of zns capping than qd528c generally and as may be appreciated from a consideration of fig8 qd528 may show a higher fluorescence in higher ph buffers the fluorescence of each of the qds may preferably be generally found to increase with increasing ph in fig8 the amount of fluorescence variation differs amongst different qds error bars indicate the 95 confidence interval on mean normalized fluorescence this trend of increasing fluorescence of qds with increasing ph may preferably also be seen with other buffers including tris hepes pbs and borate in 10 mm citric acid such as may preferably have been used in collecting the data graphically represented in fig8 these green qds showed between 40 43 change in fluorescence between ph 5 u02dc 7 yellow and orange qds with different amounts of zns capping may vary in fluorescence between 22 345 in a citrate buffer having a ph of 5 u02dc 7 such a large variation may serve to emphasize the importance of and or preference for studying these variations before qd types are used in quantitative applications since what may be observed for one sample of qds may not necessarily be repeated in another sample in all the studies described above uv vis spectroscopy did not show any qds in the supernatant preferably indicating that the variation in fluorescence intensity was not due to leakage of qds from the microbeads it may be lastly noted that fluorescence signals may also be affected by at least two other processes 1 leakage of qds out of the microbeads such as may be driven for example by a diffusion process and or 2 photobrightening of.