57
This produces specifi c, precise concentrations, which help to minimise out-of-specifi cation errors and enable faster processing. Gravimetric dosing can also result in substantial reductions in sample and solvent usage while eliminating bad batches and waste, further reducing costs.
Enhance quality and maximise safety
Another important benefi t of automated sample handling is the reduced exposure risk for the analyst. A leading pharmaceutical QA/QC department implemented gravimetric sample preparation specifi cally for this reason.
The group is responsible for in-process control of highly potent compounds. Their legacy approach, which was manual, involved working in a glovebox in a full body suit for a multi-hour weigh- out. The task was not popular among analysts, and OOS results and re-testing caused operators to spend even more time in protective gear trying to prove detected errors were reproducible.
An automated dosing process built on gravimetric preparation inside the glove box has helped the lab meet their safety requirements and eliminate human error while freeing operators to focus on more challenging and impactful tasks.
Analyte
Standard 1 (mg)
Acesulfame K 7.390 Saccharin Caffeine Vanillin Benzoate 2.695 2.800 6.285
Standard 2 (mg)
9.730 3.480 3.700 8.110
Standard 3 (mg)
9.930 3.890 3.995 8.995
Standard 4 (mg)
Standard 5 (mg)
11.450 13.650 4.305 4.355 9.860 5.085 5.220 11.655 14.050 18.100 19.965 21.910 25.855
Actual concentrations of soft drinks ingredients prepared using the automated liquid dosing system.
The time taken for manual preparation of the fi ve-component standard was 3-4 hours. The preparation of these samples much safer powder dosing heads - including the time to fi ll them - was less than one. Adding automated liquid dosing for the diluent to create a fully automated workfl ow further reduced preparation time to less than 10 minutes.
This example illustrates the time savings that can be made by automation: Multi-component standards prepared in one-quarter or less the time while still obtaining high quality data and reducing error risk.
Reduce sample volumes
In addition to enhancing safety and improving productivity, preparing samples gravimetrically presents the opportunity for a substantial reduction of sample volume and signifi cant materials savings. Gravimetric addition of diluent means the amount of solution prepared is not dictated by the sizes of volumetric fl ask that the operator must handle. Therefore, concentrations need not be prepared at discrete intervals, such as 20, 50 or 100 millilitres.
Instead, just the amount of solution required can be prepared. This factor, combined with the lower minimum weight achievable for automated gravimetric dosing, means that smaller amounts of sample can be used, smaller solution volumes prepared, and less material disposed of or wasted. This results in conservation of often costly materials, as well as a reduction in environmental impact and waste disposal fees.
Quantify Time Savings: Gravimetric Prep
Just how much time can gravimetric sample preparation save? A simple example of the preparation of a multi-component standard demonstrates the advantages of using an automated powder dosing system equipped with a liquid dosing head.
A fi ve-component mixture was prepared in a single vial per concentration level. The fi ve compounds were all weighed into the same vial at different target weights. Linearity tests were performed by UHPLC measurement at fi ve different concentrations. The correlation coeffi cient was greater than 0.999 for all analytes and the intercept was close to zero.
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