subscript in axis label when using png() in base r plot

Question

I understand how to make sub/super-scripts in axis labels in base r plot. My code works fine when sending the figure straight to the R Plots section in Rstudio. However, when I try to export my graph as png, using png() , the mtext() that contains a superscript disappears.

Below is the mtext() code that I use- this works fine when just plotting in the R Studio screen, but it disappears when exporting to png()

mtext(side = 1, cex = 1.5,  expression ("Net Change in SO "["4"] ^"2-" *" µeq/L"), line = 3)

Any suggestions would be greatly appreciated!

Answer 1

Most likely this happens because you need to adjust the line parameter.

Start by making it 0 (default):

mtext(side=1, cex=1.4, "some text", line=0)