en.wikipedia.org/wiki/Poisoning_of_Alexander_Litvinenko

The date of Litvinenko's public accusation against Putin over Anna Politkovskaya's murder is documented as 19 October 2006. The UK public inquiry's chronology lists: "19 October 2006" — "Litvinenko accuses President Putin of the Politkovskaya murder." Frontline Club's own retrospective on the event also says: "It was 19 October" when Litvinenko spoke at the club's Politkovskaya tribute.

Litvinenko died on 23 November 2006. That is 35 days later (about five weeks), not "just two weeks" before his death.

The official UK public inquiry does not place Litvinenko's fatal cardiac arrest "late on 22 November." Instead, it states that 21–22 November were the last days he was conscious, that he had lost consciousness by Thursday 23 November, and that he suffered a fatal cardiac arrest at 8.51 p.m. on 23 November. The report also states he was pronounced dead at 9.21 p.m. on 23 November 2006.

So the article's sequence is wrong: his heart did not fail on 22 November with death the next day; both the cardiac arrest and death occurred on 23 November 2006.

Testing humans for polonium-210 in the body long predates the Litvinenko case.

A 1966 Nature paper, "Measurement of Polonium-210 in Human Blood," states that body burdens of this isotope were usually determined by measuring its activity in tissue samples or urine and then reports a method for detecting Po-210 in 10 mL human blood samples. That alone contradicts the claim that Litvinenko's case was probably the first time anyone had been tested for Po-210 in their body.

A later peer-reviewed study, "210Po Log-normal distribution in human urines: Survey from Central Italy people" (2009), measured background Po-210 levels in the urine of non-contaminated people and notes that such urine measurements were also used by the UK's Health Protection Agency after the 2006 poisoning. So Po-210 bioassay in humans was an established scientific practice, not a first-time event.