Biomedical Engineering Reference
In-Depth Information
Table 1
Measured amount of water-soluble chemicals on sampling
paper/cards
Card type
a
Chemicals on card (%) Accuracy (%)
FTA Elute 53.2 101.2
FTA DMPK-B 50.9 102.8
FTA Plant 11.5 100.4
FTA DMPK-A 11.8 98.4
Indicating FTA (pink) 11.1 101.5
Blood Stain 2.5 98.5
Protein Saver 903 1.6 102.5
31ET 1.7 98.2
VWR 237 1.1 102.9
a
All paper/cards were from Whatman except VWR 237 paper from
VWR International
3
Results and Discussion
3.1
Water-Soluble Chemicals on the Cards
In order to estimate the amount of water-soluble components in the sampling paper/
cards, two 6 mm disks from each type of paper were cut into preweighed test tubes
and weighed using an analytical balance, the disks were wetted with 500 mL of dis-
tilled water, shaken well, and then weighed again. The water was carefully transferred
off the washed paper disks into preweighed test tubes with a micropipette and weighed,
then put under a stream of nitrogen gas for drying and reweighed when completely
dried. The paper disks were also dried under nitrogen and reweighed. Table
1
shows
the relative amounts of chemicals on the paper in percentage. The weight loss of the
paper disks before and after water washing was confirmed by the weight of the water-
soluble chemicals released into water which confirmed the quantitative transfer of the
liquids between the vials. The ratio of weight of the chemicals released into water to
the weight loss of the disk is presented as accuracy (%) in Table
1
. FTA elute card
appears to carry the most water-soluble chemicals (³50 % of total card weight) among
all sampling cards. FTA DMPK-A, FTA plant, and Indicating FTA cards appear to be
the same or similar paper, but Indicating FTA paper carries a pink dye additive. Blood
stain, 31ET, and VWR 237 paper/cards carry the least water-soluble chemicals.
Actually, 31ET and VWR 237 are marketed as plain cotton fiber paper.
3.2
Identities of Chemicals Impregnated on the Paper
Based on the amount of water-soluble chemicals on the paper/cards, three types of
cards (FTA Elute, Indicating FTA, and VWR 237) were used to explore the chemi-
cal identifications. The possible chemicals on the cards were checked with mass
