The Analytical Approach
Ralph L. Campbell Ruth Zuback The Standard Oil Company 4440 Warrensville Center Road Cleveland, Ohio 44128
Edited by Jeanette G. Grasselli
Search for the Elusive Phosphorus Source As p a r t of the Research and Devel o p m e n t Division of Sohio, our Petrole u m Tech Service Group can expect to receive samples and problems from nearly all of the operating petroleum divisions. Occasionally, we discover problems ourselves as a result of regu lar quality assurance audits; others are brought to our attention by alert field engineers engaged in special surveys. T h i s was the case in February 1976, when Sohio was about to take over op eration of Ohio T u r n p i k e service sta tions. At t h a t time, a quality audit conducted by our field engineers indi cated t h a t a n u m b e r of unleaded gaso line samples from p u m p s at several of t h e plazas had phosphorus concentra tions exceeding the EPA-regulated maximum of 0.005 g/gal. This situa tion was of considerable concern since a concerted and costly effort had been m a d e early in 1974 to ensure t h a t no lead or phosphorus, which might dam age automobile catalytic converter an tipollution devices, could find its way into the company's gasoline delivery system. T o track down t h e source of the contamination, the Sales Tech Divi sion (Sohio's Scotland Yard) assigned one of its crack sleuths well versed in t h e ways of analytical chemistry. I t d i d n ' t take him long to conclude t h a t the phosphorus results were correct and the problem was real. Preliminary analyses of a group of selected samples (see Table I) indicated fuels from p u m p s in intermittent service had variable and high (0.05 g/gal) phos phorus concentrations while samples from high-service p u m p s were consis tently low. Suspecting t h a t the gaso line p u m p dispensing hoses might be the source of the phosphorus, our de tective asked the lab for a series of leaching studies comparing hoses from the current supplier with those from other manufacturers. A preliminary examination was made of two similarly identified hose samples from warehouse storage. We found t h a t hose construction varied, t h a t phosphorus was present in the hose materials, and t h a t phosphorus could be extracted from the hoses by 0003-2700/80/A351-1573$01.00/0 © 1980 American Chemical Society
H
H
B
H
B
M
|
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Table 1. Phosphorus in Unleaded Fuel Samples from Ohio Turnpike Plazas Sample source
Operation
Underground tank
—
Island 1 Pump A Pump Β PumpC
Closed
Island 2 Pump A
Closed
Island 3 Pump A Pump Β
In use
Island 4 Pump A Pump Β PumpC
Closed
p
. g/gai
0.004 0.400 0.072 0.354 0.186 0.0001 0.0003 0.140 0.840 0.154
unleaded gasoline after an extended residence time. These results, shown in Tables II and III, confirmed the suspicion t h a t the p u m p hose could be considered a prime source of high phosphorus. A leach test was then designed to compare t h e weathering of gasoline p u m p hoses from a number of manu facturers. Our goals were to furnish our purchasing people with data to help t h e m make knowledgeable hose selections in the future, and to com pile evidence with which to confront the hose supplier. A quality control program for testing gasoline dispens ing hoses was also recommended as a result of this study.
Experiment I In our first controlled test, two sam ples of hose from the supplier (Codes " X - l " and "X-2") and three from other manufacturers (Codes " U , " "V," a n d " W " ) were examined. Six-foot sections of each hose were filled with
Figure 1 . Comparison of leached fuel from hose "X" with base ANALYTICAL CHEMISTRY, VOL. 52, NO. 14, DECEMBER 1980 · 1573 A
unleaded gasoline and suspended in a U shape with both ends plugged. After a week at room temperature the fuel was removed and tested for API gravi ty, SIMDIS (simulated distillation by gas chromatography [GC]), Ρ, Ζη, Μη, Pb, S, and color. The used hoses were rinsed with unleaded gasoline, filled again with fresh fuel, and allowed to soak for a second week. This fuel was subjected to the same tests as the first weeks's leach fuel. Gravity and SIMDIS were run to determine whether significant boiling range changes had occurred during fuel residence in the hose. Leaching of phosphorus, sulfur, and zinc was mon itored because these elements had been found in the hose construction materials. Lead concentration was of interest because of the EPA-regulated maximum of 0.05 g/gal. Also, at that time an organo-manganese additive was being used in unleaded gasoline, and we were interested in its fate. Lead and zinc were determined by atomic absorption spectrometry (AA), sulfur and manganese by X-ray fluo rescence spectrometry (XRF), and phosphorus by the ASTM D3231 spec trometric procedure. The GC simu lated distillation was done according to the ASTM D3710 procedure. In frared spectrometry was used in mak ing qualitative identifications of high boiling materials isolated during the GC runs. Hose materials were exam ined by scanning electron microscopy (SEM) using the X-ray emission mode. The data we obtained indicated that S, Ζη, Ρ, and some high boiling materials were leached out of all the hose samples during the first test week and that lesser amounts were leached the second week. The "U"
Table II. Preliminary Gasoline Dispensing Hose Leach Test, March 1976 Analysis of unleaded test fuel After one week Untreated residence In fuel new hose 1
P, g/gal Distillation IBP, °F 10% Rec. at°F 9 0 % Rec. at°F FBP, °F
.003
0.20
95 (Typical) 118
95 118
339
420
416
605
1
" X " Soft Flex, sample 1 IBP = initial boiling point; Rec. = ; recovered; FBP = final boiling point.
hose sample was least affected, phos phorus levels in the test fuels increas ing only to 0.002 g/gal. The highest levels of phosphorus, 0.4 g/gal, were leached from the two " X " hose sam ples. Sulfur, zinc, and high boiling ma
terials followed the same pattern as phosphorus concentration. Discolora tion of the test fuel also increased with phosphorus concentration and was an instant indicator of hose deterioration. No significant variations in lead and managanese levels were noted. Experiment II A second leach test was run two months later to confirm results from the first experiment, to standardize test conditions, and to examine a re vised formula hose submitted by one of the manufacturers. In addition to unleaded gasoline, a synthetic fuel (30% toluene, 70% isooctane) was used as a leach fuel. This was done at the request of one of the hose manufacturers who was con cerned about possible effects of gaso line additives. Duplicate leach tests using un leaded gasoline were run with fresh samples of "U" and revised-formula "X" hoses, and single tests were done with the synthetic fuel. A single test with unleaded gasoline was run on a
Table III. Preliminary Gasoline Dispensing Hose Leach Test, March 1976 Phosphorus In gasoline dispensing hose Unused h o s e 1 Used h o s e 2
Outside black rubber layer, wt % Ρ Inside black rubber layer, wt % Ρ Red rubber inner layer, wt % Ρ Fibers from inner layer, wt % Ρ Total wt. % Ρ 1
" X " Soft Flex, s a m p l e 2
2
" X " Soft Flex, s a m p l e 1
.0169 .0207 (no red layer) .0086 .0376
.0479 .0359 .0505 .0291 .1343
Table IV. Gasoline Dispensing Hose Leach Test, Experiment II Base
Hose
Synthetic f u e l 1 ••U"
U n l e a d e d gasoline "X"
A
Replicate 3
Week no. API Grav. SIMDIS IBP, °F 9 6 % Rec. a t ° F 9 8 % Rec. at °F FBP, °F Est. % >450 °F P, g/gal 4 Zn, ppm 5 Mn, g/gal 6 Pb, g/gal 5 S, Wt % 6 Color 2 IR ID, > 4 5 0 °F 1
1 58.2
2 58.3
1 57.0
2 58.3 61.0
193 242 243 244
193 243 797 804 4
195 242 243 800 2
192 675 678 682 10
193 241 407 675 4
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