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These procedures were designed and tested for internal use by OSHA personnel. Mention of any company name or commercial product does not constitute endorsement by OSHA.
|Target concentration:||0.1 mg/m3 ACGIH TLV. There is no OSHA PEL for disulfoton.|
|Procedure:||Samples are collected by drawing known volumes of air through OSHA versatile sampler (OVS-2) tubes, containing a glass fiber filter and two sections of XAD-2 adsorbent. Samples are extracted with toluene and analyzed by gas chromatography (GC using a flame photometric detector (FPD).|
|Recommended sampling time and sampling rate:||480L and 1.0 L/min|
|Detection limit of the overall procedure based on the recommended air volume:||0.0020 mg/m3|
|Status of method:||Stopgap method. This method has been only partially evaluated and is presented for information and trial use.|
Date: July, 1987
David B. Armitage
Carcinogen And Pesticide Branch
OSHA Analytical Laboratory
Salt Lake City, Utah
This evaluation was undertaken to determine the effectiveness of the OVS-2 sampling tube as a sampling device for disulfoton. It follows the procedure developed for several other organophosphorus pesticides. (Ref. 5.1)
It should be noted that in this evaluation for disulfoton several other analytes were also present in the analytical procedure. These other analytes are not mentioned in this evaluation, but can be seen on the sample chromatogram.
Organophosphorus pesticides act as irreversible inhibitors of cholinesterase, thereby allowing the accumulation of large amounts of acetylcholine. When a critical level of cholinesterase depletion is reached, usually about 20% of normal, symptoms and signs of acety1choline accumulationpoisoning become manifest. (Ref. 5.2)
These symptoms may include blurred vision, weakness, nausea, headache, abdominal cramps, chest discomfort, and diarrhea. Signs may include miosis, muscle twitching, salivation, sweating, tearing, cyanosis, convulsions, and coma. (Ref. 5.2) Besides being absorbed following inhalation or ingestion, organophosphorus pesticides are readily absorbed through, the intact skin. (Ref. 5.2) Disulfoton is a highly toxic chemical with an acute oral LD50 for male rats of 6.8 mg/kg and females rates of 2.3 mg/kg. The dermal LD50's are 25 and 6 mg/kg for male and female rats respectively. (Ref.5.3) Due to these factors disulfoton has been given a TLV of 0.1 mg/m3 by the ACGIH (ref. 5.3)
|Boiling point:||132-133°C at 1.5 mmHg|
|Vapor Pressure:||0.00018 mmHg at 20°C|
|Appearance:||colorless oily liquid|
|Solubility:||insoluble in water soluble in most organic solvents|
|Synonyms:||Disyston, dithiodemeton, dithiosystox, Disyston, dithiodemeton, dithios|
|Chemical name:||O,O-Diethyl S-2-(ethylthio) ethyl phosphorodithioate|
The detection limit of analytical procedure is 0.6 ng per injection. This is the amount of analyte which will give a peak whose height is approximately five times the baseline noise.
No sampling reagents are required.
Two 13-mm glass fiber filters were each spiked with 48.06 µg of disulfoton. The two filters, along with a blank filter, were each extracted with 2 mL of toluene in separate 4-mL vials which also contained 270 mg of XAD-2 adsorbent. The average extraction efficiency for these two filters (with the XAD-2 adsorbent present, also) was 89%.
Two OVS-2 tubes were each spiked with 48.06 µg of disulfoton by spiking the 13 mm glass fiber filter in the tube with the analyte of interest. 350 liters of humid air was drawn through each filter. The two filters were then extracted as above. The average retention efficiency for these two filters was 8O%.
Two OVS-2 tubes were each spiked with 48.06 µg of disulfoton asabove. 470 liters of humid air was drawn through each filter. These two tubes were stored for ten daysat ambient temperature in a drawer. They were then extracted as above. The average recovery after ten days of storage was 77%.
It is not known if any compounds will interfere with the collection of disulfoton. Suspected interferences should be reported to the laboratory with submitted samples.
Stock standard solutions are prepared by adding toluene topreweighed amounts of disulfoton. Working range standard solutions are prepared by diluting stock solutions with toluene. Stock and dilute standards are stored in a freezer.
|Column temperature: (initial)||150°C|
|Temperature program rate:||8°C/min|
|Column temperature: (final)||200°C|
|Nitrogen flow rate:||5 mL/min|
|Initial hold time:||0 min|
|Final hold time:||4 min|
|Injection volume:||1.3 µL|
|GC column:||30-m × 0.53-mm i.d. DB-21 Megabore, 1.0-µm thick film|
|Hydrogen flow rate||200 mL/min|
|Oxygen flow rate:||60 mL/min|
|Air flow rate:||30 mL/min|
|Retention time:||6.0 min|
(mg/mL in sample) (desorption volume, mL)
(air volume, L) (desorption efficiency, decimal)
There appears to be some loss of disulfoton with increased sampling time and/or storage time at ambient temperature. More statistically valid retention and storage studies should be done to clarify this loss of analyte. This method should be fully validated.
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