During the first half of 2023, we entered into nine new collaborations and successfully completed twelve collaborations resulting in a total of 38 active collaborations at June 30, 2023, compared to 41 active collaborations at December 31, 2022 and 45 active collaborations as of June 30, 2022. Revenues from our new collaborations amounted to €1,750 thousand, for the first half of 2023.
Revenues from our diagnostics segment were €16,338 thousand for the first half of 2023, an increase of €1,837 thousand, or 12.7%, from €14,501 thousand for the first half of 2022 due to a 22.2% increase in test requests received comparing to the first half year of 2022.
Total revenues from WES and WGS for the first half of 2023 amounted to €9,185 thousand, representing an increase of 17.0% as compared to €7,853 thousand for the first half of 2022. The total number of WES and WGS test requests received in the diagnostics segment for the first half of 2023 was approximately 14,704, representing an increase of 30.5% as compared to approximately 11,226 test requests received for the first half of 2022.
Cost of sales increased by €2,692 thousand, or 20.7%, to €15,728 thousand for the first half of 2023, from €13,036 thousand for the first half of 2022. Cost of sales for the first half of 2023 represented 63.9%, of total revenue, representing an increase of 2.9% percentage points, respectively, as compared to 60.9%, first half of 2022. The overall increase for the first half of 2023 was mainly driven by an increase of €1,819 thousand on consumable expenses for lab materials.
As a result of the above factors, our gross profit for the first half of 2023, increased by €543 thousand, or 6.5%, to €8,896 thousand from €8,353 thousand for the first half of 2022.
Research and development expenses decreased by €2,220 thousand, or 24.5%, to €6,851 thousand for the first half of 2023, from €9,071 thousand for the first half of 2022. The decrease is mainly driven by realization of organizational efficiencies and savings in external expenses for data storage & processsing.
General administrative expenses decreased by €112 thousand, or 0.6%, to €17,172 thousand for the first half of 2023, from €17,284 thousand for the first half of 2022. The decrease is principally due to the reduction in personnel costs due to cost savings driven by the restructuring and organizational efficiencies that was initiated in the last quarter of 2021.
However, excluding the Share Based Payments fully allocated to G&A, the underlying G&A reduction is 18% or €3,418 thousand compared to the first half of 2022.
Selling expenses for the first half of 2023 were €6,699 thousand, representing an increase of €1,507 thousand, or 29.0%, as compared to €5,192 thousand for the first half of 2022. The increase for the first half of 2023 was principally due to the reinforcement of the commercial organization as well as increases in sales commission for external distribution partners.
Impairment expenses for the first half of 2023 increased by €496 thousand, to €496 thousand as compared to nil incurred for the first half of 2022, while a gain on reversal of financial asset impairment was recorded for the first half of 2022 of €937 thousand, mainly driven by MENA region.
Other operating income decreased by €65 thousand, or 4.7%, to €1,325 thousand for the first half of 2023, from €1,390 thousand for the first half of 2022, principally due to a lower grant income released during the period.
Other operating expenses which relate to currency losses decreased by €251 thousand, to €256 thousand in the first half of 2023, compared to €507 thousand for the first half of 2022.
The change in net financial costs by €1,693 thousand, for the first half of 2023 is mainly due to the increased interest expense and unrealized foreign exchange impact of the Oxford Loan Facility, and the change in the valuation of warrants between both periods.