PDFNet does offer option to validate PDF documents for PDF/A compliance (ISO 19005-1, 2) as well as to fix/convert generic PDF to conformant PDF/A files (for example, please see PDF/A sample project - http://www.pdftron.com/pdfnet/samplecode.html#PDFA). You can also use the existing API to implement quick and dirty validation (e.g. you could inspect the header and some key document features).