TranslatePetroleum Distillate Fractions
(This method was fully evaluated with Stoddard solvent. It can also be used to determine V.M.&P. naphtha and mineral spirits.)
OSHA Method ORG-48 | November 1984
For problems with accessibility in using figures and illustrations, please contact the Salt Lake Technical Center at 801-233-4900.
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.
| Method Number: | 48 |
| Matrix: | Air |
| Target concentration: | 2900 mg/m3 Stoddard solvent (OSHA PEL) |
| Procedure: | Samples are collected by drawing a known volume of air through charcoal tubes. Samples are desorbed with carbon disulfide (CS2) and analyzed by gas chromatography (GC) using a flame ionization detector (FID). |
| Recommended air volume and sampling rate: |
3 L at 0.2 L/min |
| Reliable quantitation limit: | 0.77 mg/sample (260 mg/m3) |
| Precision: (1.96 SD) (Section 4.3.2.) |
17.8% |
| Status of method: | Evaluated method. This method has been subjected to the established evaluation procedures of the Organic Methods Evaluation Branch. |
| Date: November 1984 | Chemist: Michael L. Shulsky |
Organic Methods Evaluation Branch
OSHA Analytical Laboratory
Salt Lake City, Utah
- General Discussion
- Background
- History
Three refined petroleum mixtures are routinely analyzed at this laboratory. They are Stoddard solvent (boiling range 160-210°C), mineral spirits (boiling range 150-200°C), and petroleum distillates (V.M.&P. naphtha; boiling range 95-160°C). These mixtures will collectively be termed petroleum distillate fractions (PDF) throughout this method. All of these PDFs contain aliphatic and to a lesser extent aromatic hydrocarbons. (Ref. 5.1.)
The procedures for collection (charcoal tubes) and analysis (GC/FID) of PDFs described in this evaluation are basically those used in NIOSH methods S380 and S382. (Ref. 5.2.) For preparation of analytical standards, these NIOSH methods require a sample of the bulk material presumed to be the source of the air contamination (this bulk material will be referred to as the "source PDF" throughout this method). The shipment of source PDFs, which are often flammable, is inconvenient and the materials sometime require distillation before use in standards. For these reasons and because similar responses to different hydrocarbons are observed using a FID (Ref. 5.3.), the use of analytical standards prepared from a PDF which is not the source PDF was investigated. In order to determine analytical conditions, it was assumed that this substitute PDF ("
non-source PDF") should be of the same type, i.e. Stoddard solvent, mineral spirits, or petroleum distillates, as that used at the sampling site.Internal standards (Istd) are routinely used in solvent analyses at this laboratory. Since the actual constituents of PDFs are unknown, the presence of an internal standard may cause an interference with the PDF or unduly lengthen the analysis time. For these reasons, the possibility of using an external standard (Estd) procedure was examined.
Also, in preliminary work it became apparent that the manner in which the baseline was set was a concern. If the data system was allowed to automatically set the baseline, inconsistencies in the positions to which the baseline was drawn were noticed (Figures 4.8.1. and 4.8.2.). This produced calibration errors at lower concentrations of PDFs. To overcome this problem, an evaluation of certain "integrate functions" available in the data system software which control the baseline was done (Section 4.8.4.).
In order to evaluate the parameters of baseline, Estd, and material used to prepare analytical standards, a study was done utilizing eight different PDFs consisting of five Stoddard solvents, two V.M.&P. naphthas and one mineral spirits. These were used to spike 8 sets of 12 charcoal tubes. Each 12-tube set was quantitated using analytical standards prepared from both source and
non-source PDF. There were no restrictions on the analytical conditions or GC column used for these analyses, in order to avoid having data which would apply to only certain analytical conditions. (Section 4.8.)The results of this study indicate several things; there is no significant difference in results obtained by using either the source or
non-source PDF (Section 4.8.2.), an internal standard is not needed when consistent injection size can be maintained (Section 4.8.2.), and consistent setting of the baseline may be obtained by using "integrate functions". (Section 4.8.4.).Other tests performed for this evaluation were break through, storage stability, desorption efficiencies, precision of the analytical procedure, sensitivity and reliable quantitation limit. The breakthrough tests were performed with both a Stoddard solvent (Section 4.4.1.) and a V.M.&P. naphtha (Section 4.4.2.) to ensure the collection procedure would work for the more volatile constituents of a V.M.&P. naphtha. All of the other tests were performed using a Stoddard solvent but the collection and analytical procedure should also be applicable to petroleum distillates and mineral spirits.
There are two OSHA PELs that pertain to petroleum distil late fractions. The PELs are 2900 mg/m3 for Stoddard solvent and 2000 mg/m3 for petroleum distillates (naphtha). Due to numerous synonyms and the overlapping boiling range fractions that are available, there is much confusion as to which standard is applicable in many instances. Mineral spirits, which is almost identical to Stoddard solvent in boiling range, should be compared to the Stoddard solvent PEL; while the lower boiling range petroleum distillate fractions should be compared to the petroleum distillate (naphtha) PEL.
This evaluation shows that PDFs can be collected using charcoal with a 3-L air volume, analyzed by GC/FID and a
non-source PDF may be used to prepare analytical standards. - Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy).
"Short-term Exposure: Overexposure to Stoddard solvent causes irritation of the eyes, nose, and throat and may cause dizziness. Very high air concentrations may cause unconsciousness and death. Long-term Exposure: Prolonged overexposure to the liquid may cause skin irritation." (Ref. 5.4.)
"Short-term Exposure: Overexposure to petroleum distillates may cause dizziness, drowsiness, headache, and nausea. They may also cause irritation of the eyes, throat, and skin. Long-term Exposure: Prolonged exposure may cause drying and cracking of the skin." (Ref. 5.5.)
Men were exposed to mineral spirits concentrations of 2500 to 5000 mg/m3 for an unspecified time period. Both concentrations produced nausea and vertigo in the subjects. In another study at 4000 mg/m3 there was a prolongation of reaction time. (Ref. 5.1.)
