CARBARYL (SEVIN)
OSHA Analytical Laboratory Salt Lake City, Utah 1. General Discussion
This evaluation was undertaken to determine the effectiveness of
the OSHA Versatile Sampler containing In the past, carbaryl was collected on a 37-mm glass fiber filter
in a cassette. The analytical procedure developed by NIOSH (NIOSH
Method 5006) required that the sample be derivatized and analyzed by
absorption spectrophotometry (Ref. 5.2.). The analytical procedure
used by OSHA required that the sample be extracted and analyzed by
HPLC with a UV detector (Ref. 5.3.). The 1.1.2. Toxic effects (This section is for information only and should not be taken as a basis for OSHA policy.) Carbaryl inactivates cholinesterase, resulting in the accumulation of acetylcholine at the synapses in the nervous system, at neuromuscular junctions of the skeletal and smooth muscles, and secretory glands. Signs and symptoms of overexposure may include miosis, blurred vision, lacrimation, excessive nasal discharge or salivation, sweating, abdominal cramps, nausea, vomiting, diarrhea, tremor, cyanosis and convulsions. (Ref. 5.4.) The LD50 for rats (oral) is 500 mg/kg. A man who had consumed 0.5 L of an 80% solution of carbaryl died 6 h after exposure. (Ref. 5.5.) 1.1.3. Workplace exposure Occupational exposure of carbaryl can occur in the manufacture, formulation, distribution, and application of carbaryl. This includes agricultural crop workers, farmers, plant nursery workers, spray pilots, and others engaged in spraying and dusting operations. NIOSH estimates that 100,000 U.S. workers are potentially exposed to carbaryl. (Ref. 5.5.) 1.1.4. Physical properties and other descriptive information (Ref. 5.5.)
1.2. Limit defining parameters (The analyte air concentrations listed throughout this method are based on an air volume of 60 L and a solvent extraction volume of 2 mL.)
The detection limit of the analytical procedure is 6.8 ng per injection. This is the amount of analyte which will give a peak whose height is about 5 times the height of the baseline noise. (Section 4.1.) 1.2.2. Detection limit of the overall procedure The detection limit of the overall procedure is 1.66 µg per sample (0.028 mg/m3). This is the amount of analyte spiked on the sampling device which allows recovery of an amount equivalent to the detection limit of the analytical procedure. (Section 4.2.) 1.2.3. Reliable quantitation limit The reliable quantitation limit is 1.66 µg per sample (0.028 mg/m3). This is the smallest amount of analyte which can be quantitated within the requirements of a recovery of at least 75% and a precision (±1.96 SD) of ±25% or better. (Section 4.2.)
1.2.4. Instrument response to the analyte The instrument response over the concentration range of 0.5 to 2 times the target concentrations is linear. (Section 4.4.) 1.2.5. Recovery The recovery of carbaryl from samples used in a 16-day storage test remained above 92.6% when the samples were stored at about 22°C. (Section 4.6.) The recovery of analyte from the collection medium during storage must be 75% or greater. 1.2.6. Precision (analytical procedure) The pooled coefficient of variation obtained from replicate determinations of analytical standards at 0.5, 1 and 2 times the target concentration is 0.003. (Section 4.3.) 1.2.7. Precision (overall procedure) The precision at the 95% confidence level for the 16-day ambient temperature storage test is ±10.1%. (Section 4.6.) This includes an additional ±5% for sampling error. The overall procedure must provide results at the target concentration that are ±25% or better at the 95% confidence level. 1.2.8. Reproducibility Six samples, spiked by liquid injection with carbaryl, and a draft copy of this procedure were given to a chemist unassociated with this evaluation. The samples were analyzed after 20 days of storage at about 5°C. No individual sample deviated from its theoretical value by more than the precision reported in Section 1.2.7. (Section 4.7.) 1.3. Advantages
1.3.2. The analytical procedure is more specific for the analysis of carbaryl than the NIOSH method. 1.4. Disadvantage Currently, the 2. Sampling Procedure
2.1.2. Samples are collected with 2.2. Reagents No sampling reagents are required. 2.3. Sampling technique
2.3.2. After sampling for the appropriate time, remove the sampling device and seal the tube with plastic end caps. 2.3.3. Wrap each sample end-to-end with an OSHA seal (Form 21). 2.3.4. With each set of samples, submit at least one blank. The blank should be handled the same as the other samples except that no air is drawn through it. 2.3.5. Bulk samples should be submitted for analysis in a separate container. Do not ship with the air samples. 2.4. Retention efficiency To test the sampler's ability to retain carbaryl, twice the target
concentration amount of carbaryl (604 µg) was liquid spiked onto eight
sampling tubes. Humid air (about 72% relative humidity) was pulled
through the tubes for 15 min to 4 h at 1 L/min. When the samples were
analyzed, it was found that the analyte was present on the glass fiber
filter and the front section of 2.5. Extraction and desorption efficiencies (Section 4.5.)
