A comparison of spectrophotometric methods for the determination
of furosemide in urine samples with reflectometric methods;
their features and drawbacks are enumerated in Table 4. Spectrophotometric
procedures [20] for furosemide determination based on
diazo-coupling reaction resulting in dye formation are characterized
by high sensitivity, but often have drawbacks of pH dependence, coupling
time and diazotation temperature. Besides, these procedures
use large volumes of carcinogenic reagent(s) or organic solvents,
which make it outside of the standards of green chemistry. The
other methods [16,18] are not applied to real urine samples.