Captan and Thiophanate-Methyl on Dermal Patch (9205)
CAPTAN and THIOPHANATE-METHYL on Dermal Patch Thiophanate-Methyl: C12 H14 N4 O4 S2 Captan: C9 H8 Cl3 NO2 S METHOD: 9205, Issue 1 Captan OSHA: N/A NIOSH: N/A ACGIH: N/A
MW: 342.40 300.59
CAS: 23564-05-8 133-06-2
EVALUATION: PARTIAL Thiophanate-methyl N/A N/A N/A
9205
RTECS: BA3675000 GW5075000 Issue 1: 15 March 2003
PROPERTIES: Thiophanate-methyl: Colorless prisms, mp 181.5182.5°C, soluble in acetone, methanol, chloroform, acetonitrile, insoluble in water. Captan: Odorless crystals, mp 178°C, soluble in chloroform, practically insoluble in H2 O
NAMES & SYNONYMS: Thiophanate-Methyl: Topsin-M, [1,2-phenylenebis(iminocarbonothioyl)]bisdimethyl ester carbamic acid Captan: N-(trichloromethyl)thio-4-cyclohexene-1,2-dicarboximide, Captec SAMPLING SAMPLER:
PASSIVE EXPOSURE:
SHIPMENT:
MEASUREMENT TECHNIQUE:
HPLC, UV detector
ANALYTE:
Captan, Thiophanate-methyl
place patch in card holder with 7.6-cm diameter circle cut in one side. Affix to worker’s clothing or skin.
EXTRACTION:
30 mL 40% isopropanol:60% acetonitrile (V/V) w/ TEA-PO4 preservative.
transfer patch to 50-mL centrifuge tubes with caps. Ship cold.
INJECTION VOLUME:
DERMAL PATCH (Cleanroom wipe, 4" x 4")
SAMPLE STABILITY:
At least 28 days at 4°C.
BLANKS:
2 to 10 field blanks per set.
ACCURACY RANGE STUDIED:
Not determined
BIAS:
Not determined
5 µL
MOBILE PHASE:
A=2% n-propanol in water, 0.02 M TEAPO4 , pH adjusted to 7.0 +/- 0.1 using phosphoric acid B=2% n-propanol in acetonitrile. Gradient from 20% B to 70% B (20 min.), decreasing to 20% B (2 min.), hold at 20% B (5 min.)
COLUMN:
reversed phase C-18, 4µm, 250 x 2.00 mm or equivalent.
DETECTOR:
UV @200 nm
CALIBRATION:
Solutions prepared in extract solvent
OVERALL PRECISION ( Ö r T ):
Not determined
RANGE:
Table 1
ACCURACY:
Not determined
ESTIMATED LOD:
Table 1
PRECISION ( þ r ):
Table 1
APPLICABILITY: This method was developed for the analysis of the two analytes listed above on a dermal patch sampler from orchard workers. (See Figure 1.) In addition, this method may be used to analyze other fungicides and pesticides that may be present as long as they are separated from the two analytes by the analytical conditions of the method. It may be necessary to make adjustments to the gradient conditions of the method to obtain the required separation. INTERFERENCES: The potential interferences include other organic compounds, in particular other pesticides or fungicides that have the same retention time on a C18 column. Positive identification may be confirmed by dual column chromatography using an appropriate alternative LC column. Possible interferences include: ziram, myclobutanil, mancozeb, imidacloprid, and phosmet. OTHER METHODS: This method was developed in conjunction with method NMAM 5606, Thiophanate-methyl in air, and NMAM 9202, Captan and Thiophanate-methyl in handrnise.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition CAP TAN and T HIOP HAN ATE -MET HYL: M ETH OD 9205, Issue 1, dated 1 5 Ma rch 2003 - Page 2 of 4 EQUIPMENT:
REAGENTS: 1. 2. 3. 4. 5. 6.
7. 8. 9.
10.
11.
