In compliance with international pharmacopeias

Impurities in pharmaceuticals mostly stem from synthesis and/or the starting materials used. Generally, their concentration is very low, and therefore analysis at trace levels is required. We offer you the appropriate instruments and a broad range of applications that deal with impurity profiling – pharmacopeia-compliant, of course.

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Heavy metals in pharmaceuticals: New chapters <232> and <233>

Collected works of the United States Pharmocopeia
In the past: heavy metal as a sum parameter

For more than a century now, international pharmacopeias have relied on sulfide precipitation for a semiquantitative determination of the heavy metal content in pharmaceutical products.

Today: individual heavy metal analysis

The United States Pharmacopeia (USP) has been enforcing new regulations concerning the determination of heavy metals in medicines, with new chapters <232> and <233> specifying the limit values and requirements relating to the determination method. Any method may be selected as long as it is validated. Where this application is concerned, the sensitive, cost-effective technique of voltammetry is an ideal choice. USP announced to establish January 1, 2018 as the new date of applicability to drug products. Prior adoption of USP <232> and <233> will be permitted by USP.

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Water content via USP<921>

Monitoring of impurities in pharmaceutical products, such as tablets
Water as an unwanted component

Although not an impurity in the strict sense, water can be regarded as an unwanted substance in pharmaceuticals. The quality, effectiveness, and shelf life of pharmaceutical products depend to a very great extent on their water content, which is why a great deal of importance is attached to water determination in pharmaceutical analysis.

Karl Fischer titration for accurate water determination 

Thanks to its specific and selective reaction with water, Karl Fischer titration (KFT) is one of the most accurate and reproducible water determination methods. This is why numerous pharmacopeias have prescribed it for years as a standard method for fast, automation-ready water determination. Depending on the sample’s characteristics, different types of Karl Fischer titrations are available.

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Azide in pharmaceuticals in line to <621>

Chromatogram of acid in pharmaceutical analysis
Even small concentrations of an impurity can cause significant side effects. The azide used in the synthesis of the antihypertensive irbesartan can be detected in trace amounts as an impurity in the product. The U.S. Pharmacopeia recommends ion chromatographic azide determination after direct injection in accordance with USP<621>. The azide determination is more selective, more sensitive, and, most importantly, faster when using Inline Matrix Elimination, whereby the interfering pharmaceutical matrix is separated from the target analyte already during the sample preparation step.

Metrohm IC has much more to offer! See document "Impurity profiling with ion chromatography". 

Precision and recovery of the azide


Peak area


Mean value



5 µg/L spike




30 µg/L spike




n = 3 measurements


Testimonial: Sanofi-aventis

"Why did I choose Metrohm? I have been working with Metrohm for 25 years. When a new lab was to be built here in Montpellier, we naturally chose Metrohm. These instruments are very robust and hardly ever fail."

Sandrine Caristan and her team provide analytical support at Sanofi-aventis’ R&D center in Montpellier, France. Determination of the water content by Karl Fischer titration is one of their most frequent analyses.