diff --git a/data_import/spectrum-fix.js b/data_import/spectrum-fix.js
new file mode 100644
index 0000000..2cf38b6
--- /dev/null
+++ b/data_import/spectrum-fix.js
@@ -0,0 +1,70 @@
+const axios = require('axios');
+
+
+const host = 'http://localhost:3000';
+// const host = 'https://definma-api.apps.de1.bosch-iot-cloud.com';
+
+let errors = [];
+
+async function fix() {
+  let res = await axios({
+    method: 'get',
+    url: host + '/samples?status[]=new&status[]=validated&status[]=deleted&fields[]=_id&fields[]=number',
+    auth: {
+      username: 'admin',
+      password: 'Abc123!#'
+    }
+  }).catch(err => {
+    if (err.response) {
+      console.error(err.response.data);
+      errors.push(`Could not fetch samples: ${JSON.stringify(err.response.data)}`);
+    }
+  });
+  console.log(res.data);
+  // for all samples
+  for (let sampleIndex in res.data) {
+    console.log(`SAMPLE ${sampleIndex}/${res.data.length}`);
+    const measurements = await axios({  // get all measurements
+      method: 'get',
+      url: host + '/measurement/sample/' + res.data[sampleIndex]._id,
+      auth: {
+        username: 'admin',
+        password: 'Abc123!#'
+      }
+    }).catch(err => {
+      if (err.response) {
+        console.error(err.response.data);
+        errors.push(`Could not fetch measurements: ${JSON.stringify(err.response.data)}`);
+      }
+    });
+
+    if (measurements && measurements.data) {  // found measurements
+      for (let measurementIndex in measurements.data) {
+        console.log(`${measurementIndex}/${measurements.data.length}`);
+        const measurement = measurements.data[measurementIndex];
+        if (measurement.values.hasOwnProperty('dpt')) {  // is spectrum
+          await axios({  // get all measurements
+            method: 'put',
+            url: host + '/measurement/' + measurement._id,
+            auth: {
+              username: 'admin',
+              password: 'Abc123!#'
+            },
+            data: {values: {dpt: measurement.values.dpt
+                  .filter(e => e.length === 2)
+                  .map(e => e.map(el => parseFloat(el)))
+              }}
+          }).catch(err => {
+            if (err.response) {
+              console.error(err.response.data);
+              errors.push(`Could not save measurements: ${JSON.stringify(err.response.data)}`);
+            }
+          });
+        }
+      }
+    }
+  }
+  console.log(errors);
+}
+
+fix();
\ No newline at end of file
diff --git a/package.json b/package.json
index 7854a57..2097e66 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,8 @@
     "start-local": "node dist/index.js",
     "loadDev": "node dist/test/loadDev.js",
     "coverage": "tsc && nyc --reporter=html --reporter=text mocha dist/**/**.spec.js --timeout 5000",
-    "import": "node data_import/import.js"
+    "import": "node data_import/import.js",
+    "spectrum-fix": "node data_import/spectrum-fix.js"
   },
   "keywords": [],
   "author": "",
diff --git a/src/routes/sample.spec.ts b/src/routes/sample.spec.ts
index a4498d0..0aee97c 100644
--- a/src/routes/sample.spec.ts
+++ b/src/routes/sample.spec.ts
@@ -402,6 +402,45 @@ describe('/sample', () => {
         done();
       });
     });
+    it('filters for empty comments', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/samples?status[]=new&status[]=validated&fields[]=number&fields[]=notes.comment&filters[]=%7B%22mode%22%3A%22in%22%2C%22field%22%3A%22notes.comment%22%2C%22values%22%3A%5Bnull%2C%22%22%5D%7D',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        const json = require('../test/db.json');
+        should(res.body).have.lengthOf(
+          json.collections.samples
+            .filter(e => e.status !== 'deleted')
+            .filter(e => e.note_id === null || json.collections.notes.find(el => el._id.toString() == e.note_id.toString()).comment === '')
+            .length
+        );
+        should(res.body).matchEach(sample => {
+          should(sample.notes.comment).be.equalOneOf(null, '');
+        });
+        done();
+      });
+    });
+    it('returns comment fields', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/samples?status[]=new&status[]=validated&fields[]=number&fields[]=notes.comment',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        console.log(res.body);
+        const json = require('../test/db.json');
+        should(res.body).have.lengthOf(json.collections.samples.filter(e => e.status !== 'deleted').length);
+        should(res.body).matchEach(sample => {
+          should(sample).have.only.keys('number', 'notes');
+          should(sample.notes).have.only.keys('comment');
+        });
+        done();
+      });
+    });
     it('rejects returning spectral data for a write user', done => {
       TestHelper.request(server, done, {
         method: 'get',
diff --git a/src/routes/sample.ts b/src/routes/sample.ts
index a8d9357..c55d42c 100644
--- a/src/routes/sample.ts
+++ b/src/routes/sample.ts
@@ -255,6 +255,11 @@ router.get('/samples', async (req, res, next) => {
     );  // measurement filters
   }
 