- Potential workplace exposure
NIOSH estimates that about 600,000 workers in the United States are potentially exposed to all "specialized naphthas" (Ref. 5.1.).
Petroleum distillates (V.M.&P. naphtha) is used as a quick evaporating paint thinner. Stoddard solvent is used in the dry cleaning industry. Mineral spirits is a general purpose thinner, a dry cleaning agent, and a solvent for paint and varnish industries. (Ref. 5.1.)
- Physical properties (Ref. 5.1. unless otherwise stated)
Petroleum distillates molecular weight: approximately 87-114 odor: pleasant aromatic odor boiling range: 95 - 160°C specific gravity: 0.7275 - 0.7603 color: clear, water white to yellow vapor pressure: 2 - 20 mm Hg at 20°C flashpoint: -6.7 to 12.8°C (closed cup) synonyms: benzine, naphtha 76, ligroin, high boiling petroleum ether molecular species: C7-C11 Stoddard solvent molecular weight: approximately 135 - 145 odor: kerosene-like boiling range: 160 - 210°C specific gravity: 0.75 - 0.80 color: colorless vapor pressure: 4 - 4.5 mm Hg at 25°C flashpoint: 37.8°C (closed cup) synonyms: 140 flash solvent, odorless solvent and low end point solvent molecular species: C9-C11 Mineral spirits molecular weight: approximately 144 - 169 odor: pleasant sweet odor boiling range: 150 - 200°C specific gravity: 0.77 - 0.81 color: clear, water white vapor pressure: 0.8 mm (Hg) at 20°C flashpoint: 30.2 - 40.5°C (closed cup) synonyms: white spirits, petroleum spirits, and light petrol molecular species: C9-C12
- History
- Limit defining parameters (Air concentrations are based on the recommended air volume (3 L) and a desorption volume of 1 mL.)
- Detection limits
Since PDF consist of numerous and varying components, the determination of meaningful detection limits was not considered feasible.
- Reliable quantitation limit
The reliable quantitation limit is 0.77 mg/sample (260 mg/m3) This concentration was arrived at by taking all the results for calibration methods #4 and #5 from Tables 4.8.1. through 4.8.8. that were near certain concentrations, i.e. 0.3 mg/mL and 0.7 mg/mL, and finding the average recoveries, the average concentrations, and standard deviations (SD) near those concentrations. The results for samples near 0.77 mg/mL met both the requirements of 75% recovery and a precision (1.96 SD) of ±25% or better. (Section 4.2.)
- Sensitivity
The sensitivity of the analytical procedure over a range representing 0.5 to 2 times the target concentration based on the recommended air volume is 300954 area units per mg/mL. This is determined by the slope of the calibration curve. (Section 4.3.3.)
- Recovery
The recovery of samples used in a 15-day storage test remained above 94% (Section 4.6.). The recovery of the analyte from the collection medium during storage must be 75% or greater.
- Precision of the analytical procedure
The pooled coefficient of variation obtained from replicate determinations of analytical standards at 0.5, 1, and 2 times the target concentration is 0.019 (Section 4.3.1.).
- Precision of the overall procedure
The precision of the overall procedure at the 95% confidence level is ±17.8% (Section 4.3.2.). This includes an additional 5% for sampling error. The overall procedure must provide results that are ±25% or better at the 95% confidence level.
- Reproducibility
Six samples spiked by liquid injection and a draft copy of this procedure were given to a chemist unassociated with this evaluation. The samples were analyzed after 2 days of storage at 22°C. The average recovery was 97.7% with a SD of ±3.53%. (Section 4.7.)
- Detection limits
- Advantages
- The collection procedure is convenient.
- The analytical procedure is rapid and precise.
- Disadvantages
None
- Background
- Sampling Procedure
- Apparatus
- A personal sampling pump which can be calibrated within ±5% of the recommended flow rate is needed.
- Coconut shell charcoal tubes which consist of glass tubes 7 cm long, 6-mm o.d., and 4-mm i.d., containing a 100-mg section and a 50-mg section of charcoal separated with a urethane foam plug are used. The glass tube is flame sealed at both ends. For this evaluation, SKC, Inc. charcoal tubes, lot 120, were used.
- Reagents
None required
- Technique
- Immediately before sampling, break open the ends of the charcoal tube. All tubes should be from the same lot of charcoal.
- Connect the charcoal tube to the pump with a short piece of flexible tubing. The 50-mg portion of the charcoal tube is used as the backup section; therefore, air should flow through the 100-mg portion first.
- Position the tube vertically to avoid channeling through the charcoal.
- Air being sampled should not pass through any hose or tubing before entering the charcoal tube.
- Record the temperature and relative humidity of the atmosphere being sampled.
- Immediately after sampling, seal the ends of the tubes with the plastic caps.
- With each set of samples, submit at least one blank charcoal tube from the same lot as the sample tubes. The blank tube should be treated in the same manner as the samples (break ends, seal, transport) except no air is drawn through it.
- Transport the samples and corresponding paperwork to the laboratory for analysis.
- Submit source PDF whenever possible. Place the material in glass bottles with Teflon-lined caps, and transport to laboratory separately from air samples.
- Breakthrough
Studies to determine the 5% breakthrough value were done near the PEL for Stoddard solvent, using a dynamically generated atmosphere with approximately 75% relative humidity at 22°C and a sampling rate of 0.203 L/min. These studies were performed using only the 100 mg portion of a charcoal tube. The average breakthrough for Stoddard solvent was 6.9 L and average capacity was 20 mg. (Section 4.4.1.). Breakthrough studies were performed with a petroleum distillate (V.M.&P.) naphtha since this type of PDF boils at a lower temperature. The average breakthrough volume for this V.M.&P. naphtha was 9.4 L and the average capacity was 20.3 mg. (Section 4.4.2.)
- Desorption efficiency
Desorption efficiencies were determined at several different loadings of Stoddard solvent. These loadings corresponded to the mass of Stoddard solvent which would be collected on a charcoal tube when sampling 3 L of an atmosphere containing 0.1, 0.5, 1, and 2 times the PEL. The tubes were prepared by liquid injection of the Stoddard solvent and stored in a refrigerator for 24 h before analysis. The average desorption efficiency was 100%. (Section 4.5.)
