Use of Multiple 3rd Party Laboratories for Testing

Has anyone else been using multiple 3rd party laboratories for carrying out nitrosamine screening, method development and validation, and quantification across a range of different products and dose formats. (No one laboratory could handle the number of samples required within the timeframes due to amount of testing being carried out for other companies).

Due to an internal error one sample was sent to multiple laboratories, who are reporting significantly different results (none detected versus >LOQ), despite developing similar methods (LC-MS). Sensitivities of the different methods are being investigated with both labs to try and identify if this is what is driving the difference. Hi-res MS at one lab has shown the presence of the NDSRI in the sample.

Thanks for adding this discussion topic, It’s indisputable that not every organization has the capabilities to perform all the nitrosamine testing that has been required, so we need to rely heavily on 3rd party labs.
Vendor and lab qualification is essential due diligence when deciding where to send samples for analysis. I have seen some testing labs relying or demonstrating proficiency by using specific proficiency testing programs out there that rely on independent parties to provide such validation.
It is known that the analytical challenges for nitrosamine testing do not reside only in the operation of the HRMS but in the sample preparation strategy and the quality of the reagents (solvents, reference standards, consumables, etc.). All these considerations need to be weighed in the vendor qualification.
I’m interested to learn what others are doing to qualify or assure the quality of the results generated by their labs.