2.5.2. The extraction efficiency for carbaryl from glass fiber filters at the target concentration was 99.1%. 2.5.3. The average desorption efficiency for carbaryl from the
lot of cleaned 2.5.4. Extracted/desorbed samples remain stable for at least 48 h. 2.6. Recommended air volume and sampling rate
2.6.2. The recommended air sampling rate is 1.0 L/min. 2.6.3. When short-term air samples are required, the recommended
sampling rate is 1 L/min. The reliable quantitation limit is 0.11
mg/m3 for a 2.7. Interferences (sampling) Suspected interferences should be reported to the laboratory with submitted samples. 2.8. Safety precautions (sampling)
2.8.2. All safety practices that apply to the work area being sampled should be followed. 3. Analytical Procedure
3.1.2. HPLC column capable of separating carbaryl from any
interferences. A 3.1.3. An electronic integrator or other suitable means of
measuring detector response. A 3.1.4. Vials, 4-mL glass with PTFE-lined caps. 3.1.5. Volumetric flasks, pipets and syringes for preparing standards, making dilutions and performing injections. 3.2. Reagents
3.2.2. Water, HPLC grade. A Millipore Milli-Q system was used to prepare the water for this evaluation. 3.2.3. Carbaryl, 98% pure, (Chem Services Inc). 3.3. Standard preparation Stock standard solutions are prepared by adding acetonitrile to preweighed amounts of carbaryl. Working range standard solutions are prepared by diluting the stock solutions with acetonitrile. 3.4. Sample preparation
3.4.2. Add 2.0 mL of acetonitrile to each vial. 3.4.3. Seal the vials with PTFE-lined caps and extract/desorb the samples for 1 h. Shake the vials by hand with vigorous force several times during the extraction/desorption time. 3.5. Analysis
3.5.2. Measure detector response using a suitable method, such as electronic integration. 3.5.3. Prepare a calibration curve using several solutions over a range of concentrations. The calibration curve is prepared daily. The samples are bracketed with analytical standards. 3.6. Interferences (analytical)
3.6.2. Retention time on a single column is not proof of chemical identity. Analysis by an alternate HPLC column, detection at another wavelength, comparison of absorbance response ratios, and confirmation by mass spectrometry are additional means of identification. 3.7. Calculations
3.7.2. The concentration, in µg/mL, for a particular sample is determined by comparing its detector response to the calibration curve. If carbaryl is found on the backup section, it is added to the amount found on the front section. Blank corrections for each section should be performed before adding the results together. 3.7.3. The air concentration of carbaryl can be expressed using the following equation. mg/m3 = (A)(B) / (C)(D)
The combined extraction/desorption efficiency should be determined for the particular batch of resin and lot of filter used for the sample. 3.8. Safety precautions (analytical)
3.8.2. Avoid exposure to all solvents. 3.8.3. Wear safety glasses at all times. 4. Backup Data
The detection limit of the analytical procedure is 6.8 ng per injection. This amount produced a peak whose height is about 5 times the height of the baseline noise. The injection volume recommended in the analytical procedure (10 µL) was used in the determination of the detection limit for the analytical procedure. (Figure 4.1.) 4.2. Detection limit of the overall procedure and reliable quantitation limit The detection limit of the overall procedure and reliable quantitation limit are 1.66 µg per sample (0.028 mg/m3). The injection size recommended in the analytical procedure (10 µL) was used in this determination. Six samples were each liquid spiked with a solution containing carbaryl about equivalent to its analytical detection limit (1.4 µg per sample) and analyzed. The recovery of carbaryl from the samples was approximately equal to the detection limit of the analytical procedure. Since the recovery was above 75% and the precision (1.96 SD) better than ±25%, 1.66 µg per sample is also the reliable quantitation limit.
