Creatinine Content Detection: Main Methods, Reaction Principles, and Result Control
Creatinine Content Detection: Main Methods, Reaction Principles, and Result Control
Creatinine content detection is commonly used for renal function assessment, urinary indicator normalization, and drug nephrotoxicity studies in serum, plasma, urine, and animal experimental samples. The core differences among detection methods lie in reaction principle, signal generation mode, interference control capability, and sample compatibility. Common methods include the alkaline picrate method, creatininase method, creatinine deiminase method, dry chemistry method, HPLC, and LC-MS/MS. Enzymatic methods generally offer higher specificity, the Jaffe method has a broad application base, and chromatographic and mass spectrometric methods are more suitable for complex matrices and high-accuracy research.
Keywords: creatinine; creatinine content detection; Jaffe method; alkaline picrate method; creatininase method; sarcosine oxidase method; creatinine deiminase method; dry chemistry method; HPLC; LC-MS/MS; urinary creatinine; serum creatinine
1 Analytical Basis of Creatinine Detection
1.1 Source and Sample Distribution of Creatinine
(1) Formation source
Creatinine is a small-molecule metabolite formed by the non-enzymatic cyclization and degradation of creatine and phosphocreatine, mainly originating from skeletal muscle. Its production is related to muscle mass, age, sex, nutritional status, exercise status, and metabolic level. Therefore, baseline creatinine levels may differ markedly among different individuals or animal models.
(2) Excretion characteristics
Creatinine is mainly excreted by glomerular filtration, with a small amount secreted by renal tubules. Serum or plasma creatinine is commonly used to evaluate changes in glomerular filtration function. Urinary creatinine is often used to correct for urine concentration, such as in the urine protein/creatinine ratio, urine albumin/creatinine ratio, and urinary metabolite/creatinine ratio.
(3) Detection boundaries
Creatinine results are affected by glomerular filtration rate, muscle mass, sampling time, diet, medications, and hydration status. Increased blood creatinine usually suggests impaired renal function, but creatinine changes may lag behind in early kidney injury. Urinary creatinine is suitable for normalization analysis, but it should be interpreted cautiously in oliguria, polyuria, or abnormal creatinine excretion.
1.2 Sample Types and Method Compatibility
(1) Serum and plasma
Serum and plasma are the most common sample types for creatinine detection. Serum has a relatively stable background and is suitable for the Jaffe method, creatininase method, and automated biochemical platforms. For plasma samples, attention should be paid to the anticoagulant type. Heparin plasma is commonly used, while the compatibility of EDTA-, citrate-, or oxalate-anticoagulated samples should be verified according to the specific reagent system.
(2) Urine
Urinary creatinine concentration is usually higher than blood creatinine concentration, so dilution is often required before detection. Urine pH, salt concentration, color, drug metabolites, and bacterial contamination may affect the chromogenic background. Therefore, urine samples require more stringent dilution linearity and spike recovery validation.
(3) Animal and cell experimental samples
Samples from mice, rats, and other animals are limited in volume, and baseline blood creatinine levels are low, requiring higher method sensitivity and better low-value accuracy. Tissue homogenates and cell supernatants have complex matrices; proteins, lipids, reducing substances, and culture medium components may all affect colorimetric or enzymatic chromogenic systems, so serum detection conditions cannot be directly applied.
2 Alkaline Picrate Method
2.1 Reaction Principle
(1) Jaffe reaction
The alkaline picrate method, also known as the Jaffe method, is based on the reaction between creatinine and picric acid under alkaline conditions to form an orange-red complex. Creatinine content is calculated by measuring absorbance changes at a specific wavelength. This method does not rely on enzymatic reactions, has a simple system and relatively low cost, and is a classic method used early in creatinine detection.
(2) Chromogenic process
The detection system usually includes picric acid, an alkaline buffer system, and the sample. After the reaction starts, creatinine reacts with picric acid to form a colored product, and absorbance changes over time. Depending on the reading mode, the method can be divided into endpoint and rate methods.
