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@@ -68,6 +68,25 @@ Ah - and add in a flowmeter after the second OPC sampler!
 - andersen sampler?? could be nice to bin different size particles - six-stage viable particle cascade impactor
 - OPC would be better than andersen sampler
 
+
+# particle counting
+### optical particle counter 
+
+### fluorescent particle counter
+fluorescently labeled microscpheres - https://www.thermofisher.com/order/catalog/product/93470350011150?SID=srch-srp-93470350011150#/93470350011150?SID=srch-srp-93470350011150 \
+Measure particles: \
+CBA has a plate reader - can return flourescent concentration (not individual particle #) but requries optimization \
+or confocal microscope - collect particels in iminger with water solution, let colloidal solution evaporate leaving particles on stage and record particle desnity in an image
+
+
+### microgram mass comparison of gold particles 
+test measurement with 100nm gold particles \
+from bbi solutions dataseet for 100nm gold particles - mass of 1L of gold is 5.66E-05 g, too small for the analytical balance in BL1 \
+also, I tried measuring evaporated solution on a few microscope slides and the slides are not uniform enough to do comparative measurements. \
+but can see the particles in the Olympus microscope 
+![](100nm_gold_particles.jpg)
+
+
 ### Resources
 [^DIYmask]: University of Cambridge [DIY mask efficacy testing](https://www.researchgate.net/publication/258525804_Testing_the_Efficacy_of_Homemade_Masks_Would_They_Protect_in_an_Influenza_Pandemic)
 [^filterPerformance]: AR Wilkes [The bacterial and viral filtration performance of breathing system filters](https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2044.2000.01327.x)