Bureau of Mines Report of Investigations/l978 

Gas-Sampling Capability 

of Vacutainers 

UNITED STATES DEPARTMENT OF THE INTERIOR 
UNITED STATES DEPARTMENT OF THE INTERIOR 

Cecil D. Andrus, Secretary 

BUREAU OF MINES 
This publication has been cataloged as follows: 

L 

Freedman, Robert W 

Gas-sampling capability of Vacutainers / by Robert W. 

Freedman, Benjamin I. Ferber, and Wayne H. Duerr. [Washington] : U.S. Dept. of the Interior, Bureau of Mines, 1978. 

6 p. t ill., diagrams ; 27 cm. (Report of investigations - Bureau 

of Mines ; 8281) 

Includes bibIiographies. 

1. Mine gases - Measurement. 2. Mine safety - Equipment and 

supplies, I. Ferber, Benjamin I., joint author. 11. Duerr, Wayne H., 

joint author. 111. United States. Bureau of Mines. IV. 'ritle. V. 

Series: United States. Bureau of Mines, Report of investigations - 

Bureau of Mines ; 8281. 

TN23.U7 no. 8281 622.06173 

U.S. Dept. of the Int. Library 
CONTENTS 

Page 

Abstract ................................................................ 1 

Introduction . ...................................................... 1 

Acknowledgment .......................................................... 2 

Experimental procedure .................................................. 2 

Results and discussion .................................................. 4 

Conclusions ............................................................. 6 

ILLUSTRATIONS 

1 . Evacuation chamber .................................................. 3 

2 . Concentration change of hydrocarbons during storage ................ 5 

3 . Effect of ethylene oxide treatment prior to storage of evacuated 

Vacutainers ....................................................... 5 

TABLES 

1 . Concentrations of gases accumulating in 10- and 30-ml Vacutainers at 

25' C ............................................................. 4 

2 . Effect of storage of gas for 41 days (20 samples) ................... 4 
GAS-SAMPLING CAPABILITY OF VACUTAINERS 

Robert W, Freedman, 1 Benjamin I. Ferber,2 

and Wayne Ha Duerr3 

ABSTRACT 

Vacutainers are employed by the Bureau of Mines and the Mining Enforcement and Safety Administration for sampling mine air and other atmospheres 

containing fixed gases, low-molecular-weight hydrocarbons, and products of 

combustion. Tests were conducted to study shelf life of evacuated samplers 

prior to sampling and also to check the stability of sampled gases prior to 

analysis. An unexplained phenomenon, slow accumulation of carbon monoxide in 

evacuated samplers, occurred after a few weeks' storage; levels were low but 

increased with time and could pose a problem for critical applications. 

Accordingly, attempts to halt CO release by additional means of treatment were 

made, and storage at low temperature was found to be effective. 

INTRODUCTION 

Onsite sampling of ambient atmospheres is generally accomplished by gastight syringes, evacuated vessels, and plastic bags. vacutainersj4 normally 

employed for blood sampling, are currently in use for sampling mine air, which 

may contain methane, traces of higher alkanes, and products of combustion such 

as carbon monoxide and oxygenates. The latter arise from diesel engine operation, fromtheuse of explosives, and from mine fires and explosions. Carbon 

monoxide also can be present, resulting from the slow ambient oxidation of 

coal. 

Vacutainers are glass, test-tube-shaped vessels capped with butyl rubber 

septums. These samplers, as supplied commercially in three sizes, are evacuated to only about 250 mm pressure and have the capability of drawing in 10, 

20, or 30 ml of fluid. Actual volumes are somewhat larger (13 ml for the 10- 

ml size). 

l~upervisory research chemist. 

~esearch chemist . 3 Mechanical engineering technician. 

All authors are with the Industrial Hazards and Communications group, Pittsburgh Mining and Safety Research Center, Bureau of Mines, Pittsburgh, Pa. 

4~eference to trade names does not imply endorsement by the Bureau of Mines. 
Vacutainers were first used as received. The need for complete evacuation was soon realized, and evacuation chambers were built for this purpose by 

both the Mining Enforcement and Safety Administration (MESA) and the Bureau of 

Mines. These chambers are described in the initial Bureau publication on 

Va~utainers.~ Since many of the gaseous samples analyzed in Bureau research 

are products of combustion, the stability of samples of saturated and unsaturated hydrocarbons in the C1-C5 range was studied and reported in a second 

publication.6 

The shelf life of evacuated Vacutainers was studied to determine the 

extent of leakage or contamination on standing prior to use for analysis. 

This was essential since in the field several weeks or even months may elapse 

before samples are taken. In the previous studies, it was concluded that the 

shelf life of evacuated Vacutainers should be limited to 1 to 2 months owing 

to the accumulation of contaminant gases, particularly CO. The mechanism for 

the appearance of that gas is unknown; it is tentatively explained by 

absorption-desorption into and from the stoppers. 

