Accounts receivable (Tables)

12 Months Ended

Dec. 31, 2012

Receivables [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]

Accounts receivable

	December 31,
	2012			2011
Trade accounts receivable	$	12,098,566		$	8,079,194
Receivable from affiliate		110,544			144,291
Other accounts receivable		530,399			473,881
		12,739,509			8,697,366
Allowance for doubtful accounts		(223,043	)		(160,134	)
	$	12,516,466		$	8,537,232

Schedule Of Allowance For Doubtful Accounts Activity [Table Text Block]

The activity for the allowance for doubtful accounts consisted of:

	December 31,
	2012		2011
Opening allowance for doubtful accounts	$	160,134	$	160,134
Provision for doubtful accounts		62,909		-
Ending allowance for doubtful accounts	$	223,043	$	160,134