Rapid and direct determination of creatinine in urine using capillary zone electrophoresis

Determination of creatinine in urine and blood serum human samples by CZE-UV using on-column internal standard injection

Creatinine is a well-stablished biomarker for kidney malfunctions and for normalization parameter of urinary quantitative information. Recently, metabolic studies have been discovering other functionalities for creatinine tests in human urine and blood serum. In this work we present an enhanced capillary electrophoresis (CE) based protocol for determination of creatinine. CE is a high-throughput separation technique that have been getting attention through the last decades and might be considered to be adopted as an analytical instrumentation for clinical purposes. In the proposed method, we performed a short injection program with on-column addition of internal standard. Additionally, the method allows a simultaneous screening of non-proteinogenic amino acids that could be considered for metabolomics purposes. We design a pilot study that successfully estimated the creatinine value in 100 urine samples with (2.85 ± 1.78) mg dL^-1 LOD; (8.24 ± 5.93) mg dL^-1 LOQ and 82.4% accuracy. Considering that serum creatinine is also included in the clinical laboratory routines for estimated Glomerular Filtration Rate dosage, the method was complementary applied to 10 blood serum samples, which resulted in a model with (0.4 ± 0.2) mg dL^-1 LOD; (2.0 ± 0.6) mg dL^-1 LOQ and 83.8% of accuracy. All results were in agreement with reference values. The proposed method promotes a great analytical frequency and reproducibility with enhanced specificity compared with the ongoing protocol by Jaffe's reaction, thereby proving to be useful as an alternative for creatinine exams that might help complete a diagnosis of a series of health-related issues.

Sensitivity Detection of Uric Acid and Creatinine in Human Urine Based on Nanoporous Gold

Given the significance of uric acid and creatinine in clinical diagnostic, disease prevention and treatment, a multifunctional electrochemical sensor was proposed for sensitive detection of uric acid and creatinine. The sensitive detection of uric acid was realized based on the unique electrochemical oxidation of nanoporous gold (NPG) towards uric acid, showing good linearity from 10 μM to 750 μM with a satisfactory sensitivity of 222.91 μA mM−1 cm−2 and a limit of detection (LOD) of 0.06 μM. Based on the Jaffé reaction between creatinine and picric acid, the sensitive detection of creatinine was indirectly achieved in a range from 10 to 2000 μM by determining the consumption of picric acid in the Jaffé reaction with a detection sensitivity of 195.05 μA mM−1 cm−2 and a LOD of 10 μM. For human urine detection using the proposed electrochemical sensor, the uric acid detection results were comparable to that of high-performance liquid chromatography (HPLC), with a deviation rate of less than 10.28% and the recoveries of uric acid spiked in urine samples were 89~118%. Compared with HPLC results, the deviation rate of creatinine detection in urine samples was less than 4.17% and the recoveries of creatinine spiked in urine samples ranged from 92.50% to 117.40%. The multifunctional electrochemical sensor exhibited many advantages in practical applications, including short detection time, high stability, simple operation, strong anti-interference ability, cost-effectiveness, and easy fabrication, which provided a promising alternative for urine analysis in clinical diagnosis.

Urine S-Adenosylmethionine are Related to Degree of Renal Insufficiency in Patients with Chronic Kidney Disease

OBJECTIVE

To determine whether urine S-adenosylmethionine (SAM) might be an indicator of chronic kidney disease (CKD).

METHODS

We investigated urine levels of SAM and related metabolites (S-adenosylhomocysteine and homocysteine cysteine) in 62 patients (average age, 65.9 years) with CKD (stages II-V).

RESULTS

Patients with stages III-V CKD stages have significantly decreased urine levels and SAM/S-adenosylhomocysteine ratio and also cysteine/homocysteine ratio in blood plasma (P <.05), compared with patients with stage II CKD. Urine SAM levels allowed us to distinguish patients with mildly decreased kidney function from those with moderate to severe renal impairment (AUC, 0.791; sensitivity, 85%; specificity, 78.6%).

CONCLUSIONS

Our study results demonstrate that urine SAM is a potent biomarker for monitoring renal function decline at early CKD stages. Urine SAM testing confers an additional advantage to healthcare professionals in that it is noninvasive.