- Recommended air volume and sampling rate.
The recommended air volume is 3 L at 0.2 L/min.
- Interferences
- Since charcoal will collect vapors from many organic compounds all organics being used in significant amounts near the sampling area could decrease the capacity of the charcoal for PDF.
- Water vapor also may decrease the capacity of charcoal.
- Safety precautions
- Wear eye protection when breaking the ends of the charcoal tubes.
- Place the sampling pump on the employee in a manner so it will not interfere with the work being done.
- Place the charcoal tube in a holder so the broken ends are not exposed.
- Obey all safety regulations of the workplace.
- Apparatus
- Analytical Procedure
- Apparatus
- A gas chromatograph (GC) equipped with a flame ionization detector (FID) is used for analysis. A Hewlett-Packard 5710 GC was primarily used in this evaluation.
- A GC column capable of separating carbon disulfide (CS2) and the internal standard, if any, from the constituents of the PDF. For this evaluation, a 20 ft by 1/8 in. stainless steel column packed with 10% SP-1000 on 80/100 Supelcoport was used.
- An integrator for determining peak area is needed. A Hewlett-Packard 3357 data system was used.
- Small vials with Teflon-lined caps for desorption of charcoal: Two-milliliter vials are preferable.
- Microliter syringes such as 10-µL for preparing standards and 1-µL for sample injection are needed.
- Pipettes for dispensing the desorbing solution may be used. A 1-mL reagent dispenser is convenient.
- Volumetric flasks are used for standard preparation.
- An analytical balance is used to prepare standards.
- A distillation apparatus may be needed.
- Reagents
- Carbon disulfide, reagent grade.
- Source PDF, when possible, from the operation where sampling was done.
- Internal standard compound such as hexylbenzene, reagent grade (optional).
- GC grade hydrogen, air and nitrogen.
- Desorbing solvent: CS2 or 1 µL internal standard/mL CS2.
- Standard preparation
- Analytical standards are prepared in the desorbing solvent.
- Source PDF received from the sampling site may be used as the analytical standard if it appears clear and colorless, and has a density in the range of 0.74-0.79 g/mL. If the bulk is colored or has a density greater than 0.79 g/mL, it needs to be distilled to separate the volatile solvents from the pigments or heavier oils before it can be used as an analytical standard.
- If source PDF is not submitted or is unusable, a nonsource PDF from the laboratory should be used.
- Standards must be prepared at four different concentrations so proper integration of the peaks may be confirmed (Section 3.5.3.). A useful range for standard concentrations is approximately 1 µL/mL to 10 µL/mL.
- Sample preparation
- The 100-mg portion of the charcoal tube is placed in a vial and the 50-mg portion is placed in a separate vial. The glass wool and urethane plugs are discarded.
- One milliliter of desorbing solvent is added to each vial.
- The vials are immediately capped and shaken periodically for 30 min before analysis.
- Analysis
- GC conditions
oven: initial temperature 100°C for 4 min programmed to 180°C at 8°/min injector: 200°C detector: 225°C nitrogen (carrier): 22 mL/min hydrogen: 30 mL/min air: 250 mL/min injection size: 1 µL chromatogram: Figure 3.5.1. - The data system used in this evaluation was a Hewlett-Packard 3357 which contains several "integrate functions." The integrate function termed "hold the baseline" should be used for the analyses. This function should be started before the constituents of the petroleum distillate fraction begin to elute from the column and it should be canceled after the PDF constituents have eluted or when column bleed becomes significant whichever occurs first.
- The areas of the peaks due to PDF constituents are added together (area summation) in the analysis of the standards and samples. The summed areas and the concentration of the analytical standards are used to determine a linear least squares fit equation. The concentration of the samples is determined by entering their summed areas into the least squares equation.
- If the peaks present in the samples do not elute in approximately the same time range as the standards, a comparison of the constituents in the samples and standard should be done by GC/MS to confirm that the samples do contain PDF type compounds and of what type for reporting purposes. If distinct analytes are confirmed by GC/MS, their identity and approximate concentration should be reported.
- Any sample above the PEL should be confirmed by GC/MS or another suitable technique.
- GC conditions
- Interferences
- Since PDF are mixtures of aliphatic and aromatic hydrocarbons and elute from a GC in a peak cluster, it may be difficult to eliminate interfering compounds. If a large interfering peak appears in an air sample, identification by GC/MS may be necessary.
- It may be difficult to separate a single analyte which is requested for analysis from the PDF constituents. Changing columns such as from a polar to a non-polar (SP-1000 to an SP-2100) may help separate the analyte.
- Calculations
- PDF should be reported as mg/m3 since any ppm value would require the use of an approximate molecular weight.
- The air concentration in mg/m3 is determined from the mass of analyte in the sample as in the following example:
Upon analysis, 3.5 mg was found for a sample with a 3-L air volume.
mg/m3 = (mg/desorption efficiency)/air vol.
mg/m3 = (3.5 mg/1.00)/(0.003 m3)
mg/m3 = 1167 mg/m3
- Safety precautions
- Work in a hood when using solvents during sample and standard preparation.
- Keep solvents away from sources of high temperatures such as detectors and injectors.
- Avoid skin contact with solvents.
- Wear safety glasses at all times.
- Apparatus
- Backup Data
- Detection limits of the analytical and overall procedure
The determination of detection limit values is not practical in the context of a rigid definition such as a peak with a height of 5 times the baseline noise. Since PDFs may have similar constituents which have unsimilar concentrations, there is no one representative peak that can be used to determine detection limits for all PDFs.
- Reliable quantitation limit
The amount of 0.77 mg/sample (260 mg/m3) is determined to be the approximate amount reliably quantitated for any applicable petroleum distillate fraction within the requirements of at least 75% recovery and a precision (1.96 SD) of ±25% or better. The injection size recommended in the analytical procedure (1 µL) was used in the determination of the reliable quantitation limit.
Table 4.2.
