Determination Of Creatinine In Urine Samples Research Articles

Molecularly Imprinted Polymer as Sorbent Phase for Disposable Pipette Extraction: A Potential Approach for Creatinine Analysis in Human Urine Samples

The traditional creatinine determination is made by a spectrophotometric method. However, some interferents present in biological samples can decrease the sensitivity in the determination of creatinine in urine samples with this spectrophotometric method. Due to this, this study developed a new molecularly imprinted polymer (MIP) as a sorbent phase to disposable pipette extraction (DPX) for the creatinine determination in urine samples by high-performance liquid chromatography with UV detection (HPLC/UV). The synthesized polymer showed a high superficial area presenting a first-order kinetic reaction and a high selectivity for creatinine compared to the non-molecularly imprinted polymer. The main DPX variables were evaluated: number of draw/eject cycles, pH solution, and type of the desorption solvent. The developed methodology showed an inter and intra-day precision of 1.3 to 2.0% and 0.8 to 1.6% respectively, the accuracy values ranging from 82.3% to 102.1% respectively, and recovery values between 96.5 to 101.3% with the limit of quantification of 0,339 g L-1. The developed methodology was applied to real urine samples which showed creatinine concentrations ranging from 0.55 to 6.61 g L-1. Thus, the developed DPX-MIP-HPLC/UV methodology showed to be efficient for creatinine determination, reducing the time of analysis (3 min), solvent uses, and increasing the selectivity.

Voltammetric determination of creatinine using a gold electrode modified with Nafion mixed with graphene quantum dots-copper

Creatinine levels in blood and urine can be used as an important biomarker for the diagnosis of renal, thyroid, and muscle malfunctions. In this work, a square-wave voltammetric method for creatinine was developed using a gold electrode modified with a film composed by Nafion mixed with a graphene quantum dots dispersion prepared in the presence of Cu 2+. Such Au/Nafion-GQDs-Cu electrode relies on the interactions of creatinine with Cu 2+ released from the oxidation of Cu thus decreasing the characteristic Cu/Cu 2+ anodic peak at +350 mV. A linear response was obtained for the analyte in the concentration range from 1.0 × 10 −6 mol L −1 (0.11 mg L −1 ) to 4.5 × 10 −4 mol L −1 (50.9 mg L −1 ). The proposed sensor was simple to prepare and the method was successfully applied for creatinine determination in urine samples. • Creatinine was determined using a Nafion-GQDs-Cu modified gold electrode. • Nanocomposite formed by graphene quantum dots modified with copper (GQDs-Cu). • Creatinine decreased the characteristic Cu/Cu 2+ signal of the modified electrode. • Limit of quantification was adequate for urine analysis.

Graphene Oxides Coated Paper as a Substrate to Paper Spray Ionization Mass Spectrometry for Creatinine Determination in Urine Samples

Paper spray ionization (PSI) is a promising analytical tool for direct analysis in mass spectrometry (MS). However, this technique usually uses chromatographic paper, which rarely accomplishes a stable MS signal and could vary with the sample matrix effect. In the present study, the application of graphene oxides (GO) was scrutinized as modifier paper substrate for PSI-MS methods. The developed substrate efficiency was evaluated towards creatinine determination in urine samples. The GO-PSI-MS developed method for creatinine in urine samples showed linearity in the range of 0.1 to 3.4 ppm with R2 = 0.9991. The precision was evaluated and the values were between 1.1 to 6.8% and the accuracy above 96.8%. The limit of quantification (LOQ) and limit of detection (LOD) were 0.05 and 0.17 ppm, respectively. The GO-PSI developed was compared to conventional chromatographic paper for PSI-MS methods, and the results showed that the modified paper with GO bolsters method linearity, precision, and LOQ values.

An alternative, single-point method for creatinine determination in urine samples with optoelectronic detector. Critical comparison to Jaffé method

A rapid, single-point method for colorimetric creatinine determination has been developed as an alternative for a well-established Jaffé assay, which lacks analytical specificity. 3,5-dinitrobenzoic acid was employed in an alkaline environment as a chromophore instead of picric acid. Apart from the spectrophotometer, a simple optoelectronic detector was applied as an alternative detection method. The conditions of the reaction were optimized to provide satisfactory analytical parameters. The linear ranges of the proposed assays were 40–4000 and 10–300 µmol L−1 of creatinine for conventional spectrophotometry and a PEDD detector, respectively. A broad spectrum of potential interferents was examined. The presence of compounds such as glucose, urea or uric acid was the source of a significantly smaller bias in the examined method than in the case of the Jaffé method variants. The presented method was validated with the use of 10 human urine samples with the creatinine level determined by the recommended method. Two-tail paired Student's t-tests with 9 degrees of freedom at the 95% confidence level showed the agreement between the proposed and the reference methods.

FIA-MS/MS determination of creatinine in urine samples undergoing butylation

Flow injection analysis-tandem mass spectrometry has become widely used for analysis of many biomarkers in various biological matrices. To improve the sensitivity, the compounds are often determined as their butylesters. Since the concentration of urinary excreted compounds are generally reported after normalization to creatinine, the aim of this study was to investigate the possibility of creatinine determination in urine samples which underwent butylation. The impact of derivatization on urinary creatinine determination was investigated by measuring of underivatized and derivatized samples. The 10% creatine to creatinine conversion was observed during butylation, what above 700 μmol creatine/mmol creatinine caused significant creatinine overestimation. In that case, correction for creatine conversion rate was done. QC samples at six concentration levels were examined and precision and accuracy values fulfill the European Medicine Agency validation requirements. The elaborated method was applied for determination of creatinine in 41 real human urine samples. Determined creatinine concentrations were in the range of 0.27–22.3 mmol/L, linearity was confirmed within the concentration range of 0.27–31.7 mmol/L. Obtained results highly correlated with routinely used enzymatic assay for all tested samples and proposed method provide reliable determination of creatinine in butylated urine in a single run with butylesters of other analytes of interest.

Creatinine determination in urine samples by batchwise kinetic procedure and flow injection analysis using the Jaffé reaction: chemometric study

The classical Jaffé reaction for the determination of creatinine in urine samples is tested. A comparative study of the main analytical characteristics focussed to minimize the bias error and improve the precision, for the batchwise and flow injection (FI) methods is realized. Also, the effect of the albumin concentration in the determination of creatinine has been studied. Different analytical signals were studied. Absorbance increments at different times permit to estimate the creatinine concentration free from bias error in urine by the batchwise method using the calibration graph obtained with creatinine standards and no measurement of the blank solution is needed. The lineal interval was 0.92–50 mg l −1 and seven samples can be processed per hour by an operator. No previous treatment of the urine sample is necessary. The FI method provides also good results. The lineal interval was 30–100 mg l −1 and the sample rate was around 20 samples per hour. If increased albumin levels are detected in the urine, standard addition method or the calibration graphs with standards in presence of albumin are needed in order to obtain accurate results when FI method is employed. The obtained accuracy of the both methods allows its application as diagnostic tool to establish the urinary creatinine levels.