Colorimetric Detection Based on Localized Surface Plasmon Resonance for Determination of Chemicals in Urine

Colorimetric sensors based on localized surface plasmon resonance (LSPR) have attracted much attention for biosensor and chemical sensor applications. The unique optical effect of LSPR is based on the nanostructure of noble metals (e.g., Au, Ag, and Al) and the refractive index of the environment surrounding these metal nanomaterials. When either the structure or the environment of these nanomaterials is changed, their optical properties change and can be observed by spectroscopic techniques or the naked eye. Colorimetric-probe-based LSPR provides a simple, rapid, real-time, nonlabelled, sensitive biochemical detection and can be used for point-of-care testing as well as rapid screening for the diagnosis of various diseases. Gold and silver nanoparticles, which are the two most widely used plasmonic nanomaterials, demonstrate strong and sensitive LSPR signals that can be used for the selective detection of several chemicals in biochemical compounds provided by the human body (e.g., urine and blood). This information can be used for the diagnosis of several human health conditions. This paper provides information regarding colorimetric probes based on LSPR for the detection of three major chemicals in human urine: creatinine, albumin, and glucose. In addition, the mechanisms of selective detection and quantitative analysis of these chemicals using metal nanoparticles are discussed along with colorimetric-detection-based LSPR for many other specific chemicals that can be detected in urine, such as catecholamine neurotransmitters, thymine, and various medicines. Furthermore, issues regarding the use of portable platforms for health monitoring with colorimetric detection based on LSPR are discussed.

Colorimetric Determination of Urinary Creatinine in Proteinuria Patients by Chromaticity Analysis of Gold Nanoparticle Colloidal Solutions

Several scientific works have reported the use of colloidal gold nanoparticle (AuNP) solutions as a colorimetric probe for creatinine detection. Nonetheless, urinary protein is one of the primary chemical components that can interfere with creatinine detection. In this work, we developed a colorimetric probe using AuNP colloidal solution to detect creatinine in the urine of proteinuria patients. A microchamber array was prepared to minimize the sample volume and was used to simultaneously perform spectral recording and image acquisition of several samples. The analyzed volume for each sample was 15 μL. A camera coupled with liquid crystal tunable filters was used to record hyperspectral images, and the signals were then converted to localized surface plasmon resonance (LSPR) spectra. Color changes in the AuNP colloidal solution in the presence of varying concentrations of creatinine and human serum albumin (HSA) indicated different features and could be detected by a hyperspectral imaging technique. The relevant concentration ranges of creatinine and HSA were 5 - 200 and 50 - 250 mg dL^-1, respectively. Furthermore, a smartphone camera was adopted to record a color mapping image of the AuNP colloidal solution in the presence of creatinine and HSA at these concentration ranges. Contour plots of red and blue chromaticity levels from color mappings were produced, and 2D fitting equations obtained from these contour plots were adopted to determine the creatinine concentration in the urine of proteinuria patients. This practical technique can be used for screening and can be further developed as a household biosensing device for urinalysis.

Dilute-and-Shoot HPLC-UV Method for Determination of Urinary Creatinine as a Normalization Tool in Mycotoxin Biomonitoring in Pigs

A simple, rapid, and accurate HPLC-UV method was developed for the determination of creatinine in pig urine. Usually, it is determined in urine in biomonitoring of xenobiotics to correct for variations in dilutions of urine samples. The colorimetric method (based on Jaffe reaction), which was mainly used for this purpose in mycotoxin biomonitoring, is not a reliable approach for pig urine. Therefore, a novel and accurate HPLC method for creatinine determination was developed. The sample preparation was based on the dilute and shoot approach. An HPLC separation was performed with a porous graphitic carbon column with an aqueous mobile phase to achieve satisfactory retention time for creatinine. The method has been successfully validated, applied for the determination of creatinine in pig urine, and compared with other methods commonly used for that purpose—a colorimetric method based on Jaffe reaction and commercial ELISA test. The developed HPLC method shows the highest precision and accuracy for pig urine samples. Finally, the method was applied as a normalization tool in LC-MS/MS mycotoxin biomarkers analysis. The standardization to a constant creatinine level (0.5 mg/mL) enables similar matrix effects for eleven mycotoxin biomarkers for pig urine samples with different creatinine levels.

