From: YU, Laipu (yu@paprican.ca)
Date: Tue Mar 03 1998 - 15:28:08 EST
Hi, there: I am a chemist and new to the flow cytometry business. I wonder if anybody out there can help me with my problem. We recently purchased a home made (and patented) flow cytometer to analyse the "pitch" particle concentration in papermaking mills. The procedure involves dyeing the sample with a hydrophobic fluorescence laser dye (commercial name Fluorol 7GA by Lamda Physica) and measures the fluorescence signal which gives particle number and size distribution. Sounds good so far. The "pitch" consists chemically of fatty acids, resin acids, triglycerides, sterols etc and dispersed in water in the size range of 0.2 to 2 micros. Unfortunately the papermaking furnish is a very complex system. Apart from the above pitch particles, large amount of wood fiber debrics (we call it fines) are also present. Separating these fines from pitch particles are difficult and not practical for on-line process control. According to the inventor of this technique, the laser dye should only adsorb on pitch particles and not on cellulose fines and thus the cellulose fines will not be counted. However, from a fluorescence microscope it was found the dye adsorb on both cellulose fines and pitch particles. This of course is undesirerable. My question is: is it possible to find some fluorescence dyes which only interact with "pitch" but not with cellulose and yet suitable for flow cytometer? I know you bioguys have lots of experience using all kinds of dyes. Any input will be greatly appreciated. Also, according to your experience, it is possible to count < 0.5 micro particle using a stream in air system with a sample feeding tube of 200 micros and a nuzzle of 300 micros? What is the possible lower limit for this kind of system? This is what I have got to do now. I apologize if I confuse you guys. Laipu Yu Paprican yu@paprican.ca
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