Reliable Quantitation Limit Datasample
numbercalibration
method*
Istdmass (mg)
spikedmass (mg)
recovered%
recovered1
8
14
21
31
35
39
47
51
60
65
70
76
83#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5
#4
#5yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no0.789
0.789
0.789
0.789
0.789
0.789
0.789
0.789
0.777
0.777
0.777
0.777
0.777
0.777
0.777
0.777
0.753
0.753
0.753
0.753
0.753
0.753
0.753
0.753
0.754
0.754
0.754
0.754
0.754
0.754
0.754
0.754
0.779
0.779
0.779
0.779
0.779
0.779
0.779
0.779
0.761
0.761
0.761
0.761
0.761
0.761
0.761
0.761
0.776
0.776
0.776
0.776
0.776
0.776
0.776
0.7760.873
0.823
0.773
0.762
0.847
0.806
0.751
0.746
0.812
0.779
0.930
0.863
0.753
0.778
0.845
0.845
0.643
0.663
0.703
0.689
0.684
0.696
0.748
0.723
0.658
0.552
0.602
0.529
0.655
0.715
0.609
0.685
0.828
0.823
0.825
0.821
0.820
0.810
0.818
0.809
0.793
0.778
0.816
0.788
0.824
0.793
0.831
0.819
0.900
0.949
0.838
0.845
0.851
0.912
0.792
0.815111
104
98
96
107
102
95
95
104
100
120
111
97
100
109
109
85
88
93
92
91
92
99
96
87
73
80
70
87
95
81
91
106
106
106
105
105
104
105
104
104
102
107
102
108
104
109
108
116
122
108
109
110
117
102
105X = 100.7%
SD = 10.76
1.96 SD = 21.09%*Explanation of calibration methods under Table 4.8.2. - Precision and Sensitivity
- The precision of the analytical method was determined by replicate injections of analytical standards prepared at 0.5, 1, and 2 times the target concentration. The pooled coefficient of variation is 0.019.
Table 4.3.1.
Precision of Analytical Method× target conc. 0.5×
1×
2×
area counts 1322304
1272435
1328744
1350244
1377105
13817082761497
2731651
2757576
2735224
2731653
26933285482172
5394150
505614
5451850
5466193
5413149X
SD
CV1338756
40538
0.0302735155
24375
0.00895452188
42052
0.0077CV = 0.019 - The precision of the overall procedure was calculated by taking the average of the SDs for methods #4 and #5 (both Istd and Estd) from Table 4.8.1. and multiplying by 1.96. This number includes ±5% for sampling error. The usual value on the cover page is the standard error of estimate from the storage test but in this evaluation this value would not have included variability for using different PDFs for analytical standards.
- Sensitivity is defined as the slope of the calibration curve for analytical standards from 0.5 to 2 times the target concentration. (Table 4.3.1., Figure 4.3.2.) The sensitivity is 300954 area counts/(mg/mL). The sensitivity will change depending on the detector and method of integration.
- The precision of the analytical method was determined by replicate injections of analytical standards prepared at 0.5, 1, and 2 times the target concentration. The pooled coefficient of variation is 0.019.
- Breakthrough
- Breakthrough was determined by sampling a dynamically generated test atmosphere of Stoddard solvent (about 2900 mg/m3 with 76% RH at 23°C), using a charcoal tube containing only the 100-mg portion of charcoal and monitoring the concentration of Stoddard solvent in the air which had passed through the charcoal.
Five-percent breakthrough is defined as the point during this sampling when the air exiting the charcoal tube has a concentration of Stoddard solvent that is 5% of the test atmosphere. Two tests were performed, with 5% breakthrough air volumes of 6.5 L and 7.3 L and capacities of 19.1 mg and 21.5 mg being obtained respectively. The average 5% breakthrough air volume was 6.9 L and capacity was 20.3 mg. (Fig. 4.4.) - Breakthrough tests were also performed using a petroleum distillate bulk since its boiling range is lower than Stoddard solvent and it contains more volatile constituents. The test atmospheres were about 2000 mg/m3 with 74% RH at 23°C. Three tests were performed, with 5% breakthrough air volumes of 9.6, 9.1 and 9.5 L and capacities of 20.82, 19.73 and 19.95 mg being obtained respectively. The average capacity was 20.3 mg and the average 5% breakthrough air volume was 9.4 L.
- Breakthrough was determined by sampling a dynamically generated test atmosphere of Stoddard solvent (about 2900 mg/m3 with 76% RH at 23°C), using a charcoal tube containing only the 100-mg portion of charcoal and monitoring the concentration of Stoddard solvent in the air which had passed through the charcoal.
- Desorption efficiency
Desorption efficiencies were determined by injecting known amounts of Stoddard solvent onto the 100-mg portion of six charcoal tubes, allowing them to sit overnight and analyzing the tubes on the next day. The average desorption efficiency over the range of 0.08 to 2 times the target concentration is 100%.
Table 4.5.
Desorption Efficiencies× target conc.
µg/sample0.08×
0.760.5×
4.551×
9.12×
18.6desorption
efficiency,
%
X
X = 100%103
102
99
102
100
103
102100
101
102
102
101
101
101100
100
100
101
101
101
10199
99
98
95
96
94
97 - Storage data
Thirty-six samples were collected from a dynamically generated atmosphere of Stoddard solvent. The atmosphere was approximately 2900 mg/m3 and 75% RH at 22°C. Of these 36 samples, six were analyzed immediately, while the remaining 30 were stored; 15 at ambient temperature and 15 at -5°C. Approximately every third day, 3 samples from each of the storage sets were analyzed. The average recovery was 96% for ambient storage and 97% for refrigerated storage. The data of Table 4.6. are shown graphically in Figures 4.6.1. and 4.6.2.
Table 4.6.
Storage Testsstorage time
(days)% recovery
(refrigerated)% recovery
(ambient)0
3
7
11
13
1999
96
96
97
96
9799
97
97
96
96
9999
96
97
96
96
9797
95
95
95
95
9899
96
96
96
96
96100
96
97
97
96
96 - Reproducibility data
Six samples, spiked by liquid injection, and a draft copy of this procedure were given to a chemist unassociated with this evaluation. The samples were analyzed after 3 days of storage at 22°C. The average recovery was 97.7% with a standard deviation of ±3.53%.