Low-Cost Synthesis of Gold Nanoparticles from Reused Traditional Gold Leaf and its Application for Sensitive and Selective Colorimetric Sensing of Creatinine in Urine

Background:

Gold nanoparticles (Au NPs) are normally prepared using standard gold (III) trichloride which is much expensive and irritant. This work is aimed at demonstrating simple and low-cost synthesis of Au NPs from the reused traditional gold leaf which is cost-free and less toxic.

Methods:

The reused gold leaf was donated by the local temple. It was digested and used as the precursor for the preparation of the Au NPs by Turkevich method. Poly (vinyl alcohol) (PVA) was employed as a stabilizer. The as-prepared Au NPs were applied for the colorimetric determination of creatinine in urine without any sample pretreatment.

Results:

Long-term stability of the gold colloids was achieved for at least 3 months. Morphology and purity of the as-prepared Au NPs were the same as the ones prepared from standard gold (III) salt and standard gold foil. Colorimetric response of the Au NPs was linear to the standard creatinine up to 200 mg L-1. The limit of detection (0.16 mg L-1 or 1.41 μM) was enough sensitive for urinary creatinine detection in patients with kidney disease. Good recoveries (97-108%) and fast analysis time (3 min) were achieved. The developed method was successfully validated against the HPLC method.

Conclusion:

Facile and cost-effective synthesis of the Au NPs from the reused traditional gold leaf, was accomplished. The as-prepared Au NPs were successfully applied for the determination of urinary creatinine with high sensitivity and selectivity.

Determination of S-adenosylmethionine, S-adenosylhomocysteine, and methylthioadenosine in urine using solvent-modified micellar electrokinetic chromatography

A new approach for direct determination of S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and methylthioadenosine (MTA) in urine was developed based on MEKC by using SDS modified with isobutanol in the presence of PEG-300. Analytes were first extracted with grafted phenylborononic acid. Using a 50 µm internal diameter silica capillary of 32 cm total length filled with 0.05 M SDS, 0.05 M H₃ PO₄ , 5% (v/v) isobutanol, and 10% (v/v) PEG-300, LOQ of 0.15 µM for SAM and SAH, and 0.2 µM for MTA was reached. Accuracy was 92% for MTA, 109% for SAH, and 105% for SAM, intra- and interday imprecision were <2.5 and ≤3%, respectively. The total time of analysis for one sample was 10 min. Analysis of 30 urine samples from healthy volunteers showed that the median SAM and SAH levels were 12.1 and 0.73 µM, respectively. MTA levels, which were determined in urine for the first time (according to our data), were 0.43 µM, and these values correlated well with the SAM level (r = 0.748, p < 0.01).

Low S-adenosylmethionine/ S-adenosylhomocysteine Ratio in Urine is Associated with Chronic Kidney Disease

Objective

To evaluate the association of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in urine with chronic kidney disease (CKD).

Methods

Case-control study including 50 patients with CKD and 20 healthy volunteers.

Results

SAM level and SAM/SAH ratio in urine were significantly lower in patients than in control individuals (P &lt;.001 and P = .01, respectively). The estimated glomerular filtration rate was associated with the SAM level (P = .04) and the SAM/SAH ratio in urine (P = .01).

Conclusion

CKD is associated not only with the decline in the SAM level but also with the decrease in the SAM/SAH ratio in urine. Thus, use of the urinary SAM/SAH ratio as a noninvasive diagnostic indicator of renal function seems promising.

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.

