I got one once, Topfin brand, too. Well, two technically. It was completely rotten and fell apart as soon as I took it out of the package. All gooey and disintegrating where the stems meet the roots. If I remember correctly it was some type of sword plant. Maybe I would have noticed the damage if the giant sticker label hadn't covered it up. I returned it to the store (which took it back even though the packaging was totally dismantled and I had to put everything in a ziplock to hold the mess) and got another one, that I peeked under the label to see if it was OK. It looked fine and healthy, the leaves were all green and the stems looked good and everything. But then I took that one out and it was totally rotten too! Not a leaf stayed on it. I didn't even have a chance to get it in my tank, it fell apart in the bathroom sink. I don't remember if I exchanged that one too or not, but I finally threw the whole thing away because I was sick of having to go back and return the stupid plants. I'd rather buy my plants "submersed" at the store than in the tubes because you can see that they can hold up on their own, rather than being disguised in some tube with mystery gel. That said, all the plants in my current tank were mailed lol. For all I know those tube plants sat in the store on the shelf for weeks.
I think maybe if you can get them soon after the shipment arrives so the plants are "fresh" at the store you might have better luck than I have had. But petsmart (which is the only place that sells topfin as far as I know) has a really good return policy so if the plants are rotten, you can just return them. So it's worth a try imo.
I don't think the plants have preservatives. And you have to make sure its actually an aquatic plant instead of a houseplant, but that easy to check online.