I'm sorry, but the answer to your question is a NO. Store bought juices, organic or not, are dead because they are pasteurized. Dead juices on a fast can be hazardous to your health.
The idea behind a juice fast is to use raw LIVING juices because they contain vital enzymes and an abundance of nutrients, anutrients, vitamins and minerals that are important to the living body during a detoxifying fast.
Your body is crying out for the very qualities that are killed in store bought juices. There are ways in which you can package juices to take with you to work. AJ takes a thermos for example. This maintains the temps and keeps the air out. Air oxidyzes (kills) enzymes etc (think: an apple browning after peeling).
My suggestion would be to begin your fast on the evening before your day off from work. I would suggest you request your days off back to back... so you have two days off together, then begin your fast the evening before your first day off... It takes the digestive system three to five days to shut down... so, you could be through most of the worst of the beginning of a fast before you have to go back to work. Then bring your juices in a thermos. Experiment, play around, see what works. You should drink lots of water with your fast, in addition to herbal teas... so you can supplement your juices with those.