Spectrophotometric determination of pentaerythritol tetranitrate in tablets.

A sensitive spectrophotometric method is reported for the quantitative determination of pentaerythritol tetranitrate in tablets. The method is based on reduction of pentaerythritol tetranitrate with zinc and calcium chloride, and reaction of the nitroso compound thus formed with 1-naphthylamine in acidic medium. The reaction gives a purple product having an absorbance maximum at 545 nm. Beer's law is obeyed in the concentration range of 1-10 micrograms/mL of reaction mixture. The presence of meprobamate in tablets does not interfere with the proposed analytical determination.