4.3. Precision (analytical method only) The precision of the analytical method was evaluated by doing multiple injections of analytical standards. The results of this study are presented below.
4.4. Instrument response to the analyte The data in Table 4.3. are presented graphically in Figure 4.4. This figure is a calibration curve over the concentration range of 0.5 to 2 times the target concentration. The instrument response is linear over this range. The slope of the line (2880 area counts per µg/mL) is a measure of the response of the instrument to the analyte. 4.5. Extraction/desorption efficiencies
The extraction efficiency of carbaryl was determined by liquid spiking six glass fiber filters (GFF) with carbaryl at the target concentration (302 µg/sample). These samples were stored overnight and then extracted with acetonitrile and analyzed.
4.5.2. Desorption from The desorption efficiency of carbaryl was determined by liquid
spiking
The average desorption efficiency over the studied range was 92.8%. 4.5.3. The combined extraction/desorption efficiency of carbaryl
was determined by liquid spiking glass fiber filters with the target
concentration and placing the filter and the large section of
4.6. Storage data Storage samples were generated by liquid spiking 36 sampling tubes
with carbaryl (302 µg) and then pulling 30 L of humid air through them
(about 85% relative humidity).
4.7. Reproducibility data Six samples, liquid spiked with carbaryl, were given to a chemist unassociated with this study. The samples were analyzed after being stored for 20 days at 5°C. The results were not corrected for extraction/desorption efficiency and are shown below. None of the data had a percent deviation greater than the precision of the overall procedure of ±10.1%.
4.8. Retention efficiency To test the ability of the sampler to retain the analytes, eight samplers were liquid spiked with twice the target concentration (604 µg) of carbaryl. Humid air (about 72% relative humidity) was pulled through the samplers for 15 min to 4 h at 1 L/min. The results show no carbaryl breakthrough onto the backup section of the sampling tube.
4.9. Preparation of the It is anticipated that this sampler containing different adsorbents
can be used to collect a broad range of airborne contaminants. For
these applications the suffix will also reflect the type of resin
contained in the sampler. For example, a sampler containing Tenax will
be designated
4.9.1.2. Rotary evaporator 4.9.1.3. Miscellaneous glassware: vacuum flask, 2-L
4.9.1.4. Urethane foam plugs, 3/8 in. × 1/2-in. diameter and
3/16 in. × 4.9.1.5. Glass fiber filters, 1/2-in. diameter or 13-mm diameter. 4.9.1.6. PTFE retainer. The retainer is made by removing a 50°
arc from a piece of PTFE tubing, 1/8 in. × 4.9.1.7. Glass sampling tube. The sampling tube is constructed
of two pieces of borosilicate glass tubing that have been joined
together by a glass blower. One of the pieces is 50 mm ×
4.9.1.8. Plastic cap, 7/8 in. × 1/2-in. i.d. (Alliance Plastics, Inc., Erie PA). 4.9.1.9. Plastic cap, 3/4 in. × 7/32-in. i.d. (SKC, Inc,
4.9.2. Reagents
4.9.2.2. Toluene, HPLC grade. 4.9.2.3. Amberlite 4.9.3. Cleaning of adsorbent Add 500 g of crude 4.9.4. Assembly of the Place a large foam plug in the bottom of the large end of the
glass tube. Add 140 mg of cleaned
5. References
5.2. "NIOSH Manual of Analytical Methods", 3rd ed.; US Department
of Health and Human Services, Centers for Disease Control, NIOSH;
Cincinnati, OH, Feb. 1984; Vol. 1, Method 5006, Publ. No.
5.3. "Chemical Information File", U.S. Department of Labor, Occupational Safety and Health Administration, Directorate of Technical Support, June 14, 1985. 5.4. "Occupational Health Guidelines for Chemical Hazards"
NIOSH/OSHA, Jan. 1981, DHHS(NIOSH) Publ. No. 5.5. "Criteria for a Recommended Standard ... Occupational Exposure
of Carbaryl", U.S. Department of Health, Education, and Welfare,
National Institute for Occupational Safety and Health; Cincinnati, OH;
1976; DHEW (NIOSH) Publ. No.
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