(3) Quantitative logic
The endpoint method reads absorbance after the reaction reaches a certain stage and calculates concentration from a standard curve. The rate method detects the absorbance change rate within a short time window, taking advantage of the relatively fast reaction between creatinine and picric acid to reduce interference from some slowly reacting substances.
2.2 Method Types
(1) Endpoint Jaffe method
The endpoint method is straightforward and suitable for manual colorimetry and some basic experiments. However, because many non-creatinine substances in samples may also produce color in the alkaline picrate system, endpoint readings are prone to cumulative background interference. This is especially obvious in low-creatinine serum samples, complex urine matrices, and animal samples.
(2) Rate Jaffe method
The rate method calculates creatinine concentration based on absorbance changes within a fixed time window, which can reduce the influence of some slowly reacting non-creatinine chromogens. Automated biochemical platforms often use rate or compensated Jaffe systems, but this method still cannot completely eliminate nonspecific interference.
(3) Compensated Jaffe method
Some detection systems use methodological compensation or blank correction to reduce interference from proteins, glucose, ketone bodies, bilirubin, and other substances. Compensation parameters usually depend on the detection platform and sample type, so results from different systems should not be directly compared.
2.3 Interference and Scope of Application
(1) Positive interference
Glucose, ketone bodies, proteins, cephalosporin drugs, and certain non-creatinine chromogens may cause falsely elevated results. In urine samples, drug metabolites and color background may also increase absorbance.
(2) Negative interference
Bilirubin, ascorbic acid, and other reducing or absorbance-interfering substances may cause falsely low results. Samples with severe icterus or high ascorbic acid should be interpreted with particular caution.
(3) Application positioning
The Jaffe method is suitable for routine screening where cost is a major concern, sample volume is large, and very high accuracy is not required. If used for key scientific conclusions, comparison with the creatininase method or chromatographic/mass spectrometric methods is recommended.
3 Creatininase Method
3.1 Cascade Reaction System
(1) Creatinine hydrolysis
Creatininase catalyzes the hydrolysis of creatinine to creatine. This step is the initial reaction of the creatininase method and one of the main sources of method specificity.
(2) Creatine conversion
Creatine is converted into sarcosine and urea by creatinase or creatine amidinohydrolase. This step introduces the creatinine-derived reaction product into the subsequent oxidation reaction chain.
(3) Sarcosine oxidation
Sarcosine oxidase catalyzes sarcosine to produce glycine, formaldehyde, and hydrogen peroxide. The generated hydrogen peroxide corresponds to the sample creatinine content and serves as the direct signal source for the chromogenic reaction.
(4) POD color development
Peroxidase catalyzes the reaction between hydrogen peroxide, 4-aminoantipyrine, and phenolic or aniline-type chromogenic substrates to form a colored quinoneimine product. The creatinine concentration in the sample can be calculated by measuring the absorbance change.
3.2 Detection System Types
(1) Endpoint enzymatic method
The endpoint enzymatic method reads absorbance after the reaction is sufficiently complete. It is suitable for assay kits, microplate detection, and some semi-automated analysis. This method requires strict control of reaction time, incubation temperature, and blank correction.
(2) Rate enzymatic method
The rate enzymatic method detects the change in chromogenic signal per unit time and is suitable for automated biochemical analysis platforms. Its advantages include high throughput and good repeatability, and it can reduce some fixed background effects.
(3) Dual-reagent enzymatic method
A dual-reagent system usually first processes sample background or endogenous interferents such as creatine and sarcosine, and then initiates the creatinine-specific reaction. In complex samples, serum samples, and automated platforms, dual-reagent systems are more conducive to improving accuracy.
3.3 Method Advantages and Interference Control
(1) Specificity advantage
The creatininase method relies on enzymatic substrate recognition, and its specificity is generally higher than that of the Jaffe method. It is less affected by non-creatinine chromogens and is suitable for low-concentration serum samples, small-animal samples, and studies requiring higher accuracy.
(2) Effect of enzyme activity
A decrease in the activity of any component—creatininase, creatinase, sarcosine oxidase, or peroxidase—may lead to falsely low results or poor linearity. Reagent storage temperature, freeze-thaw cycles, expiration date, and reaction temperature should all be strictly controlled.
