[data,labels] = xlsread('ammonium.xlsx','Sheet1');

feed = data(:,1);
resid = data(:,2);

plot(feed,resid,'^-.','LineWidth',3,'MarkerSize',12)
title('Residual NH4 vs NH4 feed concentration')
xlabel('NH4 feed concentration, mM')
ylabel('Residual NH4, mM')
legend('Residual NH4')
print -djpeg myNewFirstFig