The highest contrast ratio of the 223E1SB is 25000:1. That's 100% less contrast ratio than the most common dynamic contrast ratio of 20000000:1. Across all medium monitors that have been available for around the same time as the 223E1SB the worst contrast ratio is Mega Contrast and the best is 100000000:1.
There are a number of alternative PC monitors that have a 25000:1 dynamic contrast ratio currently available that you might want to look at including the MultiSync EA234 (£231.95), or the MultiSync EA244WMI (£331.91) both from NEC which has a better Rating.
If the contrast ratio of this Philips PC screen is not high enough for you then you might also want to consider the E2442TC (500000:1), or the 32WL30 (£521.80) (500000:1) both from LG.