Table 4.7.
Reproducibility Resultsamount spiked (µg)
amount recovered (µg)
% recovered
7756
7756
7756
7756
7756
77567432
7510
7443
7493
7466
813695.8
96.8
95.8
96.6
96.3
104.9
X = 97.7
SD = 3.53 - Quantitation factors
- A total of 96 samples were used to evaluate differences between source and
non-source PDF, automatic baseline set and controlled baseline set, and internal and external standard procedures. They were prepared by liquid injection of each of 8 PDFs on 12 charcoal tubes. These 8 sets were prepared at different times. Each set and an aliquot of the source PDF were given to the branch of this laboratory which routinely analyzes samples for PDF. The samples were desorbed with a CS2/Istd solution and analytical standards were prepared in the same solution from the source PDF and anon-source PDF chosen by the analyst. The data for these standards and samples was quantitated with nine different calibration methods. Explanations of these calibration methods are given at the bottom of Table 4.8.2. Both internal and external standard procedures were used for calibration methods #1-5. For the external standard procedure, the peak from the internal standard was ignored in all the calculations. The results from these 8 sets of PDF samples are presented in Tables 4.8.2. 4.8.9., each table represents the data from one PDF. Table 4.8.1. summarizes the data as average percent recoveries for all PDFs analyzed with each calibration method using internal and external standard procedures. For all calibration methods except #3 the summation of the peak areas for the constituents of the PDF was used to determine the response factors. Method #3 used the peak area of the largest peak in the PDF for determination of the response factors. - The six analytical standards were analyzed at the same time as the samples. A linear least squares fit for each set of standards was used in all of the calibration methods except methods #3, #8 and #9. In these cases only one standard was used for calibration. Source PDF was used with calibration methods #1, #4, #6 and #8. By comparing the average results and the standard deviations obtained for method #1 to #2, #4 to #5, #6 to #7, and #8 to #9 in Table 4.8.1., it can be seen that there is no significant difference in the results; therefore, source or
non-source PDF may be used to prepare analytical standards. - An internal standard was present in all of the samples used but results were calculated both with the internal standard correction and without it for calibration methods #1 through #5. (Tables 4.8.1. to 4.8.9.). For all of the analyses, automatic liquid sampling devices were used with a single injection of each sample. At the bottom of Table 4.8.1. are the average results for all the PDFs using all the calibration methods calculated with both the internal standard (Istd) and external standard (Estd) procedures. From this data there appears to be no real difference between the results using the Istd correction and not (Estd). The use of an internal standard is left to the judgment of the analyst since the lengthening of the analysis and possible interferences caused by an internal standard compound will be different for each set of samples.
- Three different techniques of setting the baseline during analysis were investigated. One technique was to allow the data system (Hewlett-Packard 3357) to calculate the baseline and set it automatically. The other techniques require the analyst to control the baseline by using either a basic program to set the baseline and integrate the area under the chromatogram or an "integrate function" built into the data system to set the baseline.
- At lower concentrations of PDFs, the technique of allowing the data system to automatically set the baseline produced inconsistent results. (Figure 4.8.1. and 4.8.2.) This may be due to a parameter in the data system termed "slope sensitivity", but since single analytes are often requested in addition to PDF, setting the slope sensitivity for PDF may not be accurate for the single analytes. Calibration methods #6, #7, #8 and #9 used this technique (Tables 4.8.1. - 4.8.9.). The results in Table 4.8.1. are the average recoveries for each calibration technique with the 8 different PDFs. As can be seen in this table, the percent recoveries for each separate PDF using calibration methods #6, #7, #8 and #9 ranged from
28-143%. The average results listed at the bottom of the table for all PDFs using these four calibration methods ranged from 74-103%. Methods #6 and #7 used a linear least squares fit for calibration while methods #8 and #9 used a one point calibration. The linear least squares fit does provide results (103 and 96%) closer to the expected value but the standard deviation is larger than for methods #1-#5 in which the baseline is controlled. Therefore, controlling the baseline is recommended. - Calibration methods #1 and #2 used a basic program for baseline setting and integration. This basic program was written to be used after analyzing the standards, blanks and samples. The raw data collected during an analysis is in the form of area slices which are simply detector voltages taken and stored every 0.5 s. The analyst enters into the basic program the time span over which the PDF constituents elute. The program saves the value of the first area slice in the analytical run to be used as the baseline and when the start time of the PDF is reached the program subtracts the baseline area slice from all the area slices in the specified time span and sums the differences. This summation is used as the area of PDF constituents. This program integrated the area above the baseline but not as individual peaks. The average recoveries are presented in Table 4.8.1. Since this program did not have any peak detection routine, it would not differentiate between a rise in the baseline due to a peak and column bleed. Therefore, if the baseline was not consistent and PDF constituents were eluting from the column at these times, area may be added to the PDF area which was caused by column bleed and not PDF constituents. This technique of baseline control is not recommended.
- The two evaluated integrate functions which control the baseline were "hold the baseline" (Figure. 4.8.2.) and "valley reset" (Figure 4.8.4.). The "valley reset" function resets the baseline every time the data system detects a zero slope or a switch from negative to positive slope of the detector output. This function is performed by the data system with start and stop times entered by the analyst. Calibration method #3 used this function and the area of the largest peak for calibration of a response factor. As can be seen in Table 4.8.1., the average results for all the PDFs analyzed with method #4 were 102(±2.3)% with the internal standard procedure and 102(±4.1)% with the external standard procedure. Comparing these results to those of the other calibration methods, method #4 is the most accurate. However, this method requires that the source PDF be used as analytical standards because the ratio of the area of the chosen peak to the others in the PDF must be constant.