(3) Chromogenic interference
Ascorbic acid, bilirubin, hemolysis, lipemia, and sample turbidity may still affect the hydrogen peroxide-POD chromogenic system. Some reagents include ascorbate oxidase to reduce interference from reducing substances, but complex samples still require blank correction and recovery validation.
4 Creatinine Deiminase Method
4.1 Reaction Principle
(1) Creatinine deimination
Creatinine deiminase catalyzes creatinine to generate N-methylhydantoin and ammonia. This pathway does not pass through creatine, sarcosine, or hydrogen peroxide generation, and differs from the classical creatininase-creatinase-sarcosine oxidase system.
(2) Signal detection
The generated ammonia can be detected through coupled reactions. Common strategies include linking ammonia to the glutamate dehydrogenase reaction and quantifying it through NADH consumption or other chromogenic systems.
(3) Method positioning
The creatinine deiminase method is another enzymatic route for creatinine detection and can be used in specific reagent systems or method development. Its advantage lies in its different reaction chain, which can serve as a complementary detection strategy to the sarcosine oxidase method.
4.2 Differences from the Sarcosine Oxidase Method
(1) Different substrate conversion pathways
The sarcosine oxidase method generates signals through the creatinine-creatine-sarcosine-hydrogen peroxide chain. The creatinine deiminase method directly deiminates creatinine to generate products, followed by ammonia-related detection.
(2) Different interference types
The sarcosine oxidase method is mainly affected by the peroxidase chromogenic system, endogenous creatine/sarcosine, and reducing substances. The creatinine deiminase method requires greater attention to sample ammonia, ammonium salts, or nitrogen metabolism-related background.
(3) Different application scenarios
The sarcosine oxidase method is more commonly used in clinical biochemistry and assay kit systems. The creatinine deiminase method is more commonly used in specific method development, enzymology research, or exploration of alternative detection routes.
5 Dry Chemistry and Rapid Detection
5.1 Dry Slide Detection
(1) Basic format
Dry chemistry methods usually immobilize reaction reagents on dry slides, test strips, or detection cards. After sample addition, diffusion, reaction, and color development occur within the solid-phase carrier. Instruments read results through reflectance, color change, or electrochemical signals.
(2) Reaction basis
Most dry chemistry creatinine assays are still based on enzymatic reactions, but transfer liquid-phase reactions to solid-phase carriers. Different platforms may use different enzyme systems, chromogenic systems, and correction algorithms.
(3) Operational characteristics
Dry chemistry methods require small sample volumes, are fast, and can be miniaturized. They are suitable for point-of-care testing, rapid screening, small-volume animal samples, and on-site detection.
5.2 Quality Control Points
(1) Platform dependence
Dry chemistry methods are highly dependent on instruments, test strip batches, calibration chips, or built-in algorithms. Results from different platforms should not be directly combined for analysis.
(2) Sample volume control
Insufficient sample volume, uneven loading, or moisture-exposed strips can affect result stability. For micro blood or urine samples, sample loading volume and reading time should be strictly controlled according to the instructions.
(3) Application boundaries
Dry chemistry methods are suitable for obtaining rapid results. However, if high-accuracy scientific conclusions or complex matrix analysis is required, liquid-phase enzymatic systems, HPLC, or LC-MS/MS should be used for verification.
6 Chromatographic and Mass Spectrometric Methods
6.1 HPLC Method
(1) Detection principle
HPLC separates creatinine from other interfering substances in the sample using a chromatographic column, followed by quantification with ultraviolet, diode array, or other detectors. This method improves specificity through separation and reduces the influence of co-chromogenic substances in colorimetric methods.
(2) Sample pretreatment
Serum, urine, or tissue samples usually require protein precipitation, centrifugation, filtration, or dilution. Pretreatment quality directly affects chromatographic peak shape, recovery, and quantitative stability.
(3) Application positioning
HPLC is suitable for complex samples, method validation, abnormal result confirmation, and scientific quantitative analysis. Its throughput is lower than automated biochemical methods, but its specificity and interpretability are stronger.