+  if (sortFilterKeys.find(e => e === 'notes.comment')) {
+    addNotes(queryPtr);
+    addFilterQueries(queryPtr, filters.filters.filter(e => e.field === 'notes.comment'));
+  }
+
   // count total number of items before $skip and $limit, only works when from-id is not specified and spectra are not
   // included
   if (!filters.fields.find(e =>
@@ -279,11 +284,8 @@ router.get('/samples', async (req, res, next) => {
     && e !== filters.sort[0]                           // field was not in sort
   );
 
-  if (fieldsToAdd.find(e => e === 'notes')) {  // add notes
-    queryPtr.push(
-      {$lookup: {from: 'notes', localField: 'note_id', foreignField: '_id', as: 'notes'}},
-      {$addFields: {notes: { $arrayElemAt: ['$notes', 0]}}}
-    );
+  if (fieldsToAdd.find(e => /^notes(\..+|$)/m.test(e))) {  // add notes
+    addNotes(queryPtr);
   }
 
   if (fieldsToAdd.find(e => /material\./.test(e)) && !materialAdded) {  // add material, was not added already
@@ -857,6 +859,17 @@ function addMeasurements(queryPtr, templates) {
   );
 }
 
+function addNotes(queryPtr) {  // add note fields with default, if no notes are found
+  queryPtr.push(
+    {$lookup: {from: 'notes', localField: 'note_id', foreignField: '_id', as: 'notes'}},
+    {$addFields: {notes: {$cond: [
+            {'$arrayElemAt': ['$notes', 0]},
+            {'$arrayElemAt': ['$notes', 0]},
+            {comment: null, sample_references: []}
+          ]}}}
+  );
+}
+
 function dateToOId (date) {  // convert date to ObjectId
   return mongoose.Types.ObjectId(Math.floor(date / 1000).toString(16) + '0000000000000000');
 }
diff --git a/src/routes/user.ts b/src/routes/user.ts
index 976c1a7..8c60eda 100644
--- a/src/routes/user.ts
+++ b/src/routes/user.ts
@@ -65,7 +65,7 @@ router.put('/user:username([/](?!key|new).?*|/?)', async (req, res, next) => {
   await UserModel.findOneAndUpdate({name: username}, user, {new: true}).log(req).lean().exec(  (err, data:any) => {
     if (err) return next(err);
     if (data) {
-      if (data.mail !== oldUserData.email) {  // mail address was changed, send notice to old address
+      if (data.email !== oldUserData.email) {  // mail address was changed, send notice to old address
         Mail.send(oldUserData.email, 'Email change in your DeFinMa database account',
           'Hi, <br><br> Your email address of your DeFinMa account was changed to ' + data.mail +
           '<br><br>If you actually did this, just delete this email.' +
diff --git a/src/routes/validate/sample.ts b/src/routes/validate/sample.ts
index 6e8e497..9c5ad0d 100644
--- a/src/routes/validate/sample.ts
+++ b/src/routes/validate/sample.ts
@@ -28,7 +28,8 @@ export default class SampleValidate {
     notes: Joi.object({
       comment: Joi.string()
         .max(512)
-        .allow(''),
+        .allow('')
+        .allow(null),
 
       sample_references: Joi.array()
         .items(Joi.object({
@@ -78,6 +79,7 @@ export default class SampleValidate {
     'batch',
     'added',
     'status',
+    'notes.comment',
     'material.name',
     'material.supplier',
     'material.group',
@@ -196,6 +198,7 @@ export default class SampleValidate {
             data.filters[i] = decodeURIComponent(data.filters[i]);
           }
           catch (ignore) {}
+          console.log(data.filters[i]);
           data.filters[i] = JSON.parse(data.filters[i]);
           data.filters[i].values = data.filters[i].values.map(e => {  // validate filter values
             if (e === null) {  // null values are always allowed
@@ -223,11 +226,14 @@ export default class SampleValidate {
               });
               field = 'value';
             }
+            else if (field === 'notes.comment') {
+              field = 'comment';
+              validator = this.sample.notes
+            }
             else {
               validator = Joi.object(this.sample);
             }
             const {value, error} = validator.validate({[field]: e});
-            console.log(error);
             if (error) throw error;  // reject invalid values
             return value[field];
           });
@@ -260,7 +266,7 @@ export default class SampleValidate {
           new RegExp('^(' + this.fieldKeys.join('|').replace(/\./g, '\\.').replace(/\*/g, '.+') + ')$', 'm')
         ).messages({'string.pattern.base': 'Invalid filter field name'}),
         values: Joi.array().items(Joi.alternatives().try(
-          Joi.string().max(128), Joi.number(), Joi.boolean(), Joi.date().iso(), Joi.object(), null
+          Joi.string().max(128).allow(''), Joi.number(), Joi.boolean(), Joi.date().iso(), Joi.object(), null
         )).min(1)
       })).default([])
     }).with('to-page', 'page-size').validate(data);