A Technique
for Reducing
Static Charge
One of the most common laboratory techniques for preserving and storing biological samples involves concentration and drying by lyophilization ( 1). Unfortunately the resulting material often exists as a light fluffy powder which has accumulated a static charge. If this material must be transferred prior to reconstitution or storage, the static electricity causes the preparation to behave as charged particles. The particles tend to disperse and cling to various surfaces making handling difficult or hazardous depending on the nature of the preparation (2-4).
FIG. I. Example of a lyophilization by the insertion of a short length of wire 0003.2697/79/010128-02$02.00/O CopyrIght o 1979 hy Academic Press. Inc All right5 of rrproductton m any form rcwrved
vessel through
in Lyophilized
Materials
During studies with a variety of bacterial and biochemical samples difficulty was encountered in handling certain lyophilized materials and a simple inexpensive technique was developed to reduce this problem. The technique may be implemented in one of two ways. The first method is particularly applicable with lyophilization flasks that are composed of two components and joined by a flexible seal. With these flasks a piece of OOOO-gauge Nichrome wire is inserted into the sample vessel between the seal of the component parts of the flask
permanently the base.
128
modified
to
reduce
static
charge
accumulation
REDUCING
STATIC
CHARGE
before the preparation is frozen. The wire must be long enough to remain in contact with the sample at the inside base of the flask while extending approximately 5 cm outside the flask. The alternate procedure involves utilization of one-piece lyophilization flasks in which a short length of 26gauge platinum-iridium wire has been inserted through the center base of the flask (Fig. I). The vessel should be sealed such that the two ends of the wire extend approximately 2 to 4 mm perpendicularly out from the inside and outside glass surfaces. With either type of vessel, momentary grounding of the wire immediately after lyophilization reduces static charge in the sample. Powdery preparations processed in this manner are more uniform and can be more easily manipulated with reduced loss and contamination. When required, both types of flasks readily accommodate the utilization of aseptic techniques. It is important to note that this technique
IN LYOPHILIZED
129
MATERIALS
is designed to facilitate the ease of quantitatively transferring valuable powdered lyophilized preparations and is not intended as an alternative to the usual precautions that should be observed when handling hazardous biological agents (51. ACKNOWLEDGMENT This work was wpported by Public Health Service Granl. DE 07014 from the National Institute for Dental Research.
REFERENCES I. F’losdorf. 29.
E. W.. and Mudd.
3. Reitman. R. L..
M.. Moss, and Gross.
68, 541-544. 3. Reitman. M..
R. L.. 68,
S. (1935)5.
fnrn~rrnol.
389-393.
Moss. and Gross.
M. L.. Harstad. J. B.. .4lg. N. H. f 1954) J. Btic,t~~k)l. M. L., Harstad. J. B.. .4lg. N. H. (19.54) J. L(wrc~rio/.
545-548.
Reitman. M., Alg. R. L.. Miller, W. S.. and Gross. N. H. (1954) .I. Ba
for Reducing
Static Charge
One of the most common laboratory techniques for preserving and storing biological samples involves concentration and drying by lyophilization ( 1). Unfortunately the resulting material often exists as a light fluffy powder which has accumulated a static charge. If this material must be transferred prior to reconstitution or storage, the static electricity causes the preparation to behave as charged particles. The particles tend to disperse and cling to various surfaces making handling difficult or hazardous depending on the nature of the preparation (2-4).
FIG. I. Example of a lyophilization by the insertion of a short length of wire 0003.2697/79/010128-02$02.00/O CopyrIght o 1979 hy Academic Press. Inc All right5 of rrproductton m any form rcwrved
vessel through
in Lyophilized
Materials
During studies with a variety of bacterial and biochemical samples difficulty was encountered in handling certain lyophilized materials and a simple inexpensive technique was developed to reduce this problem. The technique may be implemented in one of two ways. The first method is particularly applicable with lyophilization flasks that are composed of two components and joined by a flexible seal. With these flasks a piece of OOOO-gauge Nichrome wire is inserted into the sample vessel between the seal of the component parts of the flask
permanently the base.
128
modified
to
reduce
static
charge
accumulation
REDUCING
STATIC
CHARGE
before the preparation is frozen. The wire must be long enough to remain in contact with the sample at the inside base of the flask while extending approximately 5 cm outside the flask. The alternate procedure involves utilization of one-piece lyophilization flasks in which a short length of 26gauge platinum-iridium wire has been inserted through the center base of the flask (Fig. I). The vessel should be sealed such that the two ends of the wire extend approximately 2 to 4 mm perpendicularly out from the inside and outside glass surfaces. With either type of vessel, momentary grounding of the wire immediately after lyophilization reduces static charge in the sample. Powdery preparations processed in this manner are more uniform and can be more easily manipulated with reduced loss and contamination. When required, both types of flasks readily accommodate the utilization of aseptic techniques. It is important to note that this technique
IN LYOPHILIZED
129
MATERIALS
is designed to facilitate the ease of quantitatively transferring valuable powdered lyophilized preparations and is not intended as an alternative to the usual precautions that should be observed when handling hazardous biological agents (51. ACKNOWLEDGMENT This work was wpported by Public Health Service Granl. DE 07014 from the National Institute for Dental Research.
REFERENCES I. F’losdorf. 29.
E. W.. and Mudd.
3. Reitman. R. L..
M.. Moss, and Gross.
68, 541-544. 3. Reitman. M..
R. L.. 68,
S. (1935)5.
fnrn~rrnol.
389-393.
Moss. and Gross.
M. L.. Harstad. J. B.. .4lg. N. H. f 1954) J. Btic,t~~k)l. M. L., Harstad. J. B.. .4lg. N. H. (19.54) J. L(wrc~rio/.
545-548.
Reitman. M., Alg. R. L.. Miller, W. S.. and Gross. N. H. (1954) .I. Ba