6.2 LC-MS/MS Method
(1) Detection principle
LC-MS/MS performs quantification through liquid chromatographic separation and monitoring of characteristic mass spectrometric ions. Stable isotope internal standards can be used to correct matrix effects and instrumental fluctuations. This method has high sensitivity and specificity.
(2) Internal standard correction
Using isotope-labeled creatinine internal standards can correct sample pretreatment loss, ion suppression, and injection variation, improving quantitative reliability in complex samples.
(3) Application positioning
LC-MS/MS is suitable for reference quantification, high-accuracy research, complex matrix analysis, and multi-metabolite combined detection. Its cost, instrument requirements, and operator requirements are high, so it is not suitable as a routine rapid detection method for all samples.
Table 1 Principles and Application Differences of Creatinine Content Detection Methods
Method type | Core principle | Main advantages | Main limitations | More suitable samples or scenarios |
Alkaline picrate method | Creatinine reacts with picric acid under alkaline conditions to form color | Low cost, simple system, mature application | More interference from non-creatinine chromogens | Routine screening, basic experiments, large-sample preliminary testing |
Rate Jaffe method | Detects color development rate within a short time | Can reduce some slow-reaction interference | Nonspecific interference still exists | Routine detection on automated biochemical analyzers |
Creatininase method | Creatininase-creatinase-sarcosine oxidase-POD cascade color development | Higher specificity, suitable for automation | Requires stable enzyme activity and chromogenic system | Serum, plasma, urine, animal samples |
Creatinine deiminase method | Creatinine is deiminated to generate ammonia for coupled detection | Different reaction route; can serve as an alternative enzymatic method | Requires control of ammonia/ammonium background | Method development, specific enzymatic systems |
Dry chemistry method | Enzymatic or electrochemical reaction on a solid-phase carrier | Fast, low sample volume, suitable for on-site testing | Strong platform dependence | POCT, small-volume samples, rapid screening |
HPLC method | Quantification after chromatographic separation | Good specificity and less matrix interference | High pretreatment and instrument requirements | Complex samples, method validation |
LC-MS/MS method | Chromatographic separation combined with mass spectrometric detection | High sensitivity and specificity; allows internal standard correction | High cost and relatively limited throughput | High-accuracy quantification, complex matrices, reference research |
7 Sample Processing and Method Selection
7.1 Serum and Plasma Samples
(1) Routine selection
For serum and plasma creatinine detection, the creatininase method or automated biochemical platforms are preferred. If the Jaffe method is used, interference from glucose, ketone bodies, bilirubin, ascorbic acid, and drugs should be considered.
(2) Small-animal samples
Baseline blood creatinine levels in mice and rats are low, and sample volumes are small. Low-value fluctuations in the Jaffe method may be large. Such samples are more suitable for high-sensitivity enzymatic methods, dry chemistry micro-platforms, or LC-MS/MS confirmation.
(3) Abnormal samples
Severely hemolyzed, lipemic, or icteric samples should be interpreted cautiously. If results are clearly inconsistent with blood urea nitrogen, pathological findings, or model expectations, blank correction, dilution retesting, or method replacement should be considered.
7.2 Urine Samples
(1) Dilution linearity
Urinary creatinine concentration varies widely, so the dilution factor should be determined according to the reagent linear range before detection. Direct detection of high-concentration urine samples may exceed linearity, while excessive dilution may reduce low-value resolution.
(2) Normalization use
Urinary creatinine is commonly used to correct urine protein, urine albumin, urinary metabolites, or drug excretion. When used for ratio calculation, the target analyte and creatinine should come from the same urine sample and preferably be detected in the same batch.
(3) Matrix validation
Urine color, pH, salt content, and drug metabolites may all affect colorimetric systems. In research testing, dilution linearity and spike recovery validation are recommended, especially for urine samples from animal models or drug-treated subjects.
7.3 Tissue Homogenates and Cell Samples
(1) Tissue homogenates
Tissue homogenates contain abundant proteins, lipids, heme, reducing substances, and endogenous peroxides, which can easily affect chromogenic reactions. If tissue creatinine is to be detected, protein precipitation, dilution, centrifugation, and blank correction procedures should first be optimized.