Development of Ratiometric Fluorescent Biosensors for the Determination of Creatine and Creatinine in Urine

In this study, the oxazine 170 perchlorate (O17)-ethylcellulose (EC) membrane was successfully exploited for the fabrication of creatine- and creatinine-sensing membranes. The sensing membrane exhibited a double layer of O17-EC membrane and a layer of enzyme(s) entrapped in the EC and polyurethane hydrogel (PU) matrix. The sensing principle of the membranes was based on the hydrolytic catalysis of urea, creatine, and creatinine by the enzymes. The reaction end product, ammonia, reacted with O17-EC membrane, resulting in the change in fluorescence intensities at two emission wavelengths (λ_em = 565 and 625 nm). Data collected from the ratio of fluorescence intensities at λ_em = 565 and 625 nm were proportional to the concentrations of creatine or creatinine. Creatine- and creatinine-sensing membranes were very sensitive to creatine and creatinine at the concentration range of 0.1–1.0 mM, with a limit of detection (LOD) of 0.015 and 0.0325 mM, respectively. Furthermore, these sensing membranes showed good features in terms of response time, reversibility, and long-term stability. The interference study demonstrated that some components such as amino acids and salts had some negative effects on the analytical performance of the membranes. Thus, the simple and sensitive ratiometric fluorescent sensors provide a simple and comprehensive method for the determination of creatine and creatinine concentrations in urine.

Capillary electrophoresis coupled with chloroform-acetonitrile extraction for rapid and highly selective determination of cysteine and homocysteine levels in human blood plasma and urine

A rapid and selective method has been developed for highly sensitive determination of total cysteine and homocysteine levels in human blood plasma and urine by capillary electrophoresis (CE) coupled with liquid-liquid extraction. Analytes were first derivatized with 1,1'-thiocarbonyldiimidazole and then samples were purified by chloroform-ACN extraction. Electrophoretic separation was performed using 0.1 M phosphate with 30 mM triethanolamine, pH 2, containing 25 μM CTAB, 2.5 μM SDS, and 2.5% polyethylene glycol 600. Samples were injected into the capillary (with total length 32 cm and 50 μm id) at 2250 mbar*s and subsequent injection was performed for 30 s with 0.5 M KОН. The total analysis time was less than 9 min, accuracy was 98%, and precision was <2.6%. The LOD was 0.2 μM for homocysteine and 0.5 μM for cysteine. The use of liquid-liquid extraction allowed the precision and sensitivity of the CE method to be significantly increased. The validated method was applied to determine total cysteine and homocysteine content in human blood plasma and urine samples obtained from healthy volunteers and patients with kidney disorders.

Enantioseparation of d,l-2-hydroxyglutaric acid by capillary electrophoresis with tandem mass spectrometry-Fast and efficient tool for d- and l-2-hydroxyglutaracidurias diagnosis

A novel capillary electrophoresis-tandem mass spectrometry method for the enantioseparation and identification of 2-hydroxyglutaric acid enantiomers without derivatization for clinical purposes was described. Vancomycin chloride was used as an efficient chiral selector for the discrimination of 2-hydroxyglutaric acid enantiomers by capillary electrophoresis employed complete capillary filling method. The obtained resolution was 2.05. Hyphenation of CE with tandem mass spectrometry allows a reliable identification of separated enantiomers as well as their quantification. The method was validated and applied for the separation, identification and determination of 2-hydroxyglutaric enantiomers in urine samples obtained from healthy patients and two urine samples obtained from child patients suffering from high urine excretion of 2-hydroxyglutaric acid. Abnormal excretion of d-hydroxyglutaric acid was found in both child urine samples (104.5±2.1 and 2200.0±12.6mmol/mol of creatinine, respectively). The limits of detection for d- and l-hydroxyglutaric acid were 31 and 38nmol/L, respectively.

Picric acid capped silver nanoparticles as a probe for colorimetric sensing of creatinine in human blood and cerebrospinal fluid samples

A new approach has been proposed for the traditional Jaffe's reaction by coating Ag NPs with picric acid to form an assembly that can selectively detect creatinine. This sensor proficiently and selectively recognizes creatinine due to the ability of picric acid to bind with it and form a complex.

A fluorescent probe for the selective detection of creatinine in aqueous buffer applicable to human blood serum

A naphthalimide-based fluorescence light-up probe detects creatinine selectively in PBS buffer of pH 7.2 at 37 °C. It exhibits a ‘turn-on’ response to creatinine over a variety of biologically relevant ions and species and can also detect creatinine in human blood serum.

