade, would provide the most desirable approach. A unified procedure would eliminate the need for using separate multiresidue methods to screen food commodities for potential drug residues, and combinations of suitable single- or multianalyte methods to identify and quantify residues of individual analytes. 

Most residue methods used in field applications are qualitative or semiquantitative and are classified as screening methods. Quantitative methods require much more technical expertise, and, therefore, their primary use is in laboratory applications primarily for confirmation purposes. Both screening and confirmation methods can be subclassified into multiresidue methods aiming at the detection of groups of compounds having similar analytical characteristics, and singleresidue methods applicable to only one specific analyte. 

Although both polyclonal and monoclonal antibodies have been effectively used in immunochemical assays, only the latter can provide the high specificity required in some applications. Antibody specificity, on the other hand, is both a major advantage and disadvantage for immunochemical methods. It allows for highly selective detection of analytes but at the same time may complicate the development of multiresidue methods. Moreover, production of monoclonal antibodies requires special expertise and it is much more expensive than polyclonal antibodies. Thus, in cases where a range of analytes similar in molecular structure are required to be determined, a polyclonal may be more suitable than a monoclonal antibody. 

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