Why an ethyl methyl carbonate purity retest needs a separate moisture sample

Trial design and interpretation

Split the same sampling event between main-component analysis and moisture testing and record when each portion was sealed. For a stored sample, compare sampling times before deciding whether the original package exceeded the moisture limit.

Recording Moisture

Moisture (ppm): Winigen WM-SOL-EMC third-party example ≤15 ppm. Agree the method and limit for the proposed grade and record the time from opening to testing. Principal component purity (%): Winigen WM-SOL-EMC third-party example ≥99.99 wt%. Request the quantification method and chromatographic resolution of impurities for the grade offered.

Will checking only the main chromatographic peak detect a change in water content?

Retest using a separate moisture method. Review blanks, time since opening and transfer conditions against an unopened same-lot sample. Electrolyte co-solvent: Compare EMC moisture, acidity and chromatographic impurity profiles under the same conditions. Record sealing and opening times.

What to record

• Sampling point in time
• Sealing time
• Main chromatographic peak
• Measured moisture

Technical references

• Winigen WM-SOL-EMC: purity, water and alcohol impurities in a battery-grade solvent ↗

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