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We describe an HPLC method for quantifying creatinine, separating the analyte from other compounds in serum and urine by cation-exchange chromatography and measuring its absorbance at 234 nm. The precision of the method (CV) varied from 2.9% (mean creatinine concentration, 31 mumol/L) to 1.7% (361 mumol/L) within a series of assays and from 3.9% (34 mumol/L) to 2.4% (391 mumol/L) between series. A comparison with the Jaffé method, as performed with a Technicon SMA analyzer, gave the regression line yHPLC = 1.00xJaffé - 12.0 (n = 141, r = 0.998, and Syx = 19). Results also are comparable with those of an enzymatic method, if the enzymatic method is standardized with a serum-based standard when serum samples are measured. An aqueous standard has to be used for enzymatic determination of creatinine in urine.

The traditional method for DNA separation is slab gel electrophoresis. Because slab gel electrophoresis, which involves the casting, loading, running, and staining of the gel is labor-intensive and time-consuming, high-resolution capillary electrophoresis (CE) has become an attractive alternative. CE, by contrast to conventional electrophoretic techniques, is capable of rapid, automated, reproducible, and high-resolution separation of minute amounts of DNA samples. To separate DNA fragments by CE, polyacrylamide gels or liquid buffers containing soluble polymers are used. Soluble polymers, such as hydroxyethyl cellulose, hydroxypropylmethyl cellulose, and methyl cellulose act as effective molecular sieves and allow for separation of DNA according to size (1). CE has recently shown promising results for the analysis of double-stranded DNA such as restriction fragment length polymorphisms and polymerase chain reaction (PCR) products (2)(3). The insertion (I)/deletion (D) of a 287-bp sequence polymorphism within intron 16 of the gene for angiotensin-converting enzyme (ACE) is strongly associated with serum ACE concentrations (4). The D allele has been identified as a risk factor for the development of coronary heart disease and myocardial infarction (5). In addition, the deletion polymorphism has been associated with either microalbuminuria or overt nephropathy in diabetic patients (6)(7). Here we report a sensitive, simple, rapid, and nonisotopic procedure for identification of …