(2) Cell supernatants
Phenol red, serum supplements, drugs, antioxidants, or metabolic substrates in culture medium may affect detection. When using cell supernatants, culture medium blanks, treatment blanks, and spike recovery should be included.
(3) Method recommendation
In complex matrices, the creatininase method can be used for preliminary detection, but key conclusions should be confirmed by HPLC or LC-MS/MS. If only a colorimetric method is used, matrix compatibility validation must be provided.
8 Quality Control and Result Interpretation
8.1 Standard Curve and Calibration
(1) Standard curve
Manual colorimetry and assay kit detection usually use creatinine standards to establish a concentration-absorbance curve. The standard curve should cover the expected sample concentration range, and samples beyond the linear range should not be extrapolated.
(2) Calibrators
Automated biochemical and dry chemistry platforms depend more on calibrators, instrument parameters, and platform algorithms. Inconsistent calibration systems can cause systematic bias.
(3) Quality controls
Low-, medium-, and high-level quality controls can monitor within-day precision, between-day drift, and reagent batch differences. In scientific experiments, it is recommended that samples from the same batch be tested using the same detection platform and reagent batch.
8.2 Common Interferences
(1) Colorimetric interference
Lipemia, icterus, hemolysis, sample turbidity, and strong background color can all affect absorbance readings. The Jaffe method is particularly susceptible to non-creatinine chromogens, while enzymatic methods require more attention to interference in the POD chromogenic system.
(2) Reducing interference
Ascorbic acid, glutathione, and other reducing substances may consume hydrogen peroxide or affect the chromogenic product, causing falsely low enzymatic results. Ascorbate oxidase treatment or another detection method may be used when necessary.
(3) Endogenous intermediates
The creatininase method involves creatine, sarcosine, and hydrogen peroxide generation. Abnormally elevated endogenous creatine or sarcosine in samples may affect the background. Dual-reagent methods and sample blanks can reduce this type of interference.
8.3 Troubleshooting Abnormal Results
(1) Falsely high results
When results are abnormally high, check sample turbidity, color, urine dilution factor, nonspecific color development in the Jaffe method, endogenous creatine/sarcosine background, and whether the standard curve has exceeded linearity.
(2) Falsely low results
When results are abnormally low, check whether enzyme activity has decreased, whether reagents have expired, whether the reaction temperature is insufficient, whether ascorbic acid is high, and whether the sample has been over-diluted.
(3) Poor repeatability
Poor repeatability is commonly caused by pipetting errors, insufficient sample mixing, bubbles in wells, unremoved precipitates, inconsistent incubation temperature, and inconsistent reading time. Micro methods especially require strict control of pipetting precision.
Table 2 Abnormal Creatinine Detection Results and Methodological Troubleshooting
Result pattern | Possible cause | Priority checks | Recommended handling |
Abnormally high result | Nonspecific color development, sample turbidity, urine beyond linear range, endogenous intermediate interference | Sample blank, dilution linearity, standard curve range | Dilute and retest, set blanks, switch to enzymatic method or LC-MS/MS if necessary |
Abnormally low result | Decreased enzyme activity, ascorbic acid interference, insufficient reaction time, excessive dilution | Quality control results, reagent expiration, reaction temperature | Replace reagent, retest controls, optimize dilution factor |
Large differences between replicates | Pipetting error, bubbles, sample precipitate, insufficient mixing | Replicate CV, sample state, pipetting process | Centrifuge sample, remix, standardize pipetting |
Inconsistency with blood urea nitrogen | Physiological effects of creatinine or method interference | Sample quality, other renal function indicators | Combine with pathology, cystatin C, or confirmatory testing |
