Luminescence dating measurements can be made on multi-grain aliquots of sand adhered to stainless steel or aluminum discs, or on individual sand grains mounted on single-grain discs with holes of up to 300 µm in diameter. There are two main advantages of single-grain analysis:
1) grains with undesirable luminescence properties can be identified and disregarded from analysis, and
Grains that should be disregarded from analysis include those with optical properties not suitable for dating, or contaminating grains of a different mineral (feldspar grains in a quartz aliquot, for example). When dating K-feldspar at the single-grain scale, grains that suffer from anomalous fading can also be excluded, so that corrections for this effect do not have to made later.
Single-grain analysis also allows geochronologists to assess how well a sample has been bleached by the sun prior to burial. In many depositional environments, grain signals may only be partially depleted, or not at all due to turbid subaqueous conditions, or rapid deposition by gravity or water. This can lead to a highly spread or skewed De distribution, where the true age of the deposit must be calculated from the youngest grains only.
In some instances, single grain analysis can also reveal evidence of mixing between two or more deposits of different age. In these cases, statistical models may be applied to help distinguish one component from another.
Of course, single-grain dating does have its disadvantages – first, measurements are much more time consuming, and second, measurement errors from individual grains tend to be higher than those from aliquots. If the sample of interest is derived from a depositional environment where partial bleaching is unlikely (sand dunes, for instance), it may be more time and cost efficient to measure multi-grain aliquots.