A 46-year-old man is found vomiting beside an open container of an automotive fluid. He has tachypnoea, flank pain and oliguria; arterial blood gas analysis shows pH 7.12 (7.35–7.45) with a high anion gap and an increased osmolal gap. His serum calcium is 1.72 mmol/L (2.10–2.60), and urine microscopy later shows numerous envelope-shaped crystals. Which one of the following is the most likely diagnosis?