Q: Superscript in mtext with variable I want include a variable in mtext as well as superscript some text:
My ideal output is
y.label ADC (10^-6 mm^2/s) 

where y.label is the value of a variable, -6 is superscripted and 2 is superscripted
The most promising approach so far is:
mtext(expression(paste(y.label, " ADC (", 10^-6, " ", mm^2, "/s)")), side=2, line=2.5, cex=1.2, font=1)

This almost works but outputs "y.label" instead of the value of y.label
Grateful for any suggestions.

A: This should work:
y.label <- 1
plot(1:10,1:10, type = "n", ylab = "")
gaa <- parse(text=paste(y.label, "*~ADC(10^-6*~mm^2/s)"))
mtext(gaa, side=2, line=2.5, cex=1.2, font=1)


For explanation see here
EDIT parse freaks out because of the % sign. You could use substitute instead. Here you have to pass y.label into the function through a list/environment. See the help sheet.
y.label <- "PVP 10%"
gaa <- substitute(paste(N, " ADC (", 10^-6, " ", mm^2, "/s)"), list(N=y.label))
plot(1:10,1:10, type = "n", ylab = "")
mtext(gaa, side=2, line=2.5, cex=1.2, font=1)


