Analytical procedures for determining niacin or vitamin B3 content of foods
are tedious, require large quantities of toxic chemicals, and are time-con
suming. In addition, food matrices are difficult as samples because of thei
r complex nature. A selective, sensitive HPLC technique was developed with
postcolumn derivatization as well as fluorescence and spectroscopic detecti
on systems. Niacin was separated and retained for 6.5 min on a polymeric co
lumn with an aqueous mobile phase containing sodium acetate buffer. A postc
olumn system consisting of a stainless-steel pump and reaction coil allowed
detection and quantitation of niacin. An acid-enzyme sample-extraction met
hod was most compatible with HPLC and postcolumn derivatization with 5% eac
h of acidified p-aminophenol and cyanogen bromide. Lower detection limit an
d mean recovery were 3.6 ng and 99.43%, respectively. Fluorescence response
for nicotinamide was half that of nicotinic acid. A lower response for nic
otinamide was also noted with conventional spectroscopy. However, the new m
ethod yielded comparable values for six of eight ready-to-eat commercial ce
real samples. No significant difference was observed between the AACC refer
ence and HPLC fluorimetric methods. Chemical derivatization was done within
a reaction coil with reagents at half strength, limiting exposure to hazar
ds and minimizing waste-disposal problems.