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A simple, sensitive, and rapid spectrophotometric method for the assay of glyphosate (= N-(phosphonomethyl)glycine) in various formulations (Roundup, Excel Mera 71) and environmental water samples is described. The method is based on the reaction of glyphosate with ninhydrin in presence of sodium molybdate in neutral aqueous medium at 1008 to give a Ruhemanns purple product having the VIS absorption maximum at 570 nm (Scheme, Fig. 1). The product is stable for 10 h. Beers law is obeyed in the concentration range of 0.1 -3.5 mg ml À1 . The molar absorptivity and Sandells sensitivity are 3.2816 · 10 4 l mol À1 cm À1 and 5.2 ng cm À2 , respectively ( Table 1). The method is highly reproducible, as confirmed by the relative-standard-deviation (r.s.d.) values (1.70%; Table 2). Recovery studies establish that this method is accurate ( Table 5) and can be successfully employed for the determination of glyphosate.

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Sildenafil citrate is well known as Viagra for the treatment of erectile dysfuncion. In the title compound (systematic name: 1‐{[3‐(6,7‐Di­hydro‐1‐methyl‐7‐oxo‐3‐propyl‐1H‐pyrazolo­[4,3‐d]­pyrimidin‐5‐yl)‐4‐ethoxy­phenyl]­sulfonyl}‐4‐methyl­piper­az­in­ium citrate monohydrate), C22H31N6O4S+·C6H7O7−·H2O, the pyrazolopyrimidone ring system and the benzene ring are almost coplanar, enabling an intramolecular hydrogen bond between the pyrazolopyrimidone NH group and the O atom of the ethoxy group. One of the N atoms of the piperazine ring is protonated and the citrate mol­ecule exists as an anion. The crystal packing is stabilized by several hydrogen bonds.