- The "hold the baseline" function simply records the detector voltage at a certain time during the analysis and maintains that as the baseline until the function is canceled. The time to start this function is slightly before the PDF constituents begin to elute and the time to cancel it is after the constituents have eluted or when column bleed becomes significant. Both of these times are set by the analyst. After the function is canceled, the data system is free to set the baseline and it usually does correct for baseline drift due to column bleed; therefore, excess area is not added to the PDF as it was with the basic program. Calibration methods #4 and 5 used this technique. The average results and standard deviations for all PDFs for these two methods given at the bottom of Table 4.8.1. are better than the other calibration methods except #3, although this calibration method (#3) requires the use of source PDF in preparing analytical standards. Therefore, using the integrate function of "hold the baseline" is recommended and a linear least squares fit of the standards should be used to quantitate the samples.
- At lower concentrations of PDFs, the technique of allowing the data system to automatically set the baseline produced inconsistent results. (Figure 4.8.1. and 4.8.2.) This may be due to a parameter in the data system termed "slope sensitivity", but since single analytes are often requested in addition to PDF, setting the slope sensitivity for PDF may not be accurate for the single analytes. Calibration methods #6, #7, #8 and #9 used this technique (Tables 4.8.1. - 4.8.9.). The results in Table 4.8.1. are the average recoveries for each calibration technique with the 8 different PDFs. As can be seen in this table, the percent recoveries for each separate PDF using calibration methods #6, #7, #8 and #9 ranged from
- Recommendations
For analysis of petroleum distillate fractions, either the source PDF (Section 3.3.2.) or a
non-source PDF may be used to prepare analytical standards. It is recommended that the baseline be controlled with the "hold the baseline" integrate function during elution of the PDF constituents or until column bleed becomes significant whichever occurs first. Finally, either internal standard or external standard may be used with no loss in accuracy or precision.Table 4.8.1.
Average Percent Recoveries
Calculated from Tables 4.8.2. to 4.8.9.(see notes) calibration methods
table Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
4.8.2. yes
105
96
104
107
95
97
92
100
93
no
103
95
100
102
95
x
x
x
x
4.8.3. yes
106
115
104
100
111
99
101
110
110
no
108
115
104
106
109
x
x
x
x
4.8.4. yes
109
104
99
91
99
93
113
91
93
no
115
106
103
94
98
x
x
x
x
4.8.5. yes
103
102
104
90
83
110
93
93
91
no
103
105
102
87
83
x
x
x
x
4.8.6. yes
99
97
100
104
103
95
84
75
75
no
98
96
99
103
103
x
x
x
x
4.8.7. yes
100
95
104
103
104
107
110
31
32
no
99
97
100
100
102
x
x
x
x
4.8.8. yes
95
91
100
106
99
143
100
29
28
no
104
93
109
114
101
x
x
x
x
4.8.9. yes
119
125
100
99
100
83
73
67
73
no
135
135
95
95
95
x
x
x
x
X(PDFs-Istd) 105
103
102
100
99
103
96
74
74
SD 7.3
11.5
2.3
6.4
8.1
18.0
13.2
30.6
29.7
X(PDFs-Estd) 108
105
102
100
98
x
x
x
x
SD 12.1
14.1
4.1
8.2
7.7
x
x
x
x
notes:
1.) Explanation of Calibration methods under table 4.8.2.
2.) Istd column: "yes" indicates internal standard was used; "no" indicates an external standard procedure used.
3.) "x" under calibration methods #6, 7, 8 9 indicates no data was collected with an external standard procedure.Table 4.8.2.
Percent Found for Stoddard solvent A(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
1
789
yes
104
96
102
111
98
96
91
101
93
no
102
93
97
104
96
x
x
x
x
2
3159
yes
101
94
103
106
94
99
93
102
94
no
100
92
98
100
93
x
x
x
x
3
4739
yes
102
94
104
107
95
99
92
101
93
no
101
94
100
103
95
x
x
x
x
4
237
yes
120
103
107
109
97
91
87
96
88
no
108
98
102
101
94
x
x
x
x
5
6318
yes
103
94
104
104
93
103
96
104
96
no
101
94
101
101
93
x
x
x
x
6
3159
yes
102
95
105
105
94
102
102
105
9
no
103
95
101
101
94
x
x
x
x
7
6318
yes
103
94
104
106
94
101
93
102
94
no
101
95
101
103
95
x
x
x
x
8
789
yes
102
94
101
107
95
91
86
95
88
no
100
92
97
102
95
x
x
x
x
9
4739
yes
103
95
105
107
95
102
95
104
96
no
103
95
102
104
96
x
x
x
x
10
2369
yes
102
95
104
108
96
97
92
101
93
no
103
95
101
104
97
x
x
x
x
11
237
yes
115
99
105
104
92
86
81
90
83
no
105
95
101
99
91
x
x
x
x
12
2369
yes
104
97
106
110
98
99
94
97
95
no
106
97
104
107
99
x
x
x
x
notes:
1.) Calibration method #1 uses as analytical standards the source PDF, the basic program for peak integration and area summation of the standards for calibration.
2.) Calibration method #2 uses as analytical standards anon-source PDF, otherwise the same as #1.
3.) Calibration method #3 uses the source PDF, "valley reset" for peak integration and a single peak in the standards for calibration.
4.) Calibration method #4 uses as analytical standards the source PDF, "hold the baseline" for peak integration and area summation of standards for calibration.
5.) Calibration method #5 uses as analytical standards anon-source PDF, otherwise the same as #4.
6.) Calibration method #6 uses as analytical standards the source PDF, the data system sets the baseline for peak integration, and area summation of standards for calibration.
7.) Calibration method #7 uses as analytical standards anon-source PDF, otherwise the same as #6.
8.) Calibration method #8 uses as analytical standards the source PDF, the data system sets the baseline for peak integration, and area summation of only one standard for calibration.
9.) Calibration method #9 uses as analytical standards anon-source PDF, otherwise the same as #8.Table 4.8.3.
