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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.
Related Information: Chemical Sampling - Phenothiazine
1. General Discussion
1.1.1. History of procedure
The PEL for phenothiazine is 5 mg/m3. Since phenothiazine is a solid at room temperature, collection on a glass fiber filter was tried and found successful. There was no loss of phenothiazine in the retention studies. The extraction, and storage studies were near 100%.
1.1.2. Potential workplace exposure (Ref. 5.1.)
Phenothiazine is used as a pesticide, and is used orally to treat pinworm, threadworm, and roundworm infestations. It is used as a base for the manufacture of pharmaceuticals. It is used as a urinary antiseptic.
1.1.3. Toxic Effects (This section is for information purposes and should not be taken as the basis for OSHA policy.)(Ref. 5.1.)
Oral doses of 1 or more grams per day may cause toxic hepatitis, hemolytic anemia, abdominal
cramps, tachycardia, gastrointestinal and skin irritation, skin photosensitization, kidney
damage, and pruritus. Workers applying phenothiazine in orchards reported skin
irritation, including itching, and redness on any exposed surface. The photosensitizing dose is
less than 0.75 grams. Workers exposed to between 15 and 48 mg/m3 during pulverizing and packaging
phenothiazine dust developed
1.1.4. Physical properties (Ref. 5.2.):
1.2. Limit defining parameters
1.2.1. The detection limit of the analytical procedure is 1 ng. This is the smallest amount that could be detected under normal operating conditions.
1.2.2. The overall detection limit is 0.03 mg/m3, based on a 3 mL extraction and a 100 liter air volume. (All mg/m3 amounts in this study are based on a 100 liter air volume and a 3 mL desorption.)
1.3.1. The sampling procedure is convenient.
1.3.2. The analytical method is reproducible and sensitive.
1.3.3. Reanalysis of samples is possible.
1.3.4. It may be possible to analyze other compounds at the same time.
1.3.5. Interferences may be avoided by proper selection of column and GC parameters.
2. Sampling procedure
2.1.1. A calibrated personal sampling pump, the flow of which can be determined within + 5% at the recommended flow.
2.2. Sampling technique
2.2.1. The ends of the filter cassette are opened immediately before sampling.
2.2.2. Connect the filter cassette to the sampling pump with flexible tubing.
2.2.3. Air being sampled should not pass through any hose or tubing before entering the cassette.
2.2.4. Seal the ends of the cassette with plastic caps immediately after sampling. Seal each sample
lengthwise with OSHA
2.2.5. With each batch of samples, submit at least one blank filter from the same lot used for samples. This filter should be subjected to exactly the same handling as the samples except that no air is drawn through it.
2.2.6. Transport the samples (and corresponding paperwork) to the lab for analysis.
2.2.7. Bulks submitted for analysis must be shipped in a separate mailing container from the samples.
2.3. Extraction efficiency
Six glass fiber filters were liquid spiked at each
loading of 16.56 µg (0.4968 mg/m3), 82.8 µg (2.484
mg/m3), and 165.6 µg (4.968 mg/m3) phenothiazine. They
were allowed to equilibrate overnight at room
temperature. They were opened, placed into a 4 mL vial,
extracted with 3 mL of methyl
2.4. Retention efficiency
Six glass fiber filters were liquid spiked with 165.6 µg
(4.968 mg/m3) phenothiazine. They were placed in a
cassette with a second glass fiber filter, and a spacer
between the two filters. They were allowed to
equilibrate overnight , and had 100 liters humid air (90%
RH) pulled through them. They were opened, extracted, and
Glass fiber filters were spiked with 165.6 µg (4.968 mg/m3) phenothiazine and stored at room temperature on the benchtop until opened and analyzed. Half of the storage samples were stored in brown vials, as phenothiazine decomposes in sunlight. The storage samples were exposed to room light. There was little difference between the samples stored in brown and clear glass. The spectrum of room light does not compare to sunlight, so this comparison probably does not mimic sunlight conditions. The recoveries averaged 98.9% for brown glass vials, and 99.6 % for clear glass vials for the 14 days stored (Table 3).
The precision was calculated using the area counts from six injections of each standard at concentrations of 16.56, 82.8, 165.6, and 331.2 µg/mL. The pooled coefficient of variation was 0.0152 (Table 4).
A(1), A(2),A(3),A(4) = # of injections at each level
2.7. Air volume and sampling rate studied
2.7.1. The air volume studied is 100 liters.
2.7.2. The sampling rate studied is 1.0 liter per minute.
Suspected interferences should be listed on sample data sheets.
2.9. Safety precautions
2.9.1. Sampling equipment should be placed on an employee in a manner that does not interfere with work performance or safety.
2.9.2. Safety glasses should be worn at all times.
2.9.3. Follow all safety practices that apply to the workplace being sampled.
3. Analytical method
3.1.1. Gas chromatograph equipped with a
3.1.2. GC column capable of separating the analyte from any interferences. The column used in this study
was a 60 M
3.1.3. An electronic integrator or some other suitable method of measuring peak areas.
3.1.4. Two and four milliliter vials with
3.1.5. A 10 µL syringe or other convenient size for sample injection.
3.1.6. 3 mL pipets for dispensing the methyl
3.1.7. Volumetric flasks - 10 mL and other convenient sizes for preparing standards.
3.1.8. Analytical balance capable of weighing milligram amounts.
3.2.1. Purified GC grade nitrogen, hydrogen, and air.
3.2.3. Phenothiazine, Reagent grade
3.3. Sample preparation
3.3.1. Sample cassettes are opened and the filter is placed in a 4 mL vial.
3.3.2. The filter is extracted with 3 mL of methyl
3.3.3. The vials are sealed immediately and allowed to extract 30 minutes with occasional shaking.
3.3.4. An aliquot is placed in a 2 mL vial for analysis.
3.4. Standard preparation
3.4.1. Standards are prepared by diluting a known quantity of phenothiazine with methyl
3.4.2. A series of standards are prepared covering the range from detection limit to the highest sample. At least five different concentrations should be made so that there are enough data points to plot a curve. The range used in this study was 1.656 to 165.6 µg/mL.
3.5.2. Peak areas are measured by an integrator or other suitable means.
3.6. Interferences (analytical)
3.6.1. Any compound having the general retention time of the analyte is an interference. Possible interferences should be listed on the sample data sheet. GC parameters should be adjusted if necessary so these interferences will pose no problems.
3.6.2. Retention time data on a single column is not considered proof of chemical identity. Samples over the target concentration should be confirmed by GC/Mass Spec or other suitable means.
3.7.1. A curve with area counts versus concentration is calculated from the calibration standards.
3.7.2. The area counts for the samples are plotted with the calibration curve to obtain the concentration of phenothiazine in solution.
3.7.3. To calculate the air concentration of phenothiazine (PT) the following equation is used:
3.8. Safety precautions
3.8.1. All handling of solvents should be done in a hood.
3.8.2. Avoid skin contact with all solvents.
3.8.3. Wear safety glasses at all times.
4. Recommendations for further study
Collection studies should be performed. Analysis of phenothiazine can also be done by liquid chromatography
according to literature.
5.1. "Documentation of the Threshold Limit Values and Biological Exposure Indices", Fifth Edition, American Conference of Governmental Industrial Hygienists Inc., Cincinnati, OH, 1986, p. 472.
5.2. Windholz, M., "The Merck Index", Tenth Edition, Merck & Co., Rahway N.J., 1983, p. 1046.