FORD FLTM AP 151-01-2016 Determination of Cyclical Volatile Siloxane Compounds in Seals Using Thermal Extraction and Gas Chromatography-Mass Spectrometry (GC-MS).pdf

1、 FORD LABORATORY TEST METHOD AP 151-01 Date Action Revisions Rev. 0 2016 10 21 Released A. Olejnik and D. Bellile, NA Controlled document at www.MATS Copyright 2016, Ford Global Technologies, LLC Page 1 of 5 Determination of Cyclical Volatile Siloxane Compounds in Seals Using Thermal Extraction and

2、Gas Chromatography-Mass Spectrometry (GC-MS) Application This procedure is used to quantitatively determine thermal extraction rates of selected cyclical volatile siloxane compounds (D3, D4, D5, D6 and D9) in elastomeric materials. Other cyclical volatile siloxane compounds (D7, D8, others) can be d

3、etermined semi-quantitatively. Apparatus and Materials Required Thermal Desorption Tubes for the Gerstel Twister Thermal Desorption System (supplier Gerstel): Tubes with glass frit (Gerstel part # 013742-005-0) Tubes with Tenax GR (Gerstel part # 015953-005-0) GC-MS Chromatographic Column: DB-5 MS,

4、column dimensions: length: 30 m, diameter: 0.25 mm, film thickness: 0.25 m (Supplier: Agilent or equivalent) Gerstel Twister Inlet Liner: CS4 liner with silanized glass wool; ID=1 mm; length= 76 mm; Gerstel Part# 013409-010-00 GC-MS Carrier and Gerstel ThermoExtractor Conditioning Unit Gas: Ultra Hi

5、gh Purity Helium (Supplier: AirGas or equivalent) Individual Standards: neat dimethylsilicone cyclic compounds (purity 99.8% or better): D3 (Cyclotrisiloxane, hexamethyl-; CAS # 541-05-9) D4 (Cyclotetrasiloxane, octamethyl-; CAS # 556-67-1) D5 (Cyclopentasiloxane, decamethyl-; CAS # 541-02-6) D6 (Cy

6、clohexasiloxane, dodecamethyl-; CAS # 540-97-6) D9 (Cyclononasiloxane, octadecamethyl-; CAS # 556-71-8) (Supplier: Ohio Valley Specialty Company or equivalent) Glass volumetric cylinders: 10 mL and 50 mL Pipets (9”, Fisher Brand) Stainless Steel Surgical Blade Syringe: 10 L Liquid Nitrogen: low pres

7、sure liquid nitrogen required for GC-MS “Cryo Cooling” (Supplier: AirGas or equivalent) Solvent: Methanol, certified (Supplier: Fisher Scientific or equivalent) Thermal Desorption System: Gerstel Twister Thermal Desorption Unit (TDU) with MPS2 auto-sampler Chromatography System: Agilent Gas Chromato

8、graph, 6890N Agilent Mass Spectrometer, 5975B VL MS FORD LABORATORY TEST METHOD AP 151-01 Copyright 2016, Ford Global Technologies, LLC Page 2of 5 Controlling Software: Agilent Chemstation GC-MS, Data Acquisition/Data Analysis Software Version: D.03.00, SP1 Gerstel MASter, Thermal Extraction Control

9、 Software, Version 2.8.0.0 Tube Conditioner: Gerstel TubeConditioner, model: TC (with a metal extension for short tubes) Analytical Balance: Mettler-Toledo, model: PM400 Note: All the above listed equipment and/or software may be substituted with alternatives of equivalent performance. Chemicals, ma

10、terials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. Procedure Preparation of standard and quality control solutions: Prepare a stock standard solution in methanol (1,000 g/mL

11、 mixture of each target volatile siloxane compound). From the stock standard solution prepare calibration standards of 250 and 500 g/mL mixtures of each compound by serial dilutions by volume. Separately prepare a solution of the 500 g/mL mixture of each compound from the stock solution. This soluti

12、on will be used as a quality assurance /quality control check solution (QA/QC). Store the solutions in sealed vials in a refrigerator; the solutions are stable for 2 months. FORD LABORATORY TEST METHOD AP 151-01 Copyright 2016, Ford Global Technologies, LLC Page 3of 5 GC-MS Data Acquisition Methods

