A method for testing an analytical unit (202,302, 402, 502, 602), comprising the following steps: a. Providing the analytical unit (202,302, 402, 502, 602), comprising at least one sensor (206, 306, 406, 506, 606), a control unit (207, 307, 407, 507, 607), and a test program; b. Selecting the test program; c. Providing at least one first and one second blind sample (205, 305, 405, 505, 605), which are unknown to the user and each of which comprises a test substance and an identification means (209, 309, 409, 509, 609) with a unique identification of the respective test substance; d. Checking the unit configuration of the analytical unit (202,302, 402, 502, 602); e. Measuring the first blind sample (205, 305, 405, 505, 605) with the analytical unit (202,302, 402, 502, 602) and recording at least one first measurement value; f. Measuring the second blind sample (205, 305, 405, 505, 605) with the analytical unit and recording at least one second measurement value; g. Recording and transmitting the identifications of the first and second measurement values to a test unit (204, 304, 404, 504, 606) and, by means of the test unit (204, 304, 404, 504, 606), i. Identifying the first and second test substances and a first and a second target value of the first and second blind samples by means of the identifications thereof; ii. Determining a test result through comparison of the measurement values and/or at least one test value determined by means of the first and/or second measurement value, to the target values of the first and second blind samples with consideration of a first and a second limit value, which are stored in the test unit; h. Providing an output unit (203, 303, 403, 503, 603); i. Transmitting the test result to the control unit (207, 307, 407, 507, 607) and outputting the test result by means of the output unit (203, 303, 403, 503, 603). a. Providing the analytical unit (202,302, 402, 502, 602), comprising at least one sensor (206, 306, 406, 506, 606), a control unit (207, 307, 407, 507, 607), and a test program; b. Selecting the test program; c. Providing at least one first and one second blind sample (205, 305, 405, 505, 605), which are unknown to the user and each of which comprises a test substance and an identification means (209, 309, 409, 509, 609) with a unique identification of the respective test substance; d. Checking the unit configuration of the analytical unit (202,302, 402, 502, 602); e. Measuring the first blind sample (205, 305, 405, 505, 605) with the analytical unit (202,302, 402, 502, 602) and recording at least one first measurement value; f. Measuring the second blind sample (205, 305, 405, 505, 605) with the analytical unit and recording at least one second measurement value; g. Recording and transmitting the identifications of the first and second measurement values to a test unit (204, 304, 404, 504, 606) and, by means of the test unit (204, 304, 404, 504, 606), i. Identifying the first and second test substances and a first and a second target value of the first and second blind samples by means of the identifications thereof; ii. Determining a test result through comparison of the measurement values and/or at least one test value determined by means of the first and/or second measurement value, to the target values of the first and second blind samples with consideration of a first and a second limit value, which are stored in the test unit; i. Identifying the first and second test substances and a first and a second target value of the first and second blind samples by means of the identifications thereof; ii. Determining a test result through comparison of the measurement values and/or at least one test value determined by means of the first and/or second measurement value, to the target values of the first and second blind samples with consideration of a first and a second limit value, which are stored in the test unit; h. Providing an output unit (203, 303, 403, 503, 603); i. Transmitting the test result to the control unit (207, 307, 407, 507, 607) and outputting the test result by means of the output unit (203, 303, 403, 503, 603).