1、 IT IS THE USERS RESPONSIBILITY TO ESTABLISH APPROPRIATE PRECAUTIONARY PRACTICES AND TO DETERMINE THE APPLICABILITY OF REGULATORY LIMITATIONS PRIOR TO USE. EFFECTIVE HEALTH AND SAFETY PRACTICES ARE TO BE FOLLOWED WHEN UTILIZING THIS PROCEDURE. FAILURE TO UTILIZE THIS PROCEDURE IN THE MANNER PRESCRIB
2、ED HEREIN CAN BE HAZARDOUS. MATERIAL SAFETY DATA SHEETS (MSDS) OR EXPERIMENTAL MATERIAL SAFETY DATA SHEETS (EMSDS) FOR ALL OF THE MATERIALS USED IN THIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). COPYRIGHT 2011, 2015 UOP LLC. All rights reserve
3、d. Nonconfidential UOP Methods are available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, USA. The UOP Methods may be obtained through the ASTM website, www.astm.org, or by contacting Customer Service at serviceastm.org, 610.832.9555 FAX, or 610.83
4、2.9585 PHONE. Low Trace Sulfur in Liquid Hydrocarbons by Oxidative Combustion with Ultraviolet Fluorescence Detection UOP Method 987-15 Scope This method is for determining sulfur in liquid hydrocarbons at concentrations ranging from 10 to 1500 ng/g (mass-ppb). A direct measurement procedure (Part A
5、) is used for samples above 100 ng/g. A trap & release procedure (Part B) is used for samples between 10 and 200 ng/g where high precision is required. This method is applicable to highly volatile samples, such as pentane, through the use of a cooled sampling system. Higher concentrations can be det
6、ermined by ASTM Method D5453, “Standard Test Method for Determination of Total Sulfur in Light Hydrocarbons, Spark Ignition Engine Fuel, Diesel Engine Fuel, and Engine Oil by Ultraviolet Fluorescence,” and D7183, “Standard Test Method for Determination of Total Sulfur in Aromatic Hydrocarbons and Re
7、lated Chemicals by Ultraviolet Fluorescence,” using the cooled sampling system described herein for highly volatile matrices. Halogens interfere at concentrations greater than approximately 0.3%. The method has reduced sensitivity to sulfur present as sulfate. For Part A, nitrogen content must not e
8、xceed sulfur by more than 100-fold to prevent a positive bias to the results. References ASTM Method D4052, “Density and Relative Density of Liquids by Digital Density Meter,” www.astm.org ASTM Method D5453, “Standard Test Method for Determination of Total Sulfur in Light Hydrocarbons, Spark Ignitio
9、n Engine Fuel, Diesel Engine Fuel, and Engine Oil by Ultraviolet Fluorescence” www.astm.org ASTM Method D7183, “Standard Test Method for Determination of Total Sulfur in Aromatic Hydrocarbons and Related Chemicals by Ultraviolet Fluorescence” www.astm.org UOP Method 999, “Precision Statements in UOP
10、 Methods,” www.astm.org Outline of Method A commercial instrument is set up and calibrated with liquid standards. For samples containing volatile components such as pentane, the sample tray is cooled (see Note 1). The sample is directly injected by autosampler into the combustion tube where it vapor
11、izes into an argon carrier. The vapors 2 of 13 987-15 are mixed with oxygen at high temperature. The organic material is converted to carbon dioxide and water. The sulfur in the sample is converted to sulfur dioxide and measured by Ultraviolet Fluorescence (UVF) as described in Part A. For samples c
12、ontaining sulfur between 10 and 200 ng S/g, the SO2 produced during sample combustion is preconcentrated using a Trap & Release Unit prior to measurement as described in Part B. Samples between 100 and 200 ng S/g can be analyzed either directly (Part A) or by preconcentration (Part B), although Part
13、 B will yield higher precision. The signal is proportional to the total sulfur in the sample. Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Balance, analytical, readable to 0.0001 g Flasks, volumetric, Class A, bo
14、rosilicate glass, 100- and 250-mL, Fisher Scientific, Cat. Nos. 10-210-8C and -8E, respectively Pipet, volumetric, Class A, 1-, 2-, 5-, 10- and 15-mL, Fisher Scientific, Cat. No. 13-650-2B, -2C, -2F, -2L and -2M, respectively Pipet filler, VWR, Cat. No. 53497-055 Refrigerator, flammable storage or e
15、xplosion proof, Fisher Scientific, Cat. No. 55703-190 Regulator, argon, single-stage, with stainless steel diaphragm, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Cat. No. 3231, with connection fittings appropriate to the installation. This regulator is installed downstream of t
16、he two-stage regulator to provide better flow control. Regulator, argon, two-stage, with stainless steel diaphragm, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Cat. No. 3122-580 Regulator, oxygen, single-stage, with stainless steel diaphragm, delivery pressure range 30-700 kPa
17、(4-100 psi), Matheson Tri-Gas, Cat. No. 3231, with connection fittings appropriate to the installation. This regulator is installed downstream of the two-stage regulator to provide better flow control. Regulator, oxygen, two-stage, with stainless steel diaphragm, delivery pressure range 30-700 kPa (
18、4-100 psi), Matheson Tri-Gas, Cat. No. 3122-540 Sulfur analyzer, with attached furnace, autosampler, controls and computer. This method was developed and validated using the Mitsubishi analyzer Model TS-100V, with SD-100 Sulfur Detector, TRU-100 Trap & Release Unit and STC-210L Sample Temperature Co
19、ntroller, Mitsubishi Chemical Analytech, available from COSA Xentaur. Part A has also been validated on the Mitsubishi NSX-2100V, with SD-210 Sulfur Detector and STC-210L Sample Temperature Controller. Manufacturer recommended operation parameters for the use of the NSX-2100V with Part B of the meth
20、od are also provided. The procedure for analysis may be different for other instruments and all other instruments need to be validated before using for this method. Not all combustion/UV fluorescence instruments are capable of running this analysis, since controlled temperature sampling is required.