13、(Method 1 and Method 2): Method 1 Create a data acquisition Method 1. This method is a calibration method and will be used to thermally desorb the Twister GR thermal extraction tubes spiked with calibration standard solutions or QC/QA check solution. In Method 1 the thermal extraction temperature of

14、 the Twister unit is set at 300C to thermally desorb spiked/trapped target cyclical siloxane compounds onto the GC-MS system. It is recommended to exclude the data analysis segment from the Method 1. For the data analysis segment create Method 3 (see below). Instrument control parameters: Oven: Init

15、ial Temperature=50C; Initial Time=0.00 min; Temperature Ramps: 5C/min to 200C (hold 1.00 min); 20C/min to 300C (hold 5 min); Run Time=41.00 min; Cryo=On (enabled). Inlet: Mode=Split; Split Ratio: 20:1; Initial Temperature=OFF; Pressure=7.64 psi; Gas=Helium. Column: DB5-MS; 30.0 m; 0.25 mm ID; 0.25 u

16、m film thickness; Constant Flow 1.0 mL/min; Outlet Pressure=Vacuum. MS Acquisition Parameters: Tune File= stune.u; Acquistion Mode=Scan; MSD Transfer Line Heater=250C; Solvent Delay=2.00 min; Low Mass=33.0; High Mass=550.0; MS Quad=150C; MS Source=230C. Gerstel CIS: Initial Temperature=-90C; Equilbr

17、ation Time=0.10 min; Initial Time=0.20 min; Temperature Ramp=12.00C/sec; End Temperature=300C; Hold Time=3.00 min. Gerstel TDU: Initial Temperature=30C; Delay Time=0.40 min; Initial Time=0.10 min; Ramp: Rate=300C/min; End Temperature=300C; Hold Time=5.00 min; Splitless Mode. Method 2 Create a data a

18、cquisition Method 2. This method will be used to thermally desorb the volatile siloxane compounds from seal materials using glass frit thermal extraction tubes. In Method 2 the thermal extraction temperature of the Twister unit is set at 120C to thermally desorb the cyclical siloxane compounds (and

19、other VOC) from the tested seal specimen onto the GC-MS system. It is recommended to exclude the data analysis segment from the Method 2. For the data analysis segment create Method 3 (see below). Instrument Control Parameters: Same as in the Method 1 except one parameter in the Gerstel TDU: End Tem

20、perature=120C. GC-MS calibration of the cyclical siloxanes standards: Draw 1 L of 250 g/mL of the cyclical siloxane standard solution into a 10 L syringe and dispense it on the frit surface of the Tenax GR thermal extraction tube. Then apply a slight upstream helium flow into the tube to evaporate t

21、he solution and move the constituents onto the Tenax GR layer. Use approximately 100 mL/min flow of helium for 10 minutes to complete the evaporation and trap of the cyclical siloxane compounds. Similarly load 1 L the 500 g/mL and 1,000 g/mL standard solutions into additional Tenax GR tubes. Analyze

22、 the loaded tubes on the Gerstel/GC-MS system using data acquisition Method 1. FORD LABORATORY TEST METHOD AP 151-01 Copyright 2016, Ford Global Technologies, LLC Page 4of 5 GC-MS Data Analysis Method (Method 3): Method 3 Create a data analysis Method 3. It is recommended to create this stand-alone

23、data analysis method (and exclude data acquisition segment of the method) in order to process the analytical data in offline session. Choose the chromatogram obtained from analysis of the 250 g/mL volatile siloxanes standard mixture. Use “Autointegrate” to integrate the peaks. Save the “Autointegrat

24、e” events to Method 3. Method 3 creates calibration curves and response factors for each target volatile siloxane compound. The volatile siloxane load units will be expressed in ng (load) per each volatile siloxane compound. Perform the calibration step for Level 1 (250 ng); during this process prop

25、erly assign retention times, and Target and Qualifier masses. Resave the Method 3. Load chromatogram for Level 2 (500 ng) and update the calibration step for this level. Similarly load chromatogram for Level 3 (1,000 ng) and update this level. Resave the Method 3. Examine the calibration curves for

26、linearity. Make sure that Coefficient of Detection (R2) is greater than 0.995. If any calibration curve does not meet the linearity requirement, the data acquisition Method 3 must be properly adjusted. Use Method 3 for quantifying extracted volatile siloxane compounds from samples. Print the calibra

