shows how to loop through a subset of columns

test.r

Redox=read.csv('Redox.csv', header=TRUE)

col = c("pH", "mmol.DOC", "SUVA", "mmol.fe2")

newRedox = Redox[col] # removes columns not in col

for(item in newRedox) # for each column in newRedox
    {
    ylim = range(item, na.rm=TRUE)
    xlim = range(Redox$day, na.rm=TRUE)
    }