0000000000542003
AUTHOR
E. Bonet Domingo
showing 3 related works from this author
Use of the o-Phthalaldehyde and N-Acetyl-L-Cysteine the Evaluation of Milk Proteins
1991
Abstract o -Phthalaldehyde and N-acetyl-Lcysteine are used in the determination of milk proteins. Three procedures are proposed and compared. One of them is based on reaction of o -phthalaldehyde and N-acetyl-Lcysteine with the intact proteins and the two others on reaction of the reagents with the released amino acids after total acid hydrolysis of the protein samples. When the protein sample is hydrolyzed, calibration is performed either with a hydrolyzed protein standard or with isoleucine. A procedure for the measurement of the degree of enzymatic hydrolysis of milk proteins without separation of the unhydrolyzed protein, which makes use of the same reagents, is also described. In all c…
Evaluation of the proteolysis degree with the o-phthalaldehyde/N-acetyl-L-cysteine reagent
1990
The o-phthalaldehyde/N-acetyl-L-cysteine (OPA-NAC) reagent is applied to the spectrophotometric evaluation of the proteolytic activity of enzymes. The high stability of the OPA-NAC isoindoles makes a strict control of the time of reaction unnecessary. A mathematical expression is proposed to calculate proteolysis degrees, where the absorbance decrease of the OPA-NAC derivative of the protein itself during the hydrolysis process is taken into account. The method is applied to bovine serum albumine, caseine, lysozyme, lactoglobuline and protamine sulphate as substrates, and pronase, papaine, trypsin and chymotrypsin as enzymes.
High-performance liquid chromatographic determination of diuretics in urine by micellar liquid chromatography.
1992
The use of micellar liquid chromatography for the determination of diuretics in urine by direct injection of the sample into the chromatographic system is discussed. The retention of the urine matrix at the beginning of the chromatograms was observed for different sodium dodecyl sulphate (SDS) mobile phases. The eluent strengths of a hybrid SDS-methanol micellar mobile phase for several diuretics were compared and related to the stationary phase/water partition coefficient with a purely micellar mobile phase. The urine band was appreciably narrower with a mobile phase of 0.05 M SDS-5% methanol (v/v) at 50 degrees C (pH 6.9). With this mobile phase the determination of bendroflumethiazide an…