21、 The Mitsubishi analyzer must be equipped with the following accessories: Autosampler, Mitsubishi ASC-250L or ASC-150L, COSA Xentaur Autosampler syringes, gas tight, 100-L, Mitsubishi, Cat. No. MSSG10, COSA Xentaur (for Part A) 3 of 13 987-15 Autosampler syringes, gas tight, 250-L, Mitsubishi, Cat.
22、No. MSSGGQ, COSA Xentaur (for Part B) Autosampler bottles, rinse, pre-fill, and waste, Mitsubishi, Cat. No. TX3LSW, COSA Xentaur Membrane drier, Perma Pure MD-110-24F-4 or Tube Dryer, Mitsubishi, Cat. No. TN6RPC, COSA Xentaur (see Note 2) Sample Temperature Controller, Mitsubishi STC-210L, COSA Xent
23、aur Trap & Release Unit, Mitsubishi TRU-100 or TRU-210, COSA Xentaur Reagents and Materials References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. The following items are required to perform the analysis. Additional reagents and mat
24、erials may be required depending on the specific instrument. Air, compressed, dry, oil-free, for membrane drier (if instrument does not purge the drier with argon), local supply Alumina balls, Mitsubishi, Cat. No. TS3CAT, COSA Xentaur Argon, compressed gas, 99.99% minimum purity. UHP, Matheson Tri-G
25、as or local supply Autosampler vials, 15x45-mm, Grace Davison Discovery Sciences, Cat. No. 98008 Catalyst, Mitsubishi, Cat. No. TN5CAT, COSA Xentaur Dibenzothiophene, 98%, VWR, Cat. No. AAA12288-14, optional (see Procedure, Preparation of Standards) Isooctane, should be as low in residual sulfur as
26、possible to minimize the blank value, B&J Brand, Burdick & Jackson, Cat. No. BJ362-1, VWR or Fisher Pesticide grade, Fisher Scientific, Cat. No. O297-4. Test each new lot of solvent before use. Oxygen, compressed gas, 99.98% minimum purity, UHP, Matheson Tri-Gas or local supply Pipet, transfer, disp
27、osable plastic, 152-mm length, Fisher Scientific, Cat. No. 13-711-SA Quartz wool, Mitsubishi, Cat. No. TNQWL, COSA Xentaur Sulfur standard, commercial certified, Accustandard or VHG, optional (see Procedure, Preparation of Standards). Purchase the lowest sulfur concentrations available, generally ab
28、out 5 mg/kg. Toluene, B&J Brand, Burdick & Jackson, VWR Cat. No. BJ347-4 Procedure The analyst is expected to be familiar with general laboratory techniques, sulfur analysis, and the equipment being used. Preparation of Standards Calibration standards can be prepared as serial dilutions from a prepa
29、red volumetric standard solution or by diluting a commercial certified standard on a mass/volume basis. Suitable commercial standards are available, prepared in isooctane/toluene or diesel matrices, and sold by vendors such as AccuStandard and VHG. Prepare volumetric standard solutions as follows: 4
30、 of 13 987-15 Dibenzothiophene stock solution, 1000-g S/mL 1. Tare a clean, dry, 100-mL volumetric flask. Dispense 0.575 g of dibenzothiophene and record the mass to the nearest 0.0001 g. 2. Dilute to the mark with toluene. Cap and mix well. 3. Calculate the actual concentration of the stock solutio
31、n using Equation 1: 100 101740.0AmL/g,S 6 (1) where: A = mass of dibenzothiophene, g 0.1740 = S mass-fraction of dibenzothiophene (32.066/184.26) 32.066 = molecular mass of sulfur, g/mol 184.26 = molecular mass of dibenzothiophene, g/mol 100 = dilution volume, mL 106 = factor to convert g to g Diben
32、zothiophene stock solution, 10-g S/mL 1. Dispense 1.0 mL of the 1000-g/mL S stock solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 2. Dilute to the mark with low S isooctane. Cap and mix well. The actual concentration is 1/100th the concentration of the stock solution ab
33、ove. Calibration standard solution, 1500-ng S/mL 1. Dispense 15.0 mL of the 10-g/mL S stock solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 2. Dilute to the mark with low S isooctane. Cap and mix well. The actual concentration is 15/100th the concentration of the nomina
34、l 10-g S/mL stock solution above. Calibration standard solution, 1000-ng S/mL 1. Dispense 10.0 mL of the 10-g/mL S stock solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 2. Dilute to the mark with low S isooctane. Cap and mix well. The actual concentration is 1/10th the
35、concentration of the nominal 10-g S/mL stock solution above. Calibration standard solution, 500-ng S/mL 1. Dispense 5.0 mL of the 10-g/mL S stock solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 2. Dilute to the mark with low S isooctane. Cap and mix well. The actual con