In-line coupling of single-drop microextraction with capillary electrophoresis-mass spectrometry

Single-drop microextraction (SDME) was in-line coupled with capillary electrophoresis-mass spectrometry to provide sample cleanup and enrichment simultaneously. Since there is no outlet vial in a conventional capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) configuration, it is not easy to hang a single drop in the capillary inlet for extraction. We overcame the difficulty of coupling SDME and CE-MS by using a temporary outlet reservoir. Basic drugs such as methamphetamine, amphetamine, phenethylamine, methoxyphenamine, and mephentermine were extracted from a basic sample solution to an acidic acceptor drop covered with a thin octanol layer formed at the capillary inlet tip. Compared to the CE-MS method in the multiple reaction monitoring (MRM) mode, the in-line SDME-CE-MS/MS technique showed 130∼150-fold enrichment in 10 min. The relative standard deviations (RSDs) of peak height ranged from 9 to 13 %. RSDs can be reduced from 4 to 6 % using mephentermine as an internal standard. We examined the pretreatment of sample with and without SDME from human urine under the full-scan mode, which confirmed that many metabolites were cleaned up by the selective extraction method of SDME. Even if the analytes from human urine were analyzed under the MRM mode used as a mass filter, there was an isobaric compound causing a disturbance to the analysis. However, in-line SDME-CE-MS/MS made it possible to perform a sample cleanup as well as sample enrichment. The research is extremely advantageous in that it is rapid, convenient, and highly sensitive for the analysis of biological samples using a commercially available instrument.

Detection of urinary creatinine using gold nanoparticles after solid phase extraction

Label-free gold nanoparticles (AuNPs) were utilized in the detection of creatinine in human urine after a sample preparation by extraction of creatinine on sulfonic acid functionalized silica gel. With the proposed sample preparation method, the interfering effects of the urine matrix on creatinine detection by AuNPs were eliminated. Parameters affecting creatinine extraction were investigated. The aggregation of AuNPs induced by creatinine resulted in a change in the surface plasmon resonance signal with a concomitant color change that could be observed by the naked eye and quantified spectrometrically. The effect of AuNP concentration and reaction time on AuNP aggregation was investigated. The method described herein provides a determination of creatinine in a range of 15-40mgL(-1) with a detection limit of 13.7mgL(-1) and it was successfully used in the detection of creatinine in human urine samples.

Reagent- and separation-free measurements of urine creatinine concentration using stamping surface enhanced Raman scattering (S-SERS)

We report a novel reagent- and separation-free method for urine creatinine concentration measurement using stamping surface enhanced Raman scattering (S-SERS) technique with nanoporous gold disk (NPGD) plasmonic substrates, a label-free, multiplexed molecular sensing and imaging technique recently developed by us. The performance of this new technology is evaluated by the detection and quantification of creatinine spiked in three different liquids: creatinine in water, mixture of creatinine and urea in water, and creatinine in artificial urine within physiologically relevant concentration ranges. Moreover, the potential application of our method is demonstrated by creatinine concentration measurements in urine samples collected from a mouse model of nephritis. The limit of detection of creatinine was 13.2 nM (0.15 µg/dl) and 0.68 mg/dl in water and urine, respectively. Our method would provide an alternative tool for rapid, cost-effective, and reliable urine analysis for non-invasive diagnosis and monitoring of renal function.

Development and validation of an ultra-high performance liquid chromatography-tandem mass spectrometry method to measure creatinine in human urine

