GC bias in small RNA-seq data

Hello everyone. I am dealing with small RNA seq data to extract information on miRNAs and other small RNAs. I was wondering if there is a tool (python/R based or any other pipeline) or any other way to check out GC bias as well as PCR artifacts in small RNAseq data. I was reading about Alpine tool. But there are no studies of this tool for small RNAseq data (really small: 21nt).