36、centration is 1/20th the concentration of the nominal 10-g S/mL stock solution above. Calibration standard solution, 200-ng S/mL 1. Dispense 2.0 mL of the 10-g/mL S stock solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 5 of 13 987-15 2. Dilute to the mark with low S iso
37、octane. Cap and mix well. The actual concentration is 1/50th the concentration of the nominal 10-g S/mL stock solution above. Calibration standard solution, 100-ng S/mL 1. Dispense 1.0 mL of the 10-g/mL S stock solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 2. Dilute t
38、o the mark with low S isooctane. Cap and mix well. The actual concentration is 1/100th the concentration of the nominal 10-g S/mL stock solution above. Calibration standard solution, 50-ng S/mL 1. Dispense 10.0 mL of the 500-ng/mL S calibration standard solution using a volumetric pipet into a clean
39、, dry, 100-mL volumetric flask. 2. Dilute to the mark with low S isooctane. Cap and mix well. The actual concentration is 1/10th the concentration of the nominal 500-ng S/mL calibration standard solution above. Calibration standard solution, 20-ng S/mL 1. Dispense 10.0 mL of the 200-ng/mL S calibrat
40、ion standard solution using a volumetric pipet into a clean, dry, 100-mL volumetric flask. 2. Dilute to the mark with low S isooctane. Cap and mix well. The actual concentration is 1/10th the concentration of the nominal 200-ng S/mL calibration standard solution above. The stock solutions can be ret
41、ained, if refrigerated, for up to six months. The calibration standard solutions of 100-ng S/mL and higher can be retained, if refrigerated, for up to 3 months. The 20- and 50-ng S/mL standard solutions should be made fresh daily. Part A Samples between 100- and 1500-ng/g Sulfur Preparation of Appar
42、atus 1. Set up the instrument according to the manufacturers instructions. New combustion tubes need to be conditioned with catalyst before use, following the manufacturers procedure. For Mitsubishi instruments, procedure ZINF026 MUST be followed. Connect the membrane drier in series between the com
43、bustion tube and the detector. Allow the instrument to warm up and the baseline to stabilize before injecting samples. Suggested Operating Conditions for the Mitsubishi TS-100V analyzer are listed in Table 1 and for the NSX-2100V in Table 2. 2. Set the STC-210 temperature controller set points to 15
44、C (see Note 1) for both the sample tray and the syringe. Allow at least 30 minutes for the temperature to stabilize before injecting samples. For samples that do not contain volatiles such as pentane, the temperature of the sample tray may be set at 20C. For heavier samples, such as n-paraffins in t
45、he C16 to C18 range which may solidify upon cooling, maintain the sample tray above room temperature (see Note 1). 3. Fill the rinse and pre-fill bottles with low sulfur isooctane. Empty the waste bottle. 6 of 13 987-15 Dispose of all materials in an environmentally safe manner according to local re
46、gulations. 4. Before starting to measure either calibration standards or samples, run an instrument program with 3 (or more) injections of isooctane to condition the instrument. The response should be a stable, level baseline, free of drift before proceeding. Table 1 Operating Conditions for Mitsubi
47、shi TS-100V/SD-100 Upper temperaturea 900C Lower temperatureb 1000C Argon main 250 mL/min Oxygen main 150 mL/min Argon auxiliary 50 mL/min Oxygen auxiliary 400 mL/min Gain Ultra Normal end Off Timer start 3 sec Timer end 400 sec Minimum area 40000 Base line 25% Syringe pre-fill 10 L Sample volume 80
48、 L Injection rate 1.2 L/sec aCombustion tube, upper portion bCombustion tube, lower portion Table 2 Suggested Operating Conditions for Mitsubishi NSX-2100V/SD-210 Inlet heater temperature 900 C Outlet Heater temperature 1000 C Argon 100 mL/min Oxygen 500 mL/min Dryer gas flow 1000 mL/min (or higher)
49、 Argon Time 30 sec Oxygen Time 120 sec PMT Sensitivity High (For Low Concentration) Type Timer Waiting Time 10 sec Measurement Time 300 sec Syringe pre-fill 10 L Sample Volume 80 L Injection rate 1.2 L/sec Precedent Rinse Enable Calibration Calibrate the instrument weekly when in use. Check the calibration daily when in use, by analyzing one of the calibration standards or a reference material. Calibration data are in a separate program from the sample analysis with the TS-100V, but part of the same sample schedule when using th