Isop ropa nol, H PLC pesticide grade .* Aceton itrile, HPL C grade .* Triethylam ine (T EA).* Ortho-phosphoric acid >85% by weight, ACS grad e or b etter.* Deionized water. Extraction solution: 40% isopropanol/60% acetonitrile w/2 mL TEA-PO 4 preservative for every liter of extraction solution prepared. Thiophanate-methyl * stock solution, 10 mg/m L. Prepare in acetonitrile. Ca ptan * (Ch em Service) stoc k solution, 5 mg/m L. Prepare in acetonitrile. TEA-PO 4 Preservative. Dissolve 1.4 mL of TEA in 90 mL of deionized water in a 100 mL volumetric flask. Add phosphoric acid to lower pH to 7.0(± 0.1) as indicated by a calibrated pH m eter. B ring vo lum e to 100 m L with w ater. Keep tightly capped and refrigerated. Solution stable for 12 months. Mobile phase A. Com bine 20 mL of npropanol and 2.8 m L T EA in a 1 L volum etric flask and bring to volume using deionized wate r. Adju st pH to 7.0 (+/- 0.1) with phosphoric acid using a pH m eter. Final concentrations: 2% n-propanol, 0.02 M TEAPO 4. Degas prior to use. Mo bile phase B. Ad d 20 m L of n -propan ol to acetonitrile in a 1 L volumetric flask and bring to volume. Degas prior to use.
1. Dermal Patch: Texwipe™ AlphaW ipe® polyes ter cleanro om wipe (4" x 4") in holder. The wipe is available com m ercially. 2. Patch Holder: W hite, 2-side chipboard, 0.08 SBS with a 7.6 cm diameter circle cut in one side (W ellman C ontainer Corp, Fairfield, Ohio). 3. High Performance Liquid Chromatograph (HPLC ). 4. Autosampler capable of 5 µL injections. 5. An alytic al colum n: P henom enex® Synergi™ 4µ Hydro-RP 80A (250 mm x 2.00 mm) or equ ivalent. 6. UV detector at 200 nm. 7. Vials, 2 mL, PTFE-lined caps. 8. Centrifuge tubes, polypropylene, 50 mL. 9. Syringes, 50-:L, 1-mL, and 5-mL. 10. Volumetric flasks, 5-mL, 100-mL, and 1-L. 11. PTFE syringe filter, 4-mm , 0.45-µm pore. 12. Large vial/tube rotator. 13. pH m eter. 14. Graduated cylinders, 50-mL. 15. Pipettes, glass, disposable, 2-mL. 16. Forceps. 17. Bagge d refrigera nt.
- See SPECIAL PRECAUTIONS
SPECIAL PRECAUTIONS: Th iophana te-m ethyl: Avo id inhaling vap ors or du st; avo id sk in con tact. W ear glo ves and suitab le cloth ing when handling pure m ate rial. So lvents: Avoid sk in contac t and open flam e. Us e in a h ood . Pho sph oric acid: Avoid s kin c onta ct. Ca ptan : Use in ho od. A void c onta ct with sk in, eyes, and clothing an d inge stion o r inhalation. Eye protection sho uld be worn. SAMPLING: 1. Secure the patch m aterial in the pa tch holder with staples at two opposite corners. Attach the patch and holder to the appropriate location of the skin or clothing and sample for designated time period. 2. At the end of the sampling time, remove the patch from holder using clean forceps and trans fer to a 50-m L centrifuge tube. 3. Label and pack the tube securely for shipment. These are shipped cold with other samples. 4. Sam ples should be stored under refrigeration until needed for analysis.
SAMPLE PREPARATION: 5. Add 30 mL of extraction solvent to each centrifuge tube and recap. 6. Mix by rotating the tubes end-over-end fo r at least one hour. 7. Filter an extra ct aliquot into a 2-m L au tosa m pler vial throug h a 4-m m , 0.45 µm pore , PT FE filter.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition CAP TAN and T HIOP HAN ATE -MET HYL: M ETH OD 9205, Issue 1, dated 1 5 Ma rch 2003 - Page 3 of 4 CALIBRATION AND QUALITY CONTRO L: 8. Determine retention times for analytes using the column and chrom atographic conditions as outlined on pages 920 5-1 a nd 9 205 -2. The approximate retention time of thiophanate-methyl is 14 minutes and cap tan is 2 1 m inutes . (See Figure 1.) 9. Ca librate daily with at least six working standards containing each of the two analytes and covering the analytical range (Table 1) for thiophanate-methyl and captan. 10. Prepare QC sam ples by placing a new patch in a 50 mL tube and spiking with known amounts of the two analytes. Allow the samples to set open until the solvent has evaporated. Cap the tube and prepare for analysis in the same manner as the field samples in steps 5-7.
