Wassersensitives Papier (WSP)

WSP is a special slide-strip serving as a visible control of spray distribution, which discolours by contact with aqueous drops. Water Sensitive Paper is a special novel slide-strip with the standard size of 76 x 26 mm. It is covered with a yellow surface on the upper side serving as a visible control of the array quality.

Spotting aqueous probe droplets on it, this water-sensitive surface is turning dark blue immediately.

It has been also developed for the quick and easy control of the microarray spotting process and the detection of array defaults. It helps to visualize droplet distributions, droplet densities and array quality. WSP should always be used prior to spotting to detect any array defaults. To evaluate array quality, just place the WSP instead of a microarray slide on the micro arrayer. Spot the array according to the array pattern, remove the strip and cover it with adhesive scotch-tape. Then check the droplet pattern or compare it with the default array.

Handling, Limitations and Storage

To ensure a constant quality, the WSP is packaged in a dust-safe bag and sealed under inert gas. Sealed WSP is stable for at least 12 months if stored at room temperature. Unsealed packages, which are not used immediately, should be stored dry at room temperature in a dust-safe bag.

Analysis and Evaluation Check the droplet pattern

For a quick estimate compare the exposed droplets with a known standard or examine the droplets either using a hand lens or an automatic image analyzer. Droplet counting by hand lens on WSP is limited to a maximum of around 600 droplets per cm2. For higher droplet densities use automatic image analyzer. Accurate drop size and pattern measurements with commercial imaging software can only be made if the drop density is low enough for the majority of droplets not to overlap each other.

---

Notes

• WSP is produced under careful and rigid process control. To maintain this high quality standard, follow the instruction below.
• Use always gloves (polyethylene or rubber) when handling the WSP to avoid any staining and contamination of the water-sensitive surface.
• The WSP should be processed under clean conditions only. Dust particles may cause local alterations in the wetting characteristics of the slide surface, which result in depositing failures.
• Since the yellow surface is sensitive, direct contact and any touch of the spotted slide surface must be avoided.
• The WSP cannot be used at a relative humidity of more than 80 %. Although it turns light blue at a relative humidity of 80 % the stains produced by droplets still show sufficient contrast to allow visual control beyond this limit.
• If you want to produce high-density arrays with a spot size smaller than 100 µm you should adjust the relative humidity to approximately 40 - 50 %. Pure water stains the WSP in drop size as small as 70 µm at room temperature and relative humidity of 30 %.
• WSP is not recommended for use at temperatures below 10 °C.
• After spotting the WSP must be protected with a colourless, thin adhesive foil (e.g. scotch tape). Avoid air pockets while adhering the tape.

Areas of application

• Used in agronomy
• Monitoring the distribution of herbicide/pesticide spray in fields
• Visible control of spray distribution
• Monitoring the microarray spotting process
• Monitoring the humidity

Specifications

Dimensions over all	76 x 26 mm
Material	Special water sensitive paper (yellow colored)
Package Size	1 pack a 50 pieces
Packaging	in a dust-safe aluminium bag and sealed under inert gas
Recommended accessories	Thin adhesive foil (e.g. scotch tape)

.