27、tion curve for each compound and attach into the current job report. Semi-quantitative determination of other cyclical siloxane volatile compounds: Due to a lack of availability of additional cyclical siloxane compound standards (D7, D8, D10, etc.) it is necessary to add the compounds into the calib

28、ration table on semi-quantitative basis. Locate the peaks for the D7, D8 and D10 (and higher, if required and detected) on the chromatogram from the thermally extracted seal specimen. Add the compounds into a calibration table; assign the “semi-quantitative analysis” option and assign the D5 TIC res

29、ponse factor for D7, D8, D10 (and other cyclical volatile siloxane) peaks. For qualifying masses (“Qualifiers”) use major M/Z obtained from the D7, D8 and D10 peaks. Note: D7 (Cycloheptasiloxane, tetradecamethyl-; CAS # 107-50-6; Major M/Z=281, 327, 415, 503, 147) D8 (Cyclooctasiloxane,hexadecamethy

30、l-; CAS # 556-68-3; Major M/Z=355, 73, 147, 221, 281, 401) D10 (Cyclodecasiloxane, eicosamethyl-; CAS # 18772-36-6; Major M/Z=73,147, 207, 221, 281, 355) For additional cyclical volatile siloxane compounds see NIST Mass Spectra Library to assign the M/Z fragments. FORD LABORATORY TEST METHOD AP 151-

31、01 Copyright 2016, Ford Global Technologies, LLC Page 5of 5 Specimen preparation and thermal extraction: The requester should select the section of the seal material to be dissected for the thermal extraction analysis. Cut one 20 mg piece (+/- 1 mg) from the specimen using a surgical blade. Place th

32、e freshly cut specimen into an empty Gerstel Twister tube on the glass frit and perform the thermal extraction test immediately. It is recommended to analyze each specimen in duplicate. Note: This thermal extraction technique is only a partial extraction under the testing conditions. An additional t

33、hermal extraction of the pre-extracted specimen may be performed (multiple step extraction). Quality Assurance/Quality Control: Before testing the seal specimens, analyze blank Gerstel tubes to assure the GC-MS system is free of contaminants. If the chromatograms show unacceptable contamination leve

34、ls (more than 25 ng per any target cyclical siloxane compound), clean the GC-MS system and perform additional thermal cleaning of the blank tubes (using the Gerstel Tube Conditioner for 1 hour at 300C in 100 mL/min helium flow). The Quality Control Check (load of 1 L of 500 g/mL QC solution yields 5

35、00 ng mass of each siloxane compound) should recover between 90 and 110% (450-550 ng) of the expected amounts. The QA/QC check should be analyzed before and after running the sealer specimens. If the QA/QC recoveries are outside the expected amounts, remedy the problem (repeat the calibration, check

36、 the hardware performance, etc.) then repeat the calibration and QA/QC checks until satisfactory baseline and recovery data are obtained. Then proceed to test the submitted seal specimens, analyze, validate and report the analytical results. Data Reporting: The data analysis “Method 3” (software) wi

37、ll calculate the extracted amount for each target volatile siloxane compound (D3, D4, D5, D6 and D9) in mass unit (“ng”). The amounts may be combined and reported as a sum. Target Compounds Report the thermal extraction rates of each target volatile siloxane compound using the units ng/20 mg*5 minut

38、es where: ng = mass of each thermally extracted siloxane compound 20 mg = mass of the tested seal specimen (the tested specimen mass is a variable and may be normalized) 5 minutes = thermal extraction time (thermal extraction time is a variable and may not be normalized). Other reporting units may b

39、e used, converted or normalized, as requested. Non-target Compounds Other cyclical siloxane compound thermal extraction rates (non-target compounds) will be calculated on a semi-quantitative basis using the TIC response factor of D5. The reporting units are the same as per the target compounds, ng/2

40、0 mg*5 minutes, with the qualifier “semi-quantitatively as D5 equivalent” added. The report shall include the following notes: Results are reported as “Thermal extraction rates of selected volatile cyclical siloxane compounds under testing conditions”. Semi-quantitative calculation of selected volatile cyclical siloxane compounds as D5 equivalent Data are not blank corrected Limit of quantitation (LoQ) has not been established