TABLE 2.
Detection of a variety of surfactants with a droplet collapse assay and an atomized oil assay
| Surfactantd | HLBa | Type of halo | Limit of detectionb (g/liter) |
|
|---|---|---|---|---|
| Drop collapse | Atomized oil | |||
| Crude syringafactinc | NA | Bright | 0.5 | 0.01 |
| Crude surfactinc | NA | Bright | 15 | 0.25 |
| Crude rhamnolipidc | 9.5 | Bright | 7.5 | 0.25 |
| Silwet L-77 | 8-10 | Bright | 0.25 | 0.0125 |
| CTAB | NA | Bright | 0.5 | 0.001 |
| Tergitol-7 | NA | Bright | 2.5 | 0.025 |
| Triton X-100 | 13.5 | Dark | 0.25 | 0.125 |
| Tween 80 | 15.0 | Dark | NA | 0.25 |
| Tween 20 | 16.7 | Dark | 10 | 0.5 |
| SDS | 40.0 | Dark | 2 | 0.1 |
a
HLB values are as given in McCutcheon's Emulsifiers & Detergents, North American Edition (25a), with the exception of rhamnolipid (29) and Silwet (17). NA indicates surfactants for which an HLB value has not been conclusively determined.
b
These values are the lowest dilutions of surfactant that still yielded visual detection by the respective assays. NA indicates samples that were undetectable by the assay at any concentration.
c
Sample represents ethyl acetate extract of culture supernatant from biosurfactant-producing strains.
d
CTAB, cetyltrimethylammonium bromide.