Large urinary creatinine fluctuation | Differences in water intake, sampling time, dilution factor | Urine volume, urine specific gravity, sampling process | Fix sampling time and dilution strategy |
Unstable low values in animal samples | Close to detection limit, small sample volume, high background proportion | Detection limit, blank absorbance, quality control | Choose a more sensitive method or increase sample volume |
9 Selection of Related Reagents and Detection Materials
Table 3 Reagents and Detection Tools Related to Creatinine Content Detection Methods
Cat. No. | Product Name | Grade/Specification | Product category | Corresponding detection method or step | Application positioning |
Creatinine (Cr) Content Assay Kit (PA Rate, Micro Method) | BioReagent | Creatinine assay kit | Jaffe/PA rate detection | Used for rapid colorimetric detection of creatinine content; can serve as an alkaline picrate-related detection system or methodological control for enzymatic results | |
Creatinine (Cr) Content Assay Kit (SOX, Micro Method) | BioReagent | Creatinine assay kit | Sarcosine oxidase method | Used for creatinine quantification in micro-samples; suitable for serum, plasma, urine, and animal experimental samples | |
Creatinine (Cr) Content Assay Kit (SOX, Colorimetric Method) | BioReagent | Creatinine assay kit | Sarcosine oxidase colorimetric method | Used for routine colorimetric creatinine quantification; suitable for standard curves, sample blanks, and batch sample testing | |
Creatinine | ≥99% | Creatinine standard | Standard curve and recovery validation | Used as a creatinine standard for standard curve establishment, spike recovery, and method evaluation | |
Creatinine | 10mM in Water | Creatinine standard solution | Standard curve and positive control | Suitable for direct preparation of standard curves or validation of enzymatic/Jaffe detection systems | |
Creatinine hydrochloride | ≥97% | Creatinine-related reference material | Method validation | Can be used for creatinine-related detection system development or control experiments; salt-form differences should be considered | |
Creatinine-(methyl-d₃) | ≥98 atom% D,≥97% | Isotope-labeled creatinine | LC-MS/MS internal standard | Suitable as a stable isotope internal standard in LC-MS/MS creatinine quantification, improving quantitative reliability in complex matrices | |
Creatinine-(methyl-¹³C) | ≥99 atom% 13C | Isotope-labeled creatinine | LC-MS/MS internal standard | Used as an internal standard or method validation material for mass spectrometric creatinine quantification, suitable for high-accuracy detection systems | |
Creatinine deiminase (CNI) | Bioactive, ActiBioPure™, EnzymoPure™, High Performance, ≥100 U/mg protein | Creatinine deiminase | Creatinine deiminase method | Catalyzes creatinine deimination; suitable for creatinine deiminase methods or alternative enzymatic detection route development | |
Creatinine amidohydrolase (CAH) | BioReagent, EnzymoPure™, ≥90%(SDS-PAGE), ≥ 400 U/mg | Creatininase | Initial step of the sarcosine oxidase method | Catalyzes creatinine to creatine and is the core initiating enzyme in the creatininase cascade | |
Creatininase (CAH) from Microorganism | Bioactive,ActiBioPure™,Native,High Performance,EnzymoPure™,≥450 U/mg enzyme powder | Microbial creatininase | Initial step of the sarcosine oxidase method | Used for creatinine-specific conversion; suitable for enzymatic creatinine assay development, enzyme activity comparison, and reaction condition optimization | |
Creatine amidinohydrolase (CR) | EnzymoPure™, BioReagent, ≥90%(SDS-PAGE), ≥ 5.8 U/mg | Creatinase / creatine amidinohydrolase | Creatine conversion step | Catalyzes creatine to sarcosine, linking creatinine hydrolysis with sarcosine oxidation | |
Sarcosine oxidase (SOX) | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥90%(SDS-PAGE),≥15 U/mg enzyme powder; expressed in E.coli | Sarcosine oxidase | Hydrogen peroxide generation step | Catalyzes sarcosine oxidation to generate hydrogen peroxide and is the key upstream enzyme for chromogenic signal formation | |
Recombinant Sarcosine Oxidase (SOX) | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥25U/mg enzyme powder; ≥40U/mg protein | Recombinant sarcosine oxidase | Hydrogen peroxide generation step | Used to improve sarcosine oxidation efficiency; suitable for microassays, colorimetric systems, and method optimization | |