Percent Found for Stoddard Solvent B(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
13
3109
yes
112
119
111
116
128
103
95
103
103
no
107
114
106
111
118
x
x
x
x
14
777
yes
111
120
108
104
120
125
122
137
136
no
108
116
103
100
111
x
x
x
x
15
233
yes
122
141
103
89
96
79
132
136
136
no
117
125
94
lost
89
x
x
x
x
16
5440
yes
106
113
106
106
117
107
98
105
105
no
104
110
104
104
112
x
x
x
x
17
7772
yes
106
114
104
105
116
107
103
106
105
no
104
110
103
105
112
x
x
x
x
18
233
yes
107
125
103
79
78
55
101
114
113
no
108
116
103
lost
76
x
x
x
x
19
4663
yes
101
108
101
lost
113
99
89
98
98
no
107
114
106
107
115
x
x
x
x
20
3109
yes
100
106
100
99
114
97
86
97
97
no
109
116
107
106
119
x
x
x
x
21
777
yes
99
108
100
97
109
105
102
118
118
no
104
112
103
100
109
x
x
x
x
22
7772
yes
104
112
103
104
114
105
101
104
104
no
106
113
107
108
115
x
x
x
x
23
5440
yes
103
110
104
104
115
104
95
103
103
no
110
117
111
111
119
x
x
x
x
24
4663
yes
100
107
101
102
113
99
89
98
98
no
107
114
108
108
116
x
x
x
x
note: Explanation of calibration methods under Table 4.8.2. Table 4.8.4.
Percent Found for V.M.&P. Naphtha A(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
25
7528
yes
103
102
104
89
98
102
104
102
104
no
120
105
106
94
98
x
x
x
x
26
5270
yes
102
104
103
89
97
101
105
102
104
no
112
107
107
95
99
x
x
x
x
27
7528
yes
106
104
107
92
100
105
107
105
107
no
119
105
106
94
98
x
x
x
x
28
1506
yes
106
107
98
92
100
93
105
93
95
no
110
109
105
98
102
x
x
x
x
29
3011
yes
100
103
97
88
96
98
104
98
100
no
106
106
104
94
98
x
x
x
x
30
226
yes
172
119
96
100
110
72
148
65
66
no
177
121
101
100
102
x
x
x
x
31
753
yes
98
99
94
85
93
88
111
86
88
no
99
99
99
88
92
x
x
x
x
32
5270
yes
99
102
101
88
96
101
103
100
102
no
106
103
103
92
96
x
x
x
x
33
753
yes
101
103
94
91
99
91
114
89
91
no
101
102
98
92
96
x
x
x
x
34
1506
yes
100
106
98
92
100
93
105
93
95
no
103
108
105
97
101
x
x
x
x
35
226
yes
124
103
95
97
106
71
146
64
65
no
126
103
99
93
96
x
x
x
x
36
3011
yes
97
103
98
89
97
98
104
98
100
no
103
106
105
95
99
x
x
x
x
note: Explanation of calibration methods under Table 4.8.2. Table 4.8.5.
Percent Found for V.M.&P. Naphtha B(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
37
3768
yes
103
98
106
96
88
103
98
101
99
no
95
93
97
86
83
x
x
x
x
38
6029
yes
102
100
110
96
87
103
99
103
101
no
95
98
97
86
82
x
x
x
x
39
754
yes
102
100
101
87
80
106
84
87
85
no
94
94
93
73
70
x
x
x
x
40
2261
yes
106
100
105
97
89
100
92
95
93
no
99
95
98
88
85
x
x
x
x
41
301
yes
95
109
100
72
66
111
54
58
57
no
90
106
94
52
50
x
x
x
x
42
4522
yes
101
97
102
92
85
100
97
100
98
no
104
105
104
94
90
x
x
x
x
43
3768
yes
104
99
105
94
86
104
99
102
100
no
107
106
107
96
86
x
x
x
x
44
2261
yes
106
99
104
95
87
102
95
97
95
no
109
104
108
98
94
x
x
x
x
45
301
yes
113
124
101
77
70
127
70
74
73
no
117
129
105
79
75
x
x
x
x
46
6028
yes
102
100
111
95
87
103
100
103
101
no
107
114
110
98
94
x
x
x
x
47
754
yes
106
104
191
87
81
157
133
89
87
no
113
111
108
95
91
x
x
x
x
48
4522
yes
103
97
106
94
86
103
99
102
100
no
109
111
112
100
95
x
x
x
x
note: Explanation of calibration methods under Table 4.8.2. Table 4.8.6.
Percent Found for Stoddard Solvent D(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
49
3897
yes
99
99
101
100
98
100
90
88
88
no
98
97
98
98
97
x
x
x
x
50
6235
yes
99
98
101
98
98
94
88
88
88
no
97
96
99
97
97
x
x
x
x
51
779
yes
96
92
97
106
106
96
78
61
61
no
95
91
96
106
105
x
x
x
x
52
545
yes
92
87
95
105
105
105
82
59
59
no
91
85
94
104
104
x
x
x
x
53
6235
yes
100
99
102
99
98
95
88
89
88
no
100
99
102
99
99
x
x
x
x
54
2338
yes
102
101
102
106
105
109
95
89
89
no
100
99
100
104
104
x
x
x
x
55
545
yes
99
94
101
112
112
69
82
60
60
no
98
93
100
112
112
x
x
x
x
56
3897
yes
101
100
102
101
100
101
91
89
89
no
100
100
101
100
100
x
x
x
x
57
1559
yes
100
99
101
105
105
94
79
70
70
no
101
99
101
106
105
x
x
x
x
58
2338
yes
101
100
101
103
102
89
77
71
71
no
100
99
100
101
101
x
x
x
x
59
1559
yes
100
98
101
105
104
93
79
70
70
no
102
100
102
107
106
x
x
x
x
60
779
yes
100
96
100
105
105
99
80
63
63
no
767
739
769
810
809
x
x
x
x
note: Explanation of calibration methods under Table 4.8.2. Table 4.8.7.
