Albuterol Testing

Albuterol (or albuterol sulfate) is used for the treatment of asthma. It's generally taken as either tablets or from an inhaler. WCAS provides testing for albuterol according to USP monographs as well as in inhalers.

There are at least two methods for determining the dose of Albuterol from an inhaler, an HPLC method based upon the USP monograph for the API or LC-MS. USP sets standards for albuterol tablets but not inhalers. The method for assaying tablets is based on reverse phase HPLC with an ion pair reagent with detection using UV absorbance at 276 nm. For legal cases, we prefer the following method using LC-MS because it provides definitive identification of the albuterol active ingredient as well as the dose assay.

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Albuterol by LC-MS
(update 12-2006)

We have developed a method for confirmation of Albuterol in Inhalation Solutions. This method uses LC-MS with electrospray ionization. With a relatively high capillary voltage, some fragmentation is induced to give a representative spectrum. The chromatographic conditions use a mixed mode LC column. This gives good peak shape for the albuterol and

resolves it well from the ipratropium bromide also present in the inhaler. Identity is then confirmed by both retention time and mass spectral match. Quantitation is performed using external standards to confirm the dosage level, although not to the degree of precision required by USP testing for the API.

A representative LC-MS chromatogram and mass spectrum are shown below.

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Albuterol by GCMS

First, the samples are prepared by removing the canisters from the mouthpiece and dispensing five actuations from each sample into water containing salicyl alcohol as an internal standard. An aliquot of the water is then evaporated to dryness and the TMS derivatizing agent is added to the residue. The solutions are then analyzed by GCMS. Quantitation is performed using the internal standard method against a five-point initial calibration. Additionally, one sample is prepared in duplicate. Results are given as free albuterol and albuterol sulfate per actuation from the valve.

Example Report:

	Micrograms/Actuation
Sample	as Albuterol	as Albuterol Sulfate
Control	100	120
Sample	115	138
Sample Duplicate	103	124
Detection Limit	4	5

Sample	actuations taken	Weight before (g)	Weight after (g)	grams lost per actuation
Control	5	28.2366	27.8609	0.0751
Sample	10	28.4295	27.5794	0.0850

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Albuterol by LC-MS (update 12-2006)

Albuterol by GCMS

Albuterol by LC-MS
(update 12-2006)