GENERAL METHOD FOR PESTICIDE RESIDUES ANALYSIS
Where used in this Pharmacopeia, the designation pesticide applies to any substance or mixture of substances intended to prevent, destroy, or control any unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of pure articles. The designation includes substances intended for use as growth regulators, defoliants, or desiccants, and any substance applied to crops before or after harvest to protect the product from deterioration during storage and transport.
Within the United States, many botanicals are treated as dietary supplements and are subject to the statutory provisions of the Federal Food, Drug, and Cosmetic Act that governs foods but not drugs. Limits for pesticides for foods are determined by the Environmental Protection Agency (EPA), and where no limit is set, the limit is zero. The limits contained herein, therefore, are not applicable in the United States when articles of botanical origins are labeled for food purposes. The limits, however, may be applicable in other countries where the presence of pesticide residues is permitted. Unless otherwise specified in the individual monograph, the article under test contains not more than the amount of any pesticide indicated in Table 3
. The limits applying to pesticides not listed in Table 3
and whose presence is suspected for any reason comply with the regulations of the EPA. Where a pesticide is not listed in Table 3
or in EPA regulations, calculate the limit by the formula:
AM / 100B,
in which A
is the acceptable daily intake (ADI), in mg per kg of body weight; M
is the body weight, in kg; and B
is the daily dose of the article, in kg.
If the article is intended for the preparation of extracts, tinctures, or other pharmaceutical forms whose preparation method modifies the content of pesticides in the finished product, calculate the limits by the formula:
AME / 100B,
in which E is the extraction factor of the preparation method, determined experimentally; and A, M, and B are as defined above.
For articles in containers holding less than 1 kg, mix the contents, and withdraw a quantity sufficient for the tests. For articles in containers holding between 1 and 5 kg, withdraw equal portions from the upper, middle, and lower parts of the container, each of the samples being sufficient to carry out the tests. Thoroughly mix the samples, and withdraw an amount sufficient to carry out the tests. For containers holding more than 5 kg, withdraw three samples, each weighing not less than 250 g, from the upper, middle, and lower parts of the container. Thoroughly mix the samples, and withdraw a portion sufficient to carry out the tests.
Size of Sampling
If the number of containers, n
, is three or fewer, withdraw samples from each container as indicated above. If the number of containers is more than three, take samples from
containers, rounding up to the nearest whole number if necessary.
Conduct tests without delay to avoid possible degradation of the residues. If this is not possible, store the samples in hermetic containers suitable for food contact, at a temperature below 0
, and protected from light.
Use reagents and solvents that are free from any contaminants, especially pesticides, that might interfere with the analysis. It is often necessary to use special grade solvents suitable for pesticide residue analysis or solvents that have recently been redistilled in an apparatus made entirely of glass. In any case, suitable blank tests must be performed.
Preparation of Apparatus
Clean all equipment, especially glassware, to ensure that it is free from pesticides. Soak all glassware for a minimum of 16 hours in a solution of phosphate-free detergent, rinse with copious quantities of distilled water, and then wash with acetone, followed by hexane or heptane.
Qualitative and Quantitative Analysis of Pesticide Residues
Use validated analytical procedures that satisfy the following criteria. The method, especially with respect to its purification steps, is suitable for the combination of pesticide residue and substance under test, and is not susceptible to interference from co-extractives. Measure the limits of detection and quantification for each pesticide matrix combination to be analyzed: the method is shown to recover between 70% and 110% of each pesticide; the repeatability and reproducibility of the method are not less than the appropriate values indicated in Table 4
; and the concentrations of test and reference solutions and the setting of the apparatus are such that a linear response is obtained from the analytical detector.
|Concentration of the
(difference, ± mg/kg)