Percent Found for Stoddard Solvent D(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
61
3045
yes
102
100
102
103
102
102
104
34
34
no
96
100
96
98
103
x
x
x
x
62
3045
yes
102
101
102
104
103
102
104
34
34
no
96
101
97
98
103
x
x
x
x
63
6853
yes
103
102
104
102
102
103
105
34
34
no
100
101
99
98
102
x
x
x
x
64
1523
yes
98
94
96
101
104
100
102
30
31
no
97
98
94
100
101
x
x
x
x
65
761
yes
97
89
99
104
107
114
116
29
30
no
100
92
97
102
104
x
x
x
x
66
533
yes
99
87
119
107
110
125
127
28
28
no
106
90
117
105
106
x
x
x
x
67
6853
yes
99
97
100
98
101
98
100
33
33
no
98
99
97
96
97
x
x
x
x
68
533
yes
99
87
100
107
108
125
127
28
29
no
105
88
96
103
106
x
x
x
x
69
1523
yes
98
94
101
101
103
100
102
30
31
no
96
97
97
98
100
x
x
x
x
70
761
yes
101
93
119
108
109
117
119
30
31
no
102
94
115
104
108
x
x
x
x
71
4568
yes
100
99
99
100
101
99
102
33
34
no
9699
95
96
99
x
x
x
x
72
4568
yes
100
98
104
100
102
99
101
33
34
no
96
100
100
97
99
x
x
x
x
note: Explanation of calibration methods under Table 4.8.2. Table 4.8.8.
Percent Found for Stoddard solvent E(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
73
7756
yes
104
94
103
99
92
106
102
35
34
no
108
96
111
106
94
x
x
x
x
74
2327
yes
103
98
103
103
95
153
105
35
34
no
110
100
112
109
97
x
x
x
x
75
3878
yes
104
97
102
100
93
132
102
35
34
no
110
98
111
106
95
x
x
x
x
76
776
yes
89
88
96
116
108
139
77
17
16
no
99
88
103
122
109
x
x
x
x
77
5429
yes
101
94
102
97
90
116
98
34
32
no
108
96
109
104
93
x
x
x
x
78
7756
yes
102
93
101
96
89
103
97
33
32
no
110
97
112
106
94
x
x
x
x
79
388
yes
78
81
99
130
125
206
112
17
16
no
91
80
106
140
126
x
x
x
x
80
3878
yes
101
94
103
98
91
129
99
34
33
no
108
97
110
105
94
x
x
x
x
81
5429
yes
102
94
103
99
92
118
100
35
33
no
111
99
112
109
97
x
x
x
x
82
2327
yes
100
96
102
101
94
151
109
34
33
no
110
99
112
108
97
x
x
x
x
83
776
yes
84
83
95
110
102
170
97
24
23
no
96
86
104
117
105
x
x
x
x
84
388
yes
77
79
98
122
114
199
108
16
15
no
92
80
107
132
118
x
x
x
x
note: Explanation of calibration methods under Table 4.8.2. Table 4.8.9.
Results for Mineral Spirits A(see notes)
calibration methods
sample
µg
Istd
#1
#2
#3
#4
#5
#6
#7
#8
#9
85
7673
yes
109
113
106
101
106
103
99
94
100
no
100
98
88
91
90
x
x
x
x
86
230
yes
186
200
108
90
88
57
109
43
46
no
270
275
98
82
94
x
x
x
x
87
1534
yes
149
158
119
129
135
110
93
86
92
no
144
145
107
119
117
x
x
x
x
88
5371
yes
107
110
103
102
107
100
92
86
92
no
115
113
106
108
107
x
x
x
x
89
7673
yes
106
110
103
96
101
107
104
99
106
no
116
113
107
102
101
x
x
x
x
90
537
yes
210
224
65
123
114
50
40
37
40
no
226
228
67
108
106
x
x
x
x
91
2302
yes
110
115
104
104
107
89
76
70
75
no
112
112
101
102
99
x
x
x
x
92
1534
yes
107
113
106
106
108
91
76
70
75
no
112
112
103
103
102
x
x
x
x
93
537
yes
61
65
71
62
56
39
32
30
31
no
73
74
64
54
54
x
x
x
x
94
230
yes
82
89
106
72
78
45
36
33
35
no
143
149
96
67
66
x
x
x
x
95
5371
yes
99
103
101
93
97
110
101
95
102
no
106
105
106
99
97
x
x
x
x
96
2302
yes
104
110
106
106
110
90
77
71
76
no
103
103
104
104
102
x
x
x
x
note: Explanation of calibration methods under Table 4.8.1.
- A total of 96 samples were used to evaluate differences between source and
Figure 3.5.1. Chromatogram of PDF standard.
Figure 4.3.2. Sensitivity.
Figure 4.4. Breakthrough curve.
Figure 4.5. Desorption efficiencies.
Figure 4.6.1. Ambient storage.
Figure 4.6.2. Refrigerated storage.
Figure 4.8.1. Automatic baseline set.
Figure 4.8.2. Automatic baseline set.
Figure 4.8.3. Controlled baseline with "hold the baseline" function.
Figure 4.8.4. Controlled baseline with "valley reset" function.
- Detection limits of the analytical and overall procedure
- References
- "Criteria for a Recommended Standard...Occupational Exposure to Refined Petroleum Solvents"; Department of Health, Education and Welfare, National Institute for Occupational Safety and Health: Cincinnati, OH, 1977 (DHEW) (NIOSH) Publ. (U.S.) No. 77-192.
- "NIOSH Manual of Analytical Methods", 2nd ed.; Department of Health, Education and Welfare, National Institute for Occupational Safety and Health: Cincinnati, OH, 1977; Vol. 3, Methods S380 and S382; DHEW (NIOSH) Publ. (U.S.) No. 77-157-C.
- Drushel, Harry V. Journal of Chromatographic Science. 21, August 1983, p 375.
- "Occupational Health Guideline for Stoddard Solvent", Department of Health and Human Services, National Institute for Occupational Safety and Health: U.S. Government Printing Office, Washington, D.C., 1978; Publ. 81-123.
- "Occupational Health Guideline for Petroleum Distillates", Department of Health and Human Services, National Institute for Occupational Safety and Health: U.S. Government Printing Office, Washington, D.C. 1978; Publ. 81-123.