After collection of samples in Vacutainers, the fixed gases O,, N,, COY 

and Ar, commonly found in mine air, can be stored indefinitely without loss. 

Carbon dioxide, however, slowly decreases in concentration and should be analyzed within about 1 week of sampling. Methane and higher hydrocarbons, 

C1 -C5, can be stored for weeks with predictable decreases in the concentration. 

In the latest Bureau studies, the principal objective was to devise a 

means of eliminating or limiting the appearance of CO in stored Vacutainers. 

It was also considered desirable to establish the mechanism for gradual 

increase in the concentration of contaminants. One area that had not been 

investigated is the implication of bacteria in the contamination; experiments 

were devised to explore this possibility. 

ACKNOWLEDGMENT 

We are indebted to William Stevens of Mercy Hospital, Pittsburgh, Pa., 

for operation of an autoclave for the thermal sterilization experiments. 

EXPERIMENTAL PROCEDURE 

Vacutainers of all three sizes were evacuated to 1 mm pressure, or lower, 

using the evacuation chamber previously de~cribed.~ A simplified diagram of 

this chamber is shown in figure 1. Samples for the tests described under 

"Results and Discussion" were added to the evacuated samplers by needle insertion or by removal of stoppers manually in a test atmosphere. The samples 

were analyzed after transfer to the sample loop of a chromatograph, which was 

5Freedman, R. W., W. G. Humphrey, and R. L. Craft. Use of Vacutainers for 

Collection of Mine Atmosphere Samples. BuMines RI 7999, 1975, 7 pp. 

"Freedman, R. W., and B. I,. Ferber. Sampling Capability of Vacutainers for 

Fixed Gases and Low-Molecular-Weight Hydrocarbons. BuMines RI 8175, 1976, 

7 9 PP* 

Work cited in footnote 6. 
To vacuum 

FIGURE 1, - Evacuation chamber, 

accomplished by inserting mercury through the septum to pressurize the contents, followed by transfer using a gastight syringe. Alternatively, mercury 

displacement from the Vacutainer into the loop can be employed. 

The 20-ml Vacutainers were used to study the effects on CO and CO, of 

destroying or inhibiting bacteria by thermal sterilization, treatment with 

antiseptics, and prolonged storage at low temperature. 

Except for some samplers kept in an untreated state, the 20-ml Vacutainers were steam-sterilized in an autoclave for 30 minutes at 133O C. Some 
were then exposed to an atmosphere of ethylene oxide at 25" C for 1 hour, 

while others were prewashed with a quaternary mixture (Q-San) containing 

dimethylbenzylamrnonium chloride and ethylbenzylammonium chloride or with an 

iodine containing mixture (1-Dene) before exposure to the C2H40. The Vacutainers to be prewashed were filled with either mixture at a dilution of 

20 g/l of water, allowed to steep for 1 hour, drained, and dried under vacuum. 

All the sterilized Vacutainers were evacuated, sealed, and allowed to stand 

either at room temperature (25" C) or at -15" C in the freezing compartment of 

a refrigerator for 7 weeks. 

RESULTS AND DISCUSSION 

The concentration of gases accumulating in evacuated 10- and 30-ml 

Vacutainers over a 17-week period is shown in table 1. If the concentrations 

found in the 10- and 30-ml samplers are averaged, levels found after 17 weeks 

are 0.37 pct 02, 0.91 pct N2 , 271 pprn C02, 0.75 pprn CH4, and 20 pprn CO. 

TABLE 1. - ~oncentrations' of gasesa accumulating in 10 - and 30 -ml 

Vacutainers at 25" C 

Removal of glycerine lubricant from stoppers by detergent wash produced 

no change in gas accumulation. Heating the stoppers at 70" C for 3 weeks 

under vacuum followed by storage of the evacuated Vacutainers for 3 weeks at 

25" C removed most of the CO, (average residual concentration = 33 ppm) but 

produced no change in CO level. 

External exposure of evacuated samplers to pure CO and C02 did not significantly increase the concentrations of these gases within the Vacutainers, 

indicating lack of penetration. 

Time, 

weeks 

1 

2 

4 

8 

16.6 

A set of samplers filled with a mixture of gases and stored for 41 days 

prior to analysis displayed minor changes i n a l l gas concentrations except CO,, 

as shown in table 2. 

lAll concentrations shown are averages of 5 measurements. 

2~ercent standard deviations are predominantly about '25 pct. 

CO, ppm 

TABLE 2. - Effect of storage of gas for 41 days (20 samples), percent 

10 ml 

1.0 

1.6 

3.4 

8.6 

19.0 

02, pct 

30 ml 

1.4 

3.0 

4.0 

7.0 

21.0 

10 ml 

0.13 

.15 

.26 

.42 

30 ml 

0.05 

.03 

.10 

.08 

N2, Pet 

Percent in standard gas mixture...... 