Creatine monohydrate | ≥98% | Creatine standard/intermediate | Creatine background validation | Used to evaluate creatine-related background or the reaction efficiency of the creatinase step in the creatininase method | |
Creatine monohydrate | 10mM in Water | Creatine standard solution | Creatine background validation | Can be used as an intermediate control in the enzymatic cascade or for endogenous creatine interference validation | |
Creatine-(methyl-d₃) monohydrate | ≥98 atom% D | Isotope-labeled creatine | LC-MS/MS/intermediate tracing | Can be used for creatine-related background analysis in mass spectrometry or validation of enzymatic cascade conversion | |
Creatine-(methyl-¹³C) monohydrate | ≥99 atom% 13C | Isotope-labeled creatine | LC-MS/MS/intermediate tracing | Used as a creatine-related mass spectrometry internal standard or intermediate validation material in the creatininase method | |
Creatine Content Assay Kit (Micro Method) | BioReagent | Creatine detection tool | Endogenous creatine background troubleshooting | Can help determine whether sample creatine background affects creatininase method detection | |
Creatine Content Assay Kit (Enzymatic, Micro Method) | BioReagent | Creatine detection tool | Endogenous creatine background troubleshooting | Used to evaluate sample creatine levels; suitable for creatininase method validation | |
Creatine Content Assay Kit (Enzymatic, Colorimetric Method) | BioReagent | Creatine detection tool | Endogenous creatine background troubleshooting | Used for creatine-related background analysis and combined validation with the creatininase cascade | |
Sarcosine | Moligand™, ≥98% | Sarcosine standard/intermediate | SOX reaction validation | Used to validate the downstream sarcosine oxidase reaction efficiency and POD chromogenic system response | |
Sarcosine | Moligand™, 10mM in Water | Sarcosine standard solution | SOX reaction validation | Suitable for direct use in sarcosine oxidase reaction systems or standard curve validation | |
Sarcosine | Moligand™, for synthesis | Sarcosine reagent | SOX reaction validation | Can be used as a sarcosine substrate in method development or for downstream reaction condition optimization | |
Sarcosine | UltraBio™, Ultra pure | High-purity sarcosine | SOX reaction validation | Suitable for enzymatic reactions or background-control experiments requiring high purity | |
Sarcosine hydrochloride | ≥99% | Sarcosine salt reagent | SOX reaction validation | Can serve as a sarcosine-related substrate or methodological control; salt form and pH effects should be considered | |
Sodium sarcosinate | 30% in Water | Sarcosine salt solution | SOX reaction validation | Used for liquid substrate preparation or downstream oxidation-color development validation | |
Sodium sarcosinate | 35% in Water | Sarcosine salt solution | SOX reaction validation | Suitable for sarcosine oxidase reaction system optimization | |
Sodium sarcosinate | ca. 40% in Water | Sarcosine salt solution | SOX reaction validation | Can be used for constructing liquid-phase enzymatic reaction systems | |
Horseradish Peroxidase (HRP) | Bioactive,ActiBioPure™,Native,High Performance,EnzymoPure™,from Horseradish; ≥250 U/mg enzyme powder; RZ≥3 | Peroxidase | POD/Trinder chromogenic step | Catalyzes hydrogen peroxide-dependent color formation; suitable for terminal colorimetric signal generation in the creatininase method | |
Horseradish Peroxidase (HRP) | Bioactive,ActiBioPure™,Native,High Performance,EnzymoPure™,from Horseradish; ≥100 U/mg enzyme powder; RZ≥1 | Peroxidase | POD chromogenic step | Used in routine hydrogen peroxide-dependent chromogenic reaction systems | |
Horseradish Peroxidase (HRP) | Bioactive,ActiBioPure™,Native,High Performance,EnzymoPure™,from Horseradish; ≥150 U/mg enzyme powder; RZ≥1.5 | Peroxidase | POD chromogenic step | Suitable for terminal color development and colorimetric system optimization in the creatininase method | |
Horseradish Peroxidase (HRP) | EnzymoPure™, ＞200 U/mg, RZ 2-4 | Peroxidase | POD chromogenic step | Used for hydrogen peroxide chromogenic reactions and as the terminal enzyme in enzymatic creatinine detection systems | |
Horseradish Peroxidase (HRP) | Bioactive,ActiBioPure™,Native,High Performance,EnzymoPure™,from Horseradish; ≥160 U/mg, Rz≥2.0 | Peroxidase | POD chromogenic step | Used in terminal chromogenic reactions of the creatininase method and helps optimize chromogenic system stability | |
Horseradish Peroxidase (HRP) | Bioactive,ActiBioPure™,Native,High Performance,EnzymoPure™,≥300U/mg enzyme powder, Rz≥3; from Horseradish | High-activity peroxidase | POD chromogenic step | Suitable for creatininase systems requiring higher chromogenic sensitivity | |
Horseradish Peroxidase (HRP) | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥150U/mg enzyme powder, Rz ≥2; expressed in Nicotiana benthamiana | Recombinant peroxidase | POD chromogenic step | Used in recombinant-source POD chromogenic systems and reagent formulation consistency studies | |
Horseradish Peroxidase (HRP) | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥250U/mg enzyme powder, Rz ≥3; expressed in Nicotiana benthamiana | High-activity recombinant HRP | POD chromogenic step | Used for high-sensitivity POD chromogenic systems and signal amplification in the creatininase method | |
Horseradish Peroxidase (HRP) | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥150U/mg enzyme powder, Rz ≥2.0 | Recombinant peroxidase | POD chromogenic step | Suitable for POD reaction construction in enzymatic creatinine detection system development | |
Peroxidase from horseradish | Type I, essentially salt-free, lyophilized powder,≥50 units/mg solid (using pyrogallol) | Peroxidase | POD chromogenic step | Can be used for basic peroxidase chromogenic system screening and reaction condition exploration | |
Peroxidase from horseradish | Type X, ammonium sulfate suspension | Peroxidase | POD chromogenic step | HRP in suspension form; can be used for enzymatic chromogenic system construction | |
Peroxidase from horseradish(EIA Grade,Purified) | EnzymoPure™, RZ 2.9,≥500 units/mg protein | High-purity peroxidase | POD chromogenic step | Suitable for detection systems requiring higher enzyme purity, chromogenic efficiency, and background control | |
Peroxidase from horseradish（HRP） | EnzymoPure™,ActiBioPure™,Bioactive,High Performance,Native,≥180 U/mg powder, Rz≥2.0 | Peroxidase | POD chromogenic step | Used for hydrogen peroxide color development and terminal reaction optimization in the creatininase method | |
Peroxidase (POD), activated | from horseradish | Activated POD | POD chromogenic step | Can be used to rapidly establish peroxidase chromogenic systems and is suitable for method validation | |
Peroxidase Stabilizing Buffer | liquid | Stabilizing buffer | POD system stabilization | Used to maintain peroxidase activity and chromogenic system stability; suitable for reagent formulation optimization | |
Ascorbate Oxidase from microorganism | EnzymoPure™, ＞200 U/mg | Anti-interference enzyme | Ascorbic acid interference control | Used to reduce reducing interference from ascorbic acid in hydrogen peroxide-POD chromogenic systems | |
Ascorbate Oxidase (ASO) from Cucurbit sp. | ActiBioPure™, Bioactive, High Performance, EnzymoPure™, ≥100 U/mg powder; ≥1000 U/mg protein | Anti-interference enzyme | Ascorbic acid interference control | Suitable for controlling ascorbic acid interference in complex matrices such as serum and urine | |
Recombinant Ascorbate Oxidase (ASO) | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,245-445 U/mg enzyme powder | Recombinant anti-interference enzyme | Ascorbic acid interference control | Used in recombinant-source ascorbic acid scavenging systems and suitable for creatininase reagent formulation optimization |
The selection of a creatinine content detection method should be centered on sample type and research purpose. The Jaffe method is suitable for low-cost routine screening, the creatininase method is more suitable for high-specificity and automated detection, the creatinine deiminase method can serve as an alternative enzymatic route, the dry chemistry method is suitable for rapid detection, and HPLC and LC-MS/MS are suitable for complex matrices and high-accuracy quantification.
For more related articles, please see below:
[1] Experimental determination of serum creatinine (Cr) by the deproteinization endpoint method