Значение и использование

This test method has been developed by US EPA Region 5 Chicago Regional Laboratory (CRL).

The N-methyl carbamate (NMC) pesticides: aldicarb, carbofuran, methomyl, oxamyl, and thiofanox have been identified by EPA as working through a common mechanism. These affect the nervous system by reducing the ability of enzymes. Enzyme inhibition was the primary toxicological effect of regulatory concern to EPA in assessing the NMC’s food, drinking water, and residential risks. In most of the country, NMC residues in drinking water sources are at levels that are not likely to contribute substantially to the multi-pathway cumulative exposure. Shallow private wells extending through highly permeable soils into shallow, acidic ground water represent what the EPA believes to be the most vulnerable drinking water. Aldicarb sulfone and aldicarb sulfoxide are breakdown products of aldicarb and should also be monitored due to their toxicological effects.

This method has been investigated for use with reagent, surface, and drinking water for the selected carbamates: aldicarb, aldicarb sulfone, aldicarb sulfoxide, carbofuran, methomyl, oxamyl and thiofanox.

Область применения

1.1 This test method covers the determination of aldicarb, aldicarb sulfone, aldicarb sulfoxide, carbofuran, methomyl, oxamyl, and thiofanox (referred to collectively as carbamates in this test method) in water by direct injection using liquid chromatography (LC) and detected with tandem mass spectrometry (MS/MS). These analytes are qualitatively and quantitatively determined by this method. This method adheres to multiple reaction monitoring (MRM) mass spectrometry.

1.2 The Detection Verification Level (DVL) and Reporting Range for the carbamates are listed in Table 1.

1.2.1 The DVL is required to be at a concentration at least 3 times below the Reporting Limit (RL) and have a signal/noise ratio greater than 3:1. Fig. 1 displays the signal/noise ratios of the primary single reaction monitoring (SRM) transitions, and Fig. 2 displays the confirmatory SRM transitions at the DVLs for the carbamates.

1.2.2 The reporting limit is the concentration of the Level 1 calibration standard as shown in Table 2 for the carbamates.

1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

TABLE 1 Detection Verification Level and Reporting Range

AnalyteDVL
(ng/L)Reporting Range
(μg/L) Aldicarb2501-100 Aldicarb Sulfone2501-100 Aldicarb Sulfoxide2501-100 Carbofuran2501-100 Methomyl2501-100 Oxamyl2501-100 Thiofanox2501-100

TABLE 2 Concentrations of Calibration Standards (PPB)

Analyte/SurrogateLV 1LV 2LV 3LV 4LV 5LV 6LV 7LV 8 Aldicarb151025355075100 Aldicarb Sulfone151025355075100 Aldicarb Sulfoxide151025355075100 Carbofuran151025355075100 Methomyl151025355075100 Oxamyl151025355075100 Thiofanox151025355075100 Carbofuran-¹³C₆ (Surrogate)151025355075100 Methomyl-¹³C₂,¹⁵N (Surrogate)151025355075100

FIG. 1 Example Primary SRM Chromatograms Signal/Noise Ratios

FIG. 2 Example Confirmatory SRM Chromatograms Signal/Noise Ratios