Sample mean........................... 

standard deviation ................... Percent of standard deviation.,...,,. 

Change, sample mean minus percent in 

standard gas mixture................ 

Percentage of change (based on standard gas mixture).. ................. 

.59 

10 ml 

0.16 

.19 

.44 

.68 

CH4 

1.05 

1.0105 

-0481 

4.76 

-.040 

-3.96 

30 ml 

0.10 

.09 

.23 

.28 

C02, ppm 

02 

9.80 

10.135 

.2345 

2.31 

. 335 

3.31 

.14 11.18 

10 ml 

59 

72 

97 

152 

271 

CH4, ppm 

co 

0.45 

,446 

.0193 

4.33 

-.004 

-.go 

Na 

83.75 

84.26 

.3234 

.384 

.510 

.61 

, .63 

30 ml 

68 

101 

122 

175 

270 

10 ml 

1.0 

1.0 

1.2 

1.0 

1.0 

CO2 

5.00 

4.195 

.2038 

4.86 

- . 805 

-16.1 

30 ml 

- 

- 

0.5 

.4 

.5 
Several aliphatic hydrocarbons, C, -C5, stored in Vacutainers for 4 weeks, 

displayed decreases in concentration as shown in figure 2. In unknown samples, 

it should be possible to make a rough estimate of initial concentrations for 

several of the compounds after storage for a few weeks. 

Vacutainers exposed to ethylene oxide and evacuated yielded results shown 

in figure 3. The curves for untreated samples were obtained from previous 

data. The effect on CO is minimal, but CO, evolution is strongly suppressed 

initially. It is difficult to speculate on the cause of this behavior. 

KEY 

0 C2 Hz C3 H8 

a C2 H4 iso C4 HK) 

0 C2 H6 m C4 HIO 

TIME, weeks TIME, weeks 

FIGURE 2. - Concentration change of hydro- FIGURE 3. - Effect of ethylene oxide treatcarbons during storage. rnent prior to storage of evacuated Vacutainers. 
In the experiments designed to inhibit bacteria, with room-temperature 

storage the CO values with Q-San or 1-Dene pretreatment were similar to those 

obtained with C2H40 alone and also to those for untreated Vacutainers (fig. 3). 

The CO, values with Q-San or 1-Dene were likewise similar to those obtained 

with C2H40 alone, ranging from 4 to 12 ppm, but differed from those for 

untreated Vacutainers, which average 32 ppm CO,. In the Vacutainers stored 

at low temperatures, CO levels were zero in all cases, and CO, levels were low 

and comparable to those obtained with ethylene oxide alone. 

At this point it was suspected that low-temperature treatment alone without added antiseptics would be effective. Accordingly, a set of untreated 

Vacutainers was stored in the freezing compartment for 7 weeks and again 

yielded no measurable CO; C03 levels ranged from 12 to 20 ppm. When the same 

batch of Vacutainers was allowed to stand at 25" C for an additional 7 weeks 

after the refrigeration treatment, carbon monoxide reappeared; levels of 5 to 

6 ppm CO were measured. 

From the behavior of CO and CO, in evacuated Vacutainers, it is difficult 

to establish the presence of related microrganisms. C02 appearance at room 

temperature could conceivably be inhibited by the use of germicides. However, 

definite conclusions cannot be made based upon these experiments. 

No mechanism for gradual appearance of contaminants has been firmly 

established. However, it has been definitely shown that refrigerated storage 

can block the formation of CO, the most significant contaminant. This provides a simple and convenient means of maintaining extended shelf life for 

evacuated Vacutainers. Chemical treatment appears to be unnecessary. 

CONCLUSIONS 

1. Vacutainer storage of inert low-molecular-weight gases, such as 02, 

N,, CH4, CO, and Ar, is feasible for extended periods. Low concentrations of 

CO may show a slow increase in evacuated samplers and also in collected gases. 

2. Gases such as CO,, which are relatively soluble in rubber, slowly 

decrease in concentration and should be analyzed within 1 to 2 weeks. 

3. Aliphatic hydrocarbons in the C,-C, range also slowly decrease in concentration over several weeks' time. Analysis should be conducted promptly, 

but some extrapolation to zero time is possible. 

4. The use of germicides and heat treatment has some effect upon the 

inhibition of CO, appearance in evacuated Vacutainers. However, CO generation 

could not be suppressed by such means. 

5. A mechanism for contaminant appearance could not be established. 

6. Extended storage in a freezer at -15" C completely suppressed the 

appearance of CO in evacuated Vacutainers over a 7-week period. 

aU.S. GOVERNMENT PRINTING OFFICE: 1978-703-1 0311 5 INT.-BU.OF MINES,PGH.,P A. 22898