Despite decades of creatinine measurement in biological fluids using a large variety of analytical methods, an accurate determination of this compound remains challenging. Especially with the novel trend to assess biomarkers on large sample sets preserved in biobanks, a simple and fast method that could cope with both a high sample throughput and a low volume of sample is still of interest. In answer to these challenges, a fast and accurate ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to measure creatinine in small volumes of human urine. In this method, urine samples are simply diluted with a basic mobile phase and injected directly under positive electrospray ionization (ESI) conditions, without further purification steps. The combination of an important diluting factor (10(4) times) due to the use of a very sensitive triple quadrupole mass spectrometer (XEVO TQ) and the addition of creatinine-d3 as internal standard completely eliminates matrix effects coming from the urine. The method was validated in-house in 2012 according to the EMA guideline on bioanalytical method validation using Certified Reference samples from the German External Quality Assessment Scheme (G-Equas) proficiency test. All obtained results for accuracy and recovery are within the authorized tolerance ranges defined by G-Equas. The method is linear between 0 and 5 g/L, with LOD and LOQ of 5 × 10(-3) g/L and 10(-2) g/L, respectively. The repeatability (CV(r) = 1.03-2.07%) and intra-laboratory reproducibility (CV(RW) = 1.97-2.40%) satisfy the EMA 2012 guideline. The validated method was firstly applied to perform the German G-Equas proficiency test rounds 51 and 53, in 2013 and 2014, respectively. The obtained results were again all within the accepted tolerance ranges and very close to the reference values defined by the organizers of the proficiency test scheme, demonstrating an excellent accuracy of the developed method. The method was finally applied to measure the creatinine concentration in 210 urine samples, coming from 190 patients with a chronic kidney disease (CKD) and 20 healthy subjects. The obtained creatinine concentrations (ranging from 0.12 g/L up to 3.84 g/L) were compared, by means of a Passing Bablok regression, with the creatinine contents obtained for the same samples measured using a traditional compensated Jaffé method. The UHPLC-MS/MS method described in this paper can be used to normalize the concentration of biomarkers in urine for the extent of dilution.

Development and validation of a novel derivatization method for the determination of lactate in urine and saliva by liquid chromatography with UV and fluorescence detection

We developed a novel and straightforward derivatization method for the determination of lactate by reversed phase high-performance liquid chromatography (RP-HPLC) with fluorescence and UV detection in biological matrices as urine and saliva. The derivatization of lactate was achieved employing 9-chloromethyl anthracene (9-CMA) as fluorescence reagent, which has never been previously used to obtain a lactate derivative. Lactate reacts with 9-CMA with high selectivity in a very short time, without requiring extraction procedures from the aqueous solution, and the reaction reaches 70% completion in 30 min. The ester derivative obtained can be easily determined by RP-HPLC with fluorescence detection at 410 nm (λ ex=365 nm) and UV detection at 365 nm. The method was also optimized in order to allow for the simultaneous determination of lactate and creatinine for the application to urine samples. The lactate calibration curve was linear in the investigated range 2 × 10(-4)-3 × 10(-2)mM and the limit of detection, calculated as three times the standard deviation of the blank divided by the calibration curve slope, was 50 nM for both fluorescence and UV detection. Intra-day and inter-day repeatability were lower than 5% and 6%, respectively. The method proposed was successfully applied to the analysis of urine and saliva samples.

Otimização e validação de uma metodologia analítica para determinação de 1-hidroxipireno em urina de cortadores de cana-de-açúcar

Este trabalho teve como objetivo otimizar e validar uma metodologia analítica para determinação de 1-hidróxipireno em urina de trabalhadores envolvidos na colheita da cana-de-açúcar. O método utilizado para determinação de 1-hidroxipireno em urina humana utilizado consiste na hidrólise enzimática, extração e clean-up por extração em fase sólida (SPE) e quantificação por cromatografia líquida de alta eficiência com detector de fluorescência (CLAE/Flu). Quatro tipos de cartuchos foram testados para verificação da porcentagem de recuperação. Urina de cortadores de cana-de-açúcar (não-fumantes e de ambos os sexos) foram coletadas no período da safra (n=39) e entressafra (n=34) da cana-de-açúcar. Os melhores resultados de recuperação foram atribuídos aos cartuchos C18. Os mesmos apresentaram recuperação entre 79% e 108%, com coeficiente de variação entre 5% e 10%. O limite de quantificação do método foi de 74 ng de 1-hidroxipireno por litro de urina. A metodologia otimizada e validada foi utilizada para determinação de amostras reais. Os resultados encontrados na urina dos trabalhadores no período da safra variaram de 0,026 a 2,3 μmol de 1-hidroxipireno por mol de creatinina. No período da entressafra os resultados variaram de 0,0023 a 0,38 μmol de 1-hidroxipireno por mol de creatinina. A metodologia validada mostrou-se adequada para determinação de 1-hidroxipireno em urina humana. Os dados obtidos permitem concluir que há forte correlação entre excreção de 1-hidroxipireno e os períodos de safra e entressafra da cana de açúcar.