{HEAD ~ Certain reducible compounds} are useful in analytical compositions, elements and {TAIL ~ methods}, e.g. for assays of bacterial cells 
{ HEAD ~ Certain reducible compounds } are useful in analytical compositions , elements and { TAIL ~ methods } , e.g. for assays of bacterial cells
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH