Creatine Impurities Explained: Creatinine, DCD, and DHT

Creatinine: A Creatine Conversion Product

Origin and Formation

Creatinine is a well-known conversion product of creatine. In aqueous solutions, creatine undergoes an intramolecular cyclization reaction that converts it to creatinine. This process is accelerated by elevated temperature, low pH environments (such as acidic beverages), and prolonged exposure to moisture in solution. In dry crystalline form, creatine monohydrate is highly stable when stored under appropriate conditions. Solid-state degradation is minimal unless the material becomes deliquescent or is exposed to adverse conditions over extended periods. Creatinine also forms continuously in the body through the spontaneous conversion of creatine and phosphocreatine; the amount varies with muscle mass and physiological status.

Significance in Quality Assessment

Elevated creatinine levels in creatine monohydrate may indicate inadequate control of synthesis, purification, or drying parameters, or conversion during aqueous processing or liquid finished-product storage. EFSA’s 2004 opinion reviewed a specific creatine monohydrate preparation with a creatinine specification of ≤100 mg/kg. This value is often cited in industry specifications as a reference point, but it is not a universal regulatory limit for all creatine monohydrate. At 100 ppm, creatinine represents 0.01% of the material by weight. In a 5 g serving, this corresponds to approximately 0.5 mg of creatinine, which has At this concentration, creatinine would account for only 0.01% of the material, so the corresponding reduction in creatine content would be quantitatively small. Creatinine is best viewed as a quality and process control marker rather than a major driver of efficacy loss.

Dicyandiamide (DCD): A Cyanamide-Route Byproduct

Formation Mechanism

Dicyandiamide (DCD) is a byproduct of certain creatine synthesis routes. In a common industrial process, cyanamide reacts with sodium sarcosinate to form creatine. Cyanamide can self-dimerize to form DCD. Reaction conditions influence its formation, whereas separation, washing and recrystallization influence how much remains in the finished material.

Exposure Context and Specifications

EFSA’s 2004 opinion reviewed a specific creatine monohydrate preparation with a DCD specification of ≤50 mg/kg. In the GRN 931 dossier submitted to FDA, the notifier proposed a similar limit of ≤50 mg/kg for their product. Using EFSA’s exposure calculation approach, a daily intake of 3 g of creatine containing DCD at 50 mg/kg would result in an exposure of approximately 150 µg DCD per day. EFSA considered this exposure to be a small fraction of the tolerable daily intake referenced in their assessment. DCD levels in creatine should be interpreted in the context of the specific manufacturing route and the supplier’s process controls. DCD is particularly relevant to cyanamide-based synthesis routes; its relevance should be evaluated against the supplier’s actual process.and a reported non-detect for DCD does not automatically indicate superior overall quality.

Dihydrotriazine (DHT): A Route-Specific Impurity

Formation and Structural Context

Dihydrotriazine (DHT), specifically a dihydro-1,3,5-triazine derivative, is a synthesis-related impurity whose formation depends on the specific manufacturing route. In the GRN 931 dossier, the notifier stated that DHT formation in its evaluated process required a trace organic impurity in the sodium-sarcosinate solution. This was a process-specific explanation and should not be generalized to every creatine manufacturing route.

Toxicological Screening and Reported Limits

In the GRN 931 dossier, the notifier classified the specified DHT structure as Cramer Class III using a TTC screening approach. This was a dossier-specific computational assessment, not a universal EFSA classification for all creatine materials. The GRN 931 specification for DHT was set at ≤3 mg/kg, which corresponded to the limit of detection of the analytical method used. EFSA’s 2004 opinion referenced a different LOD (approximately 4.5 mg/kg) for the material they evaluated. These values reflect the specifications and analytical capabilities of specific submissions, not harmonized regulatory limits applicable to all creatine monohydrate products.

How to Interpret Specifications and CoAs

Reference Points, Not Universal Limits

Specifications such as creatinine ≤100 mg/kg, DCD ≤50 mg/kg, and DHT ≤3 mg/kg or not detected are commonly cited in industry discussions. However, these originate from specific regulatory opinions and GRAS notifications for particular products, not from a single overarching regulation governing all creatine monohydrate. When evaluating specifications, buyers should consider whether the values align with EFSA 2004 and GRN 931 reference points, whether the supplier’s manufacturing route is consistent with the impurity profile, and whether analytical methods, LOD, and LOQ are clearly disclosed.

What to Check on a Certificate of Analysis

Interpreting Results and Red Flags

Meaningful evaluation requires numerical values for impurities when quantifiable, clear statement of “< LOD” or “< LOQ” with corresponding limits when below quantification, consistency across batches and over time, and transparent disclosure of analytical methods and detection limits. Potential concerns include impurity values exceeding the supplier’s own specifications without explanation, missing impurity data or vague statements such as “meets specification” without numerical values, inconsistent or missing analytical method references, and unexplained batch-to-batch variability in impurity profiles.

The Practical Conclusion

Creatinine, DCD, and DHT are three commonly discussed impurities in creatine monohydrate, each reflecting different aspects of synthesis and handling quality. Creatinine is a creatine conversion product used as a quality marker; DCD is associated with cyanamide-based routes; and DHT is route- and precursor-specific. Published specifications from EFSA 2004 and GRN 931 provide useful reference points, but they are not universal regulatory limits for all creatine monohydrate. For brands and OEMs, evaluating these impurities on certificates of analysis, understanding their origins, and interpreting them in the context of specific manufacturing routes is essential for sourcing decisions and risk management.

Recommended Reading

• Creatine Monohydrate Specification Sheet: What Buyers Should Check Before Ordering
• What Actually Defines a Premium Creatine Ingredient?
• How Is Creatine Monohydrate Made? From Raw Materials to Finished Powder

References

1. EFSA. Opinion related to creatine monohydrate for use in foods for particular nutritional uses. EFSA Journal. 2004;36:1–6.
2. AlzChem Trostberg GmbH. GRAS Notice No. 931: Creatine Monohydrate. Submitted to the U.S. FDA; 2020.
3. FDA. Agency Response Letter for GRAS Notice No. 931. Revised letter signed December 3, 2020.
4. Moret S, Prevarin A, Tubaro F. Levels of creatine, organic contaminants and heavy metals in creatine dietary supplements. Food Chemistry. 2011;126(3):1232–1238.
5. Uzzan M, Nechrebeki J, Zhou P, Labuza TP. Effect of water activity and temperature on the stability of creatine during storage. Drug Development and Industrial Pharmacy. 2009;35(8):1003–1008.
6. Park SW, Yoo MS, Lee W. Simultaneous determination of creatine, dicyandiamide and dihydrotriazine in dietary supplements by high-performance liquid chromatography. KSBB Journal. 2014;29(4):232–238.