MEASUREMENT: 11. Set LC according to manufacturer’s recomm endations. Set the wavelength for detection at 200 nm and flow rate at 0.200 mL/m in. 12. Injec t 5 µL aliquot of the sam ple ex tract w ith autosam pler. NOTE: If peak area of a sample is greater than the area of the highest standard, dilute with extracting solvent and reanalyze. 13. Measure peak area of the analyte.
CALCULATIONS: 14. Perform a separate regre ssion analysis of the peak area s vs. quantity of standard for each of the two analytes. De term ine the concentration ,µg /m L, (correcte d fo r DE) of the analyte in each sam ple patch (C P) and in the m edia blank (B b) from the calibration graph. 15. Ca lculate the mass of each analyte, M (:g), on a sample patch by adjusting for the volume , V (mL) of extra ction s olven t.
EVALUATION OF METHOD: This method was evaluated with a recovery study at room temperature over the range of 306.0 - 6120 µg /sa m ple for thiophanate -m eth yl and 300.4 - 6220 µg/sample for captan using spiked laboratory samples with respective average recoveries in the range of 89.1-95.5% and 89.6-96.0%. [1] The storage study at 4°C was completed at 6000 µg/sample for thiophanate-methyl, and 1500 µg /sam ple for captan with respective recovery averages of 8 6.2 -92.2 %, and 87.6 -95.7 % over the 28 days of the study. Carbendazim , which is a decomposition product of thiophanate-methyl, may also be found in the chromatogram along with the other two a nalytes. An attempt was m ade to quantitatively analyze carbendazim as a part of this method. However, reproducibility problems for carbendazim in the presence of thiophanatem eth yl has necessita ted that the analysis be only qualitative for carbendazim. The reproducibility problem was more pronounced when the ratio of thiophanate-methyl to carbendazim was grea ter than ab out eight to one. Additionally, this problem is compounded when other materials, such as benomyl, which also decomposes to produc e ca rben dazim , are present in the sa m ple. Be cau se this m etho d is un able to distinguish the decomposition source of the carbendazim, it can only pro vide qualitative data for carbendazim . Under the method conditions, its approximate retention time is 9 minutes. Fie ld sam ples have been analyze d by this m ethod. Be cause the fie ld sam ples contain ed other org anic compounds and/or interferences, it was necessary to mak e adjustments to the analysis parameters. For example, it was nec ess ary to insert a longer column rinse at the end of the solvent gradient to elute higher molecular weight compounds and/or other material from the column. It was also necessary to change the end of the gradient solvent run to have a greater organic phase ratio to help rinse the column of these materials. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition CAP TAN and T HIOP HAN ATE -MET HYL: M ETH OD 9205, Issue 1, dated 1 5 Ma rch 2003 - Page 4 of 4 Based on the needs of the laboratory and the complexity of the samples to be analyzed, it may be necess ary to mak e other changes to the analysis parameters to get the best resolution of the compounds in the samples.
REFERENCES: [1] Jaycox LB, Andrews RN [2002]. Backup data report for Captan and Thiophanate-methyl on Dermal Patch method development, Cincinnati, OH: National Institute for Occupational Safety and Health, DAR T/NIO SH (un published, June). [2] NIOSH [1998]. Meth od 9201: Chlorinate d organonitrogen herbicides (derm al patc h). In: C assinelli ME , O’C onn or PF, ed s. NIOS H M anu al of Analytical M etho ds (N MA M), 4 th ed., 2 nd sup plem ent. Cinc innati, OH : National Ins titute for O ccu pation al Safety and Health, D HH S (N IOS H) P ubl 98 -119 .
METHOD WRITTEN BY: Larry B. Jaycox, Ph.D. and Ronnee N. Andrews, NIOSH/DART
Table 1. Analyte Captan Thiophanate -m eth yl
Range 67.5-6220 :g/s am ple 62.0-6120 :g/s am ple
Estimated LOD 20.2 :g/s am ple 18.6 :g/s am ple
Precision (þ r) 0.0256 0.0229
Figure 1 This chromatogram shows results from a spiked patch sample that was extracted and analyzed by this method. The analyte quantities were: thiophanate-methyl - 200 µg/sample and captan- 50 µg/sample.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition